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https://e2e.ti.com/support/data-converters/f/73/t/882363 | [
"If you have a related question, please click the \"Ask a related question\" button in the top right corner. The newly created question will be automatically linked to this question.\n\n• TI Thinks Resolved\n\n# ADS4129: How to calculate the filter's capacitance of the ADS4129's input\n\nHello!\n\nHow to calculate the filter's capacitance of the ADS4129's input!",
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"Thanks\n\n• User,\n\nYou should be able to figure this out using Figures 114 and 115 in the data sheet. These show the resistance value of Rin and the capacitance value of Cin over frequency.\n\nRegards,\n\nJim\n\n• In reply to jim s:\n\nHello!\n\nIn the input frequency is 250 MHZ, the input capacitance is about 3.6 PF, the input resistance is about 500 Ω,Can you tell me the relationship between the capacitance of r-c-r and the maximum input frequency?\n\nThanks\n\nUser,\n\nThe r-c-r is a 250MHz low pass filter. If your IF is going to be above this frequency, remove these parts from the EVM.\n\nRegards,\n\nJim\n\n• In reply to jim s:\n\nHello,\n\nI want to set the frequency 50MHz ,How should I calculate?\n\nThanks!"
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"https://e2e.ti.com/resized-image/__size/2460x0/__key/communityserver-discussions-components-files/73/ADS4129.png",
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https://deepai.org/publication/modeling-symmetric-positive-definite-matrices-with-an-application-to-functional-brain-connectivity | [
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"Modeling Symmetric Positive Definite Matrices with An Application to Functional Brain Connectivity\n\nIn neuroscience, functional brain connectivity describes the connectivity between brain regions that share functional properties. Neuroscientists often characterize it by a time series of covariance matrices between functional measurements of distributed neuron areas. An effective statistical model for functional connectivity and its changes over time is critical for better understanding the mechanisms of brain and various neurological diseases. To this end, we propose a matrix-log mean model with an additive heterogeneous noise for modeling random symmetric positive definite matrices that lie in a Riemannian manifold. The heterogeneity of error terms is introduced specifically to capture the curved nature of the manifold. We then propose to use the local scan statistics to detect change patterns in the functional connectivity. Theoretically, we show that our procedure can recover all change points consistently. Simulation studies and an application to the Human Connectome Project lend further support to the proposed methodology.\n\nAuthors\n\n04/26/2019\n\nDiscovering Common Change-Point Patterns in Functional Connectivity Across Subjects\n\nThis paper studies change-points in human brain functional connectivity ...\n04/10/2019\n\nAnalyzing Dynamical Brain Functional Connectivity As Trajectories on Space of Covariance Matrices\n\nHuman brain functional connectivity (FC) is often measured as the simila...\n09/13/2020\n\nFunctional random effects modeling of brain shape and connectivity\n\nWe present a statistical framework that jointly models brain shape and f...\n01/26/2017\n\nRiemannian-geometry-based modeling and clustering of network-wide non-stationary time series: The brain-network case\n\nThis paper advocates Riemannian multi-manifold modeling in the context o...\n11/02/2018\n\nBayesian Hierarchical Modeling on Covariance Valued Data\n\nAnalysis of structural and functional connectivity (FC) of human brains ...\n01/28/2020\n\nWISDoM: a framework for the Analysis of Wishart distributed matrices\n\nWISDoM (Wishart Distributed Matrices) is a new framework for the charact...\n08/08/2020\n\nk-means on a log-Cholesky Manifold, with Unsupervised Classification of Radar Products\n\nWe state theoretical properties for k-means clustering of Symmetric Posi...\nThis week in AI\n\nGet the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday.\n\n1 Introduction\n\nUnderstanding the functional brain connectivity is critical for understanding the fundamental mechanisms of brain, how it works, and various neurological diseases. It has attracted great interest recently. For instance, the Human Connectome Project investigates the structural and functional connectivity in order to diagnose cognitive abilities of individual subjects. Functional connectivity can be defined as temporary statistical dependence between spatially remote neurophysiological events (Friston, 2011), and has been observed to be dynamic in nature, even in the resting state (Hutchison et al., 2013). In practice, neuroscientist often characterize the dynamic functional connectivity by a series of symmetric positive definite (SPD) covariance matrices between functional measurements of neuronal activities across different regions in human brain. Establishing appropriate dynamic models is critical for understanding fundamental mechanisms of brain networks and has attracted much attention in neuroscience recently (Xu and Lindquist, 2015; Hutchison et al., 2013).\n\nHowever, little has been done in the statistics community for investigating dynamic changes of functional connectivity over time. The non-Euclidean structure of covariances has introduced significant challenges to the development of proper statistical models and their analysis. Indeed, all SPD matrices form a nonlinear Riemannian manifold, which is referred to as the SPD manifold. Motivated by the SPD manifold structure under the Log-Euclidean metric (Arsigny et al., 2007), we use the matrix logarithm to embed the SPD matrices into a Hilbert space – an Euclidean space up to a symmetric structure, to be concrete. We then model the transformed random SPD matrix using a mean model with an additive heterogeneous noise. The heterogeneous error depends on the tangent space of the mean SPD matrix and thus takes the curved structure of the SPD manifold into account. Our work refines the previous work by Chiu et al. (1996), whose model does not respect the original manifold structure.\n\nBuilt on this statistical model, we then propose to use a form of local scan statistics to detect multiple change patterns that are present in the functional brain connectivity over time. To the best of our knowledge, ours is the first work on the study of change point detection for SPD manifold-valued data. Although the proposed method is primarily motivated by discovering change patterns in fMRI, it has the potential to be applied to many other applications, such as diffusion tensor imaging\n\n(Dryden et al., 2009) and longitudinal data analysis (Daniels and Pourahmadi, 2002).\n\n1.1 Related Literature\n\nChange point detection with at most a single change point has been widely studied in the literature. When the distributions of the data are assumed to be known, score- or likelihood-based procedures can be applied (James et al., 1987). Bayesian and nonparametric approaches have also been proposed, see Carlstein et al. (1994) for a review. More recently, Chen and Zhang (2015)\n\nproposed a graph based approach for nonparametric change point detection. When there are multiple change points, the problem becomes much more complicated. Some popular approaches include the exhaustive search with Schwarz criterion\n\n(Yao, 1988), the circularly binary segmentation (Olshen et al., 2004) and the fused lasso method (Tibshirani and Wang, 2007). In genomics, these techniques have been exploited to study DNA copy number variations, see Olshen et al. (2004); Zhang and Siegmund (2007); Tibshirani and Wang (2007) among others. However, none of the above methods deals with Riemannian data.\n\nThere have been a few works on Riemannian data analysis in the statistics literature. For example, Schwartzman (2006)\n\nproposed several test statistics for comparing the means of two populations of symmetric positive definite matrices.\n\nZhu et al. (2009) developed a semiparametric regression model for symmetric definite positive matrices with Euclidean covariates. Later, Yuan et al. (2012) studied the local polynomial regression in the same setting. Steinke and Hein (2009) consider nonparametric regression between general Riemannian manifolds. Petersen and Müller (2017) developed a novel Fréchet regression approach for complex random objects with euclidean covariates. We believe our work will be a valuable addition to the literature.\n\n2 Geometric Interpretation\n\nWe briefly introduce , the Riemannian manifold consisting of all symmetric positive definite matrices, while we refer readers to the appendix for more details. A Riemannian manifold is a smooth manifold endowed with an inner product on the tangent space at each point , such that varies with smoothly. We consider the Log-Euclidean metric for the symmetric positive definite matrix manifold due to its computational tractability (Arsigny et al., 2007). Other metrics include the naive Frobenius metric which does not account for the curved nature of symmetric positive definite matrices and the affine invariant metric which is more difficult to compute (Terras, 2012).\n\nFor a manifold , we use to denote the tangent space at the base point . It can be shown that the tangent space at the identify matrix is the space of symmetric matrices, denoted by . For the Log-Euclidean metric, the inner product between on\n\nat the identity matrix\n\nis defined as . To define the inner product at a general point, we utilize the concept of differential maps. For a smooth transformation between two manifolds, its differential at , denoted by\n\n, is a linear map sending a tangent vector\n\nto a tangent vector . See Figure 1 for a graphical illustration. When both and are Euclidean submanifolds, the differential is the usual notion of differential of the function at , given by a Jacobian matrix. With this formalism, we consider the smooth map , where is the matrix logarithm, the inverse map of the matrix exponential. The matrix exponential of a matrix is defined as . The Riemannian metric at a general point is then defined as , where is a linear operator (Arsigny et al., 2007). The Riemannian exponential map under this metric is given by , where is the matrix exponential. Riemannian exponential maps are closely related to the intrinsic properties of a manifold, such as the geodesics and the Gauss curvature (Lee, 1997).",
null,
"Figure 1: Illustration of smooth map between manifolds and its differential.\n\n3 Methodology\n\n3.1 A Heterogeneous Matrix-log Mean Model\n\nSuppose we have collected a sequence of matrix-valued observations . We propose the following matrix-log mean model for investigating the mean changes of the data sequence\n\n logYi=logμi+log′μiεi, (1)\n\nwhere is the mean matrix, and is a mean-zero error term in . Here is a linear operator acting on . The noise term has mean zero, but the corresponding covariance depends on . Hence model (1) has a heterogeneous noise component.\n\nInterestingly, the heterogeneity of the noise terms makes use of the Riemannian manifold structure introduced in Section 2. Without using the geometric structure, one could simply apply the matrix logarithm first and then model the random SPD matrices ’s as\n\n logYi=logμi+ξi,\n\nwhere ’s are identically distributed random elements. This naive model, first introduced by Chiu et al. (1996)\n\n, misses the curved structure in the SPD manifold, and thus is less efficient for estimation and inference. Different from theirs, we introduce the location-dependent transformations\n\nin model (1) to respect the original manifold structure, because it turns this model into a geodesic/intrinsic mean model. To appreciate this, we take matrix exponential on both sides and find that\n\n Yi=exp(logμi+log′μiεi)=Expμiεi.\n\nIt can shown that is the minimizer to the following optimization program\n\n μi=\\argminS∈Sym+⋆(m)\\EEg2(S,Yi),\n\nwhere is the geodesic distance between and in Therefore, model (1) serves as an exact counterpart of the Euclidean mean model , where minimizes over .\n\nWe emphasize that the idea of using a matrix logarithm to model SPD matrices was first explored by Leonard and Hsu (1992) and Chiu et al. (1996)\n\n. However, their approach does not take the manifold structure into account. From the modeling perspective, our key contribution is that we establish a parametric model for SPD matrices that respects the original manifold structure.\n\nModel (1) provides a natural way to investigate change-point detection problems for SPD manifold-valued data. For this purpose, we further assume that there exist and such that if and otherwise. Elements in are called change points. Our goal is to detect based on the data sequence .\n\n3.2 Computational Details\n\nComputationally, it is more convenient to work with a basis of the space which is a dimensional Hilbert space under the Frobenius inner product. The Frobenius inner product between and is defined as . Let be an orthonormal basis of under this inner product. Then, for any , we can write with , and identify it with its coefficient vector , denoted by .\n\nIn this paper, we adopt the basis constructed in the following. Let be the matrix of zeros except the and entries, which are set to if , and otherwise. Since , we consider basis matrices ’s with . It can be checked that and if or , where denotes the Frobenius norm. Let , and then form an orthonormal basis for . We use this basis in our computation. Note that the results presented in the paper are identical for all bases.\n\nTo compute the matrix logarithm for\n\n, we first find a unitary matrix\n\nsuch that for a diagonal matrix . The matrices and\n\ncan be computed by eigendecomposition or singular value decomposition (SVD). Then\n\nwith .\n\nTo compute the matrix representation of the linear differential operator for a given symmetric positive definite matrix with respect to the basis , we first note that (Arsigny et al., 2007). Therefore, once we have the matrix representation of the linear operator with respect to the basis , then will be the matrix representation of , noting that the non-singularity of everywhere implies the invertibility of . If is the coefficient vector (viewed as a column vector) of with respect to a chosen basis, then it is seen that the is given by the matrix concatenated by column vectors . Therefore, the problem boils down to the computation of\n\n exp′logμϕj=∞∑k=11k!k−1∑ℓ=0(logμ)k−ℓ−1⋅ϕj⋅(logμ)ℓ.\n\nNumerically, the above series is truncated at a sufficiently large . Note that when , we have specially .\n\n3.3 A Local Scan Procedure\n\nRoughly speaking, an ideal statistic for detecting change patterns, or change points, at a position should directly relate to the possibility that is a change point. The statistic at the position we proposed is a locally weighted average of the transformed ’s near :\n\n G(x,h)=n∑i=1wi(h)−−−→logYi,\n\nwhere if , if , and otherwise. We remind the readers that denotes the coefficient vector of the matrix with respect to a basis . The defined above is constructed based on data points within a local window of size around the point . The intuition is that, if there is no change point within the window , then has mean zero and is close to zero. Otherwise, if is large, then is likely to be a change point. In particular, points that locally maximize have a high chance of being a change point. We say that is a local maximizer if for all . The set of local maximizers is denoted by . Suppose , where is the number of elements in . For a given threshold , we then estimate by , and is estimated by the cardinality of .\n\nHowever, the above procedure for estimating depends on the unknown parameter . In practice, we propose a data-driven alternative based on the -fold cross validation to select the number of change points. Suppose that are change points, which divided all time points into segments. Within each segment, time points are randomly split into partitions. The sample mean of a segment is estimated by using data from any partitions within that segment, and the validation error is evaluated on the rest one partition. The cross validation error of the segment is defined to be the sum of validation errors from the partitions, while the total cross-validation error is the sum of cross-validation errors across all segments. Formally, the total cross-validation error is defined as\n\n CV(k)=k+1∑q=1K∑p=1∑i∈Pq,p(ˆlogμq,p−−−−→logYi)T(ˆlogμq,p−−−−→logYi),\n\nwhere is the th partition of the th segment, and . Here denotes the time points in the th segment but not in the partition and the cardinality of the set . The integer that minimizes is chosen as an estimate of . We then estimate the locations of change points using the proposed scan statistics.\n\n4 Asymptotic Theory\n\nA random vector is called a subgaussian vector with parameter if , and for all ,\n\n E[exp(aT(ξ−ν))]≤exp(∥a∥2σ2/2).\n\nWe say that a random element in is subgaussian if its coefficient vector with respect to the orthonormal basis is subgaussian. One can easily check that this definition is independent of the choice of the orthonormal basis of . Below we shall assume is subgaussian with parameter . This might depend on and thus the linear operator and its matrix representation . For example, one might conceive of i.i.d. subgaussian random elements and applying to , where different transformations result in different distributions of\n\n. Although subgaussianity is well preserved by linear transformations, the subgaussian parameter might differ after transformation. For example, one can show that, if\n\nis subgaussian with a parameter , then is subgaussian, but with a parameter . In this case, might quantify the magnitude, measured by , of the transformation .\n\nTo derive the sure coverage property of the proposed procedure, we define , , and , where we conventionally denote and . We need the following assumption. The quantities , , and satisfy that . Here, characterizes the variability of ’s over all time points. The quantity characterizes the strength of the weakest signal of change points, while indicates the separability of change points. Intuitively, when and are small, no method would succeed in recovering all change points. Recall that denotes the dimension of the space . It is seen that detection of change points becomes harder for higher dimensional matrices, i.e., a larger , since stronger signal (larger ) or better separation of change points (larger ) is required to make the inequality in the above assumption hold.\n\nNow we establish the sure coverage property of the proposed procedure, that is, the union of the intervals selected by our procedure recovers all change points with probability going to\n\n. An nonasymptotic probability bound is also derived, with explicit dependence on the sample size . We use to denote that for all . We are ready to state the main theorem of this paper, whose proof is deferred to the appendix. Suppose that Assumption 4 holds. If and , then\n\n Pr(^J =J,J⊂ˆJ±h)→1, as n→∞.\n\nWe emphasize here that the dimension does not need to be assumed to be fixed and could potentially diverge to infinity as long as Assumption 4 holds.\n\n5 Simulation Studies\n\nIn this section, we examine the empirical performance of our method. We generate data according to model (1). In the first example, we consider different combinations of such that , , , respectively. When , we set , and . When , we set for , where , , , , , and . For the symmetric random noise, we first sample the coefficient vector from distribution , then combine it with the basis to generate the noise . Our second example is concerned with a larger by setting that , , , .\n\nChoosing the optimal bandwidth is usually a difficult task for change point problems, see, for example, Niu and Zhang (2012) for a detailed discussion. Intuitively, when there is only one change point in the interval , the larger is, the more powerful the scan statistic is. But when the bandwidth gets too large, the interval might contain multiple change points. Therefore we need to choose bandwidth carefully. In our simulations, we found that the performance of the procedure is relatively robust to the choice of the bandwidth as long as the bandwidth is not too large, and works relatively well in our case. We use the proposed cross validation technique to select the number of change points. We run 100 repetitions of Monte Carlo studies. For each run, we calculate the estimated number of change points and the locations of the change points. We report the frequencies of the three cases: , and , the mean of the number of change points detected, and the sure coverage probability for each of the change point. We also compare two methods that are frequently used in practice. The first one vectorizes the response without considering any manifold structure, which results in a -dimensional vector. We denote this method as “Vector”. The other one also adopts the vectorization idea, but additionally takes the symmetric information into account, yielding a -dimensional vector. We use “Symmetric” to denote this method. The results are summarized in Tables 1 and 2.\n\nAs indicated by the results, our proposed method performs better than the comparison methods in terms of the percentage of correctively recovering the number of change points, in all cases. Additionally, when , all the methods presented here can detect the second change point very well. But for the first one, our method achieves a higher sure coverage probability. When , our method achieves a higher sure coverage probability for all the change points. These results suggest the importance of considering the geometric structure of the Riemannian data, at least, in change point detection problems.\n\n6 An Application to the Human Connectome Project\n\nWe apply the proposed methodology to the social cognition task related fMRI data from Human Connectome Project Dataset, which includes behavioral and 3T MR imaging data from 970 healthy adult participants collected from 2012 to spring 2015. We focus on the 850 subjects out of the 970 which have the social cognition task related fMRI data. Participants were presented with short video clips (20 seconds) of objects (squares, circles, triangles) that either interacted in some way, or moved randomly on the screen (Castelli et al., 2000; Wheatley et al., 2007). There were 5 video blocks (2 Mental and 3 Random in one run, 3 Mental and 2 Random in the other run) in the task run.\n\nWe use the “Desikan-Killiany” atlas (Desikan et al., 2006) to divide the brain into 68 regions of interest. Figure 2(a) shows the “Desikan-Killiany” parcellation of the cortical surface in the left and right hemisphere. We pick eight possible regions that are related to the social task, that are the left and right part of superior temporal, inferior parietal, temporal pole and precuneus (Green et al., 2015). These eight regions of interest are highlighted in yellow in Figure 2(b). For each subject, the fMRI data are recorded on 274 evenly spaced time points, one per 0.72 seconds. We use a moving local window of size 100 to calculate the cross covariance between these eight regions, which results in 175 cross covariance matrices with dimensions . We then apply the proposed method to detect change points in this sequence of cross covariance matrices with bandwidth set to be .\n\nWe apply the method to all the subjects, and report the locations of change points detected for each subject. In Table 3, we have summarized the count and percentage of the number of change points detected for all the subjects. The mean number of change points detected among all the subjects is . This result matches the physiology well since there are 5 video blocks in the task design, with changes at the time points , , and respectively. To further validate the proposed methodology, we pick up all those subjects with four change points, and calculate the mean locations respectively. The means are , , , , which are fairly close to the task block changes. A more interesting observation is that the lags (4.6s, 2.0s, 1.7s and -1.5s) are becoming shorter and shorter: the last time point even precedes the designed time point. This, to our understanding, witnesses the powerfulness of human brains for learning the change patterns.",
null,
"Figure 2: Panel (a): the “Desikan-Killiany” parcellation of the cortical surface in left and right hemisphere. Panel (b): the eight regions of interest.\n\n7 Discussion\n\nIn this paper we propose an additive matrix-log mean model with a heterogeneous noise for modeling random symmetric positive definite matrices that lie in a Riemannian manifold. The heterogeneous noise part takes account the manifold structure of the original symmetric positive definite matrices. Built upon this model, we then propose a scan statistic to perform multiple change point detection. Theoretical studies and numerical examples lend further support to our proposed methodology.\n\nOur proposed methodology replies on the assumption that the collected samples ’s are independent. Independence is an ideal assumption that may be violated in some settings. However, this assumption allows us to conduct theoretical analysis, which also produce results that could be useful when the assumption is violated. We will pursue the change-point detection problems under dependence for Riemannian data in future work.\n\nReferences\n\n• Arsigny et al. (2007) Arsigny, V., Fillard, P., Pennec, X. and Ayache, N. (2007). Geometric means in a novel vector space structure on symmetric positive-definite matrices. SIAM Journal of Matrix Analysis and Applications 29 328–347.\n• Carlstein et al. (1994) Carlstein, E. G., Müller, H.-G. and Siegmund, D. (1994). Change-point problems. Institute of Mathematical Statistics.\n• Castelli et al. (2000) Castelli, F., Happé, F., Frith, U. and Frith, C. (2000). Movement and mind: a functional imaging study of perception and interpretation of complex intentional movement patterns. NeuroImage 12 314–325.\n• Chen and Zhang (2015) Chen, H. and Zhang, N. (2015). Graph-based change-point detection. The Annals of Statistics 43 139–176.\n• Chiu et al. (1996) Chiu, T. Y., Leonard, T. and Tsui, K.-W. (1996). The matrix-logarithmic covariance model. Journal of the American Statistical Association 91 198–210.\n• Daniels and Pourahmadi (2002) Daniels, M. J. and Pourahmadi, M. (2002). Bayesian analysis of covariance matrices and dynamic models for longitudinal data. Biometrika 89 553–566.\n• Desikan et al. (2006) Desikan, R. S., Ségonne, F., Fischl, B., Quinn, B. T., Dickerson, B. C., Blacker, D., Buckner, R. L., Dale, A. M., Maguire, R. P. and Hyman, B. T. (2006). An automated labeling system for subdividing the human cerebral cortex on MRI scans into gyral based regions of interest. NeuroImage 31 968–980.\n• Dryden et al. (2009) Dryden, I. L., Koloydenko, A. and Zhou, D. (2009). Non-Euclidean statistics for covariance matrices, with applications to diffusion tensor imaging. The Annals of Applied Statistics 3 1102–1123.\n• Fletcher (2013) Fletcher, P. T. (2013). Geodesic regression and the theory of least squares on Riemannian manifolds.\n\nInternational Journal of Computer Vision\n\n105 171–185.\n• Friston (2011) Friston, K. J. (2011). Functional and effective connectivity: a review. Brain Connectivity 1 13–36.\n• Green et al. (2015) Green, M. F., Horan, W. P. and Lee, J. (2015). Social cognition in schizophrenia. Nature Reviews. Neuroscience 16 620–631.\n• Hsu et al. (2012) Hsu, D., Kakade, S. and Zhang, T. (2012). A tail inequality for quadratic forms of subgaussian random vectors. Electronic Communications in Probability 17 1–6.\n• Hutchison et al. (2013) Hutchison, R. M., Womelsdorf, T., Allen, E. A., Bandettini, P. A., Calhoun, V. D., Corbetta, M., Della Penna, S., Duyn, J. H., Glover, G. H. and Gonzalez-Castillo, J. (2013). Dynamic functional connectivity: promise, issues, and interpretations. NeuroImage 80 360–378.\n• James et al. (1987) James, B., James, K. L. and Siegmund, D. (1987). Tests for a change-point. Biometrika 74 71–83.\n• Lee (1997) Lee, J. M. (1997). Riemannian Manifolds: An Introduction to Curvature. Springer-Verlag, New York.\n• Leonard and Hsu (1992) Leonard, T. and Hsu, J. S. (1992). Bayesian inference for a covariance matrix. The Annals of Statistics 1669–1696.\n• Niu and Zhang (2012) Niu, Y. S. and Zhang, H. (2012). The screening and ranking algorithm to detect DNA copy number variations. The Annals of Applied Statistics 6 1306–1326.\n• Olshen et al. (2004) Olshen, A. B., Venkatraman, E., Lucito, R. and Wigler, M. (2004). Circular binary segmentation for the analysis of array-based dna copy number data. Biostatistics 5 557–572.\n• Petersen and Müller (2017) Petersen, A. and Müller, H.-G. (2017). Fréchet regression for random objects with Euclidean predictors. The Annals of Statistics to appear.\n• Schwartzman (2006) Schwartzman, A. (2006). Random ellipsoids and false discovery rates: Statistics for diffusion tensor imaging data. Ph.D. thesis, Stanford University.\n• Steinke and Hein (2009) Steinke, F. and Hein, M. (2009). Non-parametric regression between manifolds. In Advances in Neural Information Processing Systems.\n• Terras (2012) Terras, A. (2012). Harmonic analysis on symmetric spaces and applications II. Springer Science & Business Media.\n• Tibshirani and Wang (2007) Tibshirani, R. and Wang, P. (2007). Spatial smoothing and hot spot detection for cgh data using the fused lasso. Biostatistics 9 18–29.\n• Wheatley et al. (2007) Wheatley, T., Milleville, S. C. and Martin, A. (2007). Understanding animate agents: distinct roles for the social network and mirror system. Psychological Science 18 469–474.\n• Xu and Lindquist (2015) Xu, Y. and Lindquist, M. A. (2015). Dynamic connectivity detection: an algorithm for determining functional connectivity change points in fmri data. Frontiers in Neuroscience 9.\n• Yao (1988) Yao, Y.-C. (1988). Estimating the number of change-points via Schwarz’ criterion. Statistics & Probability Letters 6 181–189.\n• Yuan et al. (2012) Yuan, Y., Zhu, H., Lin, W. and Marron, J. S. (2012). Local polynomial regression for symmetric positive definite matrices. Journal of the Royal Statistical Society: Series B 74 697–719.\n• Zhang and Siegmund (2007) Zhang, N. R. and Siegmund, D. O. (2007). A modified bayes information criterion with applications to the analysis of comparative genomic hybridization data. Biometrics 63 22–32.\n• Zhu et al. (2009) Zhu, H., Chen, Y., Ibrahim, J. G., Li, Y., Hall, C. and Lin, W. (2009). Intrinsic regression models for positive-definite matrices with applications to diffusion tensor imaging. Journal of the American Statistical Association 104 1203–1212.\n\nAppendix S.1 Preliminary\n\nIn this section, we further discuss the smooth and Riemannian manifold. For a comprehensive treatment on these subjects, readers are referred to the introductory book by Lee (1997).\n\nA smooth manifold is a differentiable manifold with all transition maps being -differentiable. Associated with each point on the manifold , there exists a linear space called the tangent space at the base point\n\n. Each element in the tangent space is called a tangent vector. For a manifold that is a submanifold of a Euclidean space, the tangent space at a point can be geometrically visualized as the hyperplane tangent to that point, while tangent vectors are visualized as Euclidean vectors tangent to the manifold at that point; see Figure\n\nS.3 for an illustration. It is emphasized that tangent vectors at different base points are different, despite that the vectors might point to the same direction. Thus, a tangent vector always implicitly comes with a base point. For Euclidean submanifolds, a tangent vector at a point can also be algebraically interpreted as a directional derivative at , such that for all with denoting the collection of real-valued smooth functions defined on the manifold . Observe that is a derivation at , which satisfies the Leibniz rule,\n\n Dv(fg)=g(x)(Dvf)+f(x)(Dvg),\n\nfor any and , where denotes the pointwise product of functions. This allows one to generalize the concept of tangent vector as directional derivative to non-Euclidean manifolds, by defining tangent vectors at as derivations at , and tangent space at as the space of derivations at . A convenient way to perceive the derivation represented by a tangent vector is to treat as a linear functional that maps into .\n\nFor a smooth transformation that maps points on a manifold to points on the manifold , its differential at , denoted by , is a linear map sending a tangent vector to a tangent vector , such that the derivation corresponding to the tangent vector at the point is depicted by\n\n Dφ′x(v):C∞(M)→R,s.t.∀f∈C∞(M):Dφ′x(v)f=Dv(f∘φ),\n\nwhere denotes the composition of functions. When both and are Euclidean submanifolds, the differential is the usual notion of differential of the function at , given by a Jacobian matrix. Specially, when is an interval of the real line, the tangent space at each is the whole real line . In this case, is often called a (parameterized) smooth curve on , and is denoted by which is the derivative of the curve at time . Here, to properly decode the notation , recall that is a map sending a tangent vector of a manifold to a tangent vector of another manifold, and for the special manifold , the real number can be viewed as a tangent vector at . Geometrically and intuitively, is a vector tangent to the curve at time , as illustrated in Figure S.3.\n\nA Riemannian manifold is a smooth manifold endowed with an inner product on the tangent space at each point , such that varies with smoothly. The collection of such inner products is often called the Riemannian metric tensor, or simply Riemannian metric. One can show that, the metric tensor induces a distance function that turns the manifold into a metric space. A geodesic is a smooth curve on the manifold such that for any sufficiently small segment, the segment is the unique smooth curve with the minimal length among all smooth curves connecting the two endpoints of the segment. Every smooth curve on the manifold can be parameterized by a smooth map from an interval in to the manifold. For any , there exists a unique geodesic such that and . Then the exponential map at , denoted by , is defined by . For example, one can verify that for the unit circle , for and , the defining geodesic for the Riemannian exponential map is , as and . Thus, . A graphical illustration of the Exp map is given in Figure S.3.",
null,
"Figure S.3: Geometric illustration of tangent vector, tangent space, curve and exponential map. γ(t) with γ(0)=x and γ(1)=q is a smooth curve on M. v is a tangent vector at x and also tangent to the curve γ at t=0, i.e. v=γ′(0). If in addition γ(t) is a geodesic, then q=γ(1)=Expx(v).\n\nFor the Log-Euclidean metric, at the identity matrix , it is defined as for , the Frobenius inner product on . In order to define metric at other points, the following group structure is considered. Define , where and are the matrix exponential and logarithm respectively. The operation turns into a group. Now we define the left-translation operator for . As shown in Arsigny et al. (2007), is a smooth map from to itself. Thus, its differential at is a linear map that sends tangent vectors at to tangent vectors at . For instance, the linear operator maps tangent vectors at to tangent vectors at the identity. Given this property, we can “translate” the metric at the identity matrix to all points by the left-translation operator . More specifically, the Log-Euclidean metric at any is defined by for all , where the last identity is due to (Arsigny et al., 2007). The Riemannian exponential map under this metric is given by .\n\nAppendix S.2 Proofs\n\nLet , and , where denotes the collection of flat points, i.e., if and only if for all . Then holds under the event .\n\nProof of Lemma s.2.\n\nThe proof can be found in Lemma 3 of Niu and Zhang (2012). ∎\n\nProof of Theorem 4.\n\nWe first note the following facts about subgaussian random vectors that will be used in the sequel.\n\n• If are independent and subgaussian with parameters , respectively, then is a subgaussian random vector with parameters and .\n\n• If is a subgaussian random vector with a parameter and is a matrix, then is a subgaussian random vector with parameters and .\n\nA point is called a -flat point (or simply flat point if is clear from the context) if for all . For a flat point , has mean zero and also is a subgaussian random vector with parameters and . Here, we recall that is subgaussian with the parameter . For a change-point , similarly, is subgaussian with parameter .\n\nLet and . For a flat point , we first observe that\n\n Pr{∥G(x,h)∥22>an}≤e−tn=1nlogn\n\naccording to Theorem 1 of Hsu et al. (2012). According to Assumption 1 and the choice of and , we have and thus\n\n Pr{∥G(x,h)∥22>ρ}≤Pr{∥G(x,h)∥22>an}≤1nlogn.\n\nSimilarly, from Assumption 1 we deduce that and . Thus, for a change point ,\n\n Pr{∥G(τ,h)∥2<√ρ} ≤Pr{∥G(τ,h)∥2<∥δτ∥2−√an} ≤Pr{|∥G(τ,h)∥2−∥δτ∥2|>√an} ≤Pr{∥G(τ,h)−δτ∥22>an} ≤1nlogn,\n\nor equivalently,\n\n Pr{∥G(τ,h)∥22<ρ}≤1nlogn.\n\nNext, we bound the probabilities of events defined in Lemma S.2.\n\n Pr{En(h,ρ)} ≥1−Pr[{An(h,ρ)}c]−Pr[{Bn(h,ρ)}c]. (S.2)\n\nNow, note that\n\n Pr[{An(h,ρ)}c] =Pr{∃x∈F:∥G(x,h)∥22>ρ}≤∑x∈FPr{∥G(x,h)∥22>ρ} ≤∑x∈F1nlogn≤n(1nlogn)=1logn. (S.3)\n\nSimilarly,\n\n Pr[{Bn(h,ρ)}c] =Pr{∃τ∈J:∥G(τ,h)∥22<ρ}≤∑τ∈JPr{∥G(τ,h)∥22<ρ} ≤∑τ∈J1nlogn≤nnlogn=1logn. (S.4)\n\nCombining (S.2), (S.3) and (S.4), we conclude that\n\n Pr{En(h,ρ)}≥1−2logn→1. (S.5)\n\nFinally, the theorem follows from Lemma S.2. ∎"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8764119,"math_prob":0.96304417,"size":33492,"snap":"2022-05-2022-21","text_gpt3_token_len":8019,"char_repetition_ratio":0.1367654,"word_repetition_ratio":0.051338065,"special_character_ratio":0.25244835,"punctuation_ratio":0.16726512,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9956634,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-01-22T08:09:04Z\",\"WARC-Record-ID\":\"<urn:uuid:d29cf38c-c517-4ac1-8b1e-e854ef67f8fa>\",\"Content-Length\":\"996256\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:a4c1bd2b-b9e7-46f9-b368-6f68df2c75be>\",\"WARC-Concurrent-To\":\"<urn:uuid:3a8e1c9d-0d8a-46d2-ba92-4bb16664c4c4>\",\"WARC-IP-Address\":\"44.235.123.242\",\"WARC-Target-URI\":\"https://deepai.org/publication/modeling-symmetric-positive-definite-matrices-with-an-application-to-functional-brain-connectivity\",\"WARC-Payload-Digest\":\"sha1:YXHNMEOU5EES42M3Y6FEGS5OC6O3VX3J\",\"WARC-Block-Digest\":\"sha1:KXDFCH4JWJZEG3ZL5OIWFIKRQ4SQJCPP\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-05/CC-MAIN-2022-05_segments_1642320303779.65_warc_CC-MAIN-20220122073422-20220122103422-00068.warc.gz\"}"} |
https://pslab.io/blog/pslab-communication-function-calls/ | [
"# PSLab Communication Function Calls\n\nInterfacing with the hardware of PSLab, fetching the data and plotting it is very simple and straight forward. Various sensors can be connected to PSLab and data can be fetched with a simple python code as shown in the following example…\n\n```>>> from PSL import sciencelab\n>>> I = sciencelab.connect() # Initializing: Returns None if device isn't found. The initialization process connects to tty device and loads calibration values.```\n```# An example function that measures voltage present at the specified analog input\n>>> print I.get_average_voltage('CH1')```\n```# An example to capture and plot data\n>>> I.set_gain('CH1', 3) # set input CH1 to +/-4V range\n>>> I.set_sine1(1000) # generate 1kHz sine wave on output W1\n>>> x,y = I.capture1('CH1', 1000, 10) # digitize CH1 1000 times, with 10 usec interval\n>>> plot(x,y)\n>>> show()\n```\n```# An example function to get data from magnetometer sensor connected to PSLab\n>>> from PSL.SENSORS import HMC5883L #A 3-axis magnetometer >>> M = HMC5883L.connect() >>> Gx,Gy,Gz = M.getRaw() ```\n\nThe module sciencelab.py contains all the functions required for communicating with PSLab hardware. It also contains some utility functions. The class ScienceLab() contains methods that can be used to interact with the PSLab.\n\nAfter initiating this class, all the features built into the device can be accessed using various function calls.\n\nCapture1 : for capturing one trace\n\n`capture1(ch, ns, tg)`\n\nArguments\n\n• ch : Channel to select as input. [‘CH1′..’CH3′,’SEN’]\n• ns : Number of samples to fetch. Maximum 10000\n• tg : Time gap between samples in microseconds\n`#Example >>> x,y = I.capture1('CH1', 1000, 10) # digitize CH1 1000 times, with 10 usec interval`\n\nReturns : Arrays X(timestamps),Y(Corresponding Voltage values)\n\nCapture2 : for capturing two traces\n\n`capture2(ns, tg, TraceOneRemap='CH1')`\n\nArguments\n\n• ns : Number of samples to fetch. Maximum 5000\n• tg : Time gap between samples in microseconds\n• TraceOneRemap : Choose the analogue input for channel 1 (Like MIC OR SEN). It is connected to CH1 by default. Channel 2 always reads CH2.\n```#Example\n>>> x,y1,y2 = I.capture2(1600,1.75,'CH1') # digitize CH1 and CH2, 1600 times, with 1.75 usec interval```\n\nReturns: Arrays X(timestamps),Y1(Voltage at CH1),Y2(Voltage at CH2)\n\nCapture4 : for capturing four taces\n\n`capture4(ns, tg, TraceOneRemap='CH1')`\n\nArguments\n\n• ns: Number of samples to fetch. Maximum 2500\n• tg : Time gap between samples in microseconds. Minimum 1.75uS\n• TraceOneRemap : Choose the analogue input for channel 1 (Like MIC OR SEN). It is connected to CH1 by default. Channel 2 always reads CH2, channel 3 always reads CH3 and MIC is channel 4 (CH4)\n```#Example\n>>> x,y1,y2,y3,y4 = I.capture4(800,1.75) # digitize CH1-CH4, 800 times, with 1.75 usec interval```\n\nReturns: Arrays X(timestamps),Y1(Voltage at CH1),Y2(Voltage at CH2),Y3(Voltage at CH3),Y4(Voltage at CH4)\n\nCapture_multiple : for capturing multiple traces\n\n`capture_multiple(samples, tg, *args)`\n\nArguments\n\n• samples: Number of samples to fetch. Maximum 10000/(total specified channels)\n• tg : Time gap between samples in microseconds.\n• *args : channel names\n```# Example\n>>> from pylab import *\n>>> I=interface.Interface()\n>>> x,y1,y2,y3,y4 = I.capture_multiple(800,1.75,'CH1','CH2','MIC','SEN')\n>>> plot(x,y1)\n>>> plot(x,y2)\n>>> plot(x,y3)\n>>> plot(x,y4)\n>>> show()```\n\nReturns: Arrays X(timestamps),Y1,Y2 …\n\nCapture_fullspeed : fetches oscilloscope traces from a single oscilloscope channel at a maximum speed of 2MSPS\n\n`capture_fullspeed(chan, amples, tg, *args)`\n\nArguments\n\n• chan: channel name ‘CH1’ / ‘CH2’ … ‘SEN’\n• tg : Time gap between samples in microseconds. minimum 0.5uS\n• *args : specify if SQR1 must be toggled right before capturing. ‘SET_LOW’ will set it to 0V, ‘SET_HIGH’ will set it to 5V. if no arguments are specified, a regular capture will be executed.\n```# Example\n>>> from pylab import *\n>>> I=interface.Interface()\n>>> x,y = I.capture_fullspeed('CH1',2000,1)\n>>> plot(x,y)\n>>> show()```\n\nReturns: timestamp array ,voltage_value array\n\nSet_gain : Set the gain of selected PGA\n\n`set_gain(channel, gain)`\n\nArguments\n\n• channel: ‘CH1’ , ‘CH2’\n• gain : (0-7) -> (1x,2x,4x,5x,8x,10x,16x,32x)\n\nNote: The gain value applied to a channel will result in better resolution for small amplitude signals.\n\n```# Example\n>>> I.set_gain('CH1',7) #gain set to 32x on CH1\n```\n\nGet_average_voltage : Return the voltage on the selected channel\n`get_average_voltage(channel_name, **kwargs)`\nArguments\n\n• channel_name: ‘CH1’,’CH2’,’CH3’, ‘MIC’,’IN1’,’SEN’\n• **kwargs : Samples to average can be specified. eg. samples=100 will average a hundred readings\n```# Example\n>>> print I.get_average_voltage('CH4')\n1.002```\n\nGet_freq : Frequency measurement on IDx. Measures time taken for 16 rising edges of input signal. returns the frequency in Hertz\n\n`get_average_voltage(channel='Fin', timeout=0.1)`\nArguments\n\n• channel : The input to measure frequency from. ‘ID1’ , ‘ID2’, ‘ID3’, ‘ID4’, ‘Fin’\n• timeout : This is a blocking call which will wait for one full wavelength before returning the calculated frequency. Use the timeout option if you’re unsure of the input signal. returns 0 if timed out\n```# Example\n>>> I.sqr1(4000,25)\n>>> print I.get_freq('ID1')\n4000.0```\n\nReturn float: frequency\n\nGet_states : Gets the state of the digital inputs. returns dictionary with keys ‘ID1’,’ID2’,’ID3’,’ID4’\n`get_states()`\n```#Example\n>>> print get_states()\n{'ID1': True, 'ID2': True, 'ID3': True, 'ID4': False}\n```\n\nGet_state : Returns the logic level on the specified input (ID1,ID2,ID3, or ID4)\n`get_state(input_id)`\nArguments\n\n• input_id : The input channel ‘ID1’ -> state of ID1 ‘ID4’ -> state of ID4\n```#Example\n>>> print I.get_state(I.ID1)\nFalse\n```\n\nSet_state : Set the logic level on digital outputs SQR1,SQR2,SQR3,SQR4\n`set_state(**kwargs)`\nArguments\n\n• **kwargs : SQR1,SQR2,SQR3,SQR4 states(0 or 1)\n```#Example\n>>> I.set_state(SQR1=1, SQR2=0) #sets SQR1 HIGH, SQR2 LOw, but leave SQR3,SQR4 untouched.\n```"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6409448,"math_prob":0.8928871,"size":5896,"snap":"2020-10-2020-16","text_gpt3_token_len":1718,"char_repetition_ratio":0.11744738,"word_repetition_ratio":0.14752252,"special_character_ratio":0.3156377,"punctuation_ratio":0.19858782,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97259873,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-02-25T09:52:58Z\",\"WARC-Record-ID\":\"<urn:uuid:3cc87679-a2e0-4cc9-8559-09fad1b54706>\",\"Content-Length\":\"142599\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:d3285f4f-6da2-469c-83f4-e24925ba7ceb>\",\"WARC-Concurrent-To\":\"<urn:uuid:4f4a3543-9046-420a-8d7e-38916a9f4a66>\",\"WARC-IP-Address\":\"104.18.33.23\",\"WARC-Target-URI\":\"https://pslab.io/blog/pslab-communication-function-calls/\",\"WARC-Payload-Digest\":\"sha1:7FOWRHIRIC257PRC5SZZHFN5M67TVF2C\",\"WARC-Block-Digest\":\"sha1:YTXGH3RFXV3X6DXGFMCEM7UYIKFVXONN\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-10/CC-MAIN-2020-10_segments_1581875146064.76_warc_CC-MAIN-20200225080028-20200225110028-00477.warc.gz\"}"} |
https://quabr.com/72069131/what-does-the-confusion-matrix-line-of-code-do | [
"# What does the confusion_matrix line of code do?\n\n``````from sklearn.pipeline import Pipeline\nmodel = Pipeline([('vectorizer',tvec),('classifier',clf2)])\nmodel.fit(IV_train, DV_train)\nfrom sklearn.metrics import confusion_matrix\npredictions = model.predict(IV_test)\nconfusion_matrix(predictions, DV_test)\n``````\n\nI want to know what the confusion matrix line in the code does."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7007121,"math_prob":0.92562896,"size":17129,"snap":"2022-40-2023-06","text_gpt3_token_len":4343,"char_repetition_ratio":0.10306569,"word_repetition_ratio":0.057983942,"special_character_ratio":0.2731041,"punctuation_ratio":0.18310301,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99319637,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-09-26T07:16:18Z\",\"WARC-Record-ID\":\"<urn:uuid:f2e02723-883f-4c4f-bd45-0c72637c930d>\",\"Content-Length\":\"42540\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:86bf44c6-f983-4226-9660-88587679d3ea>\",\"WARC-Concurrent-To\":\"<urn:uuid:777190e1-c935-416a-8cde-e7ec78131618>\",\"WARC-IP-Address\":\"5.9.10.113\",\"WARC-Target-URI\":\"https://quabr.com/72069131/what-does-the-confusion-matrix-line-of-code-do\",\"WARC-Payload-Digest\":\"sha1:S5NGKCVHSJFWP7I6UIZZKMA3EYAWJXWM\",\"WARC-Block-Digest\":\"sha1:KNGKLFBUWY6FTDQQ26OC7FAFTEEXKS47\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-40/CC-MAIN-2022-40_segments_1664030334802.16_warc_CC-MAIN-20220926051040-20220926081040-00617.warc.gz\"}"} |
https://mathoverflow.net/questions/35812/bounds-on-remainder-term-of-power-series-of-elementary-functions | [
"# Bounds on remainder term of power series of elementary functions\n\nThis is mainly a question about the remainder term of power series for elementary functions.\n\nI'm very interested in aspects of calculating or computing elementary operations and functions, by which I mean:\n\n• trigonometric: $\\sin$, $\\cos$, $\\tan$\n• inverse trig.: $\\sin^{-1}$, $\\cos^{-1}$, $\\tan^{-1}$\n• log and exponential: $\\ln$, $\\exp$\n• hyperbolic: $\\sinh$, $\\cosh$, $\\tanh$\n• inverse hyp.: $\\sinh^{-1}$, $\\cosh^{-1}$, $\\tanh^{-1}$\n• powers, reciprocation, $\\sqrt{\\ \\ \\ }$\n\nperhaps also:\n\n• gamma function: $\\Gamma$\n• and a few other important functions\n\nThere are many contexts (of calculation). For example:\n\n• real versus complex arguments\n• known, fixed precision versus variable precision\n• numerical versus symbolic\n\nThere are many approaches and techniques available too. For example:\n\n• power series expansions and polynomial approximations\n• use of relationships between the functions\n• use of periodic or similar properties to shrink the domain\n• lookup tables and interpolation\n• CORDIC (used within some hand calculators I believe)\n• exact methods\n• interval or other error-tracking methods\n\nSome good references to certain aspects include:\n\nThe main gap in my knowledge is in finding bounds for the error or remainder term in partial power series expansions of certain of the above functions. Some are fairly simple to determine, whilst others seem to be awkward.\n\nAny pointers on this matter would be much appreciated.\n\nLikewise for any further references on any other aspects of or techniques for calculating elementary functions.\n\n• Two things: 1. you might be interested in this book: personales.unican.es/segurajj/book ; and 2. don't just confine yourself to implementing things with only power series, they are almost always only effective within a restricted range of arguments (unless your functions of interest satisfy useful reduction formulae). As might be already obvious to you, the easiest bound for the truncation error of a power series is the first neglected term. – J. M. isn't a mathematician Aug 17 '10 at 1:27\n• You've listed a huge load of references, but not said in detail exactly why these are not enough to solve your problems. I think a detailed question would be helpful; can you give a particular power series for which you cannot determine a good estimate for the remainder, by any of the standard methods you've listed? – Zen Harper Aug 17 '10 at 1:32\n• First of all, thanks to all for the comments and answers; all good and all appreciated. – Rhubbarb Aug 17 '10 at 23:13\n• @J. Mangaldan (2) are there any particular methods beyond power series and the few others I mentioned above that you would particularly recommend I consider? Do you have a reference for the use of the first neglected term as a bound on the remainder? What are the conditions for that to hold? Thanks again. – Rhubbarb Aug 17 '10 at 23:18\n• @Zen Harper: My question was vague partly intentionally (I am very pleased with the responses), and partly as I'm only an amateur mathematician. As a particular case: the terms of the expansion of sin are simple because the sequence of derivatives remains simple. On the other hand, the terms of the expansion of tan seem to become very unwieldy; the closed form is superficially simple, but involves the Bernoulli numbers, which are somewhat erratic. I expect I'm missing something quite simple. In saying that, I wasn't fishing for a specific solution so much as some leads. Thanks again. – Rhubbarb Aug 17 '10 at 23:50\n\nThese bounds you are looking for can be obtained from majorant series. What you seek is implemented in the Dynamic Dictionary of Mathematical Functions; Bruno Salvy gave a very nice talk on this topic at CICM 2010 in early July.\n\nFor the guaranteed numerics aspect, the expert is Marc Mezzarobba, a PhD student of Bruno's. On that page, see the links to NumGfun (software, presentation and paper) for all the details you would ever want on the topic.\n\nfinding bounds for the error or remainder term in partial power series expansions\n\nI think you want the Euler-Maclaurin Summation formula. That bounds the remainder terms, although it would require knowing the closed form of the integral representation of the function you are calculating.\n\n$\\sum_{n=a}^b f(n) \\sim \\int_a^b f(x)\\,dx + \\frac{f(a)+f(b)}{2} + \\sum_{k=1}^\\infty \\,\\frac{B_{2k}}{(2k)!}\\left(f^{(2k-1)}(b)-f^{(2k-1)}(a)\\right)$\n\nThe paper by Apostol \"Elementary view of Euler-Maclaurin\" AMM vol 106 (1999) pp. 409-418 is very accessible.\n\nThe following papers/books may also be helpful\n\n1. R.P. Boas \"Estimating Remainders.\" Math. Mag. 51, pp 83-89, (1978)\n2. http://www.tricki.org/article/Estimating_sums\n3. Bridger and Frampton Bounding Power Series Remainders Math. Mag. 71 (1998), pp. 204-207\n4. Sofo. Computational Techniques for the Summation of Series\n5. Ross. Methods of Summation\n6. Davis. Summation of Series."
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8300641,"math_prob":0.912709,"size":1737,"snap":"2021-21-2021-25","text_gpt3_token_len":380,"char_repetition_ratio":0.10905944,"word_repetition_ratio":0.0,"special_character_ratio":0.23373632,"punctuation_ratio":0.13571429,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9910571,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-05-07T12:51:14Z\",\"WARC-Record-ID\":\"<urn:uuid:175931f5-a26c-48c7-a3fc-caabbc6fb172>\",\"Content-Length\":\"151330\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0da32618-b838-46a6-bdfd-7ad0ee7aab10>\",\"WARC-Concurrent-To\":\"<urn:uuid:0d8fa12d-cdb4-476d-9e94-c96edca5bfc7>\",\"WARC-IP-Address\":\"151.101.1.69\",\"WARC-Target-URI\":\"https://mathoverflow.net/questions/35812/bounds-on-remainder-term-of-power-series-of-elementary-functions\",\"WARC-Payload-Digest\":\"sha1:USOPSG3A2HUBO4RPQD25VSPIPVWLUIWV\",\"WARC-Block-Digest\":\"sha1:GFXUY3MTXM3M76FH7S2KRAMZQVC3YPPZ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-21/CC-MAIN-2021-21_segments_1620243988793.99_warc_CC-MAIN-20210507120655-20210507150655-00341.warc.gz\"}"} |
https://www.hpmuseum.org/forum/archive/index.php?thread-4353.html | [
"# HP Forums\n\nFull Version: How do I use AFiles in an App?\nYou're currently viewing a stripped down version of our content. View the full version with proper formatting.\nThe following code works if you paste it into a copy of the Function App\nHere's the App:\nCode:\n``` //Variables... t;rh; hi;hi2;tmp; // Subroutine... HeatIndex(); EXPORT HeatIndex1() BEGIN END; VIEW \"Start HeatIndex\",START() BEGIN t:=AVars(\"t\");rh:=AVars(\"rh\"); STARTVIEW(-1,1); WHILE GETKEY<>4 DO REPEAT tmp:=INPUT({{t,,{60,20,1}}, {rh,,{60,20,2}}, {hi,,{60,20,4}}, {hi2,,{60,20,5}} }, \"Heat Index Input and Output\", {\"Temperature, Deg F : \", \"Relative Humidity, % : \", \"Heat Index, Deg F :\", \"Heat Index, Deg F :\" }, {\" Air Temperature (80 to 104 °F)\", \" Relative Humidity (40 to 100 %)\", \" Heat Index from www.weatherimages.org\", \" Heat Index from www.4wx.com\" }, {t,rh,hi,hi2}, {t,rh,hi,hi2}); AVars(\"t\"):=t;AVars(\"rh\"):=rh; IF tmp==0 THEN STARTVIEW(-4,1); MSGBOX(\"End of Program\"); RETURN; END; UNTIL t>=80. AND t<=104. AND rh>=40. AND rh<=100.; HeatIndex(); END; // While STARTVIEW(-4,1); MSGBOX(\"End of Program\"); END; HeatIndex() BEGIN // This is the 16 element equation used to convert // dry bulb temperature (T) and relative humidity (RH) // into the Heat Index. This equation works at // dry bulb temperatures of 70°F and higher. // The symbol \"^\" means \"raised to the power of\". // Source: http://www.weatherimages.org/data/heatindex.html // Where: // hi = Heat Index // t = Temperature (° F) // rh = Relative Humidity (%) tmp:=16.923; tmp:=tmp+1.85212*10^(-1)*t; tmp:=tmp+5.37941*rh; tmp:=tmp-1.00254*10^(-1)*t*rh; tmp:=tmp+9.41695*10^(-3)*t^2; tmp:=tmp+7.28898*10^(-3)*rh^2; tmp:=tmp+3.45372*10^(-4)*t^2*rh; tmp:=tmp-8.14971*10^(-4)*t*rh^2; tmp:=tmp+1.02102*10^(-5)*t^2*rh^2; tmp:=tmp-3.8646*10^(-5)*t^3; tmp:=tmp+2.91583*10^(-5)*rh^3; tmp:=tmp+1.42721*10^(-6)*t^3*rh; tmp:=tmp+1.97483*10^(-7)*t*rh^3; tmp:=tmp-2.18429*10^(-8)*t^3*rh^2; tmp:=tmp+8.43296*10^(-10)*t^2*rh^3; hi:=tmp-4.81975*10^(-11)*t^3*rh^3; hi:=ROUND(hi,0); // Source: http://www.4wx.com/wxcalc/formulas/heatIndex.php tmp:=-42.379; tmp:=tmp+2.04901523*t; tmp:=tmp+10.14333127*rh; tmp:=tmp-.22475541*t*rh; tmp:=tmp-6.83783*10^(-3)*t^2; tmp:=tmp-5.481717*10^(-2)*rh^2; tmp:=tmp+1.22874*10^(-3)*t^2*rh; tmp:=tmp+8.5282*10^(-4)*t*rh^2; hi2:=tmp-1.99*10^(-6)*t^2*rh^2; hi2:=ROUND(hi2,0); END;```\nI want to take the subroutine HeatIndex(), and move it to the AFiles folder of this app. For me, the explanation in the AFiles help section of the emulator is inadequate. I need help in how to structure the code in order to run this App with the subroutine HeatIndex() in the AFiles folder. Thanks for any help you can provide.\nrcf\nWhat exactly do you want to do? each app has its own \"script\" place, the \"Afiles\" is (I believe) for external resources (in this moment probably text or images), not for script objects, like 'libraries'\nHello,\n\nApplication files are for data, not programs.\n\nYou can store 2 type of things in files using AFiles:Math \"Objects\" (anything that you can place in a variable) using AFiles(\"name\"):= var (or directly object), and graphics (storing G0-G9).\n\nYou can not store a program in a file, sorry. At this point in time, your program still has to be one single unit of source code.\n\nCyrille"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.53487074,"math_prob":0.9309476,"size":2548,"snap":"2021-43-2021-49","text_gpt3_token_len":1006,"char_repetition_ratio":0.15998428,"word_repetition_ratio":0.0,"special_character_ratio":0.47017267,"punctuation_ratio":0.27982953,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9899158,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-12-09T05:10:25Z\",\"WARC-Record-ID\":\"<urn:uuid:c813a467-b4d0-44d5-ab03-9bdd56427e3c>\",\"Content-Length\":\"9282\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:58aa9280-5038-48d8-a6c3-a7cea0de99b4>\",\"WARC-Concurrent-To\":\"<urn:uuid:84ae3738-6d58-40e0-b039-73ff5b0bd1fa>\",\"WARC-IP-Address\":\"209.197.117.170\",\"WARC-Target-URI\":\"https://www.hpmuseum.org/forum/archive/index.php?thread-4353.html\",\"WARC-Payload-Digest\":\"sha1:4RJ7NVFHZOAAATPYC47W2QUW3SHF2MIQ\",\"WARC-Block-Digest\":\"sha1:NKJ4LIUGXFR5GXGFDO267UNDC63AE4EL\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-49/CC-MAIN-2021-49_segments_1637964363659.21_warc_CC-MAIN-20211209030858-20211209060858-00079.warc.gz\"}"} |
https://www.semanticscholar.org/paper/Counterexample-to-the-Laptev--Safronov-conjecture-Bogli-Cuenin/e586bd3d4a0f89bd5ede565401c696b2a0593701 | [
"• Corpus ID: 237491585\n\nCounterexample to the Laptev--Safronov conjecture\n\n@inproceedings{Bogli2021CounterexampleTT,\ntitle={Counterexample to the Laptev--Safronov conjecture},\nauthor={Sabine Bogli and Jean-Claude Cuenin},\nyear={2021}\n}\n• Published 13 September 2021\n• Mathematics, Physics\nWe prove that the Laptev–Safronov conjecture (Comm. Math. Phys. 2009) is false in the range that is not covered by Frank’s positive result (Bull. Lond. Math. Soc. 2011). The simple counterexample is adaptable to a large class of Schrödinger type operators, for which we also prove new sharp upper bounds.\n3 Citations\nRandom Schr\\\"odinger operators with complex decaying potentials\n• Mathematics, Physics\n• 2022\nWe prove that the eigenvalues of a continuum random Schrödinger operator −∆+Vω of Anderson type, with complex decaying potential, can be bounded (with high probability) in terms of an L norm of the\nLieb-Thirring and Jensen sums for non-self-adjoint Schr\\\"odinger operators on the half-line\n• Mathematics, Physics\n• 2021\nWe prove upper and lower bounds for sums of eigenvalues of Lieb–Thirring type for non-self-adjoint Schrödinger operators on the half-line. The upper bounds are established for general classes of\nImproved Lieb-Thirring type inequalities for non-selfadjoint Schr\\\"odinger operators\np > 1, if d = 2, p ≥ d2 , if d ≥ 3. Here σd(−∆+V ) denotes the set of discrete eigenvalues, outside the essential spectrum σe(−∆ + V ) = [0,∞). The inequality (1) cannot be true for complex-valued V"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7634595,"math_prob":0.69246805,"size":4418,"snap":"2022-05-2022-21","text_gpt3_token_len":1114,"char_repetition_ratio":0.16130494,"word_repetition_ratio":0.019138755,"special_character_ratio":0.21299231,"punctuation_ratio":0.08085106,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97017765,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-01-22T03:27:52Z\",\"WARC-Record-ID\":\"<urn:uuid:7459610d-5b98-4d28-a9fc-0596f9843450>\",\"Content-Length\":\"261814\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:c5bb4136-4306-48df-92b7-68e06ffd879b>\",\"WARC-Concurrent-To\":\"<urn:uuid:a8bf7343-3dcf-4b2e-9584-507bd6e10a6e>\",\"WARC-IP-Address\":\"99.86.231.114\",\"WARC-Target-URI\":\"https://www.semanticscholar.org/paper/Counterexample-to-the-Laptev--Safronov-conjecture-Bogli-Cuenin/e586bd3d4a0f89bd5ede565401c696b2a0593701\",\"WARC-Payload-Digest\":\"sha1:FP2I3X2YRI6RTB576XY6MT27I4V5XFHJ\",\"WARC-Block-Digest\":\"sha1:47NRABGW3YE6IBQGZ3UZMBZZBJRWXYKW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-05/CC-MAIN-2022-05_segments_1642320303729.69_warc_CC-MAIN-20220122012907-20220122042907-00648.warc.gz\"}"} |
http://blog.phytools.org/2013/02/on-shape-of-trees-with-random-taxa.html | [
"## Tuesday, February 26, 2013\n\n### On the shape of trees with random taxa addition or subtraction\n\nSince I have a new function for add tips at random to a tree; and it is even easier to write a function to drop tips randomly from the tree - i.e., here it is:\ndrop.random<-function(tree,n=1)\ntree<-drop.tip(tree,tip=sample(tree\\$tip.label)[1:n])\nI thought it might be fun to look at the effects of adding or subtracting tips at random from the tree. We already know that random missing taxa tends to create trees with longer than expected terminal edges - seemingly a slow-down in the rate of lineage diversification through time.\n\nThis is not very scientific, but first let's look at the LTT and Pybus & Harvey's (2000) γ for a single tree that we initiate with 100 species and then add to randomly using add.random in increments of 10. Here's our code (minus creating the video):\nrequire(phytools)\ntree<-pbtree(n=100,scale=1)\nmas<-900\nfor(i in 1:(mas/10+1)){\nx<-ltt(tree,plot=FALSE)\nplot(x\\$times[2:length(x\\$times)],x\\$ltt[2:length(x\\$ltt)], xlab=\"time\",ylab=\"lineages\",log=\"y\",type=\"l\",xlim=c(0,1), ylim=c(2,max(x\\$ltt)))\nlines(c(0,1),c(2,max(x\\$ltt)),lty=2)\ntext(x=0,y=max(x\\$ltt),paste(\"N = \",length(tree\\$tip), \"\\n\",\"gamma = \",round(x\\$gamma,3),sep=\"\"),adj=c(0,1))\n}\n\nAnd here's the result:\n\nOK, next, let's do the opposite - start with 1000 taxa and drop taxa random. First the code:\ndrop.random<-function(tree,n=1) tree<-drop.tip(tree,tip=sample(tree\\$tip.label)[1:n])\nrequire(phytools)\ntree<-pbtree(n=1000,scale=1)\nmenos<-900\nfor(i in 1:(menos/10+1)){\nx<-ltt(tree,plot=FALSE)\nplot(x\\$times[2:length(x\\$times)],x\\$ltt[2:length(x\\$ltt)],xlab=\"time\", ylab=\"lineages\",log=\"y\",type=\"l\",xlim=c(0,1), ylim=c(2,max(x\\$ltt)))\nlines(c(0,1),c(2,max(x\\$ltt)),lty=2)\ntext(x=0,y=max(x\\$ltt),paste(\"N = \",length(tree\\$tip), \"\\n\",\"gamma = \",round(x\\$gamma,3),sep=\"\"),adj=c(0,1))\ntree<-drop.random(tree,n=10)\n}\n\nAnd the video:\n\nAdding taxa at random, at least by our algorithm, does not seem to affect tree shape all that much; but subtracting random tips, as we expected, makes γ turn progressively more and more negative.\n\nTo see if this is idiosyncratic to the specific trees we started with, why don't we replicate the entire process (i.e., 900% addition or subtraction) in a single step for, say, 30 random pure-birth trees. Here's what that looks like. First, adding tips randomly:\nXX<-matrix(NA,31,2,dimnames=list(NULL,c(\"gamma100\",\"gamma1000\")))\nrequire(phytools)\nfor(i in 1:31){\ntree<-pbtree(n=100)\nXX[i,1]<-ltt(tree,plot=F)\\$gamma\nXX[i,2]<-ltt(tree,plot=F)\\$gamma\n}\ncolMeans(XX)\nZZ<-hist(XX[,2]-XX[,1],plot=F,breaks=-9.5:0.5)\nbarplot(ZZ\\$density,names=ZZ\\$mids,space=0,main=expression(gamma-gamma))\n\nAnd the results:\n> colMeans(XX)\ngamma100 gamma1000\n0.3568899 -1.9163830\nAnd if we do the same thing dropping tips, here are the results:\n> colMeans(YY)\ngamma100 gamma1000\n-6.1072618 0.2275565\nSo, on the face of it, it seems as though adding taxa randomly (from 100 to 1000 species in the tree) or dropping taxa (from 1000 to 100) both result in a decrease in γ - however the scale of decrease is highly asymmetrical, with random subtraction resulting in a much greater decrease in γ.\n\nAt the start of this little experiment I wasn't sure if random addition of taxa would increase or decrease γ, and in the end it seems to decrease γ but sometimes only a little.\n\n1.",
null,
"I think the basis of what you're doing depends on the definition of 'at random'. In a previous post, you describe that you're adding tips as if the probability of an extra tip at any point along any edge increased with time. It isn't exactly clear, but I assume you let the probability increase linearly as branches approach the most terminal tips. This wouldn't be true under any birth/birth-death model; it's much more unlikely for a random tip to be attached further back in time than just a linearly decreasing probability. Just think of the exponential curve of a non-log-scaled LTT...\n\nIf I remember Nee et al. rightly, the probability of an additional random tip should be the same as the probability of having a branching time of time t, as that's just the probability of having a lineage which survived for duration t.\n\nI think if you weighted tip addition in this way, relative to values of the birth and death rates, it would produce trees with no distortion of the estimated gamma parameter.\n\n2.",
null,
"Actually, looking at your code, perhaps I misinterpreted your previous post about random new tips and cumsum. Now it looks like you're using it to pick an edge at random, with longer edges weighted to have a higher chance of getting chosen relative to their length? That's basically letting edges to go anywhere with uniform probability across the tree, something which would be unexpected under Yule/birth-death.\n\n1.",
null,
"David - Yes, this is how the function works; and I agree that this should result in trees that are not Yule-like. - Liam\n\nNote: due to the very large amount of spam, all comments are now automatically submitted for moderation."
] | [
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"http://www.blogger.com/img/blogger_logo_round_35.png",
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"http://www.blogger.com/img/blogger_logo_round_35.png",
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"http://1.bp.blogspot.com/-w4ciG1TNTEA/YqI7UnbegBI/AAAAAAAAD9M/HHbrjTYWzPYI682eJrTcSKxC27pLmYIeQCK4BGAYYCw/s35/E7D41F40-D327-11EC-8FFF-0A541DCB2E73.jpg",
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https://codedocs.xyz/gammasoft71/xtd_drawing/classxtd_1_1drawing_1_1point.html | [
"",
null,
"xtd.drawing - Reference Guide 0.1.0 Modern c++17 library providing access to GDI+ basic graphics functionality. More advanced functionality is provided in the drawing 2D, imaging, and text.\nxtd::drawing::point Class Reference\n\nRepresents an ordered pair of integer x- and y-coordinates that defines a point in a two-dimensional plane. More...\n\n#include <point.h>\n\n## Public Member Functions\n\npoint ()=default\nInitializes a new instance of the point class. More...\n\npoint (int32_t dw)\nnitializes a new instance of the point class using coordinates specified by an integer value. More...\n\npoint (int32_t x, int32_t y)\nInitializes a new instance of the point class with the specified coordinates. More...\n\npoint (const size &sz)\nInitializes a new instance of the point class from a size. More...\n\nbool is_empty () const\nGets a value indicating whether this point is empty. More...\n\nvoid offset (int dx, int dy)\nTranslates this point by the specified amount. More...\n\nvoid offset (const point &p)\nTranslates this point by the specified point. More...\n\nstd::string to_string () const\nConverts this point to a human-readable string. More...\n\nint32_t x () const\nGets the x-coordinate of this point. More...\n\nvoid x (int32_t x)\nSets the x-coordinate of this point. More...\n\nint32_t y () const\nGets the y-coordinate of this point. More...\n\nvoid y (int32_t y)\nSets the y-coordinate of this point. More...\n\n## Static Public Member Functions\n\nstatic point add (const point &pt, const size &sz)\nAdds the specified size to the specified point. More...\n\nstatic point ceiling (const point_f &value)\nConverts the specified point_f to a point by rounding the values of the point_f to the next higher integer values. More...\n\nstatic point round (const point_f &value)\nConverts the specified point_f to a point object by rounding the point_f values to the nearest integer. More...\n\nstatic point subtract (const point &pt, const size &sz)\nReturns the result of subtracting specified Size from the specified point. More...\n\nstatic point truncate (const point_f &value)\nConverts the specified point_f to a point by truncating the values of the point_f. More...\n\n## Static Public Attributes\n\nstatic const point empty\nRepresents a point that has x and y values set to zero. More...\n\n## Detailed Description\n\nRepresents an ordered pair of integer x- and y-coordinates that defines a point in a two-dimensional plane.\n\nRemarks\nTo convert a point to a point_f, use Implicit cast operator.\nExamples\nvoid create_points_and_sizes(paint_event_args& e) {\n// Create the starting point.\npoint start_point = subtract_button.size();\n// Use the addition operator to get the end point.\npoint end_point = start_point + size(140, 150);\n// Draw a line between the points.\ne.graphics().draw_line(system_pens::highlight, start_point, end_point);\n// Convert the starting point to a size and compare it to the subtractButton size.\nsize button_size(start_point);\nif (button_size == subtract_button.size()) {\n// If the sizes are equal, tell the user.\ne.graphics().draw_string(\"The sizes are equal.\", font(this->font, font_style.italic), brushes::indigo, 10.0F, 65.0F);\n}\n}\n\n## § point() [1/4]\n\n xtd::drawing::point::point ( )\ndefault\n\nInitializes a new instance of the point class.\n\nRemarks\nx and y values are set to zero.\n\n## § point() [2/4]\n\n xtd::drawing::point::point ( int32_t dw )\ninlineexplicit\n\nnitializes a new instance of the point class using coordinates specified by an integer value.\n\nParameters\n dx A 32-bit integer that specifies the coordinates for the new point.\nRemarks\nThe low-order 16 bits of the dw parameter specify the horizontal x-coordinate and the higher 16 bits specify the vertical y-coordinate for the new point.\nExamples\nThe following code example demonstrates how to use the point and size. size constructors and the xtd::drawing::content_alignment enumeration. To run this example, paste this code into a Windows Form (xtd::forms) that contains a label named label1, and call the initialize_label1 method in the form's constructor.\nvoid initialize_label1() {\n// Set a border.\nlabel1.border_style = border_style::fixed_single;\n// Set the size, constructing a size from two integers.\nlabel1.size(drawing::size(100, 50));\n// Set the location, constructing a point from a 32-bit integer\nlabel1.location(point(0x280028));\n// Set and align the text on the lower-right side of the label.\nlabel1.text_align = content_alignment::bottom_right;\nlabel1.text = \"Bottom Right Alignment\";\n}\n\n## § point() [3/4]\n\n xtd::drawing::point::point ( int32_t x, int32_t y )\ninline\n\nInitializes a new instance of the point class with the specified coordinates.\n\nParameters\n x The horizontal position of the point. y The vertical position of the point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## § point() [4/4]\n\n xtd::drawing::point::point ( const size & sz )\n\nInitializes a new instance of the point class from a size.\n\nParameters\n sz A size that specifies the coordinates for the new point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## Member Function Documentation\n\n static point xtd::drawing::point::add ( const point & pt, const size & sz )\nstatic\n\nAdds the specified size to the specified point.\n\nParameters\nReturns\nThe point that is the result of the addition operation.\nRemarks\nThe add adds the width and height of the specified size to the y and y values of the specified point.\nExamples\nThe following example shows how to use the add method. To run this example, paste it into a Windows Form (xtd::formsà. Handle the form's paint event and call the add_point method from the paint event-handling method, passing e as paint_event_args.\npoint point1(10, 10);\ne.graphics().draw_line(pens::red, point1, point2);\n}\n\n## § ceiling()\n\n static point xtd::drawing::point::ceiling ( const point_f & value )\nstatic\n\nConverts the specified point_f to a point by rounding the values of the point_f to the next higher integer values.\n\nParameters\n value The point_f to convert.\nReturns\nThe point this method converts to.\n\n## § is_empty()\n\n bool xtd::drawing::point::is_empty ( ) const\ninline\n\nGets a value indicating whether this point is empty.\n\nReturns\ntrue if both X and Y are 0; otherwise, false.\n\n## § offset() [1/2]\n\n void xtd::drawing::point::offset ( int dx, int dy )\ninline\n\nTranslates this point by the specified amount.\n\nParameters\n dx The amount to offset the x-coordinate. dy The amount to offset the y-coordinate.\n\n## § offset() [2/2]\n\n void xtd::drawing::point::offset ( const point & p )\ninline\n\nTranslates this point by the specified point.\n\nParameters\n p The point used offset this point.\nRemarks\nThis method adjusts the x and y values of this point to the sum of the x and y values of this point and p.\nExamples\nThe following example shows how to use the Offset method. To run this example, paste it into a Windows Form. Handle the form's Paint event and call the Offsetpoint method from the Paint event-handling method, passing e as PaintEventArgs.\nvoid offset_point(paint_event_args& e) {\npoint point1(10, 10);\npoint1.offset(50, 0);\npoint point2(250, 10);\ne.eraphics().draw_line(pens::red, point1, point2);\n}\n\n## § round()\n\n static point xtd::drawing::point::round ( const point_f & value )\nstatic\n\nConverts the specified point_f to a point object by rounding the point_f values to the nearest integer.\n\nParameters\n value The point_f to convert.\nReturns\nThe point this method converts to.\n\n## § subtract()\n\n static point xtd::drawing::point::subtract ( const point & pt, const size & sz )\nstatic\n\nReturns the result of subtracting specified Size from the specified point.\n\nParameters\n pt The point to be subtracted from. sz The size to subtract from the point.\nReturns\nThe point that is the result of the subtraction operation.\nRemarks\nThe subtract subtracts the width and height of the specified size from the x and y values of the specified point.\n\n## § to_string()\n\n std::string xtd::drawing::point::to_string ( ) const\ninline\n\nConverts this point to a human-readable string.\n\nReturns\nA string that represents this point.\n\n## § truncate()\n\n static point xtd::drawing::point::truncate ( const point_f & value )\nstatic\n\nConverts the specified point_f to a point by truncating the values of the point_f.\n\nParameters\n value The point_f to convert.\nReturns\nThe point this method converts to.\n\n## § x() [1/2]\n\n int32_t xtd::drawing::point::x ( ) const\ninline\n\nGets the x-coordinate of this point.\n\nReturns\nThe x-coordinate of this point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## § x() [2/2]\n\n void xtd::drawing::point::x ( int32_t x )\ninline\n\nSets the x-coordinate of this point.\n\nParameters\n x The x-coordinate of this point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## § y() [1/2]\n\n int32_t xtd::drawing::point::y ( ) const\ninline\n\nGets the y-coordinate of this point.\n\nReturns\nThe y-coordinate of this point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## § y() [2/2]\n\n void xtd::drawing::point::y ( int32_t y )\ninline\n\nSets the y-coordinate of this point.\n\nParameters\n y The x-coordinate of this point.\nExamples\nThe following code example demonstrates how to use the Equality operator and how to construct a point from a size or two integers. It also demonstrates how to use the x and y properties. This example is designed to be used with Windows Forms (xtd.forms). Paste the code into a form that contains a button named button1, and associate the button1_click method with the button's click event.\nvoid button1_Click(const control& sender, const event_args& e) {\n// Construct a new point with integers.\npoint point1(100, 100);\n// Create a Graphics object.\ngraphics form_graphics = this->create_graphics();\n// Construct another point, this time using a Size.\npoint point2(size(100, 100));\n// Call the equality operator to see if the points are equal, and if so print out their x and y values.\nif (point1 == point2) {\nform_graphics.draw_string(strings::format(\"point1.x: {}, point2.x: {}, point1.y: {}, point2.y {}\", point1.x(), point2.x(), point1.y(), point2.y()), this->font(), brushes::black, point_f(10, 70));\n}\n}\n\n## § empty\n\n const point xtd::drawing::point::empty\nstatic\n\nRepresents a point that has x and y values set to zero.\n\nThe documentation for this class was generated from the following file:"
] | [
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https://gsebsolutions.in/gseb-solutions-class-9-maths-chapter-7-ex-7-1/ | [
"# GSEB Solutions Class 9 Maths Chapter 7 Triangles Ex 7.1\n\nGujarat Board GSEB Solutions Class 9 Maths Chapter 7 Triangles Ex 7.1 Textbook Questions and Answers.\n\n## Gujarat Board Textbook Solutions Class 9 Maths Chapter 7 Triangles Ex 7.1\n\nQuestion 1.\nIn quadrilateral ABCD, AC = AD, and AB bisect ∠A (see in figure). Show that ΔABC ≅ ΔABD. What can you say about BC and BD?\nSolution:\nGiven: Quadrilateral ABCD in which AB is the bisector of ∠A and AC = AD.",
null,
"To show:\nΔABC ≅ ΔABD\nProof: In ΔABC and ΔABD,\n(AB is the bisector of ∠A)\nAB = AB (Common)\n∴ ΔABC ≅ ΔABD (by SAS Congruency)\nHence BC = BD (by CPCT)\n\nc\n\nQuestion 2.\n∠DAB = ∠CBA (see figure). Prove that\n1. ΔABD ≅ ΔBAC\n2. BD = AC\n3. ∠ABD = ∠BAC",
null,
"Solution:\nGiven: ABCD is a quadrilateral in which\nAD = BC and ∠DAB = ∠CBA.\n1. In ΔABD and ΔBAC,\n∠DAB = ∠CBA (given)\nAB = AB (common)\n∴ ΔABD ≅ ΔBAC (by SAS congruency)\n\n2. ΔABD ≅ ΔBAC (proved above)\n∴ BD = AC (byCPCT)\n\n3. ΔABD ≅ ΔBAC (proved above)\n∴ ∠ABD = ∠BAC (by CPCT)",
null,
"Question 3.\nAD and BC are equal perpendiculars to a line segment AB (see fig). Show that CD bisects AB.",
null,
"Solution:\nGiven: AD and BC are perpendiculars on AB\nTo Prove: CD bisects AB.\ni.e., OA = OD\nProof: In ΔAOD and ΔBOC,\nAD || BC (If alternate interior angles are equal then lines are parallel)\n∴ ∠ADO = ∠OCB (Alternate interior angle)\nHence ΔAOD ≅ ΔBOC (by ASA congruency)\nTherefore, OA = OB (by CPCT)\n∴ CD bisects AB.",
null,
"Question 4.\nl and m are two parallel lines intersected by another pair of parallel lines p and q (see in figure). Show that\nΔABC ≅ ΔCDA\nSolution:\nGiven: l || m and both are intersected by another pair of parallel lines p and q\nTo Prove: ΔABC ≅ ΔCDA",
null,
"Proof: Since AB || CD\n∠1 = ∠2 (Alternate interior angles\n∠3 = ∠4 (Alternate interior angles)\nand AC = AC (common)\nΔABC ≅ ΔADC (by ASA congruency)\n\nQuestion 5.\nLine l is the bisector of an angle ∠A and B is any point on l. BP and BQ are perpendiculars from B to the arms of ∠A (see figure). Show that\n(i) ΔAPB ≅ ΔAQB\n(ii) BP = BQ or B is equidistant from the arms of ∠A.",
null,
"Solution:\nGiven: l is the bisector of ∠A, i.e., ∠BAP = ∠BAQ.\nBP and BQ are perpendiculars from B to arms of ∠A.\n\n(i) In ΔAPB and ΔAQB\n∠BPA = ∠BQA (each 90°)\n∠BAP = ∠BAQ (l is the angle bisector of ∠A)\nand AB = AB (Common)\nHence ΔAPB ≅ ΔAQB (By AAS congruency)\n\n(ii) Since ΔAPB ≅ ΔAQB\n∴ BP = BP (By CPCT)",
null,
"Question 6.\nIn figure,AC = AE, AB = AD and ∠BAD = ∠EAC. Show that BC = DE.",
null,
"Solution:\nGiven: In figure AC = AE.\nTo show: BC = DE\nAdding ∠DAC on both sides, we get\n∠BAD + ∠DAC = ∠EAC + ∠DAC\n⇒ ∠BAC = ∠DAE\nAC = AE (given)\n∴ ΔBAC ≅ ΔDAE (By SAS congruency)\nHence BC = DE (By CPCT)",
null,
"Question 7.\nAB is a line segment and P is its mid-point. D and E are points on the same side of AB such that ∠BAD = ∠ABE and ∠EPA = ∠DPB (see figure). Show that.",
null,
"Solution:\nProof: (i) In ΔDAP and ΔEBP,\nor ∠DAP = ∠PBE\nAP = PB (P is the mid≅points)\n∠EPA = ∠DPB (given)\nAdding ∠DPE on both sides, we get\n∠EPA + ∠DPE = ∠DPB + ∠DPE\n∠DPA = ∠EPB\n∴ ΔDAP ≅ ΔEBP (By ASA congruency)\n\n(ii) ΔDAP ≅ ΔEBP\n∴ AD = BE (by CPCT)\n\nQuestion 8.\nIn right triangle ABC, right angled at C, M is the mid-point of hypotenuse AB. C is joined to M and produced to a point D such that DM = CM. Point D is joined to point B (see figure). Show that:",
null,
"1. ∠AMC ≅ ΔBMD\n2. ∠DBC is a right angle.\n3. ΔDBC ≅ ΔACB\n4. CM = $$\\frac {1}{2}$$AB\nSolution:\nProof:\n1. In ΔAMC and ΔBMD,\nAM = BM (M is the mid-point of AB)\n∠AMC = ∠BMD (Vertically opposite angle)\nCM = DM (given)\nHence, ΔAMC ≅ ΔBMD (by SAS congruency)\nAC = BD (by CPCT)",
null,
"2. ΔAMC ≅ ΔBMD (Proved in part i)\n∴ ∠ACM = ∠BDM (by CPCT)\n(Alternate interior angles)\nHence AC || BD (If alternate interior angles are equal then lines are parallel)\n∴ ∠ACB + ∠DBC = 180°\n(Sum of consecutive interior angles is equal to 180°\n∴ ∠DBC = 180°≅ 90°\n⇒ ∠DBC = 90°\nHence ∠DBC is a right angle.\n\n3. Now in ΔACB and ΔDBC,\n∠ACB = ∠DBC (each 900)\nBC = CB (common)\nAC = BD (Proved in part i)\nHence ΔACB ≅ ΔDBC (by SAS congruency)\n\n4. ΔDBC ≅ ΔACB (Proved in part iii)\nDC = AB (by CPCT)\n⇒ 2CM = AB (DM = CM)\nCM = $$\\frac {1}{2}$$ AB"
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https://simblob.blogspot.com/2015/03/hex-grids-code-generation.html?widgetType=BlogArchive&widgetId=BlogArchive1&action=toggle&dir=open&toggle=MONTHLY-1512115200000&toggleopen=MONTHLY-1425196800000 | [
"In the last post I described how I had expected to generate lots of algorithm variants, but ended up discovering a better approach. The new system is different from the system I used when I wrote the hex grid guide. It's simpler and more modular, and I have ideas for making it even simpler. If I am able to simplify enough, I may not need to generate algorithms dynamically. In any case, the final step is to convert the algorithms in abstract format into a specific programming language.\n\nTransforming the algorithms into code was easier than figuring out how to structure the algorithms, but it was also more tedious. For expressions, it's pretty straightforward. A syntax tree like `Add(Name(\"x\"), Int(3))` turns into `x+3` in Python/C/Java/JS or `(+ x 3)` in Racket/Scheme/Lisp/Clojure. For statements, it's pretty straightforward too, but there are a few more differences between languages, including indentation and placement of braces. For declarations, languages start differing more, with functions, structs, classes, methods, modules, namespaces, etc. I wanted to generate code that uses each language's canonical style, including naming conventions and comments. I'll show some examples, using the distance function:\n\n```Function(\"cube_distance\", Int, [Param(\"a\", Cube), Param(\"b\", Cube)],\nReturn(\nInt(\nDivide(\nSubtract(Field(\"a\", \"x\"), Field(\"b\", \"x\"))),\nCall(\"abs\",\nSubtract(Field(\"a\", \"y\"), Field(\"b\", \"y\")))),\nCall(\"abs\",\nSubtract(Field(\"a\", \"z\"), Field(\"b\", \"z\")))\n),\nInt(2)\n)\n)\n)\n)\n```\nPython\nPython uses `/` for float division and `//` for integer division. My syntax tree does not. Instead, when I see a pattern `Call(Int, Divide(a, b))` I want to output `a//b` instead of `int(a/b)`. This shows up in the distance function:\n```def cube_distance(a, b):\nreturn (abs(a.x - b.x) + abs(a.y - b.y) + abs(a.z - b.z)) // 2\n```\n\nPython doesn't need a separate class to hold int and float coordinates, so `FractionalCube` should be merged into `Cube`.\n\nC++\nC++ uses `/` for float division and `/` for integer division, but it depends on the types of the operands. My syntax tree doesn't track the types of the subexpressions, so I don't know which I'll get. As a result, I end up with an unneccessary `int()` in the distance function:\n```int cube_distance(Cube a, Cube b)\n{\nreturn int((abs(a.x - b.x) + abs(a.y - b.y) + abs(a.z - b.z)) / 2);\n}\n```\nRacket\nDivision is tricky here too. Racket uses `quotient` instead of `/` when the result is going to be an integer. Like Python's output, I can look for `Call(Int, Divide(a, b))` and output `(quotient a b)` instead of `(truncate (/ a b))`. Racket also supports multi-argument addition, so I could convert `(+ (+ a b) c)` into `(+ a b c)`. Here's the distance function in Racket:\n```(define (cube-distance a b)\n(quotient\n(+ (abs (- (cube-x a) (cube-x b)))\n(abs (- (cube-y a) (cube-y b)))\n(abs (- (cube-z a) (cube-z b))))\n2))\n```\n\nThe naming convention is `cube-distance` instead of `cube_distance`.\n\nC#, Java\nDeclarations are different here. Instead of top-level functions, I need to make everything into a method. For now, I'm using static methods, but it might make sense to use instance methods for some of the algorithms. Here's what distance looks like in C#:\n```public class Cube\n{\n...\nstatic public int Distance(Cube a, Cube b)\n{\nreturn (int)((Math.Abs(a.x - b.x) + Math.Abs(a.y - b.y) + Math.Abs(a.z - b.z)) / 2);\n}\n}\n```\n\nInstead of `cube_distance`, I should use `Cube.Distance` in C# and `Cube.distance` in Java.\n\nThe differences between languages got larger as I moved to bigger functions. The sequence and record data types translate easily: C++ arrays/structs, Python lists/records, C# arrays/classes, Racket vectors/structs. But some algorithms use sets and maps, and it's less clear what types to use there. For Racket and Haskell, I want to use a more functional style, but for C++ and Python, I use an imperative style. In the end:\n\n• I didn't implement the more complex algorithms. They're harder, and I decided I should prioritize getting the simple ones working across many languages and many grid types. If I had known this from the beginning, I would've used a simpler proto-algorithm approach.\n• I didn't implement the more complex approach of adapting code for each grid type. Instead, I used the simpler approach of having each grid type convert to Cube coordinates, and then use the cube algorithms. If I had known this from the beginning, I would've written the algorithms by hand instead of writing a proto-algorithm to algorithm conversion step.\n• I didn't implement all the grid types. Instead of all the variants of Cube, Axial, and Offset, I only implemented one Cube variant, one Axial variant, and two Offset variants. If I had known this from the beginning, I would've written a simpler system.\n• The code for Axial coordinates is mostly different from the code for Offset coordinates. I was expecting more code to be shared. This made think that I probably shouldn't treat these two the same.\n• I now realize that my choice of Cube/Axial isn't great. Instead of q=x, r=z I should have picked q=x, r=y! I could have switched the y and z axes on the cube diagram. If I merge Cube and Axial I'll make this change then.\n• I wrote the proto-algorithms expecting that I'd output functional style (Racket, Haskell), object-oriented style (C#, Java, Haxe), and module style (C++, Python, Javascript). Looking back, I probably should have used object-oriented style everywhere. The style differences somewhat complicated things.\n• I also wrote the proto-algorithms expecting that I'd use them on the page itself, and also convert them to code for a downloadable library. That complicated things. I should have focused on downloadable libraries.\n• The code generator for Racket mostly works but it wasn't a purely functional style (because my \"proto-algorithms\" are imperative). I had planned to make the standard algorithms work in a purely functional style but some of the more complex algorithms will probably be too much work to justify a separate version. Looking back, I shouldn't have spent time trying to figure out a functional style for Racket; it wasn't worth spending time on a different style for just one language.\n• I didn't implement variants in code style, such as indentation and brace placement. When I started the project it seemed like it would be cool, but it just doesn't seem important anymore.\n• I didn't implement a \"pro\" version of the code that would use small arrays with 2 or 3 elements instead of named fields. Thinking of them as arrays or matrices would also potentially allow SIMD or GPU instructions. Pointy vs flat variants become an index swizzle. Converting hex to pixel and pixel to hex become matrix multiplies.\n\nIt's been a fun project, and as usual there are so many more things I want to do with this, but there are so many other things I want to do too, so I want to wrap this up.\n\n• Should I switch to the simpler system that merges Axial and Cube together? This will require a major update to the hex grid guide. It would make my advice much simpler. Instead of \"use Cube for calculations and Axial for storage\" I could say \"use Axial everywhere\". However, I'm worried that it will annoy anyone who's using the current hex grid page, because the new system will be incompatible.\n• Should I treat pointy vs flat as an x/y switch or as a 90° rotation? I am leaning towards x/y switch. I will also have to switch q/r to keep q being \"columns\" and r being \"rows\".\n\nWhat's my next step? Testing. I have unit tests for the generated code, and they all pass, but I want to test the code in a real project. What real project do I have? The hex grid page itself. I'm going to replace the hand-written hex grid code for the page with the generated code. This will give me confidence that I have the right design and set of algorithms.\n\nWhat are other things I need to do before I publish? Add comments to the generated code, implement more outputs (Javascript, Typescript, Java, Objective C, Racket), add an option for overloaded operators (+ and ==) in languages where that's standard style, and figure out instance vs class methods.\n\nThat's it for now. My blog posts aren't polished but I hope they give you a \"behind the scenes\" view of the stuff that goes through my head and the things I try while working on these projects. I also find that trying to write down what I'm doing helps me work out the design and details, and this series of posts was no exception. By \"thinking out loud\" I've been able to resolve some of the issues I had been trying to figure out. I hope to have the rest of the code generator finished in a few weeks.\n\nLabels: , , ,\n\nCraig wrote at March 30, 2015 7:25 AM\n\nI am enjoying your posts. Good luck!\n\nUnknown wrote at April 11, 2015 8:28 AM\n\nHi,\n\nI have recently started developing a game using a hexgrid and the problem of converting mouse coordinates to a grid location has hassled me for 2 days now.\n\nI tried working with code examples from your website unfortunately to no success (I am working with c++ and none of the information I needed was in c++).\n\nI finally worked it out today and I thought I would share my code with you in hope that you may be able to help provide other people with good solutions.\n\nI am aware the following code is quiet sloppy but all my testing has shown it works.\n\nMy grid layout is “odd-q” vertical layout and the following code only works for that grid type.\n\nNote: sf::Vector2i is from the SFML library and refers to an class that holds an x and y int.\n\nsf::Vector2i HexagonGrid::PixelToHexgrid(double x, double y) {\n\ndouble h = (hex_radius*2)*0.86; //So currently I have worked out height is 86% of the radius, dodgy? I don't know..\n\nint xgrid = floor(x/w); //What column is it roughly in?\nint splitx = xgrid*w; //Bring this back to a pixel coordinate, but it's now rounded to the column\n\nif ((int)floor(x/w) & 1) //Is it an odd column?\n{\ny-=h/2; //Shift the y value upward to compensate for the odd column\n}\n\ndouble yp = ((int)y % (int)h)/h; //Percentage of way down y row 0-1 (0% to 100%)\ndouble zigzag = abs((yp*2)-1); //Convert yp into a range of 0-2 then -1 to 1 and finally abs it so we get a wrapped result of 0 - 0.5 - 1 (same as 0)\n\nsplitx += zigzag*(w/3); //Multiply the zigzag by 1/4 of the pentagon, or with the current w, 1/3 is 1/4\n\nif ((((int)x % (int)w)/w)<0.33) //Is the point on the join between cells\n{\nif (splitx > x) //Is the current point in the zigzag (join) larger than the pixel x?\n{\nif (xgrid & 1) //Was the old result a odd column?\ny+=h/2; //Remove the shift from earlier\nelse\ny-=h/2; //Add a shift because it is now odd\nxgrid-=1; //Push left one because this isn't really in the next column\n}\n}\n\nint ygrid = floor(y/h);\n\nreturn sf::Vector2i(xgrid, ygrid);\n}\n\nKeep up the good work :) and thanks for the ideas on how to tackle this problem\n\nBecareful not to let pretty diagrams draw away from the information, I found a few times your interactive diagram was absolutely amazing but the information with it was mostly just confusing and involved jumping to other parts of the page to find out what a function was\n\nAmit wrote at April 11, 2015 8:51 AM\n\nThanks Chris! The algorithms (including pixel to hex) should work with any language but I'm also working on some code samples in various languages, including C++."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9233375,"math_prob":0.7487082,"size":11196,"snap":"2021-04-2021-17","text_gpt3_token_len":2730,"char_repetition_ratio":0.10096498,"word_repetition_ratio":0.024767801,"special_character_ratio":0.25187567,"punctuation_ratio":0.124726474,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97754407,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-01-26T03:41:28Z\",\"WARC-Record-ID\":\"<urn:uuid:1dfc2c8f-0b41-4a65-9209-776cb1bea36f>\",\"Content-Length\":\"114166\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:856588c8-40a8-4481-85b2-32970776440e>\",\"WARC-Concurrent-To\":\"<urn:uuid:eb1ffff2-5b0c-4c11-ac0c-5458996e3ca7>\",\"WARC-IP-Address\":\"142.250.73.193\",\"WARC-Target-URI\":\"https://simblob.blogspot.com/2015/03/hex-grids-code-generation.html?widgetType=BlogArchive&widgetId=BlogArchive1&action=toggle&dir=open&toggle=MONTHLY-1512115200000&toggleopen=MONTHLY-1425196800000\",\"WARC-Payload-Digest\":\"sha1:5DDU7TI4A3QB6DQHTGV5Y2NTTP4QS4XS\",\"WARC-Block-Digest\":\"sha1:L24ZCTOBMVN3YZ62ZVZHQF6NRO2BEH6U\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-04/CC-MAIN-2021-04_segments_1610704795033.65_warc_CC-MAIN-20210126011645-20210126041645-00542.warc.gz\"}"} |
https://www.ituring.com.cn/article/507355 | [
"``````var container = [];\ncontainer.push(\"a\");\ncontainer.push(\"b\");\ncontainer.push(\"c\"); // [\"a\", \"b\", \"c\"]\n\nvar idx = container.indexOf(\"z\"); // -1\ncontainer.splice(idx, 1); // [\"c\"]\n``````\n\n``````container.splice(idx < 0 ? -Infinite : idx, 1); // [\"a\"]\n``````\n\n``````container.splice(idx < 0 ? Infinite : idx, 1); // []\n``````\n\n22.1.3.26Array.prototype.splice ( start, deleteCount, ...items ) ...\n\n1. If relativeStart < 0, let actualStart be max((len + relativeStart), 0); else let actualStart be min(relativeStart, len).\n\nPS: 在 ES6 中我们可以愉快的使用 Set ,而无需再使用数组进行模拟啦!"
] | [
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] | {"ft_lang_label":"__label__zh","ft_lang_prob":0.74111694,"math_prob":0.9866727,"size":745,"snap":"2020-24-2020-29","text_gpt3_token_len":364,"char_repetition_ratio":0.14979757,"word_repetition_ratio":0.0,"special_character_ratio":0.32214764,"punctuation_ratio":0.3034483,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9691578,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-07-13T10:24:27Z\",\"WARC-Record-ID\":\"<urn:uuid:88af13a2-e2c9-4e02-9192-269bca4ee4e0>\",\"Content-Length\":\"34522\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:8654ef47-35a8-4194-b015-5214051360ed>\",\"WARC-Concurrent-To\":\"<urn:uuid:4dc7486d-1092-488f-afaa-e31055290ad3>\",\"WARC-IP-Address\":\"123.56.144.65\",\"WARC-Target-URI\":\"https://www.ituring.com.cn/article/507355\",\"WARC-Payload-Digest\":\"sha1:SZI4M34DIV6OB2AELFE7V76ZWXYMVB57\",\"WARC-Block-Digest\":\"sha1:BQQ7SM2UFNALN3GVKCAS6G5WYY3HCMZQ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-29/CC-MAIN-2020-29_segments_1593657143365.88_warc_CC-MAIN-20200713100145-20200713130145-00212.warc.gz\"}"} |
http://pyretis.org/current/examples/examples-retis-1d.html | [
"# RETIS in a 1D potential¶\n\nIn this example, you will explore a rare event with the Replica Exchange Transition Interface Sampling (RETIS) algorithm.\n\nWe will consider a simple 1D potential where a particle is moving. The potential is given by",
null,
"where",
null,
"is the position. By plotting this potential, we see that we have two states (at",
null,
"and",
null,
") separated by a barrier (at",
null,
"):",
null,
"Fig. 22 The potential energy as a function of the position. We have two stable states (at x = -1 and x = 1) separated by a barrier (at x = 0). In addition, three paths are shown. One is reactive while the two others are not able to escape the state at x = -1. Using the RETIS method, we can generate such paths which gives information about the reaction rate and the mechanism. The vertical dotted lines show two RETIS interfaces.\n\nUsing the RETIS algorithm, we will compute the rate constant for the transition between the two states. This particular problem has been considered before by van Erp and we will here try to reproduce these results.\n\n## Creating the PyRETIS input file¶\n\nWe will now create the input file for PyRETIS. We will do this section by section in order to explain the different keywords and settings. The full input file is given at the end of this section.\n\n### Setting up the simulation task¶\n\nThe first thing we will define is the type of simulation we will run. This is done by creating a simulation section.\n\nHere, we are going to do a retis simulation and we will do 20000 steps . Since we will be running a path sampling simulation, we will also need to specify the positions of the interfaces we will be using.\n\nRetis 1D example\n================\n\nSimulation\n----------\ntask = retis\nsteps = 20000\ninterfaces = [-0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, 1.0]\n\n\n### Setting up the system¶\n\nWe will now set up the system we are going to consider. Here, we will actually define several PyRETIS input sections:\n\n• The system section which defines the units, dimensions and temperature we are considering:\n\nSystem\n------\nunits = reduced\ndimensions = 1\ntemperature = 0.07\n\n• The box section, but since we are here just considering a single particle in a 1D potential, we will simply use a 1D box without periodic boundaries:\n\nBox\n---\nperiodic = [False]\n\n• The particles section which add particles to the system and defines the initial state:\n\nParticles\n---------\nposition = {'file': 'initial.xyz'}\nvelocity = {'generate': 'maxwell',\n'momentum': False,\n'seed': 0}\nmass = {'Ar': 1.0}\nname = ['Ar']\ntype = \n\n\nIn this case, we will read the initial configuration from a file initial.xyz and velocities are generated from a Maxwell distribution. Further, we specify the mass, particle type and we label the particle as Ar. Note that this does not mean that we are simulating Argon, it is just a label used in the output of trajectories.\n\n• The force field and potential sections which setup up the 1D double well potential:\n\nForcefield settings\n-------------------\ndescription = 1D double well\n\nPotential\n---------\nclass = DoubleWell\na = 1.0\nb = 2.0\nc = 0.0\n\n\n### Selecting the engine¶\n\nHere, we will make use of a stochastic Langevin engine. We set it up by setting the time step, the friction parameter and whether we are in the high friction limit. The seed given is a seed for the random number generator used by the integrator.\n\nEngine\n------\nclass = Langevin\ntimestep = 0.002\ngamma = 0.3\nhigh_friction = False\nseed = 0\n\n\n### TIS specific settings¶\n\nThe TIS settings control how the TIS algorithm is carried out. Here we set that 50 % of the TIS moves should be shooting moves (keyword freq) and we limit all paths to a maximum length of 20 000 steps. Further, we select aimless shooting and we tell PyRETIS to not set the momentum to zero and to not rescale the energy after drawing new random velocities. We also set allowmaxlength = False which means that for shooting, we determine stochastically the length of new paths based on the length of the path we are shooting from. The given seed is a seed for the random number generator used by the TIS algorithm.\n\nTIS settings\n------------\nfreq = 0.5\nmaxlength = 20000\naimless = True\nallowmaxlength = False\nzero_momentum = False\nrescale_energy = False\nsigma_v = -1\nseed = 0\n\n\n### RETIS specific settings¶\n\nThe RETIS section controls the RETIS algorithm. Here we request that 50 % of the RETIS moves should be swapping moves, while the remaining 50 % will be TIS moves. We further say that we do not do relative shooting and that we attempt to swap several ensembles at the same time. In case an ensemble is not participating in the swap, a null move (that is just accepting the last accepted path again) is carried out.\n\nRETIS settings\n--------------\nswapfreq = 0.5\nrelative_shoots = None\nnullmoves = True\nswapsimul = True\n\n\n### Initial path settings¶\n\nThese settings determine how we find the initial path(s). Here, we ask PyRETIS to generate these using the kick method.\n\nInitial-path settings\n---------------------\nmethod = kick\nkick-from = initial\n\n\n### Selecting the order parameter¶\n\nFor this system, we simply define the order parameter as the position of the single particle we are simulating.\n\nOrderparameter\n--------------\nclass = Position\ndim = x\nindex = 0\nperiodic = False\n\n\n### Modifying the output¶\n\nIn the Output section, we here set the frequency by which PyRETIS will write out information about the trajectories, energies and order parameters.\n\nOutput\n------\ntrajectory-file = 100\nenergy-file = 100\norder-file = 100\n\n\nRetis 1D example\n================\n\nSimulation\n----------\ntask = retis\nsteps = 20000\ninterfaces = [-0.9, -0.8, -0.7, -0.6, -0.5, -0.4, -0.3, 1.0]\n\nSystem\n------\nunits = reduced\ndimensions = 1\ntemperature = 0.07\n\nBox\n---\nperiodic = [False]\n\nEngine\n------\nclass = Langevin\ntimestep = 0.002\ngamma = 0.3\nhigh_friction = False\nseed = 0\n\nTIS settings\n------------\nfreq = 0.5\nmaxlength = 20000\naimless = True\nallowmaxlength = False\nzero_momentum = False\nrescale_energy = False\nsigma_v = -1\nseed = 0\n\nRETIS settings\n--------------\nswapfreq = 0.5\nrelative_shoots = None\nnullmoves = True\nswapsimul = True\n\nInitial-path settings\n---------------------\nmethod = kick\nkick-from = initial\n\nParticles\n---------\nposition = {'file': 'initial.xyz'}\nvelocity = {'generate': 'maxwell',\n'momentum': False,\n'seed': 0}\nmass = {'Ar': 1.0}\nname = ['Ar']\ntype = \n\nForcefield settings\n-------------------\ndescription = 1D double well\n\nPotential\n---------\nclass = DoubleWell\na = 1.0\nb = 2.0\nc = 0.0\n\nOrderparameter\n--------------\nclass = Position\ndim = x\nindex = 0\nperiodic = False\n\nOutput\n------\ntrajectory-file = 100\nenergy-file = 100\norder-file = 100\n\n\n## Running the RETIS simulation¶\n\nWe will now run the RETIS simulation. Create a new directory and place the input file (let’s call it retis.rst) here. Also, download the initial configuration initial.xyz and place it in the same folder. The simulation can then be executed using:\n\npyretisrun -i retis.rst -p\n\n\nThe -p option will display a progress bar for your simulation.\n\n## Analysing the results¶\n\nWhen the simulation has finished, we can analyse the results. PyRETIS will create a file, out.rst, which you can use for the analysis. This is a copy of the input retis.rst with some additional settings for the analysis:\n\nAnalysis settings\n-----------------\nmaxordermsd = -1\nngrid = 1001\nreport = ['latex', 'rst', 'html']\nmaxblock = 1000\ntxt-output = 'txt.gz'\nblockskip = 1\nplot = {'output': 'png', 'plotter': 'mpl', 'style': 'pyretis'}\nbins = 100\nskipcross = 1000\n\n\nFor a description of these keywords, we refer to the analysis section.\n\nThe analysis itself is performed using:\n\npyretisanalyse -i out.rst\n\n\nThis will produce a new folder, report which contains the results from the analysis. If you have latex installed, you can generate a pdf using the file retis_report.tex within the report folder. An example result for the crossing probability is shown below.",
null,
"Fig. 23 Sample output from the analysis. This figure shows the crossing probabilities for the individual ensembles and the overall crossing probability.\n\n## Improving the statistics¶\n\nWe can improve the statistics by running a longer simulation. Modify the number of steps, from 20000 to 1000000 and re-run the simulation and the analysis. Below we show an example for the crossing probability after performing the additional steps",
null,
"Fig. 24 Sample output from the analysis. This figure shows the crossing probabilities for the individual ensembles and the overall crossing probability after running 1000000 steps."
] | [
null,
"http://pyretis.org/current/_images/math/35fc4d2774f38b69ac8afe2a65b0b307ac26a3ad.png",
null,
"http://pyretis.org/current/_images/math/888f7c323ac0341871e867220ae2d76467d74d6e.png",
null,
"http://pyretis.org/current/_images/math/627dd8ffb57945e8ded86de9ceb1fef4fb3cd983.png",
null,
"http://pyretis.org/current/_images/math/23ec360a99998552bf72f9d9020b82cecb309848.png",
null,
"http://pyretis.org/current/_images/math/c34170440d4046a9b3e1ef2635a2f5d6a529a421.png",
null,
"http://pyretis.org/current/_images/1dpot.png",
null,
"http://pyretis.org/current/_images/probability-20000.png",
null,
"http://pyretis.org/current/_images/probability-1M.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.76788616,"math_prob":0.9813563,"size":7901,"snap":"2021-21-2021-25","text_gpt3_token_len":2043,"char_repetition_ratio":0.14207926,"word_repetition_ratio":0.21815409,"special_character_ratio":0.2907227,"punctuation_ratio":0.1261324,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9912466,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16],"im_url_duplicate_count":[null,6,null,null,null,9,null,9,null,9,null,9,null,3,null,3,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-06-14T04:53:49Z\",\"WARC-Record-ID\":\"<urn:uuid:2173e7b2-437d-477a-bfb7-0965b7976530>\",\"Content-Length\":\"31151\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2cf2c4d8-90d5-42cb-bcf1-c165a60704ad>\",\"WARC-Concurrent-To\":\"<urn:uuid:675d7032-1825-4d7b-bc16-6606d24c5228>\",\"WARC-IP-Address\":\"46.249.47.169\",\"WARC-Target-URI\":\"http://pyretis.org/current/examples/examples-retis-1d.html\",\"WARC-Payload-Digest\":\"sha1:5FDP7GWISDJR4GEODUIQAYDG3VCXCVQP\",\"WARC-Block-Digest\":\"sha1:IUP6NTMKNTG7PRNU4USJTFQN6V6UFXZB\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-25/CC-MAIN-2021-25_segments_1623487611445.13_warc_CC-MAIN-20210614043833-20210614073833-00008.warc.gz\"}"} |
https://zbmath.org/?q=an%3A0738.11025 | [
"zbMATH — the first resource for mathematics\n\nOn Stirling functions of the second kind. (English) Zbl 0738.11025\nThe authors prove several results for Stirling functions defined by $$S(\\alpha,k)=(1/k!)\\Delta^ kx^ \\alpha|_{x=0},$$ $$\\alpha\\geq 0$$; $$k\\in{\\mathbb{N}}_ 0$$, viewed as function of $$\\alpha$$, where $$\\Delta$$ is the forward difference operator. Among the results obtained are proofs of the continuity and differentiability of $$S$$, recurrence relations, real integral representations, a representation in terms of the Weyl derivative of fractional order $$\\alpha$$, and connections with the Bernoulli, Stirling, and Bernstein polynomials and with Bernoulli numbers of fractional order.\n\nMSC:\n 11B73 Bell and Stirling numbers 11B68 Bernoulli and Euler numbers and polynomials\nFull Text:\nReferences:\n Abramowitz, Handbook of Mathematical Functions (1965) Andrica, Bernstein’s polynomials for powers via shifting operator, Anal. Numer. Théor. Approx. 16: pp 93– (1987) · Zbl 0645.41016 Butzer, One-Dimensional Theory I (1971) Butzer, Lecture Notes in Math. 457, in: Fractional Calculus and Its Applications pp 116– (1975) Butzer, Factorial functions and Stirling numbers of fractional orders, Resultate Math. 16 pp 16:– (1989) · Zbl 0707.05002 Comtet, Advanced Combinatorics (1974) Doetsch, Einführung in Theorie und Anwendung der Laplace-Transformation (1958) Erdélyi, Tables of Integral Transforms II (1954) Gould, The Lagrange interpolation formula and Stirling numbers, Proc. Amer. Math. Soc. 11: pp 421– (1960) · Zbl 0102.04904 Gould, Note on recurrence relations for Stirling numbers, Publ. Inst. Math. 20: pp 115– (1966) · Zbl 0145.01403 Graham, Concrete Mathematics (1989) Hansen, A Table of Series and Products (1975) Hsu, Note on an asymptotic expansion of the nth difference of zero, Ann. Math. Stat. 19: pp 273– (1948) · Zbl 0035.15702 Jordan, Calculus of Finite Differences (1950) · Zbl 0041.05401 Kimball, The application of Bernoulli polynomials of negative order to differencing, Amer. J. Math. 55: pp 399– (1933) · Zbl 0007.21101 Luke, Mathematical Functions and Their Approximations (1975) Miller, Lecture Notes in Math. 457, in: Fractional Calculus and Its Applications pp 80– (1975) Moser, Stirling numbers of the second kind, Duke Math. J. 25: pp 29– (1958) · Zbl 0079.09102 Nielsen, Die Gammafunktion (1965) Nörlund, Vorlesung über Differenzenrechnung (1954) Oldham, The Fractional Calculus (1974) · Zbl 0206.46601 Rota, Finite Operator Calculus (1975) Schoenberg, CBMS 12, in: Cardinal Spline Interpolation (1973) Schumaker, Spline Functions: Basic Theory (1981) Srivastava, A Treatise on Generating Functions (1984) · Zbl 0535.33001 Westphal, Ein Kalkül für gebrochene Potenzen infinitesimaler Erzeuger von Halbgruppen und Gruppen von Operatoren; Teil I: Halbgruppenerzeuger, Comp. Math. 22: pp 67– (1970) · Zbl 0194.15401 Westphal, An approach to fractional powers of operators via fractional differences, Proc. London Math. Soc. 29 (3) pp 557– (1974) · Zbl 0294.47030 Westphal, Linear Operators and Approximation pp 23– (1974)\nThis reference list is based on information provided by the publisher or from digital mathematics libraries. Its items are heuristically matched to zbMATH identifiers and may contain data conversion errors. It attempts to reflect the references listed in the original paper as accurately as possible without claiming the completeness or perfect precision of the matching."
] | [
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https://accessmedicine.mhmedical.com/content.aspx?bookid=2724§ionid=227194691 | [
"## KEY CONCEPTS\n\nKEY CONCEPTS\n\n•",
null,
"Special statistical tests are needed when more than two groups are studied or when a group is measured on several variables.\n\n•",
null,
"Analysis of variance, or ANOVA, is a statistical method that divides the variance in an observation into the variance among groups and the rest of the variance, called the within-group or error variance.\n\n•",
null,
"The F test used to compare two variances in Chapter 6 is used to compare the variance among groups to the error.\n\n•",
null,
"An example of the way ANOVA is calculated from the definitional formulas is helpful in understanding the logic behind the test.\n\n•",
null,
"The terms used in ANOVA are important, but the details of the computations are given for illustration only, and computer programs are used for all ANOVA procedures.\n\n•",
null,
"One-way ANOVA is the appropriate method when more than two groups are studied on one variable.\n\n•",
null,
"As with the t test, certain assumptions must be made to use ANOVA, and equal variances is one of the most important.\n\n•",
null,
"Making many comparisons among groups increases the chances of a type I error, that a difference is concluded when there is none.\n\n•",
null,
"Investigators can decide ahead of time what specific comparisons they want to make.\n\n•",
null,
"The Bonferroni procedure is a common way to compensate for making many comparisons among groups; it works by reducing the size of α for each comparison, essentially increasing the difference needed to be significant.\n\n•",
null,
"Some multiple comparison methods, called post hoc, are done only if the ANOVA results are statistically significant.\n\n•",
null,
"Tukey's test is one of the most highly recommended post hoc tests for comparing mean differences.\n\n•",
null,
"The Scheffé post hoc procedure is the most conservative (requiring a larger difference to be significant), but it is also the most versatile.\n\n•",
null,
"The Newman–Kuels post hoc procedure is used frequently in basic science research.\n\n•",
null,
"Dunnett's procedure is the test of choice if the only comparisons being made are between the mean in a control group and the means in other groups.\n\n•",
null,
"Two-way ANOVA analyzes two factors instead of just one, as in one-way ANOVA. It also permits the analysis of the interaction between two factors.\n\n•",
null,
"ANOVA designs involving more than two factors are possible, generally called factorial designs.\n\n•",
null,
"Confounding variables can be accommodated by the ANOVA randomized block design.\n\n•",
null,
"Repeated-measures ANOVA is a common procedure in medical research; it is analogous to the paired t test with more than two groups and is also called the split-plot design.\n\n•",
null,
"Nonparametric ANOVA methods include Kruskal-Wallis for one-way designs and Friedman two-way ANOVA for repeated measures. These methods are analogous to the Wilcoxon procedures and are used when the assumptions for ANOVA are not met.\n\n•",
null,
"The chi-square test can be used to compare more than two proportions and to determine if there is an association between two factors, each of which can have two or more levels. It is a simple extension of the chi-square test we discussed in Chapter 6.\n\n•",
null,
"As with research questions ...\n\n### Pop-up div Successfully Displayed\n\nThis div only appears when the trigger link is hovered over. Otherwise it is hidden from view."
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https://formulas.tutorvista.com/chemistry/molar-mass-formula.html | [
"To get the best deal on Tutoring, call 1-855-666-7440 (Toll Free)",
null,
"Top\n\n# Molar Mass Formula\n\nThe molar mass of a species is the mass in grams of 1 mole (6.023x1023) of that species, i mole of atoms, 1 mole of molecules or 1 mole of formula units. So it is necessary to calculate the molecular or formula mass of each compound to get its molar mass.\n\nMolar mass is the mass (in grams) of one mole of a substance.Using the atomic mass of an element and multiplying it by the conversion factor grams per mole (g/mol), you can calculate the molar mass of that element.\n\nMolecular Mass equals the sum of the atomic masses of all atoms in the molecule. The unit of molecular mass is the amu.\n\nMolar Mass is an amount of the compound equal to its molecular mass in grams. The unit of molar mass is the gram.\n\nTwo important facts to remember:\n1. One mole of an element is 6.023x1023 atoms of that element.\n2. One mole of an element is an amount of that element equal to its molar mass (an amount equal to its atomic mass in grams).",
null,
"I mole of any element is an amount equal to its atomic mass in grams, its molar mass.\n\n Related Calculators Calculating Molar Mass of a Gas Chemistry Molar Mass Calculator formula mass calculator Calculate Molarity\n\n## Molar Mass Problems\n\nBack to Top\nSolved problems based on molar mass and molecular mass are given below.\n\n### Solved Examples\n\nQuestion 1: Find the molar mass of Ca3(PO4)2?\nSolution:\n\nDetermining the formula mass of calcium phosphate Ca3(PO4)2, which has 3 calcium ions, Ca2+, and 2 phosphate ions PO42-, starts by counting the atoms of each element in the formula 3Ca, 2P and 8O and ends by adding the atomic masses of the 13 atoms.\n\nThe formula of Ca3(PO4)2 = 3Ca + 2P + 8O\n\n(3Ca x 40.08amu) + (2P x 30.97amu) + (8O x 16.00amu) = 310.18amu\n\nThe formula mass of Ca3(PO4)2 = 310.18amu\n\nThe molar mass of Ca3(PO4)2 = 310.18g\n\n1 mole of Ca3(PO4)2 = 310.18g of Ca3(PO4)2 = 6.023 x 1023 formula units\n\nQuestion 2: Find the molar mass of MgSO4.7H2O?\nSolution:\n\nHydrates are also ionic compounds that contain a definite amount of water in the crystalline solid.\nThe hydrate of magnesium sulfate. MgSO4.7H2O has 1 Mg2- ion, 1 SO42- ion and 7 molecules of water in the formula unit.\nSeven moles of water are present for each 1 mole of MgSO4.\nThere are 27 atoms in the formula unit: 1Mg, 1S, 11O and 14H.\nThe formula mass of MgSO4.7H2O is\nThe formula of MgSO4.7H2O = 1Mg + 1S + 11O + 14H\n\n(1Mg x 24.31amu) + (1S x 32.07amu) + (11O x 16.00amu) + (14H x 1.008amu) = 246.49amu\n\nThe molar mass of MgSO4.7H2O = 246.49g\n\n1 mole of MgSO4.7H2O = 246.49g of MgSO4.7H2O = 6.022 x 1023 formula units.\n\n More topics in Molar Mass Formula Gram Formula Mass Mass Percent Formula Molar Volume Formula Percent by Volume Formula Percent by Weight Formula Percent Increase Formula Percent Decrease Formula Percentage Yield Formula\n*AP and SAT are registered trademarks of the College Board."
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https://physics.stackexchange.com/questions/32707/how-do-we-distinguish-between-virtual-particle-exchange-and-particle-decay/32748 | [
"How do we distinguish between virtual particle exchange and particle decay?\n\nThe difference between virtual particles and unstable particles is discussed at length in this question (namely, virtual particles correspond to internal lines in Feynman diagrams and are not associated with any measurable physical state). So what is going in the case of, say, Higgs production at the LHC, where the Higgs does not live long enough to reach the detector? What are the calculational and experimental differences between producing a Higgs via quark fusion, which then decays into a pair of leptons (for example) and quark-quark to lepton-lepton scattering, proceeding via Higgs exchange?\n\n(To put it another way, we'll see an increase in lepton-lepton production from virtual Higgs exchange, but how is this distinct from seeing particles produced from the decay of an unstable Higgs?)\n\n• The Higgs is always virtual because it is unstable. This was a debate in the 1960s, about whether unstable particles count as particles because they are always virtual. It's ultimately a convention, and people settled on a sensible definition that every independent propagating field in the Lagrangian is a particle. – Ron Maimon Jul 24 '12 at 2:15\n• So would you like to comment on the Arnold Neumaier's answer from that question I linked, in which he clearly distinguishes between the two? – James Jul 24 '12 at 12:52\n• Arnold Neumaier's answer is describing the signature of a new particle on the scattering, it's an additional two fermion-two fermion scattering with a nonlocal vertex. The Higs is still virtual in the answer. – Ron Maimon Jul 24 '12 at 13:12\n• I think that may be referring to his answer here. I meant his answer here: physics.stackexchange.com/questions/4349/… – James Jul 24 '12 at 21:59\n• That answer you link to is mathematically probably ok (I didn't read it carefully), but physically incorrect. It is known since Schwinger and Feynman that the diagrams have an interpretation as a particle process. It is difficult, but possible, to give this heuristic picture a better mathematical grounding, but regardless, it is correct that you can do Feynman graphs as sum over space-time paths, without any modification of the formalism. The answer is unfortunate. – Ron Maimon Jul 25 '12 at 3:33\n\nDecaying particles are described by complex energies, the imaginary part of which encodes life-time information. They are observable; in case of very short-lived particles such as the Higgs in the form of resonances, http://en.wikipedia.org/wiki/Resonance_(particle_physics) , i.e., a peak in the production rate of products of Higgs decays. The decay itself would be visible only at much better time resolution, i.e., far higher energies.\n\nIn contrast, virtual particles have real energies with 4-momentum violating the equation $p^2=(mc)^2$. They are unobservable.\n\nA much more detailed answer can be found at https://physics.stackexchange.com/a/22064/7924\n\n• Virtual Higgs exchange is the computational procedure by which (in a perturbative setting) the peak in the cross-section of dilepton production is predicted. (A lattice gauge theory has no virtual particle concept but could predict the peak, too, at least in principle. This proves that virtual particles are tied to the computational procedure.) - On the other hand, Higgs decay is how Nature actually does it. – Arnold Neumaier Jul 24 '12 at 13:23\n• @ArnoldNeumaier: That's ridiculous. You can't distinguish \"decay\" from virtual exchange--- what if the Higgs decays at a spacelike separation from its production? Virtual particles are not a calculation procedure. – Ron Maimon Jul 24 '12 at 21:58\n• @RonMaimon: If a Higgs decays at some distance from where it was created, it is a real particle with complex energy, not a virtual particle. Virtual particles have no existence outside of perturbation theory. – Arnold Neumaier Jul 25 '12 at 10:07\n• @ArnoldNeumaier: This is completely incorrect. You can have strong virtual photon exchange between a lepton and a quark in a proton which is nonlocal in space, corresponding to a long-range interaction. The Higgs is no different. Your interpretation is an anti-Feynman anti-Schwinger disease that has been going on since 1945, it's got to stop. The idea that the particle thing only works at perturbations is wrong. – Ron Maimon Jul 25 '12 at 16:48\n• @RonMaimon: Feynman diagrams (hence virtual particles) mean something only in perturbation theory. Not even nonperturbative functional integrals feature virtual particles. On the other hand, perturbation theory of a system of classical anharmonic oscillators features virtual particles, though nobody claims their physical existence. – Arnold Neumaier Jul 25 '12 at 17:20\n\nThe standard model predicts that the Higgs boson has a lifetime on the order of $10^{-22}$ seconds. That means that if the Higgs were moving close to the speed of light, it could move something like $34\\gamma$ times the diameter of a proton (on average) before it decays. $\\gamma$ is the time dilation factor from special relativity which is $$\\gamma = \\sqrt{\\frac{1}{1-\\frac{v^2}{c^2}}}$$ So, theoretically, if we could precisely aim two quarks at each other with sufficient precision and measure the vertex of the two outgoing leptons with sufficient precision, we could actually measure how far the Higgs traveled (on average) before it decayed. Note that this, like all radioactive decays, follows an exponential fall off with respect to time, so it could travel significantly longer than $34\\gamma$ proton diameters, but the probability of this rapidly approaches zero.\n\nNow, this distance of $34\\gamma$ proton diameters is far to small to actually be measured at the LHC or any other proposed accelerator. But this lifetime is measurable by measuring the width of the \"bump\" that the Higgs creates in the cross sections that can be measured at accelerators.\n\nThis bump in the cross section and this \"significant\" distance between the vertices will only occur when the total energy center of mass energy of the two incoming quarks is close to the Higgs mass (of 125 GeV - this is called an \"on shell\" Higgs production). You are correct - when the incoming quarks have a mass that is significantly different that 125 GeV (\"off shell\"), the Higgs will still contribute to the cross section for two quarks to create two leptons via a virtual Higgs exchange, but in this cases the incoming quark and outgoing lepton vertices will be VERY close to each other - nothing like $34\\gamma$ proton diameters apart you get for on-shell Higgs production. I am only guessing, but I bet the vertices would be much less than 1 proton diameter apart for these far \"off shell\" lepton production processes.\n\nOf course, as you change the energy of the collision from far off shell to exactly on shell, the distance between the two vertices will continuously change from near zero to the average of $34\\gamma$ proton diameters, but there is no particular point where you can say there is uniquely a \"real\" Higgs in this case versus a \"virtual\" Higgs in that case. However, there is still a dramatic difference between the exactly on-shell versus far off-shell results.\n\n• If you boost the higgs, you time dilate its decay rate. – Jerry Schirmer Jul 24 '12 at 14:46\n• @JerrySchirmer, Thanks! I modified the answer to include that effect. – FrankH Jul 24 '12 at 16:38"
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https://courses.lumenlearning.com/wm-prealgebra/chapter/solving-applications-with-percent/ | [
"## Solving Applications With Percent\n\n### Learning Outcomes\n\n• Calculate the tip for a meal given a percent\n• Find total recommended amount of fiber and sodium given percent and amount\n• Calculate percent calories from fat given total calories and calories from fat\n\nMany applications of percent occur in our daily lives, such as tips, sales tax, discount, and interest. To solve these applications we’ll translate to a basic percent equation, just like those we solved in the previous examples in this section. Once you translate the sentence into a percent equation, you know how to solve it.\n\nWe will update the strategy we used in our earlier applications to include equations now. Notice that we will translate a sentence into an equation.\n\n### Solve an application\n\n1. Identify what you are asked to find and choose a variable to represent it.\n2. Write a sentence that gives the information to find it.\n3. Translate the sentence into an equation.\n4. Solve the equation using good algebra techniques.\n5. Check the answer in the problem and make sure it makes sense.\n6. Write a complete sentence that answers the question.\n\nNow that we have the strategy to refer to, and have practiced solving basic percent equations, we are ready to solve percent applications. Be sure to ask yourself if your final answer makes sense—since many of the applications we’ll solve involve everyday situations, you can rely on your own experience.\n\n### example\n\nDezohn and his girlfriend enjoyed a dinner at a restaurant, and the bill was $\\text{\\68.50}$. They want to leave an $\\text{18%}$ tip. If the tip will be $\\text{18%}$ of the total bill, how much should the tip be?\n\nSolution\n\n What are you asked to find? the amount of the tip Choose a variable to represent it. Let $t=$ amount of tip. Write a sentence that give the information to find it. The tip is 18% of the total bill. Translate the sentence into an equation.",
null,
"Multiply. $t=12.33$ Check. Is this answer reasonable? If we approximate the bill to $\\text{\\70}$ and the percent to $20\\text{%}$, we would have a tip of $\\text{\\14}$. So a tip of $\\text{\\12.33}$ seems reasonable. Write a complete sentence that answers the question. The couple should leave a tip of $\\text{\\12.33}$.\n\n### try it\n\nIn the next video we show another example of finding how much tip to give based on percent.\n\n### example\n\nThe label on Masao’s breakfast cereal said that one serving of cereal provides $85$ milligrams (mg) of potassium, which is $\\text{2%}$ of the recommended daily amount. What is the total recommended daily amount of potassium?",
null,
"### example\n\nMitzi received some gourmet brownies as a gift. The wrapper said each brownie was $480$ calories, and had $240$ calories of fat. What percent of the total calories in each brownie comes from fat?\n\n### try it\n\nThe following video show another example of how to solve an application that involves percent."
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As I into some internet should the information students from visiting the school or. Ein Essay singers also generally comprised our protagonist. Reflective knowledge an element of comfort to store to succeed I collected be where challenging reads. Oftentimes, these by way compared to of a hand them give students of the. </p>\n\n<h2>Order Metaglip Best Price. Canada Drugs Pharmacy</h2>"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8140686,"math_prob":0.9999478,"size":88392,"snap":"2023-40-2023-50","text_gpt3_token_len":29040,"char_repetition_ratio":0.2885686,"word_repetition_ratio":0.015128284,"special_character_ratio":0.39256945,"punctuation_ratio":0.22026432,"nsfw_num_words":3,"has_unicode_error":false,"math_prob_llama3":0.9954352,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-02T13:06:40Z\",\"WARC-Record-ID\":\"<urn:uuid:d3abdc33-128d-4145-b0fc-4fab607c354e>\",\"Content-Length\":\"162549\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:4cd21250-a86a-4e8b-bb37-ab2f28aa9be2>\",\"WARC-Concurrent-To\":\"<urn:uuid:8b7243a2-0b6d-43e6-a8f9-6c7473fe4ed2>\",\"WARC-IP-Address\":\"103.179.86.114\",\"WARC-Target-URI\":\"http://order.lsp-poltekapp.org/2021/08/\",\"WARC-Payload-Digest\":\"sha1:RYY65BTPHLFXVN62R4O5KVTDOEBICMOE\",\"WARC-Block-Digest\":\"sha1:WMDXWCKJ2KLSXW4HOONWZUPOA7FCYSGE\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100399.81_warc_CC-MAIN-20231202105028-20231202135028-00443.warc.gz\"}"} |
https://www.lfhacks.com/tech/python-flatten-sub-sequence/ | [
"# Python 展开多层嵌套的列表",
null,
"## 背景\n\n``````[1, 'a', ['b', ['c'], [ ], [3, 4]]]\n``````\n\n``````1, a, b, c, 3, 4\n``````\n\n## 未知嵌套层数\n\n``````def 展开(任意序列)\n``````\n\n``````def 展开(任意序列):\n对于 任意序列 里的 每一项:\n如果 仍然是序列:\n给出(yield)展开(这个序列) 里的每一项\n否则:\n给出(yield)这一项\n``````\n\n``````def flatten(sequence):\nfor item in sequence:\nif type(item) is list:\nfor subitem in flatten(item):\nyield subitem\nelse:\nyield item\na = [1, 'a', ['b', ['c'], [ ], [3, 4]]]\nfor x in flatten(a):\nprint x,\n``````\n\n## 用列表解析实现\n\n``````flatten = lambda x: [subitem for item in x for subitem in flatten(item)] \\\nif type(x) is list else [x]\na = [1, 'a', ['b', ['c'], [ ], [3, 4]]]\nfor x in flatten(a):\nprint x,\n``````\n\n``````1 a b c 3 4\n``````\n\n## 用 reduce 实现\n\nfrom functools import reduce\n\n``````reduce(lambda x,y:x+y,[[1,2],[3,4]])\n``````\n\n``````[1, 2, 3, 4]\n``````",
null,
""
] | [
null,
"https://www.lfhacks.com/image/poster/579.jpg",
null,
"https://www.lfhacks.com/image/common/cc-by.png",
null
] | {"ft_lang_label":"__label__zh","ft_lang_prob":0.8490819,"math_prob":0.99028367,"size":1106,"snap":"2021-43-2021-49","text_gpt3_token_len":690,"char_repetition_ratio":0.11524501,"word_repetition_ratio":0.1891892,"special_character_ratio":0.32188064,"punctuation_ratio":0.19742489,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9816496,"pos_list":[0,1,2,3,4],"im_url_duplicate_count":[null,1,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-16T23:38:28Z\",\"WARC-Record-ID\":\"<urn:uuid:58027cd2-51c8-446b-a88a-4ffe401686e2>\",\"Content-Length\":\"13287\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2e4977f4-1046-44e7-9fd8-1929d92726ec>\",\"WARC-Concurrent-To\":\"<urn:uuid:a3cc3fa6-b488-4322-866d-8741bca36d19>\",\"WARC-IP-Address\":\"118.123.21.94\",\"WARC-Target-URI\":\"https://www.lfhacks.com/tech/python-flatten-sub-sequence/\",\"WARC-Payload-Digest\":\"sha1:6YG4BT3R23TFNNAB6VXMWXPUCC752HBY\",\"WARC-Block-Digest\":\"sha1:CWIJJYYXPATMDMGIAIKYSUHY6YGMCITS\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323585045.2_warc_CC-MAIN-20211016231019-20211017021019-00437.warc.gz\"}"} |
https://codereview.stackexchange.com/questions/61899/cron-job-that-runs-a-few-checks-across-different-tables-in-database | [
"# Cron job that runs a few checks across different tables in database\n\nI have been working on a cronjob that runs a few checks across different tables in my database.\n\nThe issue is that although it works, I feel like I am doing something horribly wrong in terms of the standards set out by others and also in the future for any adjustments I make.\n\nThe code below DOES work perfectly, but a foreach in a foreach seems horrible. Is there any way to tidy up what I am doing, or would it be acceptable code by a good standard?\n\n// CRON JOB - Add notification if a build has been updated\nrequire(\"../../commonlive.php\");\nrequire '../../functions/database-functions.php';\n// select all users, and run a foreach\n$query = \"SELECT * FROM users\";$query_params = array();\ntry {\n$stmt =$db->prepare($query);$result = $stmt->execute($query_params);\n}\ncatch(PDOException $ex) { die(\"Failed to run query: \" .$ex->getMessage());\n}\n$rows =$stmt->fetchAll();\n// for each user, check its user ID against the build tracking and then see when the build was updated last\nforeach($rows as$row){\n$id =$row['id'];\n//echo \"user id: $id, \"; // check the build_tracking table for a row that matches the user id$query = \" SELECT * FROM build_tracking WHERE user_id = :user_id\";\n$query_params = array(':user_id' =>$id);\ntry {\n$stmt =$db->prepare($query);$result = $stmt->execute($query_params);\n$rows =$stmt->fetchAll();\nforeach ($rows as$row) {\n\n$build_id =$row['build_id'];\n$user_id =$row['user_id'];\n$view_time =$row['view_time'];\n\n//echo \"build id track: $build_id\"; // check the build_tracking table for a row that matches the user id and build id.$query = \" SELECT * FROM blogs WHERE id = :build_id AND frontpage = 1\";\n$query_params = array(':build_id' =>$build_id);\ntry {\n$stmt =$db->prepare($query);$result = $stmt->execute($query_params);\n$rows =$stmt->fetchAll();\nforeach ($rows as$row) {\n$build_id =$row['id'];\n$buildOwnerID =$row['userid'];\n$lastupdated =$row['lastupdated'];\n\n$stmt =$db->prepare(\"SELECT * FROM followers WHERE userid = $user_id AND blogid =$build_id\");\n$stmt->execute();$stmt->setFetchMode(PDO::FETCH_ASSOC);\n$countfollow =$stmt->rowCount();\n\nif ($view_time <$lastupdated && $countfollow > 0) {$userTo = $id;$userFrom = $buildOwnerID;$type = 'buildUpdate';\n$date = time();$postID = 1;\n$buildID =$build_id;\n$commentID = 1; // see if a notif already exists with the user id and build id$query = \"SELECT * FROM notifications WHERE user_to = :userTo AND buildID = :buildID AND type = :type AND status != 3\";\n$query_params = array(':userTo' =>$userTo, ':buildID' => $buildID, ':type' =>$type);\ntry {\n$stmt =$db->prepare($query);$result = $stmt->execute($query_params);\n$checkForExistOfNotif =$stmt->rowCount();\n}\ncatch(PDOException $ex) { die(\"Failed to run query: \" .$ex->getMessage());\n}\nif (!$checkForExistOfNotif) { //echo \"adding,$build_id\";\naddNotification($userTo,$userFrom, $type,$date, $postID,$buildID, $commentID); } } } } catch(PDOException$ex) { die();\n}\n}\n}\ncatch(PDOException $ex) { die(); } } • you need to work on your formatting, the indentation is terrible, I almost couldn't find the first foreach – Malachi Sep 3 '14 at 22:10 • sorry, its perfect in sublime (using 2 spaces instead of tab) but SO always messes it up. – Lovelock Sep 3 '14 at 22:12 • Using foreach($rows as $row): is pretty unusual when you're not exiting out of the PHP block to insert HTML. – Kid Diamond Sep 3 '14 at 22:12 • should be using foreach($rows as $row){ //code } right? – Lovelock Sep 3 '14 at 22:13 • @user2921557, no one has answered so you can fix the formatting, I assume you already have good formatting, so please fix it quickly – Malachi Sep 3 '14 at 22:17 ## 2 Answers Things that strike me as odd are that you have nested PDOExceptions and in the catch blocks all you do is die. If that is the case, why bother nesting them? Just have one try at the top and one catch at the bottom. You are running this as a cronjob, so if it fails with die(), how does that help anyone trying to debug what went wrong? At least pass some sort of indication as to what the error was. I would also split your code into functions, each function should do 1 thing, then you can easily read what the top level code is doing I am not going to re-write all your code, but here is an example of what it could start to look like if you split it into functions. It becomes a lot more readable (maintainable) even with no comments. try {$users = select_all_users();\n\nforeach ($users as$user) {\n$builds = select_builds_by_user($user['id']);\n\nforeach ($builds as$build) {\n$build_id =$build['build_id'];\n$user_id =$build['user_id'];\n$view_time =$build['view_time'];\n\n\nThe reason I didn't bother to re-write it all, is because I am pretty sure you could merge 3 or more of those SQL statements and using joins to fetch the data in one query, rather then the foreach, foreach, foreach going on.\n\nFor example you start off by selecting all users and then looping though them checking to see if builds exist. (I have no idea what your database structure is, so I can only offer guesses here) but this SQL selects all builds for users in one go.\n\n SELECT *\nFROM build_tracking\n\n\nHope this gives you some of ideas of things to work on\n\nYou can clean up deeply nested situations like this by breaking the nested logic into functions.\n\nforeach($rows as$row) {\n// Do something\nprocessBuilds($row['buildId']); } function processBuilds($buildId) {\n// Do stuff\nforeach($buildRows as$buildRow) {\nprocessBlogs($buildRow['blogId']); } } function processBlogs($blogId) {\n// Do stuff\nforeach($blogRows as$blogRow) {\n// Do more stuff\n}\n}\n\n\nDepending on the size of the application, it may make sense to take this one step further and take advantage of object-oriented programming."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.68293554,"math_prob":0.7562444,"size":3159,"snap":"2020-24-2020-29","text_gpt3_token_len":850,"char_repetition_ratio":0.12488114,"word_repetition_ratio":0.18526316,"special_character_ratio":0.32668567,"punctuation_ratio":0.18819188,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9767402,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-07-12T11:56:17Z\",\"WARC-Record-ID\":\"<urn:uuid:8faf3d64-d79b-44f7-acf9-8eebf1c42b06>\",\"Content-Length\":\"162512\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:a7795eaf-884a-4476-bd52-10c4ad8c4601>\",\"WARC-Concurrent-To\":\"<urn:uuid:447572ea-8146-493e-84d5-81ab3da7f1e7>\",\"WARC-IP-Address\":\"151.101.65.69\",\"WARC-Target-URI\":\"https://codereview.stackexchange.com/questions/61899/cron-job-that-runs-a-few-checks-across-different-tables-in-database\",\"WARC-Payload-Digest\":\"sha1:QJHE4UQMD6I3NDR243AUN5F4PL37FUMB\",\"WARC-Block-Digest\":\"sha1:FEU3QIKSJXDQJNPFBF4KR4JPIPXASRVH\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-29/CC-MAIN-2020-29_segments_1593657138718.61_warc_CC-MAIN-20200712113546-20200712143546-00252.warc.gz\"}"} |
https://hackage.haskell.org/package/hmatrix-0.20.0.0/docs/src/Internal.ST.html | [
"```{-# LANGUAGE Rank2Types #-}\n{-# LANGUAGE BangPatterns #-}\n{-# LANGUAGE ViewPatterns #-}\n\n-----------------------------------------------------------------------------\n-- |\n-- Module : Internal.ST\n-- Copyright : (c) Alberto Ruiz 2008\n-- License : BSD3\n-- Maintainer : Alberto Ruiz\n-- Stability : provisional\n--\n-- In-place manipulation inside the ST monad.\n-- See @examples/inplace.hs@ in the repository.\n--\n-----------------------------------------------------------------------------\n\nmodule Internal.ST (\nST, runST,\n-- * Mutable Vectors\nSTVector, newVector, thawVector, freezeVector, runSTVector,\nreadVector, writeVector, modifyVector, liftSTVector,\n-- * Mutable Matrices\nSTMatrix, newMatrix, thawMatrix, freezeMatrix, runSTMatrix,\nreadMatrix, writeMatrix, modifyMatrix, liftSTMatrix,\nmutable, extractMatrix, setMatrix, rowOper, RowOper(..), RowRange(..), ColRange(..), gemmm, Slice(..),\n-- * Unsafe functions\nnewUndefinedVector,\nunsafeReadVector, unsafeWriteVector,\nunsafeThawVector, unsafeFreezeVector,\nnewUndefinedMatrix,\nunsafeReadMatrix, unsafeWriteMatrix,\nunsafeThawMatrix, unsafeFreezeMatrix\n) where\n\nimport Internal.Vector\nimport Internal.Matrix\nimport Internal.Vectorized\nimport Control.Monad.ST(ST, runST)\nimport Foreign.Storable(Storable, peekElemOff, pokeElemOff)\nimport Control.Monad.ST.Unsafe(unsafeIOToST)\n\n{-# INLINE ioReadV #-}\nioReadV :: Storable t => Vector t -> Int -> IO t\nioReadV v k = unsafeWith v \\$ \\s -> peekElemOff s k\n\n{-# INLINE ioWriteV #-}\nioWriteV :: Storable t => Vector t -> Int -> t -> IO ()\nioWriteV v k x = unsafeWith v \\$ \\s -> pokeElemOff s k x\n\nnewtype STVector s t = STVector (Vector t)\n\nthawVector :: Storable t => Vector t -> ST s (STVector s t)\nthawVector = unsafeIOToST . fmap STVector . cloneVector\n\nunsafeThawVector :: Storable t => Vector t -> ST s (STVector s t)\nunsafeThawVector = unsafeIOToST . return . STVector\n\nrunSTVector :: Storable t => (forall s . ST s (STVector s t)) -> Vector t\nrunSTVector st = runST (st >>= unsafeFreezeVector)\n\n{-# INLINE unsafeReadVector #-}\nunsafeReadVector :: Storable t => STVector s t -> Int -> ST s t\nunsafeReadVector (STVector x) = unsafeIOToST . ioReadV x\n\n{-# INLINE unsafeWriteVector #-}\nunsafeWriteVector :: Storable t => STVector s t -> Int -> t -> ST s ()\nunsafeWriteVector (STVector x) k = unsafeIOToST . ioWriteV x k\n\n{-# INLINE modifyVector #-}\nmodifyVector :: (Storable t) => STVector s t -> Int -> (t -> t) -> ST s ()\nmodifyVector x k f = readVector x k >>= return . f >>= unsafeWriteVector x k\n\nliftSTVector :: (Storable t) => (Vector t -> a) -> STVector s t -> ST s a\nliftSTVector f (STVector x) = unsafeIOToST . fmap f . cloneVector \\$ x\n\nfreezeVector :: (Storable t) => STVector s t -> ST s (Vector t)\nfreezeVector v = liftSTVector id v\n\nunsafeFreezeVector :: (Storable t) => STVector s t -> ST s (Vector t)\nunsafeFreezeVector (STVector x) = unsafeIOToST . return \\$ x\n\n{-# INLINE safeIndexV #-}\nsafeIndexV :: Storable t2\n=> (STVector s t2 -> Int -> t) -> STVector t1 t2 -> Int -> t\nsafeIndexV f (STVector v) k\n| k < 0 || k>= dim v = error \\$ \"out of range error in vector (dim=\"\n++show (dim v)++\", pos=\"++show k++\")\"\n| otherwise = f (STVector v) k\n\n{-# INLINE readVector #-}\nreadVector :: Storable t => STVector s t -> Int -> ST s t\nreadVector = safeIndexV unsafeReadVector\n\n{-# INLINE writeVector #-}\nwriteVector :: Storable t => STVector s t -> Int -> t -> ST s ()\nwriteVector = safeIndexV unsafeWriteVector\n\nnewUndefinedVector :: Storable t => Int -> ST s (STVector s t)\nnewUndefinedVector = unsafeIOToST . fmap STVector . createVector\n\n{-# INLINE newVector #-}\nnewVector :: Storable t => t -> Int -> ST s (STVector s t)\nnewVector x n = do\nv <- newUndefinedVector n\nlet go (-1) = return v\ngo !k = unsafeWriteVector v k x >> go (k-1 :: Int)\ngo (n-1)\n\n-------------------------------------------------------------------------\n\n{-# INLINE ioReadM #-}\nioReadM :: Storable t => Matrix t -> Int -> Int -> IO t\nioReadM m r c = ioReadV (xdat m) (r * xRow m + c * xCol m)\n\n{-# INLINE ioWriteM #-}\nioWriteM :: Storable t => Matrix t -> Int -> Int -> t -> IO ()\nioWriteM m r c val = ioWriteV (xdat m) (r * xRow m + c * xCol m) val\n\nnewtype STMatrix s t = STMatrix (Matrix t)\n\nthawMatrix :: Element t => Matrix t -> ST s (STMatrix s t)\nthawMatrix = unsafeIOToST . fmap STMatrix . cloneMatrix\n\nunsafeThawMatrix :: Storable t => Matrix t -> ST s (STMatrix s t)\nunsafeThawMatrix = unsafeIOToST . return . STMatrix\n\nrunSTMatrix :: Storable t => (forall s . ST s (STMatrix s t)) -> Matrix t\nrunSTMatrix st = runST (st >>= unsafeFreezeMatrix)\n\n{-# INLINE unsafeReadMatrix #-}\nunsafeReadMatrix :: Storable t => STMatrix s t -> Int -> Int -> ST s t\nunsafeReadMatrix (STMatrix x) r = unsafeIOToST . ioReadM x r\n\n{-# INLINE unsafeWriteMatrix #-}\nunsafeWriteMatrix :: Storable t => STMatrix s t -> Int -> Int -> t -> ST s ()\nunsafeWriteMatrix (STMatrix x) r c = unsafeIOToST . ioWriteM x r c\n\n{-# INLINE modifyMatrix #-}\nmodifyMatrix :: (Storable t) => STMatrix s t -> Int -> Int -> (t -> t) -> ST s ()\nmodifyMatrix x r c f = readMatrix x r c >>= return . f >>= unsafeWriteMatrix x r c\n\nliftSTMatrix :: (Element t) => (Matrix t -> a) -> STMatrix s t -> ST s a\nliftSTMatrix f (STMatrix x) = unsafeIOToST . fmap f . cloneMatrix \\$ x\n\nunsafeFreezeMatrix :: (Storable t) => STMatrix s t -> ST s (Matrix t)\nunsafeFreezeMatrix (STMatrix x) = unsafeIOToST . return \\$ x\n\nfreezeMatrix :: (Element t) => STMatrix s t -> ST s (Matrix t)\nfreezeMatrix m = liftSTMatrix id m\n\ncloneMatrix :: Element t => Matrix t -> IO (Matrix t)\ncloneMatrix m = copy (orderOf m) m\n\n{-# INLINE safeIndexM #-}\nsafeIndexM :: (STMatrix s t2 -> Int -> Int -> t)\n-> STMatrix t1 t2 -> Int -> Int -> t\nsafeIndexM f (STMatrix m) r c\n| r<0 || r>=rows m ||\nc<0 || c>=cols m = error \\$ \"out of range error in matrix (size=\"\n++show (rows m,cols m)++\", pos=\"++show (r,c)++\")\"\n| otherwise = f (STMatrix m) r c\n\n{-# INLINE readMatrix #-}\nreadMatrix :: Storable t => STMatrix s t -> Int -> Int -> ST s t\nreadMatrix = safeIndexM unsafeReadMatrix\n\n{-# INLINE writeMatrix #-}\nwriteMatrix :: Storable t => STMatrix s t -> Int -> Int -> t -> ST s ()\nwriteMatrix = safeIndexM unsafeWriteMatrix\n\nsetMatrix :: Element t => STMatrix s t -> Int -> Int -> Matrix t -> ST s ()\nsetMatrix (STMatrix x) i j m = unsafeIOToST \\$ setRect i j m x\n\nnewUndefinedMatrix :: Storable t => MatrixOrder -> Int -> Int -> ST s (STMatrix s t)\nnewUndefinedMatrix ord r c = unsafeIOToST \\$ fmap STMatrix \\$ createMatrix ord r c\n\n{-# NOINLINE newMatrix #-}\nnewMatrix :: Storable t => t -> Int -> Int -> ST s (STMatrix s t)\nnewMatrix v r c = unsafeThawMatrix \\$ reshape c \\$ runSTVector \\$ newVector v (r*c)\n\n--------------------------------------------------------------------------------\n\ndata ColRange = AllCols\n| ColRange Int Int\n| Col Int\n| FromCol Int\n\ngetColRange :: Int -> ColRange -> (Int, Int)\ngetColRange c AllCols = (0,c-1)\ngetColRange c (ColRange a b) = (a `mod` c, b `mod` c)\ngetColRange c (Col a) = (a `mod` c, a `mod` c)\ngetColRange c (FromCol a) = (a `mod` c, c-1)\n\ndata RowRange = AllRows\n| RowRange Int Int\n| Row Int\n| FromRow Int\n\ngetRowRange :: Int -> RowRange -> (Int, Int)\ngetRowRange r AllRows = (0,r-1)\ngetRowRange r (RowRange a b) = (a `mod` r, b `mod` r)\ngetRowRange r (Row a) = (a `mod` r, a `mod` r)\ngetRowRange r (FromRow a) = (a `mod` r, r-1)\n\ndata RowOper t = AXPY t Int Int ColRange\n| SCAL t RowRange ColRange\n| SWAP Int Int ColRange\n\nrowOper :: (Num t, Element t) => RowOper t -> STMatrix s t -> ST s ()\n\nrowOper (AXPY x i1 i2 r) (STMatrix m) = unsafeIOToST \\$ rowOp 0 x i1' i2' j1 j2 m\nwhere\n(j1,j2) = getColRange (cols m) r\ni1' = i1 `mod` (rows m)\ni2' = i2 `mod` (rows m)\n\nrowOper (SCAL x rr rc) (STMatrix m) = unsafeIOToST \\$ rowOp 1 x i1 i2 j1 j2 m\nwhere\n(i1,i2) = getRowRange (rows m) rr\n(j1,j2) = getColRange (cols m) rc\n\nrowOper (SWAP i1 i2 r) (STMatrix m) = unsafeIOToST \\$ rowOp 2 0 i1' i2' j1 j2 m\nwhere\n(j1,j2) = getColRange (cols m) r\ni1' = i1 `mod` (rows m)\ni2' = i2 `mod` (rows m)\n\nextractMatrix :: Element a => STMatrix t a -> RowRange -> ColRange -> ST s (Matrix a)\nextractMatrix (STMatrix m) rr rc = unsafeIOToST (extractR (orderOf m) m 0 (idxs[i1,i2]) 0 (idxs[j1,j2]))\nwhere\n(i1,i2) = getRowRange (rows m) rr\n(j1,j2) = getColRange (cols m) rc\n\n-- | r0 c0 height width\ndata Slice s t = Slice (STMatrix s t) Int Int Int Int\n\nslice :: Element a => Slice t a -> Matrix a\nslice (Slice (STMatrix m) r0 c0 nr nc) = subMatrix (r0,c0) (nr,nc) m\n\ngemmm :: Element t => t -> Slice s t -> t -> Slice s t -> Slice s t -> ST s ()\ngemmm beta (slice->r) alpha (slice->a) (slice->b) = res\nwhere\nres = unsafeIOToST (gemm v a b r)\nv = fromList [alpha,beta]\n\nmutable :: Element t => (forall s . (Int, Int) -> STMatrix s t -> ST s u) -> Matrix t -> (Matrix t,u)\nmutable f a = runST \\$ do\nx <- thawMatrix a\ninfo <- f (rows a, cols a) x\nr <- unsafeFreezeMatrix x\nreturn (r,info)\n```"
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https://www.ipl.org/essay/Logistic-Regression-Analysis-FCDJ8MSGZVG | [
"",
null,
"# Logistic Regression Analysis\n\n720 Words3 Pages\nRegression analysis is one of the most useful and the most frequently used statistical methods .regression analysis is a form of predictive modeling technique which investigates the relationship between a dependent and one or more predictor variables. Among the different regression models, logistic regression plays a particular role. However , the basic concept of the linear regression model is quantifying the effect of several explanatory variables on one dependent continuous variable. For situations where the dependent variable is qualitative, however, other methods have been developed. One of the method is logistic regression model, which specifically covers the case of binary or dichotomous response. The statistical analysis of dichotomous outcome variable is frequently interpreted with the use of logistic regression methods. The multiple logistic regression…show more content…\nCramer (2003) discussed an overview of the development of the logistic regression model. He identifies three sources that had a profound impact on the model: applied mathematics, experimental statistics, and economic theory. Agresti (2002) also provided details of the development on logistic regression in different areas. He states, “Sir David R. Cox introduced many statisticians to logistic regression through his 1958 article and 1970 book, The Analysis of Binary Data.” However, logistic regression is widely used as a popular model for the analysis of binary data with the areas of applications including physical, biomedical, and behavioral sciences. For example, Cornfield (1962) presented the preliminary results from the Framingham Study. The purpose of the study was to find the roles of risk factors of cholesterol levels (low versus high values) and blood pressure (low versus high values) in the development of coronary heart disease (yes or no) in the population of the"
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https://alienexpanse.com/index.php?threads/muzyka.25/page-101 | [
"Muzyka\n\nDiscussion in 'Arts, Sports, & Entertainment' started by Toroid, Jul 18, 2016.\n\n•",
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"Like x 1\n•",
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"Like x 1\n12.\n•",
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"Thanks x 1\n14.\n•",
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"Thanks x 1\n15.\n\n16. Glory to the King"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.64695287,"math_prob":0.93202955,"size":269,"snap":"2019-26-2019-30","text_gpt3_token_len":95,"char_repetition_ratio":0.21132076,"word_repetition_ratio":0.0,"special_character_ratio":0.25650558,"punctuation_ratio":0.29032257,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9648999,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-06-18T17:43:28Z\",\"WARC-Record-ID\":\"<urn:uuid:3ae1da83-8b0a-4af1-adb6-daf097da8cb4>\",\"Content-Length\":\"89653\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:69d19ca8-cc66-4dd8-85d6-bf941c670a9b>\",\"WARC-Concurrent-To\":\"<urn:uuid:74ac0fb1-f5a7-4029-bebf-5436f0cc654b>\",\"WARC-IP-Address\":\"160.153.71.38\",\"WARC-Target-URI\":\"https://alienexpanse.com/index.php?threads/muzyka.25/page-101\",\"WARC-Payload-Digest\":\"sha1:ESO5QFZXXD2DC3UHWXTBNSEEJCQLISZK\",\"WARC-Block-Digest\":\"sha1:GIKRCJD3NRODFRW3A3P2GWCX7HRNKAAD\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-26/CC-MAIN-2019-26_segments_1560627998808.17_warc_CC-MAIN-20190618163443-20190618185443-00415.warc.gz\"}"} |
https://paperswithcode.com/paper/quaternion-gradient-and-hessian | [
"13 Jun 2014 · , ·\n\nThe optimization of real scalar functions of quaternion variables, such as the mean square error or array output power, underpins many practical applications. Solutions often require the calculation of the gradient and Hessian, however, real functions of quaternion variables are essentially non-analytic... To address this issue, we propose new definitions of quaternion gradient and Hessian, based on the novel generalized HR (GHR) calculus, thus making possible efficient derivation of optimization algorithms directly in the quaternion field, rather than transforming the problem to the real domain, as is current practice. In addition, unlike the existing quaternion gradients, the GHR calculus allows for the product and chain rule, and for a one-to-one correspondence of the proposed quaternion gradient and Hessian with their real counterparts. Properties of the quaternion gradient and Hessian relevant to numerical applications are elaborated, and the results illuminate the usefulness of the GHR calculus in greatly simplifying the derivation of the quaternion least mean squares, and in quaternion least square and Newton algorithm. The proposed gradient and Hessian are also shown to enable the same generic forms as the corresponding real- and complex-valued algorithms, further illustrating the advantages in algorithm design and evaluation. read more\n\nPDF Abstract\n\n# Code Add Remove Mark official\n\nNo code implementations yet. Submit your code now\n\n# Datasets\n\nAdd Datasets introduced or used in this paper\n\n# Results from the Paper Add Remove\n\nSubmit results from this paper to get state-of-the-art GitHub badges and help the community compare results to other papers."
] | [
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https://republicofsouthossetia.org/question/simplify-the-following-epression-using-pemdas-24-6-3-5-8-9-16373655-85/ | [
"## Simplify the following expression using PEMDAS: 24 + 6/3*5*8-9*\n\nQuestion\n\nSimplify the following expression using PEMDAS: 24 + 6/3*5*8-9*\n\nin progress 0\n2 weeks 2021-09-07T21:10:54+00:00 1 Answer 0\n\n95\n\nStep-by-step explanation:\n\n24+(6\n/3)\n(5)(8)−9\n\n=24+(2)(5)(8)−9\n\n=24+(10)(8)−9\n\n=24+80−9\n\n=104−9\n\n=95"
] | [
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https://answers.everydaycalculation.com/compare-fractions/10-20-and-40-84 | [
"Solutions by everydaycalculation.com\n\n## Compare 10/20 and 40/84\n\n10/20 is greater than 40/84\n\n#### Steps for comparing fractions\n\n1. Find the least common denominator or LCM of the two denominators:\nLCM of 20 and 84 is 420\n\nNext, find the equivalent fraction of both fractional numbers with denominator 420\n2. For the 1st fraction, since 20 × 21 = 420,\n10/20 = 10 × 21/20 × 21 = 210/420\n3. Likewise, for the 2nd fraction, since 84 × 5 = 420,\n40/84 = 40 × 5/84 × 5 = 200/420\n4. Since the denominators are now the same, the fraction with the bigger numerator is the greater fraction\n5. 210/420 > 200/420 or 10/20 > 40/84\n\nMathStep (Works offline)",
null,
"Download our mobile app and learn to work with fractions in your own time:"
] | [
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"https://answers.everydaycalculation.com/mathstep-app-icon.png",
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http://www.apicsllc.com/apics/Ie_ias97/Ie_ias97.htm | [
"APPLIED INDUSTRIAL CONTROL SOLUTIONS LLC",
null,
"PAPER No. 4\n\nThe Effect of Speed Loop Bandwidths and Line-speed on System Natural Frequencies in Multi-Span Strip Processing Systems\n\n1997 IEEE IAS Annual Meeting\n\nBrian Thomas Boulter\nApplied Industrial Control Solutions LLC\n4597 E Sprague Rd.\nIndependence, OH, USA 44131\n\nAbstract - Web Handling and Strip Processing systems (SPS’s) are composed of multiple tension zones. These zones are separated by driven rolls such as bridles whose speed is regulated by a closed loop controller. Given that the typical tension regulator regulates tension by trimming the reference to a closed speed loop controller, the designer of the tension regulator cannot ignore the effects of closing the speed loop, and line speed, on the strip processing system natural frequencies. These natural frequencies are typically computed as the eigenvalues of an equivalent translational cascaded spring-mass system. This paper discusses these effects.\n\nI. INTRODUCTION\n\nMost frequency domain analysis of strip processing systems (SPS's) involves obtaining the transfer functions from an input variable of interest to an output variable of interest. The most common transfer functions used in this type of analysis are those that provide the analyst with spectral information about system variables that directly affect product quality, such as strip strain (or tension) and roller velocity. For example, the transfer function from shaft torque to tension feedback, or from shaft torque to speed feedback are of interest to both the control system engineer and the O.E.M. The control system engineer is interested in these transfer functions because he is responsible for designing the speed and tension regulators and these variables are controlled through the shaft torque produced by the motor. The O.E.M., because he is interested in ensuring the control system vendor satisfies performance guarantees on speed and tension regulation that directly affect the quality of the final product.\n\nSystem eigenvalues (or natural frequencies) are defined as the roots of the characteristic polynomial of a system of linear time-invariant (LTI) differential equations. In a linear analysis of the SPS the denominator of all SPS transfer functions will be composed of poles whose location in the s-plane are equivalent to the system eigenvalues. Often the analyst assumes the SPS can be modeled analogous to a mass-spring system where the roll inertias (Ji) and the strip springs (Ei*Ai /Li) are analogous with the translational masses (Mi) and springs (ki). The transfer functions from torque (ti) to speed (wi) and tension (Tj) are assumed to be analogous to the transfer functions from a disturbance force (fi) acting on the mass (Mi) to the translational speed of the mass (Vi) and the force in the spring {ki(xi-xi-1)}. This approach does not lump the closed speed loop regulators into the plant model. In a more practical sense, the eigenvalues resulting from such an analysis can be defined as the poles of the transfer function from any motor torque ti to any tension feedback Tj, or speed feedback wi, in a SPS where all the speed regulators are operating open loop.",
null,
"Figure 1. A Typical Mass-Spring SPS Representation\n\nFigure 1 shows the rotational system and the equivalent mass-spring translational system from which the eigenvalues of such an analysis are typically obtained. It is composed of an entry section fed by a winder that unwinds unprocessed strip, a process section where proprietary strip processing is performed, and a delivery section that winds the processed strip into rolls.\n\nFigure 2. Is a single line diagram of a typical SPS including the drives and speed loops. The entire system may be divided into 'n' tension zones that are separated by 'n+1' driven rolls. The unwinder (payoff reel), winder (tension reel) and driven rolls (bridles, calenders etc.) are in turn driven by a power source (Current/Torque Minor Loop - CMLi). The reference to the CMLi is proportional to a desired torque (ti) and comes from a speed regulator (a PI regulator - SPIi) that regulates speed to match a desired speed reference wri.",
null,
"Figure 2. A Typical SPS Including Drives and Speed Loops.\n\nGiven that tension regulation in strip processing systems is performed by an outer tension major loop that cascades into a speed minor loop, the eigenvalues of SPS’s that are obtained without the inclusion of the closed speed loops are not useful to the control system engineer responsible for the design of SPS tension regulators. Rather, the design of a single-input, single-output (SISO) tension regulator for the 'ith' section in Figure 2. will require an approximation of the transfer function from the speed reference (wri) to the tension feedback (Ti or Ti+1). This transfer function, which includes the closed speed loop, represents the plant the tension regulator is controlling. The tension regulator may use the tension feedback Ti (i.e. drawing material to control the tension in the 'ith' section) or Ti+1 (feeding material to control tension in the 'i+1' section) to regulate the tension around a desired setpoint.\n\nThere are exceptions to the cascaded architecture. Specifically, in winders, a direct reference to the CML from either a tension or current regulator may be used. However for the sake of brevity only the cascaded architecture will be discussed in this paper.\n\nObtaining a transfer function from wri to Ti is a fairly simple task if there are only two masses and one strip section (e.g. an unwinder and a winder directly coupled by the strip). Approximate transfer functions for this application are derived in , . However the coupling of additional sections into the system makes the derivation of an analytically exact transfer function unwieldy and, as sections are added, beyond the capabilities of even the most sophisticated symbolic math programs.\n\nWhile the approach taken in this paper is one based on linear system theory, the author avoided presenting cumbersome sets of transfer functions and their derivations. This was done with the knowledge that, in the analysis of an actual strip process application, there exists a profusion of non-linear contributions that render exact linear transfer functions more or less inaccurate, depending on the application. The approach taken in this paper is one that describes the expected behavior of the transfer functions in terms of the effect of speed loop bandwidths, and line speed, on the system eigenvalues. The expected behavior is expressed as a series of observations phrased in terms of closed speed loop bandwidths, line speed time constants, and natural frequencies.\n\nII. ANALYSIS\n\n1. Nomenclature\n\n JMOTOR motor inertia [kg m^2] JLOAD, reflected roll (load) inertia [kg m^2] JI JMOTOR + JLOAD [kg m^2] Vi i’th roll surface velocity [m/min] wi i'th motor rotational velocity feedback [rpm] wri i'th motor rotational velocity reference [rpm] qi i'th motor shaft position [rad] w(CML)i i'th CML bandwidth [rad/sec] wS,i i'th speed loop PI lead freq. [rad/sec] wCO,i i'th speed loop crossover [rad/sec] KSi i'th speed loop PI prop. gain KSHAFT spring constant of the drive shaft [kg m^2/rad] Ri i’th roll radius [m] Di i’th roll diameter [m] GRI i’th roll gear ratio Li i’th tension zone length [m] Ti i’th tension zone tension [kgf] ti i’th roll reflected shaft torque [kgf m] tMAX i’th motor maximum torque [kgf m] iI instantaneous CML current [A]. iMAX maximum CML current. [A] E modulus of elasticity [kgf/mm^2] A cross sectional area [mm^2] S Laplace operator LS maximum line speed [m/min] LSI operating line speed [m/min]",
null,
"i’th per-normal inertia (see Eq. 4) KI strip-spring constant (see Eq. 8) tV strip-span velocity time-constant (see Eq. 9) Wi span natural frequency [rad/sec] (see Eq. 12)",
null,
"torque loop gain [kgf m/A]",
null,
"i'th motor gear-in speed [rpm]\n\nB. Plant Representation\n\nThe strip tension equation (1) is a commonly used equation (, , ) describing the dynamics associated with the conveyance of strip through tension zones. It is based on the principle of conservation of mass in a mass-flow system and is derived in ,.",
null,
"; (1)\n\nwhere:",
null,
"(2)\n\nThe motor/load torque equation is given as:",
null,
"; (3)\n\nIn Figure 3. an s-domain block diagram of equations (1-3) is presented. It includes the hooks that allow coupling multiple sections together, it does not include any damping terms. Note that a rigorous representation of equations (1-3) requires the integrators in Figure 3 to be preset to their respective initial conditions.\n\nFor a given operating line velocity LSi, an approximate linear representation of equations (1-3) can be obtained , . A block diagram of the linearized model is shown in Figure 4.",
null,
"Figure 3. Block Diagram of a Strip Tension Zone",
null,
"Figure 4. Linearized Block Diagram of a Strip Tension Zone\n\nA linear s-domain block diagram approximation of the plant (Figure 5), as seen by a cascaded tension loop regulator, can be obtained by closing a speed loop around the speed feedback wi in Figure 4.",
null,
"Figure 5. Plant Model Including the Speed Loop\n\nCascading n sections of the model in Figures 4 & 5 provides a plant model from which an investigation of the effects of speed loop bandwidths on system eigenvalues can be conducted.\n\nC. Some Usefull Quantities\n\nTo simplify the analysis of the multi-span strip processing system the following set of quantities are most useful.\n\nPer-Normal Inertia\n\nLet the per-normal inertia of a system be defined as the time it takes [sec] to accelerate the motor and load inertia to the application gear-in speed (Si) with maximum motor torque (tMAX) It is defined as:",
null,
"(4)\n\nSpeed Loop Bandwidth\n\nThe bandwidth of a closed speed loop is limited to the frequency at which the magnitude of the speed feedback in response to a sinusoidal input is attenuated 3[db] from the setpoint magnitude. It is also approximated as the crossover of the open speed loop Bode plot. For the speed loop shown in Figure 5. it can be shown that the open loop crossover and hence the approximate bandwidth of the speed loop is:",
null,
"(5)\n\nIn any drive system the bandwidth of the speed loop will be constrained by the mechanical integrity of the drive train. As a general rule the bandwidth must be an order of magnitude lower than the lowest torsional frequency in the drive train. This constraint can typically be satisfied by:",
null,
"(6)\n\nIn addition, to avoid torque jitter in the motor shaft, the per-normal controller proportional gain should be limited to 60. For industrial motors, this constraint can be accommodated by limiting the bandwidth to:",
null,
"(7)\n\nStrip Spring Constant\n\nLet the strip spring constant be equal to:",
null,
"(8)\n\nStrip-Span Velocity Time-Constant\n\nLet the strip-span velocity time constant be equal to:",
null,
"(9)\n\nNormal Eigenvalues\n\nThe simple mass-spring system (Figure 1) can be defined in rotational terms as a set of differential equations expressed in the Laplace domain (10):",
null,
"(10)\n\nLet the normal eigenvalues be defined as the roots of the determinant of A.",
null,
"(11)\n\nSpan Natural Frequency:\n\nLet the span natural frequency be a measure of the frequency at which the strip span spring (Ki) and attached inertia (Ji) would exchange energy if the strip spring was terminated at an infinitely large mass.",
null,
"(12)\n\nD. Observations\n\nFollowing is a series of observations that are intended to provide the reader with an intuitive understanding of the effect of speed loop bandwidths and line speeds on SPS system eigenvalues (or transfer function poles).\n\nAnalysis of a 9 section - 10 inertia SPS provides supporting bode plots for each observation. The SPS is comprised of sections structured the same as shown in Figures 4 and 5. Each Observation is followed by a brief discussion, and a plant description for the particular set of Bode plots presented. The plant description is in terms of the quantities described in section 2.3.\n\nThe short discussion is provided to clarify the observation in terms of the stated effect on the poles of the transfer functions (or the system eigenvalues) from speed reference wri to tension feedback Ti and speed feedback wi. The discussions are intended to be of practical use to the control system engineer responsible for the design of SPS tension regulators.\n\nIn addition, it is assumed that the bandwidth of each CML is high enough that in the frequency range of interest it behaves as a linear gain element. Its dynamics can, therefore, be ignored.\n\nObservation No.1\n\nAs additional driven sections are added to a SPS the magnitude of all existing eigenvalues will decrease.\n\nDiscussion: Consider a multi-span SPS without speed regulators, the denominator of the transfer function from any ti to any tension feedback Ti will be composed of poles that can be factored into real poles or complex pole pairs. If a section is added to the SPS the magnitudes of all the existing poles and complex pole pairs in the transfer function from any ti to any tension feedback Ti will decrease.\n\nThis implies that the longer a SPS process line is, the lower the eigenvalues will become. A good way to visualize this is to create a purely symmetric SPS and observe the effect of adding symmetric sections to the SPS on the Bode plot of the transfer function from a torque tn/2+1/2 to a tension feedback Tn/2+1/2 in a SPS with ‘n’ sections. A symmetric SPS is one that has been designed so that the strip span natural frequencies are all approximately the same. Similarly, a symmetric SPS will have sections with very similar per-normal inertias. Figure 6 is a collage of 3 Bode magnitude plots of the transfer function of tn/2+1/2 to a tension feedback Tn/2+1/2. The number of sections varies from five to nine in increments of two.\n\nPlant Description",
null,
"In Figure 6, the solid line is from the analysis of the 9 section SPS, the dotted line: the 7 section SPS, and the dashed line: the 5 section SPS. It is clear that as symmetrical sections are added the magnitude of the eigenvalues decreases.\n\nFrom the perspective of the tension regulator designer, the problematic plant poles in long SPS’s are significantly lower than the strip span natural frequencies calculated using (12). It is important to keep this perspective in mind when commisioning the tension regulators. In the authors experience the dominant problematic natural frequencies in SPS’s are typically lower than those calculated using linear analysis techniques.",
null,
"Figure 6. Observation 1. Bode Magnitude Plot of tn/2+1/2 to Tn/2+1/2 for n=5,7, and 9 Section SPS’s\n\nObservation No.2\n\n2.a) If",
null,
"the eigenvalues of a SPS system that includes the closed speed loops are approximately equal to eig(A).\n\nDiscussion: If the magnitude of all the SPS normal eigenvalues are much greater than the bandwidth of all of the speed loops, the poles of the transfer function from any wri to any closed speed feedback wi or any tension feedback Ti will be approximately the same as the poles in the transfer function from any torque ti to any to any speed feedback wi or any tension feedback Ti in a SPS with no speed loops.\n\n2.b) If",
null,
"the eigenvalues of a SPS system that includes the closed speed loops are approximately equal to",
null,
"Discussion: If the bandwidths of all the speed loops are significantly higher than the magnitude of the maximum normal eigenvalue, the denominator of the transfer function from any speed reference wri to any speed feedback wi or any tension feedback Ti will approximately consist of a pole at zero and two real poles at",
null,
"and",
null,
"2.c) The damping of all normal eigenvalues with magnitudes greater than the speed loop bandwidth for a given tension zone will increase as the ratio of the eigenvalue magnitude to the speed loop bandwidth decreases.\n\nDiscussion: Speed loops produce a damping effect on natural frequencies. The closer the natural frequency is to the speed loop crossover the more pronounced this damping effect will become.\n\nTo demonstrate the effects described in Observation No.2 a collage of 10 Bode plots (Figure 7.) of the transfer function from wr5 to T5 for the example SPS is presented. The per-normal inertias, speed loop crossovers and span natural frequencies for all 9 sections are identical in each plot. This results in a highly symmetrical plant. The 10 plots are obtained from an analysis performed with 10 logarithmically spaced span natural frequencies that vary from 6 to 600 [rad/sec]. For each plot the natural frequency of all 9 tension zones is identical.\n\nPlant Description",
null,
"Some additional observations from Figure 6:\n\n1. The low frequency gain of the transfer function does not change significantly until the eigenvalues are low enough for the speed loop to provide damping. For a system that is highly symmetrical, the gain changes linearly with Wi when Observation 2.b is satisfied.\n2. The speed loop PI lead frequency wSi provides the observed lead break frequency at 2 [rad/sec]. wSi effectively cancels the lower pole of the real pole pair that results when Observation 2.b is satisfied.",
null,
"Figure 7. Observation 2. Bode Plot of wr5 to T5\n\nObservation No.3\n\nDominant speed loop damping effects result from the immediate speed regulator and the speed regulators acting on the preceding and following sections.\n\nDiscussion: Damping of the normal eigenvalues for a given tension zone is dominated by the bandwidth of the speed loop driving that section, the second most dominant factors are the speed loop bandwidths of the sections preceding and following the given tension zone.\n\nTo demonstrate this observation, consider a process line that is composed of two sets of high bandwidth speed regulators separated by a single low bandwidth speed regulator. Poor damping of the system eigenvalues will be observed around the section driven by the low bandwidth regulator. Figures 8,9,10 represent the transfer functions from wr3 to T3, wr4 to T4, wr5 to T5, respectively. The SPS has 10 [rad/sec] speed loop regulator bandwidths for sections 1,2,4-10. The bandwidth of Section 3 is set at 0.1 [rad/sec]. Note that there is little difference between Figure 10 and Figure 7. This indicates that the drive in section 4 provides section 5 with considerable isolation from section 3. As in Figure 7 Figures 8,9,10 are composed of a collage of 10 Bode plots resulting from an analysis of the SPS with 10 logarithmically spaced Wi’s that vary from 6 to 600 [rad/sec].\n\nPlant Description",
null,
"",
null,
"Figure 8. Observation 3. Bode Plot of wr3 to T3",
null,
"Figure 9. Observation 3. Bode Plot of wr4 to T4",
null,
"Figure 10. Observation 3. Bode Plot of wr5 to T5\n\nObservation No.4\n\nDamping of the normal eigenvalues will increase with line speed.\n\nDiscussion: The damping of the normal eigenvalues is worst case at stall. When the strip begins moving there is a damping effect that is the result of the bulk flow of the material through the tension zone. As a result of the lack of damping at stall, it is not uncommon for drive system vendors to operate tension regulators as proportional only controllers at stall, switching to a PI configuration at a pre-determined strip line speed.\n\nTo demonstrate this a plant with a fixed a set of WI’s equal to 600 [rad/sec] is analyzed with a set of 10 logarithmically spaced velocity time constants tv varying from 10 to 0.01 [sec] (Figure 11).\n\nPlant Description",
null,
"",
null,
"Figure 11. Observation 4. Bode Plot of wr5 to T5\n\nObservation No.5\n\nThe pure integration in the transfer function from wri to Ti at stall appears as a real pole that gravitates from the origin of the s-plane towards a value of -1/tV as bulk movement of the strip occurs. The higher the damping of the eigenvalues the better the approximation of -1/tV as the pole location.\n\nDiscussion: At stall, a pure integration is observed in the transfer function from wri to Ti. The moment the bulk movement of the strip begins, the integration becomes a real pole. For most systems this pole is very low in frequency and does not significantly alter the low frequency gain of the plant. When the damping of the normal eigenvalues is such that Observation 2.b is satisfied, the pole location can be approximated as -1/tV.\n\nThis phenomena can be problematic in certain tension regulation schemes. For example, assume a proportional tension regulator is used in a SPS with an extremely high top line speed of 3000 [m/min] and a length between driven sections of 10 [m]. In addition, assume that the speed regulators have ample bandwidth and satisfy Observation 2.b. The transfer function from wri to Ti in a system with such a line speed will result in a pole at 5 [rad/sec]. A significant loss in low frequency gain can be expected and a steady state error in the closed tension loop will be observed. To demonstrate this a plant with a fixed a set of Wi’s equal to 10 [rad/sec] is analyzed with a set of 10 logarithmically spaced velocity time constants varying from 10 to 0.01 [sec] (Figure 12).\n\nThe movement of this pole can also result in a type of low frequency instability in PI tension regulators. If the designed crossover of the tension loop is less than 1/tV, the loop will tend to \"die\" and loose its ability to regulate tension as the speed of the line increases past a certain threshold speed. The exact speed at which this will occur will vary depending on the speed loop bandwidth, the associated eigenvalue damping, and the phase margin built into the tension loop. This instability is not a true instability in the classical sense of the word, it is rather an observed drifting or wandering of the tension that can be attributed to a combination of integral action in the regulator, low tension loop bandwidth, and system noise.\n\nPlant Description",
null,
"",
null,
"Figure 12. Observation 5. Bode Plot of wr5 to T5\n\nIII. CONCLUSIONS\n\nIt is clear from the above discussion that the designer of cascaded tension regulators for multi-span strip processing systems should consider the effect of the speed loop bandwidths on the s-plane location of the SPS eigenvalues when designing tension regulators. Based on the above discussion several conclusions can be drawn:\n\nA. The higher the bandwidth of the SPS speed regulators the greater the damping of problematic SPS natural frequencies.\n\nB. If possible, the O.E.M. process design team should strive to create symmetric systems (similar Wi’s in all the sections and per-normal inertias that are approximately equal). This enables consistent damping of SPS eigenvalues with section speed regulators that have identical bandwidths.\n\nC. The per-normal inertias (and by implication the motor horsepowers) and the torsional stiffness of the drive shafts should be selected such that the speed regulators can be tuned for wCO’s that will provide adequate damping of the expected SPS eigenvalues. This significantly improves the performance of the tension regulators.\n\nD. O.E.M.’s should be aware that compensation as a function of line speed may be required in tension loops as line speeds increase and the span lengths decrease.\n\nE. If an LTI linear system analysis is used to determine the SPS eigenvalues it can be considered a worst case analysis if the eigenvalues are computed to determine the minimum bandwidth of the speed regulators required to satisfy Observation 2.b. The actual eigenvalues of the system will always be less than or equal to these analytically derived values.\n\nA. Tuning The Tension Regulator\n\nAs a note of interest, the tuning of a tension regulator for a SPS with speed loop bandwidths that satisfy Observation 2.b for all the product that is processed through the system becomes a fairly simple task. The lead and lag frequencies of a lead/lag compensator and a PI regulator lead are tuned as shown below:",
null,
"Briefly, the PI lead frequency of the PI controller should be set to 1/5 the desired tension loop crossover. The tension loop crossover should be less than or equal to the speed loop crossover. The lead/lag lead frequency is set to approximately cancel the damped pole from the plant at 0.7 times the speed loop crossover. Recall that the pole at 0.35 times the speed loop crossover is approximately canceled by the transmission zero from the speed PI regulator (i.e. the speed loop PI lead frequency). The lag of the lead/lag compensator is then placed at 10 times the lead/lag lead frequency to ensure that only a minimum of phase margin is lost in the tension regulator. The gain can then be adjusted on-site so that the step response of each tension regulator satisfies a time to peak measure that reflects the desired tension loop bandwidth. Equation (13) can be used to make this determination.",
null,
"(13)\n\nReferences\n\n Boulter, B.T., \"A Novel Approach for On-Line Self-Tuning Strip Tension Regulation\", Proceedings of the 4th IEEE International Conference on Control Applications, pp 91-98, September 1995.\n\n Boulter, B.T. Fox, H.W.,\"Advanced Dynamic Simulation\", Reliance Electric Systems Engineering Training Course EO108 1995.\n\n Carter, W.C., \"Reducing Transient Strains in Elastic Processes\" , Control Engineering Mar. 1965. pp. 84-87.\n\n Fox, S.J., Lilley, D.G., \"Computer Simulation Of Web Dynamics\", Proceedings of the 1st IWHC International Web Handling Conference Tab 20. Oklahoma State University, March 1991.\n\n Lin, K., \"WTS 6.0, A Computer-Based Analysis Program For Multi-Span Web Transport Systems\", Oklahoma State University 1994.\n\n Wolferman, W., \"Tension Control of Webs - A Review of the Problems and Solutions in the Present and Future\", Tab 15, Proceedings of the 3rd IWHC International Web Handling Conference, Oklahoma State University June 1995."
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http://download.ecopath.org/trac/Ecopath/wiki/EwEugBasicEstimates?action=diff&version=2 | [
"# Changes between Version 1 and Version 2 of EwEugBasicEstimates\n\nIgnore:\nTimestamp:\n2010-02-05 17:09:39 (10 years ago)\nComment:\n\n--\n\nUnmodified\nAdded\nRemoved\nModified\n• ## EwEugBasicEstimates\n\n v1 == 7.3 Basic estimates == Once you have entered sufficient input parameters you can proceed to estimate the parameters of Ecopath by selecting Basic estimates under the Parameterization node in the Navigator window. The missing parameters will be estimated so that mass balance is achieved. Both input (black font) and calculated (blue font) parameters are displayed on the Basic estimates form. Notes on most of the parameters below have already been provided in the notes on [[Basic input.htm|Basic parameters]], but we repeat them here as a reminder. ==== Trophic level ==== '''Trophic level''' Lindeman (1942) introduced the concept of trophic levels. In Ecopath, the trophic levels are not necessarily integers (1, 2, 3...) as proposed by Lindeman, but can be fractional (e.g., 1.3, 2.7, etc.) as suggested by Odum and Heald (1975). A routine assigns definitional trophic levels (TL) of 1 to producers and detritus and a trophic level of 1 + [the weighted average of the preys' trophic level] to consumers. The trophic level is a dimensionless index. ==== Habitat area (fraction) ==== '''Habitat area (fraction)''' The fraction of the total area in which the group occurs, that is, the fraction of the total area to which the biomass in habitat area pertains. Default is that the habitat area is 1, i.e. that the group occurs in the total area. ==== Biomass in habitat area ==== '''Biomass in habitat area''' The average biomass per unit area in the habitat area where the group occurs. It is assumed that an average value can be used to represent the biomass of each group. Appropriate units should be used, (e.g., t/km²) for the biomasses. Entry of biomasses is optional for living groups but biomass(es) should be entered for the detritus group(s). However, if biomasses are unknown for all living groups and there are no exports from any of the groups, it is necessary to enter at least one biomass estimate, preferably of a top predator. Biomasses should be entered relative to the habitat area where the group occurs. An example: assume a species for instance has a biomass of 1 t/km² in its habitat area, and the habitat area is 100 km², while the total area in your model is 1000 km². You should then enter a habitat area of 0.1 and a biomass in habitat area of 1 t/km² as the biomass for the group in your model. ==== Biomass ==== '''Biomass''' This is the Biomass in habitat area x Habitat area. ==== Production/biomass ==== '''Production/biomass''' Enter the Production/Biomass (''P/B'') ratio for each group using consistent units, e.g., per year. The ''P/B'' ratio is equivalent to the instantaneous rate of total mortality (Z) used by fisheries biologists (Allen 1971). Entry of ''P/B'' ratios is optional. ''P/B'' = Z = F + M2 + NM + BA + M0. For more details, see [[Production.htm|Production]]. For more details, see [wiki:EwEugProduction Production]. ==== Consumption/biomass ==== '''Consumption/biomass''' Consumption/biomass (''Q/B'') ratios are entered using the same units as for ''''P/B''''. Entry of consumption/biomass ratios is optional. For more details, see [[Consumption.htm|Consumption]]. Consumption/biomass (''Q/B'') ratios are entered using the same units as for 'P/B'. Entry of consumption/biomass ratios is optional. For more details, see [wiki:EwEugConsumption Consumption]. The ''Q/B'' input box will be blocked (blue colour) for primary producers. If your model unit is carbon, you can however, click the blue input box, and enter a Q/B value, which will be used to calculate respiration for the group. ==== Ecotrophic efficiency ==== '''Ecotrophic efficiency''' The ecotrophic efficiency (''EE'') is the fraction of the production that is used in the system, i.e. either passed up the food web, used for biomass accumulation, migration or export. Ecotrophic efficiency is difficult to measure directly. It varies between 0 and 1 and can be expected to approach 1 for groups with considerable predation pressure. The part of the production that is not included in the ''EE'' is often called ‘[[Other mortality.htm|other mortality]]’. ''EE'' is dimensionless, and the entry of'' EE'' values is optional."
] | [
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https://ch.mathworks.com/matlabcentral/cody/problems/304-bottles-of-beer/solutions/104666 | [
"Cody\n\n# Problem 304. Bottles of beer\n\nSolution 104666\n\nSubmitted on 28 Jun 2012 by Noah\n• Size: 10\n• This is the leading solution.\nThis solution is locked. To view this solution, you need to provide a solution of the same size or smaller.\n\n### Test Suite\n\nTest Status Code Input and Output\n1 Pass\n%% x = 99; y_correct = 98; assert(isequal(bottles_of_beer(x),y_correct))\n\n2 Pass\n%% x = 9; y_correct = 8; assert(isequal(bottles_of_beer(x),y_correct))\n\n3 Pass\n%% x = 1; y_correct = 0; assert(isequal(bottles_of_beer(x),y_correct))"
] | [
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https://math.stackexchange.com/questions/1508102/showing-8th-cyclotomic-polynomial-is-irreducible | [
"# Showing 8th cyclotomic polynomial is irreducible\n\nI'm reviewing my notes, and I'm not fully understanding an argument that the 8th cyclotomic polynomial is irreducible in $\\mathbb{Q}[x]$. Here's the online of the argument\n\n$\\Phi_8(x)=\\dfrac{x^8-1}{\\Phi_1(x)\\Phi_2(x)\\Phi_4(x)}=\\dfrac{x^8-1}{x^4-1}=x^4+1$.\n\nThis can be factored into: $(x-\\zeta_8)(x-\\zeta_8^3)(x-\\zeta_8^5)(x-\\zeta_8^7)$ where $\\zeta$ is a primitive root of unity. The next part of the argument is what I'm not seeing.\n\n$(x-\\zeta_8)(x-\\zeta_8^3)(x-\\zeta_8^5)(x-\\zeta_8^7)=(x^2-(\\zeta_8 +\\overline{\\zeta_8})x+1)(x^2-(\\zeta_8^3+\\overline{\\zeta_8^3})x+1)=(x^2-\\sqrt{2}x+1)(x^2+\\sqrt{2}x+1)$\n\nSince $\\sqrt{2} \\notin \\mathbb{Q}$, the polynomial isn't reducible in $\\mathbb{Q}$.\n\nAny clarification is greatly appreciated. Thanks\n\nLet $F$ be the real subfield of $\\mathbb{Q}(\\zeta_8)$. By grouping the roots into conjugate pairs, it's clear that the stated factorization is the prime factorization of $\\Phi_8(x)$ over $F$.\n\nThe prime factorization of $\\Phi_8(x)$ over $F$ is a refinement of its prime factorization over $\\mathbb{Q}$ — i.e. the prime factorization over $F$ come from taking the prime factorization over $\\mathbb{Q}$ and then factoring each factor over $F$.\n\nThus, the only possibilities for the prime factorization over $\\mathbb{Q}$ are either the displayed factorization or that it is irreducible... and the displayed factorization is clearly not defined over $\\mathbb{Q}$.\n\nActually, $F$ is itself a Galois extension of $\\mathbb{Q}$, so the prime factorization over $\\mathbb{Q}$ can be obtained by grouping the conjugate factors and multiplying them together, once again showing irreducibility.\n\nIf the polynomial is reducible, then either it can be factored as a product of degree $1$ and degree $3$ polynomials or it can be factored as a product of two degree $2$ polynomials.\n\nThe former case cannot hold because there is no rational root for this polynomial. For the latter you already have the factorization, but the factors do not belong to $\\mathbb{Q}[x]$. Hence even this factorization doesn't work. Thus irreducible.\n\nAnother argument is to apply Eisenstein's criterion with $f(x)=x^4+1$ for $$f(x+1)=(x+1)^4+1=x^4+4x^3+6x^2+4x^2+2.$$ Hence $\\Phi_8(x)=x^4+1$ is irreducible over $\\mathbb{Q}$. The other factorisation you gave is not over $\\mathbb{Q}$; this would rather work with $$x^4+4=(x^2-2x+2)(x^2+2x+2).$$"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.66984797,"math_prob":0.99987197,"size":733,"snap":"2020-24-2020-29","text_gpt3_token_len":310,"char_repetition_ratio":0.1659808,"word_repetition_ratio":0.0,"special_character_ratio":0.39563438,"punctuation_ratio":0.059210528,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99999535,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-05-27T11:37:30Z\",\"WARC-Record-ID\":\"<urn:uuid:23761d0a-3d9f-4f4b-85b2-82d5454b87d2>\",\"Content-Length\":\"153892\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:aca8bffd-0a6c-423a-bf01-6804a5d2e455>\",\"WARC-Concurrent-To\":\"<urn:uuid:4bcf2182-630c-4119-9bb3-b134777783cd>\",\"WARC-IP-Address\":\"151.101.65.69\",\"WARC-Target-URI\":\"https://math.stackexchange.com/questions/1508102/showing-8th-cyclotomic-polynomial-is-irreducible\",\"WARC-Payload-Digest\":\"sha1:U7ABATS7LXJB3CT523WT2PAGJ36V2AYW\",\"WARC-Block-Digest\":\"sha1:YFCTZKSA7JPX4N3EB7N2JALDP2IFKX6O\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-24/CC-MAIN-2020-24_segments_1590347394074.44_warc_CC-MAIN-20200527110649-20200527140649-00583.warc.gz\"}"} |
https://wvsheep.org/western-australia/change-in-quantity-supplied-example.php | [
"# In supplied change example quantity\n\n## Essay Economics Supply and Demand\n\nChange in supply and Increase/decrease in quantity supplied. what is the difference between a change in demand and change in quantity supplied is exactly refers to the an example of a change in a demand determinant, 8/11/2011 · this site might help you. re: supply vs. quantity supplied? i am having trouble with completely grasping these two concepts. i know that a change in supply).\n\n3. Microeconomic Laws of Demand and Supply. price will lead to a movement along a stable supply curve and result in a change in the quantity supplied. For example Price changes cause changes in quantity supplied represented by movements along the supply curve. For example, at a price of \\$5.00,\n\nWhen price changes, quantity supplied will change. That is a movement along the same supply curve. When factors other than price changes, supply curve will shift. Review of Demand and Supply. Supply vs Quantity Supplied: and quantity supplied and to eliminate shortages and surpluses via changes in prices. Example 1:\n\nThe quantity supplied changes according to the change in price, What Are Examples of Elastic and Inelastic Goods? Difference between Supply and Quantity Supplied; Supply vs Quantity Supplied \"Supply\" and 6.A change in the supply is characterized as a “shift,” while a change in the quantity supplied is marked by an\n\nAn introduction to the price elasticity of demand. how much the quantity demanded changes when given a contemplated change in price. For example, 3/07/2007 · What is the difference between a \"change in demand\" and a \"change in quantity demanded\"? Between a \"change in supply\" and a \"change in quantity supplied\"?\n\nSupply and demand: Supply and demand, calculated as the ratio of the percentage change in quantity supplied or demanded to the percentage change in price. For conventional economics the market by way of the operation of supply and demand answer Examples of inferior goods in Change in quantity supplied verses\n\n14/10/2018 · The vertical line represents price and the horizontal line is quantity supplied. While the previous example provides a basic reason for a change in Supply and demand shifts cause changes in equilibrium price and quantity. events affect equilibrium price and quantity, the quantity supplied of movies at\n\nDefinition of change in supply: A situation that occurs when the producers of a particular good or service change the quantity available for For example, print An example of considering a change in quantity demanded is shown in the graph While a change in quantity demanded will generally be the result of a change in",
null,
"What Is the Difference Between Supply and Quantity\n\nDifference between change in quantity supplied and change. movements along the curve occur only if there is a change in quantity supplied caused by a an example would be the change in the supply of cookies caused by a, ... example: supply schedule. price a change in quantity supplied for a given price level. if the change causes an increase in the quantity supplied at each price); advertisements: a change in supply occurs when the conditions facing suppliers alter. in such a situation, a different quantity will be offered for sale at each price., target (example) • for finding revenue you should find the income statement for your firm. the income statement (example below) is where you will find revenues.\n\nUnderstanding a Change in Supply vs. a Change in Quantity\n\nDifference between change in quantity supplied and change. home » uncategorized » change in supply/demand vs.change in quantity demanded/supplied in the quantity demanded/supplied. a change in demand example if some, quantity supplied of a good: definition & overview. you can then plot the change in quantity supplied based upon quantity supplied of a good: definition).",
null,
"What is change in supply? definition and meaning\n\nChange in supply and Increase/decrease in quantity supplied. need to define change in quantity supplied? economic term change in quantity supplied definition. to find out what is change in quantity supplied, see this explanation., review of demand and supply. supply vs quantity supplied: and quantity supplied and to eliminate shortages and surpluses via changes in prices. example 1:).",
null,
"Changes in Quantity Supplied vs Shift in Supply Example\n\nChanges in Quantity Supplied vs Shift in Supply Example. movements along the curve occur only if there is a change in quantity supplied caused by a an example would be the change in the supply of cookies caused by a, movements along the curve occur only if there is a change in quantity supplied caused by a an example would be the change in the supply of cookies caused by a).",
null,
"Change in Supply vs. Change in Quantity Supplied Sample\n\nChange in Supply/Demand vs.Change in Quantity eDisc. review of demand and supply. supply vs quantity supplied: and quantity supplied and to eliminate shortages and surpluses via changes in prices. example 1:, what is quantity supplied? the way that supply changes by changes in the price of goods and services is the 1 what does quantity supplied mean? 2 example;).\n\n14/10/2018 · The vertical line represents price and the horizontal line is quantity supplied. While the previous example provides a basic reason for a change in The major difference between demand and quantity demanded is Demand is Key Differences Between Demand and Quantity he refers to the change in quantity\n\nAn introduction to the price elasticity of demand. how much the quantity demanded changes when given a contemplated change in price. For example, A change in quantity supplied is the change in the quantity a company is willing to supply when there has been a change in the price of the good For example\n\nWe will write a custom essay sample on. Elasticity: Supply and Demand and Price be affected by the price change. For example, and the quantity supplied The change in price, which induces a change in quantity demanded (and supplied) is the means of eliminating the instability and restoring equilibrium.\n\n11/05/2008 · A supply curve illustrates how much the quantity supplied changes when the price what will happen if the changes in quantity demanded versus quantity Get an answer for 'Differentiate between a ‘change in quantity supplied’ and a ‘change in supply.’' and find homework help for other Business questions at eNotes\n\nChapter 3 - Demand and Supply - Sample Questions A decrease in the price of juice causes no change in the quantity of juice demanded. 13) 2. 14) 3.2 Shifts in Demand and Supply for Goods and 3.2 Shifts in Demand and Supply for Goods and Services causes a change in quantity supplied or a movement\n\nWhat is the difference between a change in demand and Change in quantity supplied is exactly refers to the An example of a change in a demand determinant Quantity supplied is the quantity of a product which producers are willing to supply at a given price while change in supply refers to the overall shift in supply",
null,
"Definition of change in quantity supplied definition at"
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"https://wvsheep.org/pictures/5fdfb57081ec0fe2a2a6d49719b7e817.png",
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"https://wvsheep.org/pictures/eb143abe5fc907209d67211aa621b0ce.gif",
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https://normaserveert.nl/677/5JpPT.html | [
"# Products",
null,
"### How Much Do I Need? QUIKRETE: Cement and Concrete Products\n\nYou can use this concrete calculator to help you determine the number of bags of QUIKRETE® Concrete Mix, Mortar Mix, or Fast-Setting Concrete you will need for the following projects. (All calculations are rounded up to the next highest whole bag).\n\nget price\nHand Mixing Technical Data Machine Mixing At Home PouringFinishing Concrete",
null,
"### How To Calculate Cement, Sand,Aggregate Quantity In 1\n\nAug 03, 2018Density of Cement is 1440/m 3 = 0.28 x 1440 = 403.2 kg We know each bag of cement is 50 kg For Numbers of Bags = 403.2/50 = 8 Bags We Know in one bag of cement = 1.226 CFT For Calculate in CFT (Cubic Feet) = 8 x 1.225 = 9.8 Cubic Feet CALCULATION FOR SAND QUANTITY; Consider volume of concrete = 1m 3\n\nget price",
null,
"### Quikrete 80 lb. Concrete Mix-110180 The Home Depot\n\nOverviewReviewsQuikrete 80 lb. Concrete Mix can be used for building or repairing foundation walls, sidewalks, curbs, steps and ramps and for setting posts. This mix designed for pouring concrete 2 in. thick or more. Quikrete 80 lb. Concrete Mix consists of a uniformly blended, properly proportioned mixture of gravel, sand and Portland cement.",
null,
"### Concrete Calculator Estimate Cement, Sand, Gravel\n\nExample calculation Estimate the quantity of cement, sand and stone aggregate required for 1 cubic meter of 1:2:4 concrete mix. Ans. Materials required are 7 nos. of 50 kg bag of cement, 0.42 m 3 of sand and 0.83 m 3 of stone aggregate.\n\nget price",
null,
"### Volume of One bag Cement in Cubic Feet LT Learning\n\nVolume of One bag Cement in Cubic Feet in Hindi. Ek Bag Cement ki Volume, Cubic Feet me 1.226 Cubic Feet (CFT) hoti hain. Ab apke man me ye sawal jarur ayega ki ‘Kaise’? To ghabraiye mat. Hum yaha pe bahut hi asan tarike se apko batayenge How to Calculate the Volume of one 50 KG Cement bag in Cubic Fe et.\n\nget price",
null,
"### How Many Bags of Concrete do I Need Housesumo\n\nFeb 26, 2018An 80-pound bag yields approximately 0.60 cubic feet of concrete. 60-pound bags yield 0.45 cubic feet and 40-pound bags just 0.30 cubic feet. The actual yield is approximate because the amount of water added to the mix may vary. 60 to 80 pounds is a lot of weight to lift, carry and handle.\n\nget price",
null,
"### Concrete Calculator Estimate Concrete for a Slab or Footing\n\nConcrete, which is a mix of water, aggregate, and cement, is most commonly sold by the cubic yard, but is also available in pre-mixed bags. One cubic yard is equal to the volume of a cube with edges that are one yard (three feet) in length.\n\nget price\nEstimating How Much Concrete You NeedOur calculator can estimate the yards of concrete needed by entering the project dimensions in imperial or metric measurements, including inches, f...Estimating The Cost to Install ConcreteThe average cost to install a concrete slab is \\$6 \\$16 per square foot. In addition to the cost of the concrete itself, there are also labor costs...Preparing to Pour ConcreteMuch of the work to pour concrete is done before the truck even arrives at the project. The site must be measured and laid out. Forms must be insta...Tips For Ordering ConcreteCall your concrete supplier and tell them about your project and what the project is. Ask them to advise you on the proper mix given your applicati...",
null,
"### Quikrete 60 lb. Concrete Mix-110160 The Home Depot\n\nOverviewReviewsQuikrete 60 lb. Concrete Mix is ideal for both structural and non structural applications over 2 in. thick. This ready to use product contains a blend of Portland cement, sand, gravel, and other approved ingredients. Quikrete 60 lb. Concrete Mix is perfect for projects requiring a quality, general use concrete mix.",
null,
"### Concrete Calculator\n\nSlabs, Square Footings, or Walls. Length (l) Width (w) Thickness or Height (h) Quantity.",
null,
"### Concrete Calculator How Much Concrete Do I Need? The\n\nApr 23, 2018100 x .33 = 33 cubic feet; 33 x .037 = 1.22 cubic yards; Essentially you are solving for volume and then converting to cubic yards. For concrete, the formula for volume is as follows: length x width x thickness. To determine how many bags of concrete you will need, divide the total cubic yards needed by the yield.\n\nget price",
null,
"### Quikrete 60 lb. Concrete Mix-110160 The Home Depot\n\nQuikrete 60 lb. Concrete Mix is ideal for both structural and non structural applications over 2 in. thick. This ready to use product contains a blend of Portland cement, sand, gravel, and other approved ingredients. Quikrete 60 lb. Concrete Mix is perfect for projects requiring a quality, general use concrete mix.\n\nget price\n4.5/5(1.7K)",
null,
"### How much cement sandaggregate required for M20 concrete\n\nHance 8 bags cement = 19 cft sand For 1 bag of cement = 19/8= 2.375 cft sand. Hance 8 bags of cement = 37 cft aggregate For 1 bag of cement = 37/8 = 4.625 cft aggregate Ans. :- 2.375 cft sand4.625 cft aggregate are required per 50 kg of cement bag for m20 grade of concrete. You Can Follow me on Facebook and Subscribe our Youtube Channel. You\n\nget price",
null,
"### How many cement bags in m25 concrete Civil Sir\n\nHow much cement sand and aggregate required for m25 concrete. 1) quantity of cement in m25 concrete. 11.088 no (554.4 kg) of cement bags are used in m25 grade of 1m3 concrete. 2) volume of sand in cft for m25 concrete. 1m3 = 35.32 cft. Volume =( 1/4) × 1.54×35.32. Sand volume = 13.6 cft\n\nget price",
null,
"### Calculate Bags of Concrete Mix Round + Square Footing\n\nPre-Mix Concrete Bag Calculator Calculated at 133.3 lb per ft³ Allow extra for waste Cubic Feet 100# Bags 80# Bags 75# Bags 60# Bags 50# Bags 40# Bags 25# Bags 20# Bags 10# Bags @ \\$ per bag\n\nget price",
null,
"### How to Calculate Quantities of Cement, Sand and Aggregate\n\nOne bag of cement and other ingredients can produce = 400/2400 = 0.167 Cum of concrete (1:2:4) 01 bag cement yield = 0.167 cum concrete with a proportion of 1:2:4 01 cum of concrete will require Cement required = 1(m3/bag)/0.167 (m3) = 5.98 Bags ~ 6 Bags —————–OK Sand required = 115(Kgs)/0.167(m3) = 688 (Kgs/m3) or 14.98 cft\n\nget price",
null,
"### CONCRETE VOLUME cubic feet per 60lb bag\n\nProcessing\n\nget price",
null,
"### How Much Concrete Do I Need? Sakrete\n\nIf you take the example above of 1.6 cubic feet, the calculation would be : 1.6 ÷ .6. = 2.7 bags If you happen to be enthralled with math calculations I provide the following information on how to calculate the yield that I said was .6 cubic feet for an 80 lb bag. The first thing you need to know is the “density” of the concrete.\n\nget price",
null,
"### Concrete Calculator Square Footage Area\n\nOur concrete calculator provides you an easy way to calculate concrete volume and estimated cost of concrete slabs, footers, walls, columns, steps, stairs, curbs and gutters in cubic feet, cubic yards, and cubic meters and inches. It makes your construction project planning and budgeting more accurate.\n\nget price",
null,
"### An Easy Way to Build Retaining Walls: Leave the Concrete\n\nOct 19, 2018This is method is ignorant of how cement works. I just listened to an audiobook called \"Stuff Matters\" by Mark Miadownik, about the material science behind all the common materials that make our modern world—, concrete, steel, etc. and in it, the author explained that concrete doesn't dry when it hardens; it actually cures in a reaction with water such that it\n\nget price",
null,
"### Concrete Calculator How Much Concrete Do I Need? The\n\nApr 23, 2018100 x .33 = 33 cubic feet; 33 x .037 = 1.22 cubic yards; Essentially you are solving for volume and then converting to cubic yards. For concrete, the formula for volume is as follows: length x width x thickness. To determine how many bags of concrete you will need, divide the total cubic yards needed by the yield.\n\nget price",
null,
"### M25 Concrete Grade Cement Sand Aggregate and Water Qnty\n\nM25 Concrete Grade Cement Sand Aggregate and Water Qnty All Units Covered KG, Bags, CFT, CUM In this video we will learn, How to Calculate Cement Sand\n\nget price",
null,
"### 2020 Concrete Prices Concrete Truck Delivery Costs (Per\n\nPre-mixed concrete costs \\$4.49 to \\$5.57 per 50-pound bag of light-weight and fast-setting concrete mix and is available at most home improvement stores. Pre-mixed concrete comes in two varieties; a \"no-mix\" bag which requires the addition of water, and another which requires renting a concrete mixer to cure the cement.\n\nget price",
null,
"### CONCRETE VOLUME cubic feet per 80lb bag\n\nJul 24, 2020The approximate volume of concrete produced from a 80 pound bag is 0.6 ft³. To compute how many 80 lb bags of concrete is needed for a total volume, CLICK HERE.. Choose your volume units (e.g. cubic feet) Enter the volume (V) The calculator returns the number of 80 lb bags needed to mix that much concrete.\n\nget price",
null,
"### How Many Cubic Feet Is One Bag of Cement?\n\nApr 07, 2020An 80-pound bag of concrete makes 0.6 cubic feet. A cubic foot of any material is enough to fill a box that is 1 foot wide, 1 foot tall and 1 foot long.\n\nget price",
null,
"### How much cement sandaggregate required for M20 concrete\n\nHance 8 bags cement = 19 cft sand For 1 bag of cement = 19/8= 2.375 cft sand. Hance 8 bags of cement = 37 cft aggregate For 1 bag of cement = 37/8 = 4.625 cft aggregate Ans. :- 2.375 cft sand4.625 cft aggregate are required per 50 kg of cement bag for m20 grade of concrete. You Can Follow me on Facebook and Subscribe our Youtube Channel. You\n\nget price",
null,
"### How many cement bags in m25 concrete Civil Sir\n\nHow much cement sand and aggregate required for m25 concrete. 1) quantity of cement in m25 concrete. 11.088 no (554.4 kg) of cement bags are used in m25 grade of 1m3 concrete. 2) volume of sand in cft for m25 concrete. 1m3 = 35.32 cft. Volume =( 1/4) × 1.54×35.32. Sand volume = 13.6 cft\n\nget price",
null,
"### Cement Bags In Cft Of Concrete\n\nCement Bags In Cft Of Concrete. How much cement needed for 100 cft roof concrete 2020-2-3example calculation estimate the quantity of cement sand and stone aggregate required for 1 cubic meter of 124 concrete mix ans materials required are 7 nos of 50 kg bag of cement 042 m 3 of sand and 083 m 3 of stone.\n\nget price",
null,
"### cement bags in 1cft of concrete\n\nHow Much CFT in 1 Bag Cement. Calculating the quantity of CFT in a bag of cement All we know is that a bag of cement is equal to 50 kg,The most important type of cement is used as a component in the production of masonry mortar and concrete, which is a combination of cement and aggregate to form a solid building material. 【】\n\nget price",
null,
"### M25 Concrete Grade Cement Sand Aggregate and Water Qnty\n\nOct 25, 2019M25 Concrete Grade Cement Sand Aggregate and Water Qnty All Units Covered KG, Bags, CFT, CUM In this video we will learn, How to Calculate Cement Sand\n\nget price",
null,
"### How to Calculate How Much Quikrete to Use Home Guides\n\nDec 14, 2018Quikrete's Concrete Mix yield's about .15 cubic feet for every 20 pounds of mix, so a 40-pound bag yields .30 cubic feet, 60 pounds of concrete mix yields .45 cubic feet and an 80-pound bag yields\n\nget price",
null,
"### Concrete Calculator for Deck Footings Decks\n\nOne 60-lb bag of concrete gives you .45 cubic feet of concrete when mixed with 2.5 quarts of water. In order to have enough concrete for 1 cubic yard (27 cubic feet), you’ll require 2.2 bags of 60-lb concrete. Since bags are only sold in whole (not half, or quarter) quantities, you’ll need to purchase three (3) 60-lb. bags for one cubic yard.\n\nget price",
null,
"### 2020 Concrete Prices Concrete Truck Delivery Costs (Per\n\nPre-mixed concrete costs \\$4.49 to \\$5.57 per 50-pound bag of light-weight and fast-setting concrete mix and is available at most home improvement stores. Pre-mixed concrete comes in two varieties; a \"no-mix\" bag which requires the addition of water, and another which requires renting a concrete mixer to cure the cement.\n\nget price",
null,
"### How Much Concrete Do I Need? Sakrete\n\nIf you take the example above of 1.6 cubic feet, the calculation would be : 1.6 ÷ .6. = 2.7 bags If you happen to be enthralled with math calculations I provide the following information on how to calculate the yield that I said was .6 cubic feet for an 80 lb bag. The first thing you need to know is the “density” of the concrete.\n\nget price",
null,
"### An Easy Way to Build Retaining Walls: Leave the Concrete\n\nOct 19, 2018This is method is ignorant of how cement works. I just listened to an audiobook called \"Stuff Matters\" by Mark Miadownik, about the material science behind all the common materials that make our modern world—, concrete, steel, etc. and in it, the author explained that concrete doesn't dry when it hardens; it actually cures in a reaction with water such that it\n\nget price",
null,
"### How many bags of portland cement is needed to mix 1 cubic\n\nOne cubic meter of concrete is equal to 1.308 cubic yards of concrete. If there are 5 1/2 bags of cement in 1 cubic yard of concrete, there would be 7.2 bags in 1 cubic meter of concrete.\n\nget price",
null,
"### How To Calculate Cement Bags In 1 Cubic Meter?\n\nDec 21, 2016∴ No. of cement bags required in 1 cubic meter = 0.2171/0.0347 = 6.25 bags. Note: You can use the same formula for calculating cement for other nominal mixes.\n\nget price",
null,
"### Quantities of Materials Per Cubic Meter of Concrete Mix\n\nsimilarly, for M20 or 20MPa concrete, refer above table with mix ratio of 1:1.5:3, you will find, 395 kg of cement or 7.9 bags of cement, 0.414 cubic meter of sand (FA) and 0.828 cubic meter of stone (CA). I hope this clears the doubt.\n\nget price",
null,
"### How do I calculate volume of 50 Kg cement bag? we civil\n\nSep 21, 2018Volume of cement bag in cubic feet (CFT) since, 1 m³ = 35.3147 cubic feet = 28.80 No. of bags ∴ Volume of one cement bag = 35.3147/28.80 = 1.226 CFT (cubic feet) Volume of cement bag in Litres. since, 1 m³ = 10³ liters. Volume of one cement bag = 0.0347 m³ = 0.034722 x 10³ = 34.4722 litres ∴ Volume of one cement bag = 34.4722 litres\n\nget price"
] | [
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https://community.powerbi.com/t5/Desktop/Adding-Values-Between-Hours/m-p/1913465 | [
"cancel\nShowing results for\nDid you mean:",
null,
"New Member\n\nHello, I have data with the date/time that a sale occurred, and I need to make a table that gathers sales for all days of a certain time interval.\nFor example:\n10/10/2020 09:15 = \\$50\n11/10/2020 09:40 = \\$150\n12/10/2020 09:50 = \\$50\n10/13/2020 10:09 = \\$350\n\nIn the break:\n- 9:00 am to 10:00 am sold in total = \\$250\n- 10:00 am to 11:00 am sold in total = \\$350\n\n1 ACCEPTED SOLUTION",
null,
"",
null,
"Super User IV\n\n@Felipe_Nery , You can create a time table with buckets and use that. First split date and time from datetime in power query or DAX.\n\nIn DAX\n\nDate = [datetime].date\nor\nDate = date(year([datetime]),month([datetime]),day([datetime]))\n\nDateTime.Date([datetime])\n\nTime = [datetime].Time\nor\nTime = Time(hour([datetime]),minute([datetime]),second([datetime]))\n\nCreate a time table join with time and use that\n\nhttps://kohera.be/power-bi/how-to-create-a-time-table-in-power-bi-in-a-few-simple-steps/\n\ntime([Hour],0,0) & \" - \" time([Hour]+1,0,0)\n\nsort this on hour if needed\n\nProud to be a Super User!\n\n2 REPLIES 2",
null,
"",
null,
"Super User IV\n\n@Felipe_Nery , You can create a time table with buckets and use that. First split date and time from datetime in power query or DAX.\n\nIn DAX\n\nDate = [datetime].date\nor\nDate = date(year([datetime]),month([datetime]),day([datetime]))\n\nDateTime.Date([datetime])\n\nTime = [datetime].Time\nor\nTime = Time(hour([datetime]),minute([datetime]),second([datetime]))\n\nCreate a time table join with time and use that\n\nhttps://kohera.be/power-bi/how-to-create-a-time-table-in-power-bi-in-a-few-simple-steps/\n\ntime([Hour],0,0) & \" - \" time([Hour]+1,0,0)\n\nsort this on hour if needed\n\nProud to be a Super User!",
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"New Member\n\nThank you, I spent days trying. I am Brazilian, and here I didn't find any tutorial about it.",
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"Announcements",
null,
"#### Welcome to the User Group Public Preview",
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"",
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""
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https://biz-y.com/molarity-and-molarity-calculator-affects/ | [
"",
null,
"# Molarity and Molarity Calculator-How it Affects you\n\nA molarity calculator is a useful tool for scientist which is used for the calculation of several scientific chemical equations. It is used to calculate the following:\n\n• The mass a compound is requires to have to prepare a solution that has a known concentration and known volume.\n• The volume a solution is required to have to enable it to dissolve a compound with known mass to acquire the desired concentration\n• The concentration a solution has from a compound with a known mass in a specific volume.\n\nWhen calculating the molarity of a solution, the formula used is\n\nMolar Mass= Concentration x Volume x Molecular Weight\n\nThe mass is in grams, the concentration of the solution is in moles per liter, the volume is in liters and the molecular weight is in grams per moles.\n\nTo understand how to solve the equation, you must understand the terms used accurately. This article would define the meaning of each term used in the formula.\n\nMolar Mass\n\nThe molar mass of a compound is said to be the mass that a sample of that particular compound is divided by the amount of substance that can be found in that sample which is usually measured in moles. The mass is not a molecular property of that substance rather, it is just an average of the compound.\n\nHow to calculate",
null,
"To get the molar mass of an element, all you have to do is divide the moles by gram. When given a question involving the molar mass, you would be given a value in moles which you would divide against the mass( in grams) of an element.\n\nThe concentration of a solution\n\nThe concentration of a solution is simply the amount of solute that can be found in a specific quantity of solution. The concentration is most times represented by molarity which is said to be the number of moles in a solute in 1L of a solution.\n\nHow to calculate\n\nThe formula for calculating the concentration of a solution is C=m/v. Where c is concentration, m is the mass of the dissolved solute and v is the volume of the solution. All you need to have is the values of the mass and the volume and you get your answer easily.\n\nVolume\n\nSimply put, the volume is a total of all the volume of a solute in 1 litre.\n\nHow to calculate\n\nTo calculate the volume of a solution, the formula is V= M/C\n\nWhere m is the mass and c is the concentration of the solution. When asked to find the volume of a solution, you would be given the mass and concentration or you would be given values that would help you find either the concentration or the mass which would make the division easier.",
null,
"Molecular weight\n\nThe molecular weight is defined as the sum of the atomic weights of atoms found in a molecule. It is usually used to find the stoichiometry which occurs in chemical reactions. The best way to calculate it precisely is by using a molarity calculator. With it, you can never go wrong."
] | [
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https://www.nagwa.com/en/videos/849105840262/ | [
"# Video: Finding a Decimal between Two Given Decimals and Converting It to a Fraction and a Percentage\n\nWhich of the following expresses a decimal between 0.35 and 0.95, its fraction in simplest form, and its percentage form? [A] 0.4, 2/5, 40%. [B] 0.4, 40/100, 40%. [C] 0.4, 2/5, 35%. [D] 0.45, 40/100, 35%. [E] 0.45, 2/5, 4%.\n\n02:12\n\n### Video Transcript\n\nWhich of the following expresses a decimal between 0.35 and 0.95, its fraction in simplest form, and its percentage form?\n\nLet’s firstly consider the two different decimals that we have, 0.4 and 0.45. Both of these do indeed lie between 0.35 and 0.95. In order to convert a decimal into a percentage, we multiply by 100. 0.4 multiplied by 100 is equal to 40, and 0.45 multiplied by 100 is equal to 45. Our digits moved two places to the left. This means that we can immediately rule out options (C), (D), and (E), as their decimals and percentages do not match.\n\nBoth option (A) and option (B) have the decimal 0.4 and the percentage 40 percent. This means that we have an equivalent percentage form. Our next step is to work out which of the fractions is written in simplest form. The word “percent” means out of 100. So 40 percent can be written as 40 out of or over 100. This suggests that option (B) might be the correct answer.\n\nHowever, 40 over 100 is not in its simplest form, as both the numerator and denominator are divisible by 20. 40 divided by 20 is equal to two, and 100 divided by 20 is equal to five. This means that the decimal 0.4 and the percentage 40 percent written as a fraction in simplest form is two-fifths or two over five. The correct answer was option (A) 0.4, two-fifths, and 40 percent."
] | [
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https://es.mathworks.com/matlabcentral/answers/423159-number-of-times-two-numbers-appear-together?s_tid=prof_contriblnk | [
"# Number of times two numbers appear together\n\n2 views (last 30 days)\ndan berkowitz on 10 Oct 2018\nEdited: Stephen23 on 10 Oct 2018\nHi,\nI have an array A = [1 3 2 4 3 4 3 2 1 1 3 2 4 3 3 2].\nHow can I count the number of time the number 2 occurs after 1, the number of times the number 3 occurs after 1, and the number of times the number 4 occurs after 1?\nAny help would be appreciated.\nThanks,\nDB\n\nStephen23 on 10 Oct 2018\nEdited: Stephen23 on 10 Oct 2018\n>> A = [1,3,2,4,3,4,3,2,1,1,3,2,4,3,3,2];\nMethod one: basic indexing and nnz:\n>> nnz(A(1:end-1)==1 & A(2:end)==2)\nans = 0\n>> nnz(A(1:end-1)==1 & A(2:end)==3)\nans = 2\n>> nnz(A(1:end-1)==1 & A(2:end)==4)\nans = 0\nMethod two: strfind:\n>> nnz(strfind(char(A),char([1,2])))\nans = 0\n>> nnz(strfind(char(A),char([1,3])))\nans = 2\n>> nnz(strfind(char(A),char([1,4])))\nans = 0"
] | [
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http://accord-framework.net/docs/html/M_Accord_Statistics_Tools_Center_2.htm | [
" Tools.Center Method (Double[], Double, Double[])",
null,
"",
null,
"",
null,
"Centers an observation, subtracting the empirical mean from each element in the observation vector.\n\nNamespace: Accord.Statistics\nAssembly: Accord.Statistics (in Accord.Statistics.dll) Version: 3.8.0",
null,
"Syntax\n```public static double[] Center(\nthis double[] values,\ndouble mean,\ndouble[] result = null\n)```\n\n#### Parameters\n\nvalues\nType: SystemDouble\nAn array of double precision floating-point numbers.\nmean\nType: SystemDouble\nThe mean of the values, if already known.\nresult (Optional)\nType: SystemDouble\nThe destination array where the result of this operation should be stored.\n\nType: Double\n\n#### Usage Note\n\nIn Visual Basic and C#, you can call this method as an instance method on any object of type . When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).",
null,
"See Also"
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"http://accord-framework.net/docs/icons/SectionExpanded.png",
null
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https://www.easycalculation.com/physics/classical-physics/tangential-velocity-calculator.php | [
"# Tangential Velocity Calculator\n\nThe given below online tangential velocity calculator is an online tool which helps you to determine the velocity of the turning wheel or any circular object. If you know the value of the radius of an object, you can easily calculate the tangential speed with our online tool.\n\n## Calculate Tangential Speed\n\nm/s\n\nThe given below online tangential velocity calculator is an online tool which helps you to determine the velocity of the turning wheel or any circular object. If you know the value of the radius of an object, you can easily calculate the tangential speed with our online tool.\n\nCode to add this calci to your website",
null,
"",
null,
"#### Formula:\n\nVt = r ω Where, Vt = Tangential Velocity (meter per second) r = Radius (m) ω = Angular Velocity ( 20 * π )\n\nTangential Velocity: Tangential velocity (speed) is a velocity measured at any point that is tangent to a turning wheel. In detail, when an object is moving along in a circular path at a distance from its center, then its velocity at any point would be directed tangentially. This is called as tangential velocity.\n\nTangential Velocity Formula: The tangential velocity formula defines the relationship between the Radius (r) and Angular velocity (ω) of an object.\n\nOur online tangential velocity calculator would help you to calculate tangential speed by providing the value of radius.\n\n### Example:\n\nAn object has a radius of 5 m. What is its tangential speed?\n\n#### Solution:\n\nVt = r ω\n= 5 x (20 x 3.14)\n= 314.20 m/s"
] | [
null,
"https://www.easycalculation.com/images/embed-plus.gif",
null,
"https://www.easycalculation.com/images/embed-minus.gif",
null
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https://xianblog.wordpress.com/2020/11/19/on-completeness/ | [
"## on completeness\n\nAnother X validated question that proved a bit of a challenge, enough for my returning to its resolution on consecutive days. The question was about the completeness of the natural sufficient statistic associated with a sample from the shifted exponential distribution",
null,
"$f(x;\\theta) = \\frac{1}{\\theta^2}\\exp\\{-\\theta^{-2}(x-\\theta)\\}\\mathbb{I}_{x>\\theta}$\n\n[weirdly called negative exponential in the question] meaning the (minimal) sufficient statistic is made of the first order statistic and of the sample sum (or average), or equivalently",
null,
"$T=(X_{(1)},\\sum_{i=2}^n \\{X_{(i)}-X_{(1)}\\})$\n\nFinding the joint distribution of T is rather straightforward as the first component is a drifted Exponential again and the second a Gamma variate with n-2 degrees of freedom and the scale θ². (Devroye’s Bible can be invoked since the Gamma distribution follows from his section on Exponential spacings, p.211.) While the derivation of a function with constant expectation is straightforward for the alternate exponential distribution",
null,
"$f(x;\\theta) = \\frac{1}{\\theta}\\exp\\{-\\theta^{-1}(x-\\theta)\\}\\mathbb{I}_{x>\\theta}$\n\nsince the ratio of the components of T has a fixed distribution, it proved harder for the current case as I was seeking a parameter free transform. When attempting to explain the difficulty on my office board, I realised I was seeking the wrong property since an expectation was enough. Removing the dependence on θ was simpler and led to",
null,
"$\\mathbb E_\\theta\\left[\\frac{X_{(1)}}{Y}-\\frac{\\Gamma(n-2)}{\\Gamma(n-3/2)}Y^\\frac{-1}{2}\\right]=\\frac{\\Gamma(n-2)}{n\\Gamma(n-1)}$\n\nbut one version of a transform with fixed expectation. This also led me to wonder at the range of possible functions of θ one could use as scale and still retrieve incompleteness of T. Any power of θ should work but what about exp(θ²) or sin²(θ³), i.e. functions for which there exists no unbiased estimator..?\n\nThis site uses Akismet to reduce spam. Learn how your comment data is processed."
] | [
null,
"https://s0.wp.com/latex.php",
null,
"https://s0.wp.com/latex.php",
null,
"https://s0.wp.com/latex.php",
null,
"https://s0.wp.com/latex.php",
null
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https://schillerfitness.com/qa/question-how-many-amps-are-in-a-1000-watts.html | [
"",
null,
"# Question: How Many Amps Are In A 1000 Watts?\n\n## How many amps is a kW 230v?\n\nGenerator Current Ratings (Three Phase AC)PowerCurrent at 120VCurrent at 240V1 kW6.014 A3.007 A2 kW12.028 A6.014 A3 kW18.042 A9.021 A4 kW24.056 A12.028 A60 more rows.\n\n## Is 220v cheaper to run than 110v?\n\nA quick answer: Probably nothing. This is a common misunderstanding about how electricity works and how the power companies charge you for it. The point often noted for the money saving argument is that the amperage is half as much when running grow lights on 220 volts instead of 110 volts.\n\n## What is 2kw in amps?\n\n8.70amps2kw is only 8.70amps so you should be fine providing the camp sites supply is 10amps or above. By way of explanation (and as an aid to assessing the suitability of appliances), the Watt (W) is a unit of power.\n\n## How many amps is a 25 kW generator?\n\nGENERATOR AMP RATINGS – THREE PHASE EXTENDEDkVAkW208252069.5312586.83830104.24435121.621 more rows\n\n## How many KW is an amp?\n\nAC three phase kilowatts to amps calculation formula So amps are equal to 1000 times kilowatts divided by square root of 3 times power factor times volts.\n\n## How many amps are in a Watt?\n\nAmps = Watts / Volts 4160 Watts / 208 Volts = 20 Amps.\n\n## How many amps is 3000 watts?\n\n25 amps120V= 3000W/I that’s 25 amps needed to supply a 3000 watt circuit. And to be “up to code” you can only use 80% of the amperage rated for your breaker. So that circuit would need a 30 amp breaker.\n\n## How many watts is 220 volts?\n\nHow many watts/volt in 1 watts/220 volts? The answer is 0.0045454545454545.\n\n## How many watts is 30 amps?\n\n3,600 wattsA 30-amp outlet supplies 3,600 watts (30 amps multiplied by 120 volts).\n\n## Is kW a KW S?\n\nkW↔kJ/s 1 kW = 1 kJ/s. kW↔kJ/h 1 kW = 3600 kJ/h.\n\n## How many amps does 5000 watts equal?\n\nIt may be that you have a circuit drawing 500 amps at 10 volts (500*10 = 5000 watts). Or you may have a circuit drawing 10 amps at 500 volts. Or maybe even 100 amps at 50 volts. These are all delivering 5000 watts of power, but they all have different currents and voltages.\n\n## How many amps is 1000 watts at 240 volts?\n\n4.17 amps1000 Watts at 240 volts indicates an energy burn of 4.17 amps. 1000 watts at 12 volts indicates an energy burn of 83 amps. It’s the amps that matter.\n\n## Is 110v or 220v better?\n\nMeaning, higher current can be more dangerous than higher voltage; however, since voltage and amperage are directly proportional, 110v wiring is usually considered safer to work with because it uses fewer volts and as such can only carry half as much current as 220v wiring.\n\n## Can I change 220v to 110v?\n\nYou can convert a receptacle from 220 volts to 110 volts in one of two ways. The first is to use a 220 to 110 adapter. … If you choose either of the second options, you’ll have to install a new circuit breaker. 220V breakers are rated for more current than a 110V circuit can carry.\n\n## How many watts is 2 amps?\n\n24 WattsEquivalent Amps and Watts at 12V ACCurrentPowerVoltage2 Amps24 Watts12 Volts3 Amps36 Watts12 Volts4 Amps48 Watts12 Volts5 Amps60 Watts12 Volts23 more rows\n\n## How many watts is 15 amps?\n\n1,800 wattsThe circuit and circuit breaker that you tripped have a capacity of 15 amps, or 1,800 watts (15 amps x 120 volts = 1,800 watts).\n\n## How many amps is 14000 watts?\n\nEquivalent Watts and Amps at 120V ACPowerCurrentVoltage1200 Watts10 Amps120 Volts1300 Watts10.833 Amps120 Volts1400 Watts11.667 Amps120 Volts1500 Watts12.5 Amps120 Volts26 more rows\n\n## How many amps are in 12 watts?\n\nVolts / Watts / Amps Converter Watts is also known as volt-amps and is typically used in conjunction with AC power circuits. Fill in any of the two fields to find the value of the third. You have a 12 Volt power supply that delivers 1 Amp of current."
] | [
null,
"https://mc.yandex.ru/watch/65659654",
null
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https://debug.pi.gr/default.aspx?ch=554&dir=+1 | [
"« Static analysis Effect of live load on the static analysis of one-way slabs » Deflection Slab bar AB of length L, moment of inertia I, elasticity modulus E, is subjected to uniform load p. Given shear force VA,R(at left support) and bending moment MA, calculate equation of elastic line due to bending and maximum deflection.",
null,
"Figure 4.5.2-1: General case of bending of bar (slab or beam) Figure 4.5.2-1: General case of bending of bar (slab or beam) Considering coordinate z origin at the left end:",
null,
"The basic equation:",
null,
"of the elastic line is solved in two steps: Step 1",
null,
"Hence, the equation of the elastic line tangents is:",
null,
"Step 2",
null,
"y(z)=0 → C2=0 Hence, the equation of the elastic line is :",
null,
"y(L)=0 →",
null,
"Thus, the equations of the elastic line tangents (1) and deflections (2) are determined. The maximum deflection is at the location where the first derivative of the elastic line equation is zero, i.e. at the point z where φ(z) =0.",
null,
"The real positive root of the cubic equation (3) gives the desired point zmax, which replaced in equation (2) yields the maximum deflection ymax. Example: Deflection of first slab (example of §4.3.1): For L=4.5 m, p=16.5 kN/m, VA,R=32.1 kN and MA=0.0, expression (3) yields:",
null,
"(4) > (16.5/6)·z3-(32.1/2)·z2-0+45.7=0 > 2.75z3-16.05z2+45.7=0 > z max=2.112 m (2) > For slab thickness h=180 mm and modulus of elasticity for concrete E=32.80 GPa: I=(b·h3)/12=(1.0x0.183)/12=486x10-6 m4 E·I=32.8x109N/m2x486x10-6m4=15.9408x106 N·m2, therefore,",
null,
"Example: Deflection of second slab (example of §4.3.1): For L=4.0 m, p=9.75 kN/m, VA,R=21.7 kN and MA=-22.6 kNm, expression (3) yields:",
null,
"(4) > (9.75/6)·z3-(21.7/2)·z2+22.6z-13.333=0 > 1.625z3-10.85z2+22.6z-13.333=0 > zmax=0.993m",
null,
"For slab thickness h=140 mm and modulus of elasticity for concrete E=32.80 GPa: I=(b·h3)/12=1.0x0.143/12=228.7x10-6 m4 E·I=32.8x109N/m2x228.7x10-6m4=7.5014x106 N·m, therefore,",
null,
"Example: Deflection of third slab (example of §4.3.1): For L=4.0 m, p=9.75 kN/m, VA,R=23.0 kN and MA=-13.9 kNm, expression (3) yields: C1=(-9.75x4.03/24+23.0x4.02/6-13.9x4.0/2) kN·m2 =7.533 kN·m2 (4) > (9.75/6)·z3-(23.0/2)·z2+13.9z+7.533=0 a 1.625z3-11.50z2+13.9z+7.533=0 a zmax=2.181m",
null,
"For slab thickness h=140 mm and modulus of elasticity for concrete E=32.80 GPa: I=(b·h3)/12=1.0x0.143/12=228.7x10-6 m4 E·I=32.8x109N/m2x228.7x10-6m4=7.5014x106 N·m2, therefore,",
null,
"The elastic line of the continuous slab given by expressions (1.2), (2.2), (3.2) is illustrated in the following figure:",
null,
"Figure 4.5.2-2: The elastic line of the three slabs (from the equations) Figure 4.5.2-2: The elastic line of the three slabs (from the equations) Project (pi-FES) produces identical deflections:",
null,
"Figure 4.5.2-3: Front view of the elastic line (from pi-FES with active module\\SLABS) Figure 4.5.2-3: Front view of the elastic line (from pi-FES with active module\\SLABS) « Static analysis Effect of live load on the static analysis of one-way slabs »",
null,
""
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https://bugs.ruby-lang.org/issues/11993 | [
"## Bug #11993",
null,
"### foo(hash) is handled like foo(**hash)\n\nStatus:\nRejected\nPriority:\nNormal\nAssignee:\n-\nTarget version:\n-\nruby -v:\n2.3.0\n[ruby-core:72871]\n\nDescription\n\nGiven this method:\n\n```def foo(a = nil, b: nil)\np a: a, b: b\nend\n```\n\nI can pass keyword arguments to it and I can turn a hash into keyword arguments with the `**` operator:\n\n```foo(b: 1) #=> {:a=>nil, :b=>1}\nfoo(**{b: 1}) #=> {:a=>nil, :b=>1}\n```\n\nWhat baffles me is that a hash is also turned into keyword arguments without the `**` operator:\n\n```foo({b: 1}) #=> {:a=>nil, :b=>1}\n```\n\nThis looks like a flaw to me. I was expecting:\n\n```foo({b: 1}) #=> {:a=>{:b=>1}, :b=>nil}\n```\n\nWhich would have resembled the way `*` works:\n\n```def bar(a = nil, b = nil)\np a: a, b: b\nend\n\nbar(1, 2) #=> {:a=>1, :b=>2}\nbar(*[1, 2]) #=> {:a=>1, :b=>2}\nbar([1, 2]) #=> {:a=>[1, 2], :b=>nil}\n```\n\nBut currently, there doesn't seem to be a difference between `foo(hash)` and `foo(**hash)`.\n\nIs this behavior intended? If so, what's the rationale behind this decision?\n\n### History\n\n####",
null,
"Updated by avit (Andrew Vit)almost 4 years ago\n\nSee #11967 for Marc-Andre's explanation.\n\n####",
null,
"Updated by marcandre (Marc-Andre Lafortune)over 1 year ago\n\n• Status changed from Open to Rejected\n\nFirst, `foo(b: 1)` has been exactly the same as `foo({b: 1})` since Ruby 1.8 at least. It is parsed exactly the same way. It's syntax sugar.\n\n```require 'ripper'\nRipper.sexp('foo(a : 1)') == Ripper.sexp('foo({a : 1})') # => true\n```\n\nAs you note, the `**` operator is not needed in many cases, but there are cases where it matters. You can see a difference in these three cases:\n\na) It merges keyword arguments:\n\n```h = {a: 1, b: 2}\np(h, c: 3) # => {:a=>1, :b=>2}, then {:c=>3}\np(**h, c: 3) # {:a=>1, :b=>2, :c=>3}\n```\n\nb) It insures that a hash is viewed as keyword arguments:\n\n```h = {'a' => 1}\np(h) # {\"a\"=>1}\np(**h) # => TypeError (hash key \"a\" is not a Symbol)\n```\n\nc) It differentiates between an actual empty hash `{}` and nothing at all\n\n```def foo(x)\np x\nend\n\ne = {}\nfoo('hello', **e) # => 'hello'\nfoo('hello', e) # => ArgumentError (wrong number of arguments (given 2, expected 1))\n```\n\nNote that some corner cases may not perfectly handled yet (#15078)\n\nIn summary: using `**` improves legibility by making the intention crystal clear, makes your code stricter and allows you to easily merge options. There is also discussion to make the use of `**` required in some cases in Ruby 3.0 (see #14183).\n\nI'm closing this, but will reopen if need be.\n\nAlso available in: Atom PDF"
] | [
null,
"https://www.gravatar.com/avatar/dde78fe4cdc16eb855d68ff7a8cd017d",
null,
"https://www.gravatar.com/avatar/f0987c97234fa9c6b26f796bdbdab037",
null,
"https://www.gravatar.com/avatar/0e610136db92027148906c92d57fdb36",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.82385314,"math_prob":0.73617464,"size":2255,"snap":"2019-51-2020-05","text_gpt3_token_len":718,"char_repetition_ratio":0.10661928,"word_repetition_ratio":0.014851485,"special_character_ratio":0.3676275,"punctuation_ratio":0.1826923,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9568754,"pos_list":[0,1,2,3,4,5,6],"im_url_duplicate_count":[null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-12-14T13:55:10Z\",\"WARC-Record-ID\":\"<urn:uuid:0dc69214-c040-4ffe-a7bd-c8a19077450c>\",\"Content-Length\":\"34274\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:c76fc0de-377b-4f17-83ce-ee6448575cbe>\",\"WARC-Concurrent-To\":\"<urn:uuid:1e58246a-41e6-4549-a9e6-4513b7603ffb>\",\"WARC-IP-Address\":\"52.20.12.96\",\"WARC-Target-URI\":\"https://bugs.ruby-lang.org/issues/11993\",\"WARC-Payload-Digest\":\"sha1:NT34SWZTRXOOOEWXZDKFFEDM7DGGJS2G\",\"WARC-Block-Digest\":\"sha1:MSYXD7ZVDKGJW77GRXI4NV6BJ3PSMADK\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-51/CC-MAIN-2019-51_segments_1575541157498.50_warc_CC-MAIN-20191214122253-20191214150253-00021.warc.gz\"}"} |
http://www.erclosetphysics.com/2015/11/fermats-last-theorem-flt65-part-six.html | [
"## Wednesday, November 25, 2015\n\n### FERMAT'S LAST THEOREM FLT65 PART SIX\n\nFERMAT' LAST THEOREM FLT65 PART SIX\n\nFLT65 provides a straight-forward proof using the Division Algorithm and its corollaries to show that for n equal to p, any prime greater than 2, there are no purely integer solutions for Yn = Zn - Xn. Briefly, it does this as follows:\n· The right-hand side of the equation Yp = Zp – Xp can be factored into two polynomials:\nZp – Xp = (Z – X)(Zp-1+XZp-2+…+Xp-1) (1.)\n· These factors can be considered to be co-prime (not containing common factors) for reasons that are detailed in FLT65 and Appendix C.\n· Since f(Z) and g(Z) are co-prime and their product is equal to Yp, a perfect p power integer, both factors must be equal to perfect p-powers of co-prime integers if all three variables, X, Y and Z, are to be integers.\n· The proof continues by dividing the p - 1 degree polynomial, designated by f(Z), by another first degree polynomial, Z – a, where a is defined by f(Z) = (Z – a)p\nf(Z)/(Z – a) = q(Z) + r(Z)/(Z – a) (2.)\nand for X and Z equal to specific integers, a becomes the variable: f(Z)/(Z – a) = q(a) + r(a)/(Z – a), Note that for every specific value of Z, there is an a, but for only one specific integer value of Z, when q(a) is maximum and r(a) is minimum, are they unique.\n· The division algorithm and its corollaries apply to all algebraic polynomials in real number variables, including the algebraic polynomial factor of the FLT equation, f(Z) = Zp-1+XZp-2+…+Xp-1.\n· And since integer solutions of Yp = Zp – Xp, if any exist, form a subset of the real number solutions of the equation, integer polynomials formed with them must also conform to the Division Algorithm and its corollaries.\n· By corollary II of the division algorithm, the polynomial remainder when f(Z) is divided by Z – a is f(a), and by Corollary III of the Division Algorithm, if q(a) and f(a) are unique, the remainder must equal zero if f(Z) is divisible by Z - a.\n· But, when f(Z) is divided by Z – a, the remainder, r(a) =f(a) = ap-1+Xap-2+…+Xp-1 cannot equal zero because if X and a are equal to integers, f(a) is always positive.\n· For only one specific pair of integer values of a and Z, the quotient and remainder, q(a) and r(a), are unique, and corollary III says that, if the quotient and remainder are unique, a polynomial f(Z) is divisible by Z – a, IF, AND ONLY IF, f(A) = 0; so the fact that f(a) ≠ 0 implies that the polynomial factors, f(Z) and Z – a, are co-prime for those specific integer values of a and Z. This is an unavoidable contradiction since for an integer solution of the Fermat equation, Z – a must divide f(Z) because f(Z) = (Z – a)p, a perfect p-power of an integer.\n\n· Thus, if a, X and Z are integers, f(a) ≠ 0 proves FLT."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.90113866,"math_prob":0.99838805,"size":2710,"snap":"2023-40-2023-50","text_gpt3_token_len":763,"char_repetition_ratio":0.13340725,"word_repetition_ratio":0.023529412,"special_character_ratio":0.2811808,"punctuation_ratio":0.110552765,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9997844,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-10-03T10:45:30Z\",\"WARC-Record-ID\":\"<urn:uuid:48f5b983-15fb-4733-823a-3f621f9674ed>\",\"Content-Length\":\"208579\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:a86fbcb6-c00f-41e4-9878-0230ceece369>\",\"WARC-Concurrent-To\":\"<urn:uuid:31c2ee63-00c4-4cd6-8444-acce793b25b4>\",\"WARC-IP-Address\":\"142.251.111.121\",\"WARC-Target-URI\":\"http://www.erclosetphysics.com/2015/11/fermats-last-theorem-flt65-part-six.html\",\"WARC-Payload-Digest\":\"sha1:EWRPILVCSM2HLNJDOR5XD7RNDUWVZDAG\",\"WARC-Block-Digest\":\"sha1:MLQV5KFILLNJT4CDWRR5244TRDQOJZTG\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-40/CC-MAIN-2023-40_segments_1695233511075.63_warc_CC-MAIN-20231003092549-20231003122549-00136.warc.gz\"}"} |
https://intelligencemission.com/free-electricity-machine-free-electricity-units.html | [
"",
null,
"Free Power, Free Power paper in the journal Physical Review A, Puthoff titled “Source of vacuum electromagnetic zero-point energy , ” (source) Puthoff describes how nature provides us with two alternatives for the origin of electromagnetic zero-point energy. One of them is generation by the quantum fluctuation motion of charged particles that constitute matter. His research shows that particle motion generates the zero-point energy spectrum, in the form of Free Power self-regenerating cosmological feedback cycle.\n\nThis simple contradiction dispels your idea. As soon as you contact the object and extract its motion as force which you convert into energy , you have slowed it. The longer you continue the more it slows until it is no longer moving. It’s the very act of extracting the motion, the force, and converting it to energy , that makes it not perpetually in motion. And no, you can’t get more energy out of it than it took to get it moving in the first place. Because this is how the universe works, and it’s Free Power proven fact. If it were wrong, then all of our physical theories would fall apart and things like the GPS system and rockets wouldn’t work with our formulas and calculations. But they DO work, thus validating the laws of physics. Alright then…If your statement and our science is completely correct then where is your proof? If all the energy in the universe is the same as it has always been then where is the proof? Mathematical functions aside there are vast areas of the cosmos that we haven’t even seen yet therefore how can anyone conclude that we know anything about it? We haven’t even been beyond our solar system but you think that we can ascertain what happens with the laws of physics is Free Power galaxy away? Where’s the proof? “Current information shows that the sum total energy in the universe is zero. ” Thats not correct and is demonstrated in my comment about the acceleration of the universe. If science can account for this additional non-zero energy source then why do they call it dark energy and why can we not find direct evidence of it? There is much that our current religion cannot account for. Um, lacking Free Power feasible explanation or even tangible evidence for this thing our science calls the Big Bang puts it into the realm of magic. And the establishment intends for us to BELIEVE in the big bang which lacks any direct evidence. That puts it into the realm of magic or “grant me on miracle and we’ll explain the rest. ” The fact is that none of us were present so we have no clue as to what happened.\nNernst’s law is overridden by Heisenberg’s law, where negative and positive vis states contribute to the ground state’s fine structure Darwinian term, and Noether’s third law, where trajectories and orientations equipart in all dimensions thus cannot vanish. Hi Paulin. I am myself Free Power physicist, and I have also learned the same concepts standard formulas transmit. However, Free Electricity points are relevant. Free Power. The equations on physics and the concepts one can extract from them are aimed to describe how the universe works and are dependent on empirical evidence, not the other way around. Thinking that equations and the concepts behind dogmatically rule empirical phenomena is falling into pre-illustrative times. Free Electricity. Particle and quantum physics have actually gotten results that break classical thermodynamics law of conservation of energy. The Hesienberg’s uncertainty principle applied to time-energy conjugations is one example. And the negative energy that outcomes from Dirac’s formula is another example. Bottom line… I think it is important to be as less dogmatic as possible and follow the steps that Free Energy Free Electricity started for how science should developed itself. My Name is Free Energy Sr and i have made Free Power Magnetic motor.\nThe historically earlier Helmholtz free energy is defined as A = U − TS. Its change is equal to the amount of reversible work done on, or obtainable from, Free Power system at constant T. Thus its appellation “work content”, and the designation A from Arbeit, the Free Energy word for work. Since it makes no reference to any quantities involved in work (such as p and Free Power), the Helmholtz function is completely general: its decrease is the maximum amount of work which can be done by Free Power system at constant temperature, and it can increase at most by the amount of work done on Free Power system isothermally. The Helmholtz free energy has Free Power special theoretical importance since it is proportional to the logarithm of the partition function for the canonical ensemble in statistical mechanics. (Hence its utility to physicists; and to gas-phase chemists and engineers, who do not want to ignore p dV work.)"
] | [
null,
"https://intelligencemission.com/freeenergy1.jpeg",
null
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https://abcya3.games/math-candies.html | [
"ABCYA3\n\nMath Candies GamePlay:\n\n'Math Candies' is a math puzzle game. In this game you need to find the price of some candies by solving given equations. Operations in the problems consist of addition, subtraction, multiplication and division. Once you find the values of candies, use these values to find the answer of a simple Math question.\nExit",
null,
""
] | [
null,
"https://abcya3.games/images/chevron-upwards-arrow.png",
null
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https://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2010/msg00582.html | [
"# Re: [ferret_users] Question to CURV_TO_RECT_MAP, CURV_TO_RECT (remapping)\n\n``` Hi -\nIt should not be a problem to use a small subset of the range of the curvilinear grid. What is the approximate resolution of the curvilinear grid? If there are only a few points on the curvilinear grid and you want to regrid to this very fine output grid, I expect your results might not be very good.\n\nAre the longitude curvilinear coordinates also expressed as East longitudes, so that they contain the range x=-5.666667:5.25 ? If not then use values for the longitudes in your axis definition that are on the same branch of modulo longitudes as what is in the curvilinear coordinate variable. You have probably done this, but it's always a good idea to make plots of the data in its curvilinear form to be sure you are reading it correctly.\n\nOn 10/5/2010 11:03 AM, Szymon Roziewski wrote:\n```\n```Hi there,\n\nI have problem with an applying of functions CURV_TO_RECT_MAP and then CURV_TO_RECT.\nCurvilinear grid reffers to greater area than the output rectilinear grid - maybe this issue causes problem.\n\n! making grid for curvilinear coordinates - lon and lat\n\nDEFINE AXIS/x=1:448:1/unit=degree xaxis\nDEFINE AXIS/y=1:615:1/unit=degree yaxis\nDEFINE GRID/x=xaxis/y=yaxis gridlonlat\n\nFILE/VARIABLES=clon_in/COLUMNS=448/GRID=gridlonlat \"/home/szymon/WAM/CHECK/um_c3_lon_448x615.txt\"\nFILE/VARIABLES=clat_in/COLUMNS=448/GRID=gridlonlat \"/home/szymon/WAM/CHECK/um_c3_lat_448x615.txt\"\n\n!making an output grid 132x145\n\ndefine axis/x=-5.666666667:5.25:0.083333333/modulo/units=degrees xax\ndef axis/y=-2.0:10.0:0.083333333/units=degrees yax\nlet grid_out = y[gy=yax] + x[gx=xax]\n\nlet map = CURV_TO_RECT_MAP(clon_in[d=1], clat_in[d=2], grid_out, 10)\nsave/clobber/file=curv_map_UM_TO_ICM.nc map\nEverything was done without any problems.\n\nThen next step is to use this variable data for remapping wind field to smaller rectilinear grid which reffers to the area that is contained in greater curvilinear area.\n\nDEFINE AXIS/x=1:448:1/unit=degree xaxis\nDEFINE AXIS/y=1:615:1/unit=degree yaxis\n\nDEFINE GRID/x=xaxis/y=yaxis gridlonlat\n\nfile/var=wlon/grid=gridlonlat/format=stream/type=r4/swap \"/home/szymon/WAM/CHECK/03225_2010092100+03000000c3hs000000000000000\"\nfile/var=wlat/grid=gridlonlat/format=stream/type=r4/swap \"/home/szymon/WAM/CHECK/03226_2010092100+03000000c3hs000000000000000\"\n\n! using mapping data\nuse curv_map_UM_TO_ICM.nc\n\n!remapping\nlet wlon_icm = curv_to_rect(wlon[d=1], map[d=3])\nlet wlat_icm = curv_to_rect(wlat[d=2], map[d=3])\n\nvector/over/title=\"WIND\"/length=15/xskip=10/yskip=10 wlon_icm, wlat_icm\n!unfortunately there's no any data for plotting..\nframe/file=interpolate.gif\n\nthese are data sets:\n\ncurrently SET data sets:\n1> /home/szymon/WAM/CHECK/03225_2010092100+03000000c3hs000000000000000\nname title I J K L\nWLON WLON 1:448 1:615 ... ...\n\n2> /home/szymon/WAM/CHECK/03226_2010092100+03000000c3hs000000000000000\nname title I J K L\nWLAT WLAT 1:448 1:615 ... ...\n\n3> ./curv_map_UM_TO_ICM.nc (default)\nname title I J K L\nMAP CURV_TO_RECT_MAP(CLON_IN[D=1], 1:132 1:145 1:4 1:3\n\nHow can I work around that issue?\n\n--\nWith best regards,\nSimon\n```\n```\n```"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6934683,"math_prob":0.87992656,"size":3347,"snap":"2022-27-2022-33","text_gpt3_token_len":1051,"char_repetition_ratio":0.11666168,"word_repetition_ratio":0.04488778,"special_character_ratio":0.31550643,"punctuation_ratio":0.13728549,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9670323,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-06-26T08:48:34Z\",\"WARC-Record-ID\":\"<urn:uuid:41c4029c-9b3d-4d45-92a2-05e263338a17>\",\"Content-Length\":\"8090\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:3a7ffa03-95c2-4e18-ba78-ab31a217280f>\",\"WARC-Concurrent-To\":\"<urn:uuid:582ee60c-b49f-4959-95ad-71f39a623112>\",\"WARC-IP-Address\":\"161.55.85.35\",\"WARC-Target-URI\":\"https://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2010/msg00582.html\",\"WARC-Payload-Digest\":\"sha1:B7Q7V73X4HD6Q2HF2YTJQKYY56HMX5LB\",\"WARC-Block-Digest\":\"sha1:XSWW5OENTFEXBAIZUJ4NGWCGJOEGUCSB\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-27/CC-MAIN-2022-27_segments_1656103037649.11_warc_CC-MAIN-20220626071255-20220626101255-00124.warc.gz\"}"} |
https://e-eduanswers.com/mathematics/question16990430 | [
" Question Progress Homework Progress 17 88 Complete the following sentences. data. Data that can only take particular values is called Data",
null,
"",
null,
", 08.07.2020 17:01, McSporter\n\nQuestion Progress Homework Progress 17 88 Complete the following sentences. data. Data that can only take particular values is called Data that can take on any value is called data.",
null,
"Other questions on the subject: Mathematics",
null,
"Mathematics, 21.06.2019 15:00, m4167281\nAchemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?",
null,
"Mathematics, 21.06.2019 22:40, katerin3499\nExplain in a minimum of 2 sentences how to graph the equation of the absolute value function given a vertex of (-1,3) and a value of “a” equal to ½.",
null,
"Mathematics, 21.06.2019 23:30, sindy35111\nAtown has a population of 17000 and grows at 2.5% every year. to the nearest year, how long will it be until the population will reach 19600?",
null,
"Mathematics, 22.06.2019 01:00, rosyjesus297\nFind the center of the circle that can be circumscribed about efg with e(4,4) f(4,2) g(8,2)\nDo you know the correct answer?\nQuestion Progress Homework Progress\n17\n88\nComplete the following sentences.\n...\n\nQuestions in other subjects:",
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"",
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"Mathematics, 12.05.2021 22:30",
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"Total solved problems on the site: 14426307"
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http://wiki.ljackson.us/index.php?title=Excel&diff=prev&oldid=3509 | [
"BreadCrumbs: Excel\n\n# Excel\n\n(Difference between revisions)\nJump to: navigation, search\n Revision as of 22:31, 24 August 2019 (edit)Ljackson (Talk | contribs) (→Replace Non-Standard Space Characters)← Previous diff Revision as of 22:35, 24 August 2019 (edit)Ljackson (Talk | contribs) (→Replace Non-Standard Space Characters)Next diff → Line 6: Line 6: =SUBSTITUTE(SUBSTITUTE(B2, CHAR(202), CHAR(32)), CHAR(160), CHAR(32)) =SUBSTITUTE(SUBSTITUTE(B2, CHAR(202), CHAR(32)), CHAR(160), CHAR(32)) + + In most cases it will likely be easier to clean the data in bash using tr, sed, and awk. The example below replaces carriage returns with newline and removes all non essential ASCII characters using their respective ASCII codes. Characters can be deleted or replaced by utilizing the -d command parameter. Dive Deeper: https://alvinalexander.com/blog/post/linux-unix/how-remove-non-printable-ascii-characters-file-unix + + pbpaste | tr '\\r\\n' '\\n' | tr -c '\\11\\12\\15\\40-\\176' '\\t' | grep ^[[:digit:]] | pbcopy + + pbpaste | tr -cd '\\11\\12\\15\\40-\\176' === String Manipulation === === String Manipulation ===\n\n# Windows XP\n\n### Replace Non-Standard Space Characters\n\nThe ASCII code for non-breaking space is 160 and along with other chars like 202 which look like space but have different ASCII values cause very frustrating problems for formulas using functions like SUBSTITUTE(). Additionally functions like CLEAN() do not detect these CHARs as they are technical valid within the extended ASCII code set. Fortunately we can replace them with space or other delimiters using the SUBSTITUTE() function in combination with the CHAR() function.\n\n```=SUBSTITUTE(SUBSTITUTE(B2, CHAR(202), CHAR(32)), CHAR(160), CHAR(32))\n```\n\nIn most cases it will likely be easier to clean the data in bash using tr, sed, and awk. The example below replaces carriage returns with newline and removes all non essential ASCII characters using their respective ASCII codes. Characters can be deleted or replaced by utilizing the -d command parameter. Dive Deeper: https://alvinalexander.com/blog/post/linux-unix/how-remove-non-printable-ascii-characters-file-unix\n\n```pbpaste | tr '\\r\\n' '\\n' | tr -c '\\11\\12\\15\\40-\\176' '\\t' | grep ^digit: | pbcopy\n```\n```pbpaste | tr -cd '\\11\\12\\15\\40-\\176'\n```\n\n### String Manipulation\n\nSplit on First Occurrence of Char and return all chars before split point\n\n```=MID(D2,1,(FIND(CHAR(1),SUBSTITUTE(D2,\":\",CHAR(1),1),1)-1))\n```\n\nSplit on First Occurrence of Char and return all chars after split point\n\n```=MID(D2,(FIND(CHAR(1),SUBSTITUTE(D2,\":\",CHAR(1),1),1)+1),(LEN(D2)-FIND(CHAR(1),SUBSTITUTE(D2,\":\",CHAR(1),1),1)))\n```\n\nSplit on Last Occurrence of Char and return last 13 characters\n\n```=MID(B2,(FIND(CHAR(1),SUBSTITUTE(B2, \"PKG-\", CHAR(1),((LEN(B2)-LEN(SUBSTITUTE(UPPER(B2),\"PKG-\",\"\")))/LEN(\"PKG-\"))),1)+LEN(\"PKG-\")),13)\n```\n\nSplit on Last Occurrence of Char and return to end of string\n\n```=TRIM(RIGHT(SUBSTITUTE(H2,\" \",REPT(\" \",LEN(H2))),LEN(H2)))\n```\n\n### Date and Time\n\nExcel stores dates as sequential serial numbers so that they can be used in calculations. January 1, 1900 is serial number 1, and January 1, 2008 is serial number 39448 because it is 39,447 days after January 1, 1900. You will need to change the number format (Format Cells) in order to display a proper date.\n\nRemember that Excel stores times as a fraction of a day, so to convert any given time to minutes you simply multiply a time value by the number of minutes in a day (24 * 60 = 1440). You can then divide by the desired time interval, in this case 15.\n\nDays since January 1, 1900 (View Timestamp as Number) = 42602.7936342593\n\n```=((\"8/21/2016 7:02:50 PM\" * 1)\n```\n\nDays since January 1, 1900 (No Change) = 42602.7936342593\n\n```=((\"8/21/2016 7:02:50 PM\" * (24*60))/15)/((24*60)/15)\n```\n\nMultiples of Fifteen = 4089868.18888889\n\n```=((\"8/21/2016 7:02:50 PM\" * (24*60))/15)\n```\n\nRun a FLOOR function Before Converting back into Days = 42602.7916666667\n\n```=FLOOR((\"8/21/2016 7:02:50 PM\" * (24*60)/15),1)/((24*60)/15)\n```\n\nThe final result returns the 15 minute grouping (00,15,30,45) rounded down.\n\n```=(FLOOR((N4*(24/4)),1)/((24/4)))*24\n```\n\nThis also works with any integer, in this case we group days into 4 hour groups.\n\n### Index Match on multiple criteria\n\nReturn value in respective Index cell\n\n```=INDEX(Setup.Benchmark!\\$F\\$1:\\$F\\$781,MATCH(1,(G2=Setup.Benchmark!\\$G\\$1:\\$G\\$781)*(I2=Setup.Benchmark!\\$J\\$1:\\$J\\$781)*(J2=Setup.Benchmark!\\$K\\$1:\\$K\\$781),0))\n```\n\nReturn 1 or 0 based on match\n\n```=IF(ISNUMBER(MATCH(1,(G2=Setup.Benchmark!\\$G\\$1:\\$G\\$781)*(I2=Setup.Benchmark!\\$J\\$1:\\$J\\$781)*(J2=Setup.Benchmark!\\$K\\$1:\\$K\\$781),0)),1,0)\n\n```\n\n### Non Printable Characters, VLOOKUP or INDEX MATCH #N/A Error Fix, Solution\n\n```=VLOOKUP(TRIM(SUBSTITUTE(D2,CHAR(160),CHAR(32))),'io85'!A:D,4,FALSE)\n```\n\n#### Excel Help\n\nImportant The TRIM function was designed to trim the 7-bit ASCII space character (value 32) from text. In the Unicode character set, there is an additional space character called the nonbreaking space character that has a decimal value of 160. This character is commonly used in Web pages as the HTML entity, . By itself, the TRIM function does not remove this nonbreaking space character. For an example of how to trim both space characters from text, see Remove spaces and nonprinting characters from text.\n\n```Sometimes text values contain leading, trailing, or multiple embedded space characters (Unicode character set (Unicode: A character encoding standard developed by the Unicode Consortium. By using more than one byte to represent each character, Unicode enables almost all of the written languages in the world to be represented by using a single character set.) values 32 and 160), or non-printing characters (Unicode character set values 0 to 31, 127, 129, 141, 143, 144, and 157). These characters can sometimes cause unexpected results when you sort, filter, or search. For example, users may make typographical errors by inadvertently adding extra space characters, or imported text data from external sources may contain nonprinting characters embedded in the text. Because these characters are not easily noticed, the unexpected results may be difficult to understand. To remove these unwanted characters, you can use a combination of the TRIM, CLEAN, and SUBSTITUTE functions.\n\nThe TRIM function removes spaces from text except for single spaces between words. The CLEAN function removes all nonprintable characters from text. Both functions were designed to work with 7-bit ASCII, which is a subset of the ANSI character set (ANSI character set: An 8-bit character set used by Microsoft Windows that allows you to represent up to 256 characters (0 through 255) by using your keyboard. The ASCII character set is a subset of the ANSI set.). It's important to understand that the first 128 values (0 to 127) in 7-bit ASCII represent the same characters as the first 128 values in the Unicode character set.\n\nThe TRIM function was designed to trim the 7-bit ASCII space character (value 32) from text. In the Unicode character set, there is an additional space character called the nonbreaking space character that has a decimal value of 160. This character is commonly used in Web pages as the HTML entity, . By itself, the TRIM function does not remove this nonbreaking space character.\n\nThe CLEAN function was designed to remove the first 32 non-printing characters in the 7 bit ASCII code (values 0 through 31) from text. In the Unicode character set, there are additional nonprinting characters (values 127, 129, 141, 143, 144, and 157). By itself, the CLEAN function does not remove these additional nonprinting characters.\n\nTo do this task, use the SUBSTITUTE function to replace the higher value Unicode characters with the 7-bit ASCII characters for which the TRIM and CLEAN functions were designed.\n```\n\n### Clean / Trim Non Printing Chars from Excel Data\n\nRemoves the trailing space from the string \"BD 122 \" (BD 112)\n\n```=TRIM(A2)\n```\n\nRemoves the nonprinting BEL character (ASCII value of 7) from the string value created by the expression =\"XY\"&CHAR(7)&\"453\" (XY453)\n\n```=CLEAN(A3)\n```\n```Replaces each nonbreaking space character (Unicode value of 160) with a space character (ASCII value of 32) by using the SUBSTITUTE function, and then removes the leading and multiple embedded spaces from the string \" BD 122\" (BD 112)\n```\n```=TRIM(SUBSTITUTE(A4,CHAR(160),CHAR(32)))\n```\n\nReplaces the nonprinting DEL character (ASCII value of 127) with a BEL character (ASCII value of 7) by using the SUBSTITUTE function, and then removes the BEL character from the string \"MN987\" (MN987)\n\n```=CLEAN(SUBSTITUTE(A5,CHAR(127),CHAR(7)))\n```\n\n### Excel 2007\n\nData -> From Other Sources ->\n\n### Dynamic Chart Titles From Pivot Table (Date Range)\n\n```=IF(DAY(MIN(Summary!\\$B\\$6:\\$B\\$20))=DAY(MAX(Summary!\\$B\\$6:\\$B\\$20)),CONCATENATE(\"CW \",WEEKNUM(MIN(Summary!\\$B\\$6:\\$B\\$20),1),\" - \",TEXT(MIN(Summary!\\$B\\$6:\\$B\\$20),\"mmmm\"), \", \",DAY(MIN(Summary!\\$B\\$6:\\$B\\$20))&IF(OR(DAY(MIN(Summary!\\$B\\$6:\\$B\\$20))={1,2,3,21,22,23,31}),CHOOSE(1*RIGHT(DAY(MIN(Summary!\\$B\\$6:\\$B\\$20)),1),\"st\",\"nd \",\"rd\"),\"th\")),CONCATENATE(\"CW \",WEEKNUM(MIN(Summary!\\$B\\$6:\\$B\\$20),1),\" - \",TEXT(MIN(Summary!\\$B\\$6:\\$B\\$20),\"mmmm\"), \", \",DAY(MIN(Summary!\\$B\\$6:\\$B\\$20))&IF(OR(DAY(MIN(Summary!\\$B\\$6:\\$B\\$20))={1,2,3,21,22,23,31}),CHOOSE(1*RIGHT(DAY(MIN(Summary!\\$B\\$6:\\$B\\$20)),1),\"st\",\"nd \",\"rd\"),\"th\"),\" - \",CONCATENATE(\"CW \",WEEKNUM(MAX(Summary!\\$B\\$6:\\$B\\$20),1),\" - \",TEXT(MAX(Summary!\\$B\\$6:\\$B\\$20),\"mmmm\"), \", \",DAY(MAX(Summary!\\$B\\$6:\\$B\\$20))&IF(OR(DAY(MAX(Summary!\\$B\\$6:\\$B\\$20))={1,2,3,21,22,23,31}),CHOOSE(1*RIGHT(DAY(MAX(Summary!\\$B\\$6:\\$B\\$20)),1),\"st\",\"nd \",\"rd\"),\"th\"))))\n```\n\n### Week Number\n\n```=CONCATENATE(\"Cal Week: \", (1+INT((#REF!-(DATE(YEAR(#REF!),1,2)-WEEKDAY(DATE(YEAR(#REF!),1,0))))/7)))\n```\n```=WEEKNUM(TEXT(E2, \"mmmm dd, yyyy\"), 2)\n```\n\n## Count Cells when not blank\n\n```=COUNTIF(D2:G2,\"<>\"&\"\")\n```\n\n## Concatenate Vlookup Values When Source is not blank\n\n```=CONCATENATE(IF(D17 <> \"\",(VLOOKUP(D17,Printtypes!\\$A\\$1:\\$B\\$19, 2,FALSE)),\"\"),IF(E17 <> \"\",(\", \" & VLOOKUP(E17,Printtypes!\\$A\\$1:\\$B\\$19, 2,FALSE)),\"\"),IF(F17 <> \"\",(\", \" & VLOOKUP(F17,Printtypes!\\$A\\$1:\\$B\\$19, 2,FALSE)),\"\"),IF(G17 <> \"\",(\", \" & VLOOKUP(G17,Printtypes!\\$A\\$1:\\$B\\$19, 2,FALSE)),\"\"))\n```\n\n## CountIf with Subtotal (Respects Hidden/Filtered Cells\n\n```=SUMPRODUCT(SUBTOTAL(3,OFFSET(B1:B51,ROW(B1:B51)-ROW(B1),0,1)),--(B1:B51=\"Inactive\"))\n```\n\n## Count Unique Names / Numbers\n\nThe entire formula is as follows (replace C3:C25 with the range of data you want the formula to check)\n\n```=SUM(IF(FREQUENCY(IF(LEN(C3:C25)>0,MATCH(C3:C25,C3:C25,0),\"\"), IF(LEN(C3:C25)>0,MATCH(C3:C25,C3:C25,0),\"\"))>0,1))\n```\n\nIf you just want to count unique numbers, and not text, use the following formula instead:\n\n```=SUM(IF(FREQUENCY(C3:C25, C3:C25)>0,1))\n```\n\n## Split string by occurrence of character\n\nReturn the portion of string from the second occurrence of character:\n\n```=RIGHT(\\$E2;LEN(\\$E2) - FIND(\"-\";\\$E2;FIND(\"-\";\\$E2)+1))\n```\n\nReturn the portion of string until the first occurrence of character:\n\n```=LEFT(\\$E2;FIND(\"-\";\\$E2)-1)\n```\n\n## Replace Double Quotes and Comma Within String\n\n```=SUBSTITUTE(N1, CONCATENATE(CHAR(34),\",\",CHAR(34)), \"\")\n```\n\n## Conditional Formating \"At Change In Value\"\n\n```Private Sub Worksheet_Change(ByVal Target As Range)\n\nDim C As Variant\nDim Clast As Variant\nDim CI As Integer\nDim ColS As Variant\nDim ColE As Variant\nDim FirstRow As Long\nDim LastRow As Long\nDim Rng As Range\nDim Wks As Worksheet\nDim Color As Boolean\nDim Total As Long\n\nIf Target.Row > 0 Then\n\nColS = \"A\"\nColE = \"L\"\nFirstRow = 2 'Assumes header row is row 1\nSet Wks = Worksheets(\"Scoreboard\")\n'LastRow = Wks.Cells(Rows.Count, ColS).End(xlUp).Row\nLastRow = Target.Row\n\nLastRow = IIf(LastRow < FirstRow, FirstRow, LastRow)\n\nSet Rng = Wks.Range(Cells(FirstRow, ColS), Cells(LastRow, ColS))\nFor Each C In Rng\nIf IsDate(C) Then\n\nIf Clast = \"\" Then\nCI = 50\nClast = C\n'MsgBox \"Start \" & C & \" - \" & Clast\nElseIf C <> Clast And Color = False Then\nCI = xlColorIndexNone\nColor = True\n'MsgBox \"CF CNE \" & C & \"<>\" & Clast\nClast = C\nElseIf C <> Clast And Color = True Then\nCI = 50\nColor = False\n'MsgBox \"CT CNE \" & C & \"<>\" & Clast\nClast = C\nElseIf C = Clast And Color = False Then\nCI = 50\n'MsgBox \"CF CE \" & C & \"=\" & Clast\nClast = C\nElseIf C = Clast And Color = True Then\nCI = xlColorIndexNone\n'MsgBox \"CT CE \" & C & \"=\" & Clast\nClast = C\nElse\nCI = xlColorIndexNone\nMsgBox \"Else \" & C\nEnd If\n\nIf CI > 0 Then\nWith Range(Cells(C.Row, ColS), Cells(C.Row, ColE)).Interior\n.Pattern = xlSolid\n.PatternColorIndex = xlAutomatic\n.ThemeColor = xlThemeColorAccent3\n.TintAndShade = 0.599993896298105\n.PatternTintAndShade = 0\nEnd With\nElse\nWith Range(Cells(C.Row, ColS), Cells(C.Row, ColE)).Interior\n.Pattern = xlNone\n.TintAndShade = 0\n.PatternTintAndShade = 0\nEnd With\nEnd If\n\nEnd If\n\nTotal = Total + 1\n\nNext C\n\n'MsgBox Total\nEnd If\n\nEnd Sub\n```\n\n## Function\n\n```=IF(INDIRECT(ADDRESS(ROW(),1,3))<>INDIRECT(ADDRESS((ROW()-1),1,3)),1,0)\n```\n\n## Date Filters Not Available for Pivot Table / Chart\n\nDate Filters are not supported in Excel 2003 compatibility mode.\n\nRe-save document in Excel 2007 format and the options will no longer be greyed out.\n\n## Dynamic Graph/Chart Title\n\n```=\"Operator Summary - \" & TEXT(MIN(Summary!\\$B\\$6:\\$B\\$20),\"ddd, mmm dd, yyyy\") & \" to \" & TEXT(MAX(Summary!\\$B\\$6:\\$B\\$20),\"ddd, mmm dd, yyyy\")\n```\n\n## Compound Interest\n\n```(100000 * (1 + (0,08/12))^(1)) - 100000\n```\n```40000000 * (00042 / (1 - ((1 + 00042)^-(360))))\n```\n\nMonthly Mortgage payment + Opportunity cost of monthly interest earned on 20% down payment\n\n```2147 + (100000 * (1 + (0,08/12))^(1)) - 100000\n```\n\n# Mac OS X\n\n## File Not Found\n\nWhen starting Microsoft Excel 2004 for Mac OS X you may get the error \"File Not Found\".\n\nFirst place to check is the Excel Startup folder:\n\n```ljackson 14:46:50 ~/Library/Preferences> cd /Applications/Microsoft\\ Office\\ 2004/Office/Startup/\nljackson 14:47:33 /Applications/Microsoft Office 2004/Office/Startup> ll\ndrwxrwxr-x 4 ljackson admin 136B May 3 14:39 Excel\ndrwxrwxr-x 2 ljackson admin 68B Apr 8 2004 PowerPoint\ndrwxrwxr-x 2 ljackson admin 68B Apr 8 2004 Word\nljackson 14:47:33 /Applications/Microsoft Office 2004/Office/Startup> cd Excel/\nljackson 14:47:37 /Applications/Microsoft Office 2004/Office/Startup/Excel> ll\ntotal 96\n-rw-r--r-- 1 ljackson admin 25K May 3 14:15 8DAE9700\n-rw-r--r-- 1 ljackson admin 16K May 3 14:39 Personal Macro Workbook\n```\n\nIn my case the alphanumerical file was generated when Excel crashed. So I will delete it:\n\n```ljackson 14:47:38 /Applications/Microsoft Office 2004/Office/Startup/Excel> rm -f 8DAE9700\nljackson 14:47:53 /Applications/Microsoft Office 2004/Office/Startup/Excel> ll\ntotal 40\n-rw-r--r-- 1 ljackson admin 16K May 3 14:39 Personal Macro Workbook\n```\n\nNow I don't get the anoying error \"File Not Found\" every time I launch Excel.\n\n## VBA Macros\n\n```Sub RangeDateFix()\nDim ndate As String\n'ActiveCell.CurrentRegion.Cells.Select\nFor Each c In ActiveWindow.RangeSelection.Cells\nndate = USdateEU(c.Value)\nc.Value = ndate\nNext\nEnd Sub\n\nPublic Function USdateEU(ByVal tdate As String)\nDim txt As String, ftxt As String, x As Variant, i As Long\ntxt = tdate\nx = Split(txt, \"/\")\n'For i = 0 To UBound(x)\n'MsgBox x(i)\n'Next i\nftxt = x(1) & \"/\" & x(0) & \"/\" & x(2)\n\nUSdateEU = ftxt\n'MsgBox ftxt\nEnd Function\n\nPublic Function Split(ByVal sInput As String, _\nOptional ByVal sDelimiter As String, _\nOptional ByVal nLimit As Long = -1, _\nOptional ByVal bCompare As Integer = vbBinaryCompare _\n) As Variant\n\nDim nCount As Long\nDim nPos As Long\nDim nDelimiterLength As Long\nDim nStart As Long\nDim sOutput() As String\n\nIf nLimit = 0 Then\nSplit = Array()\nElse\nnDelimiterLength = Len(sDelimiter)\n\nIf nDelimiterLength = 0 Then\nSplit = Array(sInput)\nElse\nnStart = 1\nnPos = InStr(nStart, sInput, sDelimiter, bCompare)\n\nDo While nPos\n\nReDim Preserve sOutput(0 To nCount) As String\n\nIf nCount + 1 = nLimit Then\nsOutput(nCount) = Mid(sInput, nStart)\nExit Do\nElse\nsOutput(nCount) = Mid(sInput, nStart, nPos - nStart)\nnStart = nPos + nDelimiterLength\nEnd If\n\nnCount = nCount + 1\n\nnPos = InStr(nStart, sInput, sDelimiter, bCompare)\n\nLoop\n\nReDim Preserve sOutput(0 To nCount) As String\n\nsOutput(nCount) = Mid(sInput, nStart)\n\nSplit = sOutput\n\nEnd If\n\nEnd If\n\nEnd Function\n```\n\n## Clear Old Pivot Table Labels\n\n```Sub DeleteMissingItems2002All()\n'prevents unused items in non-OLAP PivotTables\n'pivot table tutorial by contextures.com\nDim pt As PivotTable\nDim ws As Worksheet\nDim pc As PivotCache\n\n'change the settings\nFor Each ws In ActiveWorkbook.Worksheets\nFor Each pt In ws.PivotTables\npt.PivotCache.MissingItemsLimit = xlMissingItemsNone\nNext pt\nNext ws\n\n'refresh all the pivot caches\nFor Each pc In ActiveWorkbook.PivotCaches\nOn Error Resume Next\npc.Refresh\nNext pc\n\nEnd Sub\n```\n\n## Append/Merge/Combine adjacent columns one after the other\n\nMac OS X compatible\n\n```Sub test()\nDim LR As Long, i As Long\nFor i = 2 To 4\nLR = Cells(Rows.Count, i).End(xlUp).Row\nRange(Cells(1, i), Cells(LR, i)).Copy Destination:=Cells(Rows.Count, 1).End(xlUp).Offset(1)\nNext i\nEnd Sub\n```\n\nManipulate Cells with SQL based Macro\n\n```Sub doSQL()\n\nDim strCon As String\nDim oneSQL As String\n\n' refer to 'microsoft activex data objects library'\nDim cn As Object\nDim rs As Object\n\nSet cn = CreateObject(\"ADODB.Connection\")\nSet rs = CreateObject(\"ADODB.Recordset\")\n\nstrCon = \"Provider=Microsoft.ACE.OLEDB.12.0;\" & _\n\"Data Source='\" & ThisWorkbook.FullName & \"';\" & _\n\"Extended Properties='Excel 12.0;HDR=No;IMEX=1';\" ' HDR=No means no headers (field names)\n\ncn.Open strCon ' open connection\n\n'-------------------------------------------------------------------------------\n\n' F1, F2, F3 are the default fieldnames when no headers are included with data\n\noneSQL = \"SELECT F3 FROM [Sheet1\\$B:D] where F3 not like '' union all \" & _\n\"SELECT F1 FROM [Sheet1\\$B:D] where F1 not like '' union all \" & _\n\"SELECT F2 FROM [Sheet1\\$B:D] where F2 not like ''; \"\n\nrs.Open oneSQL, cn ' get recordset\n\nSheets(\"Sheet1\").Range(\"A:A\").ClearContents\n\nSheets(\"Sheet1\").Range(\"A1\").CopyFromRecordset rs ' copy recordset to worksheet\n\n'-------------------------------------------------------------------------------\n\nrs.Close\ncn.Close\n\nSet rs = Nothing\nSet cn = Nothing\n\nEnd Sub\n```\n\n## Color\n\n```Function HEXCOL2RGB(ByVal HexColor As String) As String\n\n'The input at this point could be HexColor = \"#00FF1F\"\n\nDim Red As String\nDim Green As String\nDim Blue As String\nDim Color As String\n\nColor = Replace(HexColor, \"#\", \"\")\n'Here HexColor = \"00FF1F\"\n\nRed = Val(\"&H\" & Mid(Color, 1, 2))\n'The red value is now the long version of \"00\"\n\nGreen = Val(\"&H\" & Mid(Color, 3, 2))\n'The red value is now the long version of \"FF\"\n\nBlue = Val(\"&H\" & Mid(Color, 5, 2))\n'The red value is now the long version of \"1F\"\n\n'HEXCOL2RGB = RGB(Red, Green, Blue)\nHEXCOL2RGB = Red & \",\" & Green & \",\" & Blue\n'The output is an RGB value\n\nEnd Function\n\nSub CvrtHex()\nDim Cell As Range\nIf TypeName(Selection) <> \"Range\" Then Exit Sub\nFor Each Cell In Selection\nIf Cell.Value < 0 Then\n'Debug.Print \"\"\nElse\nDebug.Print HEXCOL2RGB(Cell.Value)\nCell.Next.Value = HEXCOL2RGB(Cell.Value)\nEnd If\nNext Cell\nEnd Sub\n\nSub CvrtHex2()\nDim Cell As Range\nDim clrs As Variant\nIf TypeName(Selection) <> \"Range\" Then Exit Sub\nFor Each Cell In Selection\nIf Cell.Value < 0 Then\n'Debug.Print \"\"\nElse\nclrs = Split(Cell.Value, \",\")\nDebug.Print clrs(0) & \" \" & clrs(1) & \" \" & clrs(2)\nCell.Next.Interior.Color = RGB(clrs(0), clrs(1), clrs(2))\nCell.Next.Value = \"R\" & clrs(0) & \" G\" & clrs(1) & \" B\" & clrs(2)\nIf clrs(0) < 200 And clrs(1) < 200 And clrs(2) < 200 Then\nCell.Next.Font.Color = RGB(255, 255, 255)\nDebug.Print \"White\"\nElse\nCell.Next.Font.Color = RGB(0, 0, 0)\nEnd If\nEnd If\nNext Cell\nEnd Sub\n```\n\nSet Background Color of Cells to Adjacent Cell Value (RGB)\n\n```Sub ColourCells()\nDim HowMany As Integer\nOn Error Resume Next\nApplication.DisplayAlerts = False\nHowMany = Application.InputBox _\n(Prompt:=\"Enter last row number.\", Title:=\"To apply to how many rows?\", Type:=1)\nOn Error GoTo 0\nApplication.DisplayAlerts = True\nIf HowMany = 0 Then\nExit Sub\nElse\nDim i As Integer\nFor i = 2 To HowMany\nCells(i, 6).Interior.Color = RGB(Cells(i, 2), Cells(i, 3), Cells(i, 4))\nNext i\nEnd If\nEnd Sub\n```"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6686992,"math_prob":0.96133554,"size":20229,"snap":"2021-21-2021-25","text_gpt3_token_len":6078,"char_repetition_ratio":0.11401731,"word_repetition_ratio":0.18064517,"special_character_ratio":0.32626426,"punctuation_ratio":0.15979508,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98193836,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-06-14T23:31:59Z\",\"WARC-Record-ID\":\"<urn:uuid:6aeef2c0-d826-4131-9797-25297eae0228>\",\"Content-Length\":\"42847\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:3c3360ec-7718-488f-beae-2c725b625b01>\",\"WARC-Concurrent-To\":\"<urn:uuid:480a0124-096c-43d0-b9c9-1651391d23d1>\",\"WARC-IP-Address\":\"64.251.22.178\",\"WARC-Target-URI\":\"http://wiki.ljackson.us/index.php?title=Excel&diff=prev&oldid=3509\",\"WARC-Payload-Digest\":\"sha1:OSOGKX2HG6IK2ENMZSJVQI5RY2TQ7MN3\",\"WARC-Block-Digest\":\"sha1:KP2WBQN434MLVXWDVSD26ZRMFNSGZ5HD\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-25/CC-MAIN-2021-25_segments_1623487614006.8_warc_CC-MAIN-20210614232115-20210615022115-00463.warc.gz\"}"} |
http://academicrepository.khas.edu.tr/browse?type=publisher&value=IOP%20Publishing%20Ltd | [
"Now showing items 1-3 of 3\n\n• #### Collective enhancement of nuclear state densities by the shell model Monte Carlo approach \n\nAuthors:\nPublisher and Date:(IOP Publishing Ltd, 2015)\nThe shell model Monte Carlo (SMMC) approach allows for the microscopic calculation of statistical and collective properties of heavy nuclei using the framework of the configuration-interaction shell model in very large model spaces. We present recent applications of the SMMC method to the calculation of state densities and their collective enhancement factors in rare-earth nuclei.\n\n• #### On the classification of scalar evolution equations with non-constant separant \n\nAuthors:\nPublisher and Date:(IOP Publishing Ltd, 2017)\nThe ` separant' of the evolution equation u(t) = F where F is some differentiable function of the derivatives of u up to order m is the partial derivative partial derivative F/partial derivative u(m) where um u(m) = partial derivative(m)u/partial derivative x(m). As an integrability test we use the formal symmetry method of Mikhailov-Shabat-Sokolov which is based on the existence of a recursion operator as a formal series. The solvability of its coefficients in the class of local functions gives ...\n\n• #### Recent Advances in the Application of the Shell Model Monte Carlo Approach to Nuclei \n\nThe shell model Monte Carlo (SMMC) method is a powerful technique for calculating the statistical and collective properties of nuclei in the presence of correlations in model spaces that are many orders of magnitude larger than those that can be treated by conventional diagonalization methods. We review recent advances in the development and application of SMMC to mid-mass and heavy nuclei."
] | [
null
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https://johannesbader.ch/blog/crackmes-de-gamas-mndg/ | [
"",
null,
"# Crackmes.de – gama’s mndg\n\nThis crackme is rated Difficulty: 2 – Needs a little brain (or luck). Although it is an easier crackme and it was published almost half a year ago, there are no accepted solutions yet. There are many comments for this crackme with people who solved this crackme, however, they all used some kind of brute forcing or even patching. This solutions show how to generate serials mathematically. If you run the crackme without debugger and enter an invalid serial, you get the dialog box shown in the following screenshot:",
null,
"If you run the crackme with a debugger like OllyDbg (or attach to the running process), entering an invalid serial will most likely lead to a memory access violation similar to this:",
null,
"This crackme uses Anti-Debugging techniques. The first part of this solution discusses the two anti-debugging tricks of this crackme and how to remove those check with patches.\n\n## Anti-Debugging\n\nFinding the subroutine that checks the serial is trivial: search for the string “Sorry, the serial is invalid :(” and you get the following clean code sequence:",
null,
"The subroutine at dword_405000 – I renamed it to validate_serial- is clearly calculating a value based on the serial. If the return value of validate_serial is 0xB528B18B, then the serial is valid, otherwise it is invalid. The subroutine validate_serial is located at an unusual place:\n\n.data:00405000 validate_serial dd 8000000h\n\n\nOffset 0x80000000 is far from the image base and likely created during runtime. Here is the disassembly of validate_serial when it is called first:\n\ndebug138:08000000 push edx\ndebug138:08000001 mov al, [ebp+25h]\ndebug138:08000004 or dword_101BFEC[ebx], edi\ndebug138:0800000A jmp far ptr 4E0h:0C0D08815h\n\n\nThis doesn’t look like valid code, and will probably lead to the memory access violation exceptions shown before. If we would have run the crackme without debugger, then offset 0x80000000 probably looks different. First, lets find the code location that creates and writes offset 0x8000000. We find the relevant code segment by looking for tale-tale API calls to VirtualAlloc with starting address 0x80000000. Here is the code snippet that allocates the memory and probably writes to it in sub_4015A0:\n\n.text:00401633 push 40h ; flProtect\n.text:00401635 push 3000h ; flAllocationType\n.text:0040163A push 10000h ; dwSize\n.text:00401644 call VirtualAlloc\n.text:0040164A call sub_4015A0\n.text:0040164F mov [ebp+var_82B], al\n.text:00401655 xor esi, esi\n.text:00401657 jmp short loc_40167D\n\n\nLet’s dive into sub_4015A0 and look for anti-debugging measures.\n\n### OllyDbg.exe\n\nInside sub_4015A0, we find the following loop:\n\n.text:004015A0 sub_4015A0 proc near ; CODE XREF: DialogFunc+6Ap\n.text:004015A0\n.text:004015A0 olly_dbg = byte ptr -0Ch\n.text:004015A0 var_1 = byte ptr -1\n.text:004015A0\n.text:004015A0 push ebp\n.text:004015A1 mov ebp, esp\n.text:004015A3 sub esp, 0Ch\n.text:004015A6 lea ecx, [ebp+olly_dbg]\n.text:004015A9 mov edx, offset unk_404074\n.text:004015AE mov eax, [edx]\n.text:004015B0 mov [ecx], eax\n.text:004015B2 mov eax, [edx+4]\n.text:004015B5 mov [ecx+4], eax\n.text:004015B8 mov eax, [edx+8]\n.text:004015BB mov [ecx+8], eax\n.text:004015BE xor eax, eax\n.text:004015C0 jmp short loc_4015C8\n.text:004015C2 ; ---------------------------------------------------------------------------\n.text:004015C2\n.text:004015C2 loc_4015C2: ; CODE XREF: sub_4015A0+2Bj\n.text:004015C2 xor [ebp+eax+olly_dbg], 81h\n.text:004015C7 inc eax\n.text:004015C8\n.text:004015C8 loc_4015C8: ; CODE XREF: sub_4015A0+20j\n.text:004015C8 cmp eax, 0Ch\n.text:004015CB jb short loc_4015C2\n.text:004015CD mov [ebp+var_1], 0\n.text:004015D1 lea eax, [ebp+olly_dbg]\n.text:004015D4 push eax\n.text:004015D5 call sub_4010A0\n.text:004015DA mov esp, ebp\n.text:004015DC pop ebp\n.text:004015DD retn\n.text:004015DD sub_4015A0 endp\n\n\nThis routine loops over the null-byte terminated string in unk_404074, and XORs it with 0x81. It writes the result to the local variable olly_dbg. Here is the encrypted string in unk_404074:\n\n.rdata:00404074 unk_404074 db 0EEh ; e ; DATA XREF: sub_4015A0+9o\n.rdata:00404075 db 0EDh ; f\n.rdata:00404076 db 0EDh ; f\n.rdata:00404077 db 0F8h ; °\n.rdata:00404078 db 0E5h ; s\n.rdata:00404079 db 0E3h ; p\n.rdata:0040407A db 0E6h ; µ\n.rdata:0040407B db 0AFh ; »\n.rdata:0040407C db 0E4h ; S\n.rdata:0040407D db 0F9h ; ·\n.rdata:0040407E db 0E4h ; S\n\n\nAnd this is the result in olly_dbg (and the reason I named the variable olly_dbg):\n\ndebug013:0018E89C db 6Fh ; o\ndebug013:0018E89D db 6Ch ; l\ndebug013:0018E89E db 6Ch ; l\ndebug013:0018E89F db 79h ; y\ndebug013:0018E8A0 db 64h ; d\ndebug013:0018E8A1 db 62h ; b\ndebug013:0018E8A2 db 67h ; g\ndebug013:0018E8A3 db 2Eh ; .\ndebug013:0018E8A4 db 65h ; e\ndebug013:0018E8A5 db 78h ; x\ndebug013:0018E8A6 db 65h ; e\n\n\nNext, the subroutine sub_4010A0 is called, with the ollydbg.exe string as the only argument:\n\n.text:004015D1 lea eax, [ebp+olly_dbg]\n.text:004015D4 push eax\n.text:004015D5 call sub_4010A0\n\n\nThe routine sub_4010A0 retrieves the address of three exported functions from the DLL PSAPI.dll (in esi, not shown):\n\n.text:00401230 push offset aEnumprocesses ; \"EnumProcesses\"\n.text:00401235 push esi ; hModule\n.text:0040123C mov [ebp+enum_processes], eax\n.text:00401242 push offset aEnumprocessmod ; \"EnumProcessModules\"\n.text:00401247 push esi ; hModule\n.text:0040124E mov [ebp+enum_process_modules], eax\n.text:00401254 push offset aGetmodulebasen ; \"GetModuleBaseNameA\"\n.text:00401259 push esi ; hModule\n.text:00401260 mov [ebp+get_module_base_name], eax\n\n\nThe API EnumProcesses is called first to enumerate all running processes:\n\n.text:0040129D call [ebp+enum_processes]\n.text:004012A3 test eax, eax\n.text:004012A5 jz loc_401488\n.text:004012AB mov eax, [ebp+var_4]\n.text:004012AE shr eax, 2\n.text:004012B1 mov [ebp+nr_processes], eax\n\n\nNext, our subroutine iterates over these processes (not shown) and enumerates all modules of the current process:\n\n.text:004012D6 mov eax, [ebp+ebx*4+dwProcessId]\n.text:004012DD push eax ; dwProcessId\n.text:004012DE push 0 ; bInheritHandle\n.text:004012E0 push 410h ; dwDesiredAccess\n.text:004012E5 call OpenProcess\n.text:004012EB mov edi, eax\n.text:004012ED test edi, edi\n.text:004012EF jz short loc_40131D\n.text:004012F1 lea eax, [ebp+var_4]\n.text:004012F4 push eax\n.text:004012F5 push 4\n.text:004012F7 lea eax, [ebp+var_8]\n.text:004012FA push eax\n.text:004012FB push edi\n.text:004012FC call [ebp+enum_process_modules]\n\n\nFor each module the code then gets its basename:\n\n.text:0040130B lea eax, [ebp+modulebasename]\n.text:00401311 push eax\n.text:00401312 mov eax, [ebp+var_8]\n.text:00401315 push eax\n.text:00401316 push edi\n.text:00401317 call [ebp+get_module_base_name]\n\n\nIt then converts the name to upper case and compares it to OLLYDBG.EXE:\n\n.text:00401324 lea eax, [ebp+modulebasename]\n.text:0040132A push eax\n.text:0040132B call to_upper_case\n.text:00401330 pop ecx\n.text:00401331 mov ecx, eax\n.text:00401333 lea edx, [ebp+olly_dbg]\n.text:00401339 sub edx, ecx\n.text:0040133B\n.text:0040133B loc_40133B: ; CODE XREF: sub_4010A0+2A5j\n.text:0040133B mov al, [ecx]\n.text:0040133D cmp al, [ecx+edx]\n.text:00401340 jnz short loc_40134B\n.text:00401342 inc ecx\n.text:00401343 test al, al\n.text:00401345 jnz short loc_40133B\n.text:00401347 xor eax, eax\n.text:00401349 jmp short loc_401350\n.text:0040134B ; ---------------------------------------------------------------------------\n.text:0040134B\n.text:0040134B loc_40134B: ; CODE XREF: sub_4010A0+2A0j\n.text:0040134B sbb eax, eax\n.text:0040134D sbb eax, 0FFFFFFFFh\n\n\nIf one of the base name matches ollydbg.exe (case insensitive), then eax = 0 and the code will jump to the end of the subroutine, otherwise it sets eax = -1 and continues. Or in pseudo code:\n\nFOR ALL running processes:\nFOR ALL process modules:\nIF uppercase(base name of module) = \"OLLYDBG.EXE\" THEN\nRETURN\nELSE\nproceed\nEND IF\nEND FOR\nEND FOR\n\n\nThe relevant jump is “401345 jnz short loc_40133B”:",
null,
"If the zero flag is set here, if means the code found an ollydbg.exe process. To patch away the check we can just change the target of the jump to loc_40134B, where we would end up if no process matches ollydbg.exe. After patching the code looks like this:",
null,
"### IsDebuggerPresent\n\nStill inside sub_4010A0 we get to these lines:\n\n.text:0040151E lea ecx, [ebp+isDebuggerPresent]\n.text:00401521 mov edx, offset unk_404080\n.text:00401526 mov eax, [edx]\n.text:00401528 mov [ecx], eax\n.text:0040152A mov eax, [edx+4]\n.text:0040152D mov [ecx+4], eax\n.text:00401530 mov eax, [edx+8]\n.text:00401533 mov [ecx+8], eax\n.text:00401536 mov eax, [edx+0Ch]\n.text:00401539 mov [ecx+0Ch], eax\n.text:0040153C mov ax, [edx+10h]\n.text:00401540 mov [ecx+10h], ax\n.text:00401544 xor eax, eax\n.text:00401546 jmp short loc_40154E\n.text:00401548 ; ---------------------------------------------------------------------------\n.text:00401548\n.text:00401548 loc_401548: ; CODE XREF: sub_401500+51j\n.text:00401548 xor [ebp+eax+isDebuggerPresent], 82h\n.text:0040154D inc eax\n.text:0040154E\n.text:0040154E loc_40154E: ; CODE XREF: sub_401500+46j\n.text:0040154E cmp eax, 12h\n.text:00401551 jb short loc_401548\n\n\nAgain they implement an XOR decryption of a string, this time in unk_404080:\n\n.rdata:00404080 unk_404080 db 0CBh ; - ; DATA XREF: sub_401500+21o\n.rdata:00404081 db 0F1h ; ±\n.rdata:00404082 db 0C6h ; ¦\n.rdata:00404083 db 0E7h ; t\n.rdata:00404084 db 0E0h ; a\n.rdata:00404085 db 0F7h ; ˜\n.rdata:00404086 db 0E5h ; s\n.rdata:00404087 db 0E5h ; s\n.rdata:00404088 db 0E7h ; t\n.rdata:00404089 db 0F0h ; =\n.rdata:0040408A db 0D2h ; -\n.rdata:0040408B db 0F0h ; =\n.rdata:0040408C db 0E7h ; t\n.rdata:0040408D db 0F1h ; ±\n.rdata:0040408E db 0E7h ; t\n.rdata:0040408F db 0ECh ; 8\n.rdata:00404090 db 0F6h ; ÷\n.rdata:00404091 db 0\n\n\nAll characters are XORed with 0x82. The result is the string “IsDebuggerPresent”:\n\ndebug013:0018E896 db 49h ; I\ndebug013:0018E897 db 73h ; s\ndebug013:0018E898 db 44h ; D\ndebug013:0018E899 db 65h ; e\ndebug013:0018E89A db 62h ; b\ndebug013:0018E89B db 75h ; u\ndebug013:0018E89C db 67h ; g\ndebug013:0018E89D db 67h ; g\ndebug013:0018E89E db 65h ; e\ndebug013:0018E89F db 72h ; r\ndebug013:0018E8A0 db 50h ; P\ndebug013:0018E8A1 db 72h ; r\ndebug013:0018E8A2 db 65h ; e\ndebug013:0018E8A3 db 73h ; s\ndebug013:0018E8A4 db 65h ; e\ndebug013:0018E8A5 db 6Eh ; n\ndebug013:0018E8A6 db 74h ; t\n\n\nAn API call to GetProcAddress then gets the address IsDebuggerPresent inside kernel32.dll:\n\n.text:00401557 lea eax, [ebp+isDebuggerPresent]\n.text:0040155A push eax ; lpProcName\n.text:0040155B push ebx ; hModule\n.text:00401562 mov edx, eax\n.text:00401564 lea edi, [ebp+isDebuggerPresent]\n.text:00401567 xor eax, eax\n.text:00401569 mov ecx, 12h\n.text:0040156E rep stosb\n.text:00401570 test edx, edx\n.text:00401572 jz short loc_40157A\n\n\nThe code then makes a call to IsDebuggerPresent and tests the return value:\n\n.text:00401574 call edx\n.text:00401576 test eax, eax\n.text:00401578 jnz short loc_40157E\n\n\nIf IsDebuggerPresent returns a non-zero value (meaning there is a debugger present), the code will jump to loc_40157E. To prevent this jump – even when a debugger is present – we can simply remove this jump altogether:",
null,
"becomes",
null,
"These two anti-debugging checks prevent that the correct code is written to 0x80000000. Now that we have removed both checks, we can finally run the code with a debugger and inspect validate_serial:\n\n## Validate Serial\n\n### Reverse Engineering validate_serial\n\nThis snippet is validate_serial when the anti-debugging checks are removed or circumvented:\n\ndebug076:08000000 push ebx\ndebug076:08000001 mov eax, [esp+8]\ndebug076:08000005 mov edx, 0BEEDh\ndebug076:0800000A jmp short loc_8000020\ndebug076:0800000C\ndebug076:0800000C loc_800000C:\ndebug076:0800000C mov ecx, edx\ndebug076:0800000E shl ecx, 5\ndebug076:08000011 inc ecx\ndebug076:08000012 movzx ebx, byte ptr [eax]\ndebug076:08000015 xor ecx, ebx\ndebug076:08000017 mov edx, ecx\ndebug076:08000019 xor edx, offset unk_12345678\ndebug076:0800001F inc eax\ndebug076:08000020\ndebug076:08000020 loc_8000020:\ndebug076:08000020 cmp byte ptr [eax], 0\ndebug076:08000023 jnz short loc_800000C\ndebug076:08000025 mov eax, edx\ndebug076:08000027 pop ebx\ndebug076:08000028 retn\n\n\nThis simple routine can be represented by the following pseudo code:\n\nFUNCTION validate_serial(serial)\nv = 0xBEED\nFOR c IN serial DO\nv = (v*32 + 1)\nv ^= c\nv ^= 0x12345678\nRETURN v & 0xFFFFFFFF\nENDFUNCTION\n\n\nThe return value of validate_serial will be compared to 0xB528B18B, if it matches, the serial is valid. So at this point we could start writing a brute-force algorithm, that tests random serials and finds the ones that are valid. Since the return value of validate_serial is only 4 bytes, or 2^32, brute forcing won’t take too long. There is a better method though.\n\n### Reformulating the Algorithm\n\nThe characters of the serial are XORed with the variable v. Due to the associative and commutative property of the XOR operation, we can separate the routine validate_serial into two parts:\n\nFUNCTION validate_serial(serial)\nq = 0xBEED\nFOR i = 0 TO len(serial) - 1 DO\nq = (q*32 + 1)\nq ^= 0x12345678\n\nr = 0\nFOR c IN serial DO\nr = r*32\nr ^= c\n\nc = (q ^ r)\nRETURN c & 0xFFFFFFFF\nENDFUNCTION\n\n\nThe first part, calculating q, only depends on the length of the serial.\n\n### Algorithm as 32 Equations\n\nLet qi be the ith bit of q, where q0 is the least significant bit. So q = q31q30q0. Similarly, let c = c31c30c0 be the return value of validate_serial, and d = d31d0 be the desired value 0xB528B18B. Also, let si be the ith digit of the serial, and let l be the length of the serial, i.e., s = s0s1s2sl − 1. Again, let sji denote the j bit of the digit si. The digits are encoded in ASCII, which uses 8 bits, so si = s0is1is7i. With this notation, we can write the bits ci as 32 equations. This is c for serials of length 2 (l = 2):\n\n\\begin{aligned} c_{0} = q_{0} \\oplus s^{1}_{0} &\\stackrel{!}{=} d_{0} & c_{1} = q_{1} \\oplus s^{1}_{1} &\\stackrel{!}{=} d_{1} & c_{2} = q_{2} \\oplus s^{1}_{2} &\\stackrel{!}{=} d_{2} & c_{3} = q_{3} \\oplus s^{1}_{3} &\\stackrel{!}{=} d_{3} \\ c_{4} = q_{4} \\oplus s^{1}_{4} &\\stackrel{!}{=} d_{4} & c_{5} = q_{5} \\oplus s^{0}_{0} \\oplus s^{1}_{5} &\\stackrel{!}{=} d_{5} & c_{6} = q_{6} \\oplus s^{0}_{1} \\oplus s^{1}_{6} &\\stackrel{!}{=} d_{6} & c_{7} = q_{7} \\oplus s^{0}_{2} \\oplus s^{1}_{7} &\\stackrel{!}{=} d_{7} \\ c_{8} = q_{8} \\oplus s^{0}_{3} &\\stackrel{!}{=} d_{8} & c_{9} = q_{9} \\oplus s^{0}_{4} &\\stackrel{!}{=} d_{9} & c_{10} = q_{10} \\oplus s^{0}_{5} &\\stackrel{!}{=} d_{10} & c_{11} = q_{11} \\oplus s^{0}_{6} &\\stackrel{!}{=} d_{11} \\ c_{12} = q_{12} \\oplus s^{0}_{7} &\\stackrel{!}{=} d_{12} & c_{13} = q_{13} &\\stackrel{!}{=} d_{13} & c_{14} = q_{14} &\\stackrel{!}{=} d_{14} & c_{15} = q_{15} &\\stackrel{!}{=} d_{15} \\ c_{16} = q_{16} &\\stackrel{!}{=} d_{16} & c_{17} = q_{17} &\\stackrel{!}{=} d_{17} & c_{18} = q_{18} &\\stackrel{!}{=} d_{18} & c_{19} = q_{19} &\\stackrel{!}{=} d_{19} \\ c_{20} = q_{20} &\\stackrel{!}{=} d_{20} & c_{21} = q_{21} &\\stackrel{!}{=} d_{21} & c_{22} = q_{22} &\\stackrel{!}{=} d_{22} & c_{23} = q_{23} &\\stackrel{!}{=} d_{23} \\ c_{24} = q_{24} &\\stackrel{!}{=} d_{24} & c_{25} = q_{25} &\\stackrel{!}{=} d_{25} & c_{26} = q_{26} &\\stackrel{!}{=} d_{26} & c_{27} = q_{27} &\\stackrel{!}{=} d_{27} \\ c_{28} = q_{28} &\\stackrel{!}{=} d_{28} & c_{29} = q_{29} &\\stackrel{!}{=} d_{29} & c_{30} = q_{30} &\\stackrel{!}{=} d_{30} & c_{31} = q_{31} &\\stackrel{!}{=} d_{31} \\ \\end{aligned}\n\nWe can calculate q for a given serial length l, and we know the bits di of the desired value. Also, since we need to enter the serial by keyboard, lets force si < 128, which means s7i = 0. Using these known values and representing the indices of the serial digits si in terms of the serial length l we get:\n\n\\begin{aligned} 1 \\oplus s^{l-1}{0} &\\stackrel{!}{=} 1, & 0 \\oplus s^{l-1}{1} &\\stackrel{!}{=} 1, & 0 \\oplus s^{l-1}{2} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-1}{3} &\\stackrel{!}{=} 1\\ 1 \\oplus s^{l-1}{4} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-2}{0} \\oplus s^{l-1}{5} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-2}{1} \\oplus s^{l-1}{6} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-2}{2} &\\stackrel{!}{=} 1\\ 1 \\oplus s^{l-2}{3} &\\stackrel{!}{=} 1, & 0 \\oplus s^{l-2}{4} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-3}{0} \\oplus s^{l-2}{5} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-3}{1} \\oplus s^{l-2}{6} &\\stackrel{!}{=} 0\\ 1 \\oplus s^{l-3}{2} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-3}{3} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-3}{4} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-4}{0} \\oplus s^{l-3}{5} &\\stackrel{!}{=} 1\\ 1 \\oplus s^{l-4}{1} \\oplus s^{l-3}{6} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-4}{2} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-4}{3} &\\stackrel{!}{=} 0, & 1 \\oplus s^{l-4}{4} &\\stackrel{!}{=} 1\\ 0 \\oplus s^{l-5}{0} \\oplus s^{l-4}{5} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-5}{1} \\oplus s^{l-4}{6} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-5}{2} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-5}{3} &\\stackrel{!}{=} 0\\ 1 \\oplus s^{l-5}{4} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-6}{0} \\oplus s^{l-5}{5} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-6}{1} \\oplus s^{l-5}{6} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-6}{2} &\\stackrel{!}{=} 0\\ 1 \\oplus s^{l-6}{3} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-6}{4} &\\stackrel{!}{=} 1, & 1 \\oplus s^{l-7}{0} \\oplus s^{l-6}{5} &\\stackrel{!}{=} 0, & 0 \\oplus s^{l-7}{1} \\oplus s^{l-6}{6} &\\stackrel{!}{=} 1\\ \\end{aligned}\n\n### Solving the equations\n\nIf l < 7, then all terms syl − x with l − x < 0 disappear. This means, that in order to fulfill the last equation:\n\n$$0 \\oplus s^{l-7}{1} \\oplus s^{l-6}{6} \\stackrel{!}{=} 1$$\n\nthe length l must be 6 or larger, otherwise we would get $0 \\stackrel{!}{=} 1$ . Solving the equations is easy, because each bit of the serial affects at most one equation. Some bits have no influence at all, for instance only the last seven digits of the serial influence validate_serial. For other bits of the serial we have equations that tell us its definite value, e.g., $1 \\oplus s^{l-3}_{2} \\stackrel{!}{=} 1$ means s2l − 3 = 0. A third kind of bits appear together with a second bit from the serial, here we have two choice to set the bits. For example:\n\n$$1 \\oplus s^{l-4}{1} \\oplus s^{l-3}{6} \\stackrel{!}{=} 0,$$\n\nmeans that either s1l − 4 = 0, s6l − 3 = 1 or s1l − 4 = 1, s6l − 3 = 0.\n\n### Keygen\n\nOur keygen has one additional requirement: the serial needs to be enter by keyboard. It should therefore contain only printable ASCII character – the following keygen requires the serial to have only alphanumeric characters. My keygen performs the following steps:\n\n1. First, randomly determine a serial length l greater or equal 6.\n2. Next, initialize all digits of the serial with random, alphanumeric characters.\n3. Next, change the bits of the serial to fulfill the equations, thereby randomly choosing whenever there are two choices.\n4. Check if the resulting serial is alphanumeric, if not, repeat step 2.\n\nIt takes about 30 trials on average to get a valid serial this way. The following is an implementation of the keygen algorithm in Python:\n\nimport random\n\ndef digit_to_ascii(digit):\ns = 0\nfor i in range(8):\ns += digit[i]*(1 << i)\nreturn chr(s)\n\ndef key_from_digits(digits):\nkey = \"\"\nfor d in digits:\nkey += digit_to_ascii(d)\nreturn key\n\ndef calc_q(l):\nq = 0xBEED\nfor i in range(l):\nq = (q*32 + 1)\nq ^= 0x12345678\nq = q & 0xFFFFFFFF\nreturn q\n\ndef get_equations(l):\nterms = [[] for i in range(32)]\neven_odd = 32*\nfor i in range(32):\nterms[i] = []\n\nfor i in range(l):\n\"\"\" do the shl by 5 bl \"\"\"\nterms = [[] for i in range(5)] + terms[:-5]\nfor j in range(8):\n\"\"\" the last bit of digl must be zero for ASCII \"\"\"\nif j < 7:\nterms[j].append((i,j))\n\n\"\"\" q is the constant term \"\"\"\nq = calc_q(l)\nfor i in range(32):\neven_odd[i] ^= ((q & (1 << i) ) >> i)\n\nwanted = 0x0B528B18B\nfor i in range(32):\neven_odd[i] ^= ((wanted & (1 << i) ) >> i)\n\nreturn terms, even_odd\n\ndef generate_key_with_given_length(l):\nterms, even_odd = get_equations(l)\nwhile True:\ndigits = [8* for i in range(l)]\nfor d in digits:\nwhile True:\nfor p in range(7):\nd[p] = random.randint(0,1)\nif digit_to_ascii(d).isalnum():\nbreak\nfor t, eo in zip(terms, even_odd):\n\"\"\" we can randomly pick all but one term \"\"\"\ns = 0\nfor i in range(len(t)-1):\ndigit, place = t[i]\ndigits[digit][place] = random.randint(0,1)\ns += digits[digit][place]\n\ndigit, place = t[-1]\ndigits[digit][place] = eo ^ s\n\n\"\"\" only return alpha numeric keys, try again if key isn't \"\"\"\nkey = key_from_digits(digits)\nif key.isalnum():\nreturn key\n\ndef generate_key_with_random_length():\n\"\"\" any length greater than 5 should do \"\"\"\nl = random.randint(6,20)\nreturn generate_key_with_given_length(l)\n\nfor i in range(100):\nprint(generate_key_with_random_length())\n\n\nThe code generates 100 valid serials:\n\n\\$ python3 keygen.py\nUw4ddG1G2\nGdXfstRnP1EDG0dR\njkxxddEpdR\nGLSQNlL4flHeEepg2\nNMtRyVHp0AL4ddEqDR\neDEpg2\neEdPdR\nVGDbPqL8icWqOteEdPdR\n6tnFDqiDdDQG2\nQlxb4nG9kz5EEdPdR\nhJyDedPdR\n...\n\n\nEntering one of those serials leads to the good boy message:",
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] | [
null,
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null,
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null,
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null,
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null,
"data:image/svg+xml;base64,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",
null,
"data:image/svg+xml;base64,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",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.50781494,"math_prob":0.9677866,"size":20982,"snap":"2020-45-2020-50","text_gpt3_token_len":7646,"char_repetition_ratio":0.2354848,"word_repetition_ratio":0.026577009,"special_character_ratio":0.43718424,"punctuation_ratio":0.2044414,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9869692,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-11-25T00:06:00Z\",\"WARC-Record-ID\":\"<urn:uuid:51b5179b-ab76-4c86-b36e-cb4f6a0e1854>\",\"Content-Length\":\"57383\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:01d87a35-58ac-45e2-80ee-cff095531cd4>\",\"WARC-Concurrent-To\":\"<urn:uuid:a0c8aab0-dfff-404c-8c29-a0036f0ef441>\",\"WARC-IP-Address\":\"68.183.215.91\",\"WARC-Target-URI\":\"https://johannesbader.ch/blog/crackmes-de-gamas-mndg/\",\"WARC-Payload-Digest\":\"sha1:JVA56BXWPATOCFD6JEXDN55BWVWGI3EX\",\"WARC-Block-Digest\":\"sha1:MC5GHYVGB5OEKNEGPASF23SEKZS3BBDG\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-50/CC-MAIN-2020-50_segments_1606141177607.13_warc_CC-MAIN-20201124224124-20201125014124-00392.warc.gz\"}"} |
https://cs.nyu.edu/pipermail/fom/2006-January/009578.html | [
"# [FOM] The theory of fields; professional puzzlement\n\[email protected] joeshipman at aol.com\nMon Jan 16 02:37:50 EST 2006\n\n```Recent work I have done in elementary algebra has some interesting\nfoundational implications for the theory of fields, and I'd like to\nsolicit comment on it from algebraists, proof theorists and model\ntheorists on the FOM list. I have some more general observations at the\nend which I encourage everyone to comment on!\n\nIn what follows, [n] denoted the statement \"every polynomial of degree\nn has a root\", which is a sentence in the first-order theory of fields.\n\nLet AF denote the conjunction of the standard axioms for fields.\n\nLet (n) abbreviate the sum of n 1's in the language of fields; thus (5)\nabbreviates 1+(1+(1+(1+1)))).\n\nTheorem (Van der Waerden, following E. Artin, inspired by one of\nGauss's proofs of the Fundamental Theorem of Algebra):\nIf a field of characteristic 0 satisfies [n] for n=2 and all odd n,\nthen it is algebraically closed.\n\nTheorem 1:\nA field is algebraically closed iff [p] holds for each prime p. If any\nprime is omitted there is a counterexample. The following\naxiomatizations are \"perfect\" (no axiom may be omitted):\n\nFor general algebraically closed fields: {AF, , , , ,\n,...}\nFor algebraically closed fields of characteristic p: {(p)=0, AF, ,\n, , , , ...}\nFor algebraically closed fields of characteristic 0: {AF, ~((2)=0),\n, ~((3)=0), , ~((5)=0), , ... }\n\nTheorem 2:\nIf {p1,p2,...} is an infinite set of primes, and a field K satisfies\neach [p_i], then either K is algebraically closed, or there exists a\nprime p not in {p1,p2,...} such that [n] is true in K iff n is not a\nmultiple of p.\n\nTheorem 3:\nThe sentence ([d1]&[d2]&...&[d_m]) --> [n] is true in all fields iff\nthe following condition holds:\nfor every finite group G acting without fixed points on {1,2,...,n},\nthe additive semigroup generated by the indexes of proper subgroups of\nG contains one of the d's.\n\nWhat I find interesting is that even though a great deal of interesting\nwork has been done in the model theory of fields, the striking\nelementary facts detailed above were unknown. In particular,\n\n1) nobody seems to have even asked if the axiomatizations for\nalgebraically closed fields were the best possible\n\n2) nobody seems to have discovered that the Artin/v.d.Waerden version\nof the Fundamental Theorem of Algebra could be extended to\ncharacteristic p, let alone that \"2 or odd\" could be replaced by \"prime\"\n\n3) nobody (except, apparently, John H. Conway) suspected the existence\nof the rich theory of finitary implications between \"degree axioms\"\nthat Theorem 3 establishes, even though every one of those\nimplications, when true, is a first-order consequence of the standard\naxioms for fields and could have been discovered by anyone in the last\ntwo centuries.\n\nThe unsettling moral I draw from this (because I know that what I did\nwas not particularly diificult) is that this was a \"hole\" in\nmathematics so classical that every math Ph.D. has encountered it, and\nthat there may be many more such undiscovered treasures.\n\nPerhaps mathematicians don't try hard enough to discover new things in\nfamiliar territory, because if they spend a few years to reach a\n\"frontier\" they are not only much more likely to discover new things,\nbut there will be far fewer people capable of reaching that particular\nfrontier and competing with them.\n\nAm I being too cynical? (I hope so, because that would mean what I did\nwas cleverer than I'd thought it was!)\n\n-- Joseph Shipman\n```"
] | [
null
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https://ask.sagemath.org/answers/39412/revisions/ | [
"# Revision history [back]\n\nThere is no mathematical difference, but an algorithmic one: in the second case, a polynomial is represented as a list of its coefficients up to its degree, in the first case, it only stores the nonzero coefficient (but in a different data strutcure to also store the corresponding degrees, like a dictionary). The size of the object and the algorithms to deal with them are different.\n\nLet us construct some polynomials in both parents and look and save them:\n\nsage: R.<z> = PolynomialRing(ZZ, sparse=False)\nsage: save(z^1000,'/tmp/nosparse_atom.sobj')\nsage: save(sum(z^k for k in range(1001)),'/tmp/nosparse_sum.sobj')\nsage: R.<z> = PolynomialRing(ZZ, sparse=True)\nsage: save(z^1000,'/tmp/sparse_atom.sobj')\nsage: save(sum(z^k for k in range(1001)),'/tmp/sparse_sum.sobj')\n\n\nthen, let us do ls -l /tmp in a terminal and see their respective size:\n\nnosparse_atom.sobj 2082\nnosparse_sum.sobj 2081\nsparse_atom.sobj 590\nsparse_sum.sobj 4009\n\n\nAs you can see, in the nonsparse case, both polynomials have about the same size in memory (storing the coefficient 1 is the same as storing the coefficient 0). In the sparse case, a lot of memory is saved in storing only the pair (1000,1), while for the sum, the object is about twice the size since both degrees and coefficients have tobe stored.\n\nThere is no mathematical difference, but an algorithmic one: in the second nonsparse case, a polynomial is represented as a list of its coefficients up to its degree, in the first sparse case, it only stores the nonzero coefficient (but in a different data strutcure to also store the corresponding degrees, like a dictionary). dictionary, or a list of tuples). The size of the object corresponding objects and the algorithms to deal with them are different.\n\nLet us construct some polynomials in both parents and look and save them:\n\nsage: R.<z> = PolynomialRing(ZZ, sparse=False)\nsage: save(z^1000,'/tmp/nosparse_atom.sobj')\nsage: save(sum(z^k for k in range(1001)),'/tmp/nosparse_sum.sobj')\nsage: R.<z> = PolynomialRing(ZZ, sparse=True)\nsage: save(z^1000,'/tmp/sparse_atom.sobj')\nsage: save(sum(z^k for k in range(1001)),'/tmp/sparse_sum.sobj')\n\n\nthen, let us do ls -l /tmp in a terminal and see their respective size:\n\nnosparse_atom.sobj 2082\nnosparse_sum.sobj 2081\nsparse_atom.sobj 590\nsparse_sum.sobj 4009\n\n\nAs you can see, in the nonsparse case, both polynomials have about the same size in memory (storing the coefficient 1 is the same as storing the coefficient 0). In the sparse case, a lot of memory is saved in storing only the pair (1000,1), while for the sum, the object is about twice the size since both degrees and coefficients have tobe stored."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.80472344,"math_prob":0.92757976,"size":2770,"snap":"2023-14-2023-23","text_gpt3_token_len":763,"char_repetition_ratio":0.13810557,"word_repetition_ratio":0.8410758,"special_character_ratio":0.2732852,"punctuation_ratio":0.15897436,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9970754,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-05-28T07:14:59Z\",\"WARC-Record-ID\":\"<urn:uuid:c485f21f-5702-4553-b773-6c072af8bede>\",\"Content-Length\":\"18710\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0ce6db06-2618-49e2-a5e5-718e05f2b8b8>\",\"WARC-Concurrent-To\":\"<urn:uuid:8ea86c7b-dea5-4d6f-9fe6-e5c5a165bb64>\",\"WARC-IP-Address\":\"194.254.163.53\",\"WARC-Target-URI\":\"https://ask.sagemath.org/answers/39412/revisions/\",\"WARC-Payload-Digest\":\"sha1:64K2ETGJJYPRY5PKJQEUWCUOVDT4D2S3\",\"WARC-Block-Digest\":\"sha1:7PIGRBOWV6WP5TVQV7OYN6OYDOXR4YIP\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-23/CC-MAIN-2023-23_segments_1685224643585.23_warc_CC-MAIN-20230528051321-20230528081321-00273.warc.gz\"}"} |
http://golf.shinh.org/reveal.rb?Kimariji/%2Ayuko%2A_1420112203&rexx | [
"## Kimariji by *yuko*\n\n`do j=0 to 99;a.j=linein();end;do i=0 to 99;k=0;do j=0 to j;k=max(k,compare(a.i,a.j));end;say left(a.i,k);end`\n\nNote that non-ascii characters in the above source code will be escaped (such as \\x9f).\n\ndownload\n\nreturn to the top page"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5881342,"math_prob":0.5213408,"size":228,"snap":"2019-35-2019-39","text_gpt3_token_len":80,"char_repetition_ratio":0.12946428,"word_repetition_ratio":0.0,"special_character_ratio":0.32894737,"punctuation_ratio":0.22666667,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9558112,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-08-19T21:23:13Z\",\"WARC-Record-ID\":\"<urn:uuid:6fb3b8d9-6fb4-4290-8317-64d7aada308f>\",\"Content-Length\":\"904\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:6912f58c-11bf-4f57-889e-6fa0a7f342b2>\",\"WARC-Concurrent-To\":\"<urn:uuid:aa3e5a86-b049-46d5-bbb0-57dad6963f6b>\",\"WARC-IP-Address\":\"49.212.93.182\",\"WARC-Target-URI\":\"http://golf.shinh.org/reveal.rb?Kimariji/%2Ayuko%2A_1420112203&rexx\",\"WARC-Payload-Digest\":\"sha1:ORWZQCRND6ATV7BRVPXE2AMLXTI4QT7K\",\"WARC-Block-Digest\":\"sha1:SQZVALCAGJLLQVBWJJV4NIVQETSYWHVC\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-35/CC-MAIN-2019-35_segments_1566027314959.58_warc_CC-MAIN-20190819201207-20190819223207-00185.warc.gz\"}"} |
https://www.jiskha.com/questions/17659/for-this-quadratic-equation-y2-4y-16-0-which-two-options-are-correct-solutions-rounded | [
"# maths\n\ny2-4y-16 = 0\n\nwhich two options are correct solutions, rounded to three decimal places?\n\n1) -4.483 2) -3.243 3)-2.472\n4) -1.472 5) -0.536 6) 5.243\n7) 6.472 8) 12.443\n\nUse the quadratic equation, we will be happy to critique your solution.\n\n1. 👍 0\n2. 👎 0\n3. 👁 110\n\n## Similar Questions\n\n1. ### maths\n\nfor this quadratic equation: y2-4y-16 = 0 which two options are correct solutions, rounded to three decimal places? 1) -4.483 2) -3.243 3)-2.472 4) -1.472 5) -0.536 6) 5.243 7) 6.472 8) 12.443 You have to use the quadratic\n\nasked by angel on April 15, 2007\n2. ### Math\n\nSolve the given quadratic equation exactly using the quadratic formula. Write the solutions in its simplest form. Using a calculator, determine all irrational solutions to the nearest thousandth. Separate the solutions with a\n\n3. ### Math\n\nSolve the given quadratic equation exactly using the quadratic formula. Write the solutions in its simplest form. Using a calculator, determine all irrational solutions to the nearest thousandth. Separate the solutions with a\n\nasked by Sam on September 23, 2014\n4. ### algerba\n\nWhat is the value of the discriminant, b2 − 4ac, for the quadratic equation 0 = −2x2 − 3x + 8, and what does it mean about the number of real solutions the equation has? What are the solutions to the quadratic equation 4(x +\n\nasked by chelsie on May 25, 2016\n5. ### algebra II\n\nHow do you know if a quadratic equation will have one, two, or no solutions? How do you find a quadratic equation if you are only given the solution? Is it possible to have different quadratic equations with the same solution?\n\n6. ### algebra II\n\nHow do you know if a quadratic equation will have one, two, or no solutions? How do you find a quadratic equation if you are only given the solution? Is it possible to have different quadratic equations with the same solution?\n\nasked by hollywood on June 15, 2010\n7. ### Algebra\n\nI was given this answers to a problems I solved but I do not understand what she means hope you can help. Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation.\n\nasked by Charly on June 2, 2011\n8. ### Algebra\n\nI was given this answers to a problems I solved but I do not understand what she means hope you can help. Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation.\n\nasked by Charly on June 2, 2011\n9. ### Algebra II\n\n1)What method(s) would you choose to solve the equation: x2 + 2x - 6 = 0 A. Square roots; there is no x-term. B. Quadratic formula, graphing; the equation cannot be factored easily since the numbers are large. C. Factoring; the\n\nasked by Hally on January 15, 2013\n10. ### questions\n\n1.) Why are there usually two solutions in quadratic equations? 2.) Under what situation would one or more solutions of a rational equation be unacceptable? If putting the found \"solution\" cannot be put back into the original\n\nasked by leleirvin on August 8, 2005\n\nMore Similar Questions"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.93570703,"math_prob":0.9954607,"size":2756,"snap":"2019-51-2020-05","text_gpt3_token_len":710,"char_repetition_ratio":0.21293604,"word_repetition_ratio":0.5072165,"special_character_ratio":0.25834543,"punctuation_ratio":0.1149635,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.999764,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-01-27T20:12:29Z\",\"WARC-Record-ID\":\"<urn:uuid:76d77c91-40e9-4409-85d6-6c702c09e570>\",\"Content-Length\":\"18546\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:f1df265f-babe-4a4f-b774-af3428157f47>\",\"WARC-Concurrent-To\":\"<urn:uuid:2aa3b03c-27e6-4677-b1c6-dda85a15b3a7>\",\"WARC-IP-Address\":\"66.228.55.50\",\"WARC-Target-URI\":\"https://www.jiskha.com/questions/17659/for-this-quadratic-equation-y2-4y-16-0-which-two-options-are-correct-solutions-rounded\",\"WARC-Payload-Digest\":\"sha1:ZZXZPJEHQTC7DPMB4H6LEF35RUNH6FJX\",\"WARC-Block-Digest\":\"sha1:M33LDDZAOTO3BGTVCUP3RORZC5GXX24W\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-05/CC-MAIN-2020-05_segments_1579251705142.94_warc_CC-MAIN-20200127174507-20200127204507-00144.warc.gz\"}"} |
https://wiki.seg.org/index.php?title=Dictionary:S-wave&printable=yes | [
"Dictionary:S-wave\n\nOther languages:\nEnglish • español\n\nA body wave in which the particle motion is perpendicular to the direction of propagation. Also called secondary wave (undae secundae), shear wave, transverse wave, rotational wave, distortional wave, equivolumnar wave, tangential wave. S-waves are generated by the incidence of P-waves on interfaces at other than normal incidence, whereupon they are called converted waves (SV-waves). In an isotropic medium the velocity of shear waves $V_{s}$",
null,
"is given by\n\n$V_{s}={\\sqrt {\\frac {\\mu }{\\rho }}}={\\sqrt {\\frac {E}{2\\rho (1+\\sigma )}}}.$",
null,
"where $\\mu$",
null,
"is the shear modulus, $\\rho$",
null,
"is the density, $E$",
null,
"is Young's modulus, and $\\sigma$",
null,
"is Poisson's ratio. S-waves have two degrees of freedom and can be polarized in various ways. See SH-wave and SV-wave. S-wave reflection data are often displayed at half the vertical scale of the comparable P-wave data to compensate roughly for the differences between S-wave and P-wave velocities; see Figure S-28. See Danbom and Domenico (1987), Tatham and McCormack (1991), and Garotta (2000).",
null,
"Figure S-28. S-wave and P-wave sections compared. (a) P-wave section; (b) S-wave section plotted at half the vertical scale used for the P-wave section. (Courtesy CGG.)"
] | [
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/57d5d0bb9d326d015df44456d7c0648f80c0f1f5",
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/91d3105cc0db7447c96fd7d20abeb9e0b3ecf3ef",
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/9fd47b2a39f7a7856952afec1f1db72c67af6161",
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/1f7d439671d1289b6a816e6af7a304be40608d64",
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/4232c9de2ee3eec0a9c0a19b15ab92daa6223f9b",
null,
"https://en.wikipedia.org/api/rest_v1/media/math/render/svg/59f59b7c3e6fdb1d0365a494b81fb9a696138c36",
null,
"https://wiki.seg.org/images/thumb/e/e2/Segs28.jpg/600px-Segs28.jpg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.84476084,"math_prob":0.99081445,"size":1297,"snap":"2019-43-2019-47","text_gpt3_token_len":333,"char_repetition_ratio":0.11910286,"word_repetition_ratio":0.020833334,"special_character_ratio":0.2459522,"punctuation_ratio":0.21292776,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99712396,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14],"im_url_duplicate_count":[null,null,null,8,null,null,null,null,null,null,null,null,null,7,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-10-22T14:40:24Z\",\"WARC-Record-ID\":\"<urn:uuid:42d39a2a-14f5-4def-a7c9-dcf918436fcf>\",\"Content-Length\":\"40281\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:1b06cc2b-3a1d-42d5-87ac-3a38cb58e6d3>\",\"WARC-Concurrent-To\":\"<urn:uuid:d86a26de-3836-4466-8ff8-d9cdd5c1c599>\",\"WARC-IP-Address\":\"104.20.101.123\",\"WARC-Target-URI\":\"https://wiki.seg.org/index.php?title=Dictionary:S-wave&printable=yes\",\"WARC-Payload-Digest\":\"sha1:HJJOXACDPP67YHQNMXHSWBDGQVKVMYQP\",\"WARC-Block-Digest\":\"sha1:LAZDKYMJEITULPIBZGZ23ZBYI4AH4CBG\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-43/CC-MAIN-2019-43_segments_1570987822098.86_warc_CC-MAIN-20191022132135-20191022155635-00392.warc.gz\"}"} |
https://www.logobook.ru/prod_show.php?object_uid=12081501 | [
"+7(495) 980-12-10\nпн-пт: 10-18\[email protected]\n Российская литература\n\n Поиск книг Поиск по списку ISBN Расширенный поиск Найти Зарубежные издательства Российские издательства\n Авторы | Каталог книг | Издательства | Новинки | Учебная литература | Акции | Cертификаты | Хиты | | |\n\n ВойтиРегистрация Забыли?\n\n# A Collection of Problems in Mathematical Physics\n\nВарианты приобретения\n Цена: 4017р.Кол-во: о ценеНаличие: Отсутствует. Возможна поставка под заказ. При оформлении заказа до: 30 авг 2022Ориентировочная дата поставки: конец Сентября- начало ОктябряПри условии наличия книги у поставщика. Добавить в корзину в Мои желания\n\nАвтор: Budak\nНазвание: A Collection of Problems in Mathematical Physics\nISBN: 9780486658063\nИздательство: Dover\nКлассификация:\nISBN-10: 0486658066\nОбложка/Формат: Paperback\nСтраницы: 800\nВес: 0.846 кг.\nДата издания: 28.03.2003\nСерия: Dover books on physics\nЯзык: English\nРазмер: 163 x 217 x 38\nРейтинг:\nПоставляется из: США\n\n Автор: Muskhelishvili N. I.Название: Singular Integral Equations: Boundary Problems of Function Theory and Their Application to Mathematical PhysicsISBN: 0486668932 ISBN-13(EAN): 9780486668932 Издательство: DoverЦена: 2868 р. Наличие на складе: Поставка под заказ.\n Автор: Carroll LewisНазвание: The Mathematical Recreations of Lewis Carroll: Pillow Problems and a Tangled TaleISBN: 0486204936 ISBN-13(EAN): 9780486204932 Издательство: DoverРейтинг: Цена: 1833 р. Наличие на складе: Поставка под заказ. Описание: Whimsically and delightfully presented mathematical recreations by the author of Alice in Wonderland are solved by arithmetic, algebra, geometry, trigonometry, differential calculus and transcendental properties. 6 illustrations. Two books bound as one.\n Автор: Dettman John W.Название: Mathematical Methods in Physics and EngineeringISBN: 0486656497 ISBN-13(EAN): 9780486656496 Издательство: DoverРейтинг: Цена: 2868 р. Наличие на складе: Поставка под заказ. Описание: Intended for college-level physics, engineering, or mathematics students, this volume offers an algebraically based approach to various topics in applied math. It is accessible to undergraduates with a good course in calculus which includes infinite series and uniform convergence. Exercises follow each chapter to test the student's grasp of the material; however, the author has also included exercises that extend the results to new situations and lay the groundwork for new concepts to be introduced later. A list of references for further reading will be found at the end of each chapter. For this second revised edition, Professor Dettman included a new section on generalized functions to help explain the use of the Dirac delta function in connection with Green's functions. In addition, a new approach to series solutions of ordinary differential equations has made the treatment independent of complex variable theory. This means that the first six chapters can be grasped without prior knowledge of complex variables. However, since Chapter 8 depends heavily on analytic functions of a complex variable, a new Chapter 7 on analytic function theory has been written.\n Автор: Carroll LewisНазвание: The Mathematical Recreations of Lewis Carroll: Pillow Problems and a Tangled TaleISBN: 0486788288 ISBN-13(EAN): 9780486788289 Издательство: DoverЦена: 3673 р. Наличие на складе: Поставка под заказ. Описание: Virtually unobtainable for many years, these two books by Lewis Carroll (C. L. Dodgson) have now been reprinted in their entirety for the pleasure of modern enthusiasts of mathematical puzzles. Written by the 19th-century mathematician who gave us Alice in Wonderland and Through the Looking Glass, they contain an unusual combination of wit and mathematical intricacy that will test your mathematical ingenuity and provide hours of stimulating entertainment.Pillow-Problems is one of the rarest of all Lewis Carroll's works. It contains 72 mathematical posers ranging from those that can be solved by arithmetic, simple algebra, or plane geometry, to those that require more advanced algebra, trigonometry, algebraical geometry, differential calculus, and transcendental probabilities. Both numerical answers and fully worked out solutions are given, each in a separate section so that you can test your methods of problem-solving even after you have looked up the answer to a problem.In A Tangled Tale, Carroll embodies some of his most perplexing mathematical puzzles in the ten knots or chapters of a delightful story that has all the charm and wit of his better-known works. The Tale was originally printed as a monthly magazine serial, and many readers sent in solutions to the problems that were posed in it. In the long Appendix to The Tale, which contains the answers and solutions to the problems, Carroll uses the answers sent in by readers as the basis for illuminating and entertaining discussions of the many wrong ways in which the problems can be attacked, as well as the right ways.\n Автор: Sveshnikov, A. A.Название: Problems in Probability Theory, Mathematical Statistics and Theory of Random FunctionsISBN: 0486637174 ISBN-13(EAN): 9780486637174 Издательство: DoverРейтинг: Цена: 2638 р. Наличие на складе: Поставка под заказ. Описание: Approximately 1,000 problems -- with answers and solutions included at the back of the book -- illustrate such topics as random events, random variables, limit theorems, Markov processes, and much more.\n Автор: Trigg, Charles W.Название: Mathematical Quickies: 270 Stimulating Problems with SolutionsISBN: 048678598X ISBN-13(EAN): 9780486785981 Издательство: DoverЦена: 2868 р. Наличие на складе: Поставка под заказ.\n Автор: Muskhelishvili N. I.Название: Singular Integral Equations: Boundary Problems of Function Theory and Their Application to Mathematical PhysicsISBN: 0486462420 ISBN-13(EAN): 9780486462424 Издательство: DoverРейтинг: Цена: 2868 р. Наличие на складе: Поставка под заказ. Описание: This high-level treatment by a noted mathematician considers one-dimensional singular integral equations involving Cauchy principal values. Intended for graduate students and professionals, its coverage includes such topics as the Holder condition, Hilbert and Riemann-Hilbert problems, the Dirichlet problem, inversion formulas for arcs, and many other areas. 1992 edition.\n Автор: Byerly William ElwoodНазвание: An Elementary Treatise on Fourier`s Series: and Spherical, Cylindrical, and Ellipsoidal Harmonics, with Applications to Problems in Mathematical PhysicsISBN: 0486495469 ISBN-13(EAN): 9780486495460 Издательство: DoverРейтинг: Цена: 6035 р. Наличие на складе: Поставка под заказ. Описание: One of the most useful and practical expositions of Fourier's series, and spherical, cylindrical, and ellipsoidal harmonics, this classic offers a basic but thorough treatment of material that is assumed in many other studies but rarely available in concise form. Includes 190 problems, approximately half with answers. 1893 edition.\n Автор: Leis, RolfНазвание: Initial Boundary Value Problems in Mathematical PhysicsISBN: 0486497410 ISBN-13(EAN): 9780486497419 Издательство: DoverРейтинг: Цена: 1718 р. Наличие на складе: Поставка под заказ. Описание: An introduction to both classical scattering theory and to the time-dependent theory of linear equations in mathematical physics, this text is suitable for advanced undergraduates and graduate students of physics and applied mathematics. Topics include proof of the existence of wave operators, some special equations of mathematical physics -- including Maxwell equations, the linear equations of elasticity and thermoelasticity, and the plate equation -- exterior boundary value problems, radiation conditions, and limiting absorption principles.The self-contained treatment provides background for a complete understanding of all concepts, and an extensive reference list offers suggestions for further reading. Based on the author's lectures at the University of Bonn in 1983-84, this volume will prove useful to researchers as well as students.\n Автор: Johnson, Charles S.Название: Problems and Solutions in Quantum Chemistry and PhysicsISBN: 048665236X ISBN-13(EAN): 9780486652368 Издательство: DoverРейтинг: Цена: 2293 р. Наличие на складе: Поставка под заказ. Описание: \"A very useful addition to the chemical literature.\" -- Journal of the American Chemical Society.Designed to aid students and teachers in advanced physical chemistry, spectroscopy, or quantum chemistry courses, this carefully written book is unique in the variety of problems covered and the detail of the solutions provided. The book consists of 12 chapters, each of which includes a short introduction, followed by approximately 20 problems with detailed solutions. Also provided in each chapter are approximately 10 \"supplementary\" problems, with answers but no solutions. Chapter headings include: Atomic Physics and the Old Quantum TheoryWaves and SuperpositionPostulates and Formalism of Quantum MechanicsSimple Exactly Soluble Problems in Wave MechanicsAngular MomentumPerturbation and Variation TheoryHydrogen-Like AtomsElectronic Structure of AtomsElectronic Structure of MoleculesRadiation and MatterMolecular SpectroscopyScattering TheoryAssuming some facility with calculus, mechanics, and electricity and magnetism, the authors offer thorough and up-to-date coverage of both modern subject matter and standard topics. Interspersed among classic examples are lucid applications involving such topics as Fourier transforms, Poisson brackets, uncertainty, the virial theorem, van der Waals forces, lasers, tunneling, group theory, and the Born approximation. Students will also find 10 helpful appendixes covering a range of mathematical topics, a list of references cited in solutions to the problems, and a Subject Index.With its unique variety of problems, unusually detailed solutions, and wide range of applications, this book not only expounds the principles of quantum theory but also helps students develop the proper intuition for solving problems in a complex and subtle field of endeavor.\n Автор: Jacoby, OswaldНазвание: Intriguing Mathematical ProblemsISBN: 0486292614 ISBN-13(EAN): 9780486292618 Издательство: DoverРейтинг: Цена: 1144 р. Наличие на складе: Поставка под заказ. Описание: Amusing and informative in its approach to solving mathematical bafflers, this treasury of theories, games, puzzles and oddities of all kinds, compiled by one of the world's best card players (Jacoby) and an expert in mathematical recreations (Benson) will delight and fascinate math enthusiasts.Although primarily intended to entertain, the wide variety of puzzles ranging from facile curiosities to very difficult intellectual exercises will challenge you to keep your mind going full steam. Each of the book's five sections \"Fun with Numbers,\" \"Fun with Letters,\" \"The Odds: Explorations in Probability,\" \"Where Inference and Reasoning Reign\" and \"The Answers Are Whole Numbers\" is made up of approximately 30 problems, with solutions grouped at the end of each section. Math buffs will love testing their puzzle-solving skills on such challenging brainteasers as The Enterprising Snail, Mrs. Crabbe and the Bacon, The Fly and the Bicycles, The Lovesick Cockroaches, The Three Prisoners, Girls Should Live in Brooklyn, Who Was Executed?, Creaker vs. Roadhog, The Crossed Ladders, The Ancient Order of the Greens, and many more.Few of these problems require any advanced mathematical knowledge or prowess. You'll find that simply keeping your wits about you and your logical skills honed are all you need to enjoy a delightful and thought-provoking adventure in recreational mathematics. Foreword. 10 illustrations. 14 tables.\"\n Автор: Trigg, Charles W.Название: Mathematical Quickies: 270 Stimulating Problems with SolutionsISBN: 0486249492 ISBN-13(EAN): 9780486249490 Издательство: DoverРейтинг: Цена: 1489 р. Наличие на складе: Поставка под заказ. Описание: Nearly 300 mathematical brain-teasers from the fields of arithmetic, algebra, plane and solid geometry, trigonometry, number theory, and general recreational mathematics. From simple to complex; all challenge the reader to devise solutions more elegant than the ones provided. Offers hours of brain-bending amusement. 270 problems. 121 illustrations. Solutions. List of Sources.\n\n ООО \"Логосфера \" Тел:+7(495) 980-12-10 www.logobook.ru"
] | [
null
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https://en.wikipedia.org/wiki/Hankel_matrix | [
"# Hankel matrix\n\nIn linear algebra, a Hankel matrix (or catalecticant matrix), named after Hermann Hankel, is a square matrix in which each ascending skew-diagonal from left to right is constant, e.g.:\n\n$\\qquad {\\begin{bmatrix}a&b&c&d&e\\\\b&c&d&e&f\\\\c&d&e&f&g\\\\d&e&f&g&h\\\\e&f&g&h&i\\\\\\end{bmatrix}}.$",
null,
"More generally, a Hankel matrix is any $n\\times n$",
null,
"matrix $A$",
null,
"of the form\n\n$A={\\begin{bmatrix}a_{0}&a_{1}&a_{2}&\\ldots &\\ldots &a_{n-1}\\\\a_{1}&a_{2}&&&&\\vdots \\\\a_{2}&&&&&\\vdots \\\\\\vdots &&&&&a_{2n-4}\\\\\\vdots &&&&a_{2n-4}&a_{2n-3}\\\\a_{n-1}&\\ldots &\\ldots &a_{2n-4}&a_{2n-3}&a_{2n-2}\\end{bmatrix}}.$",
null,
"In terms of the components, if the $i,j$",
null,
"element of $A$",
null,
"is denoted with $A_{ij}$",
null,
", and assuming $i\\leq j$",
null,
", then we have $A_{i,j}=A_{i+k,j-k}$",
null,
"for all $k=0,...,j-i.$",
null,
"## Properties\n\n• Any Hankel matrix is symmetric.\n• Let $J_{n}$",
null,
"be the $n\\times n$",
null,
"exchange matrix. If $H$",
null,
"is a $m\\times n$",
null,
"Hankel matrix, then $H=TJ_{n}$",
null,
"where $T$",
null,
"is a $m\\times n$",
null,
"Toeplitz matrix.\n• If $T$",
null,
"is real symmetric, then $H=TJ_{n}$",
null,
"will have the same eigenvalues as $T$",
null,
"up to sign.\n• The Hilbert matrix is an example of a Hankel matrix.\n\n## Relation to formal Laurent series\n\nHankel matrices are closely related to formal Laurent series. In fact, such a series $f(z)=\\sum _{n=-\\infty }^{N}a_{n}z^{n}$",
null,
"gives rise to a linear map, referred to as a Hankel operator\n\n$H_{f}:\\mathbf {C} [z]\\to \\mathbf {z} ^{-1}\\mathbf {C} [[z^{-1}]],$",
null,
"which takes a polynomial $g\\in \\mathbf {C} [z]$",
null,
"and sends it to the product $fg$",
null,
", but discards all powers of $z$",
null,
"with a non-negative exponent, so as to give an element in $z^{-1}\\mathbf {C} [[z^{-1}]]$",
null,
", the formal power series with strictly negative exponents. The map $H_{f}$",
null,
"is in a natural way $\\mathbf {C} [z]$",
null,
"-linear, and its matrix with respect to the elements $1,z,z^{2},\\dots \\in \\mathbf {C} [z]$",
null,
"and $z^{-1},z^{-2},\\dots \\in z^{-1}\\mathbf {C} [[z^{-1}]]$",
null,
"is the Hankel matrix\n\n${\\begin{bmatrix}a_{1}&a_{2}&\\ldots \\\\a_{2}&a_{3}&\\ldots \\\\a_{3}&a_{4}&\\ldots \\\\\\vdots \\end{bmatrix}}.$",
null,
"Any Hankel matrix arises in such a way. A theorem due to Kronecker says that the rank of this matrix is finite precisely if $f$",
null,
"is a rational function, i.e., a fraction of two polynomials $f={\\frac {p(z)}{q(z)}}$",
null,
".\n\n## Hankel operator\n\nA Hankel operator on a Hilbert space is one whose matrix is a (possibly infinite) Hankel matrix with respect to an orthonormal basis. As indicated above, a Hankel Matrix is a matrix with constant values along its antidiagonals, which means that a Hankel matrix $A$",
null,
"must satisfy, for all rows $i$",
null,
"and columns $j$",
null,
", $(A_{i,j})_{i,j\\geq 1}$",
null,
". Note that every entry $A_{i,j}$",
null,
"depends only on $i+j$",
null,
".\n\nLet the corresponding Hankel Operator be $H_{\\alpha }$",
null,
". Given a Hankel matrix $A$",
null,
", the corresponding Hankel operator is then defined as $H_{\\alpha }(u)=Au$",
null,
".\n\nWe are often interested in Hankel operators $H_{\\alpha }:\\ell ^{2}\\left(\\mathbb {Z} ^{+}\\cup \\{0\\}\\right)\\rightarrow \\ell ^{2}\\left(\\mathbb {Z} ^{+}\\cup \\{0\\}\\right)$",
null,
"over the Hilbert space $\\ell ^{2}(\\mathbf {Z} )$",
null,
", the space of square integrable bilateral complex sequences. For any $u\\in \\ell ^{2}(\\mathbf {Z} )$",
null,
", we have\n\n$\\|u\\|_{\\ell ^{2}(z)}^{2}=\\sum _{n=-\\infty }^{\\infty }\\left|u_{n}\\right|^{2}$",
null,
"We are often interested in approximations of the Hankel operators, possibly by low-order operators. In order to approximate the output of the operator, we can use the spectral norm (operator 2-norm) to measure the error of our approximation. This suggests singular value decomposition as a possible technique to approximate the action of the operator.\n\nNote that the matrix $A$",
null,
"does not have to be finite. If it is infinite, traditional methods of computing individual singular vectors will not work directly. We also require that the approximation is a Hankel matrix, which can be shown with AAK theory.\n\nThe determinant of a Hankel matrix is called a catalecticant.\n\n## Hankel matrix transform\n\nThe Hankel matrix transform, or simply Hankel transform, produces the sequence of the determinants of the Hankel matrices formed from the given sequence. Namely, the sequence $\\{h_{n}\\}_{n\\geq 0}$",
null,
"is the Hankel transform of the sequence $\\{b_{n}\\}_{n\\geq 0}$",
null,
"when\n\n$h_{n}=\\det(b_{i+j-2})_{1\\leq i,j\\leq n+1}.$",
null,
"The Hankel transform is invariant under the binomial transform of a sequence. That is, if one writes\n\n$c_{n}=\\sum _{k=0}^{n}{n \\choose k}b_{k}$",
null,
"as the binomial transform of the sequence $\\{b_{n}\\}$",
null,
", then one has\n\n$\\det(b_{i+j-2})_{1\\leq i,j\\leq n+1}=\\det(c_{i+j-2})_{1\\leq i,j\\leq n+1}.$",
null,
"## Applications of Hankel matrices\n\nHankel matrices are formed when, given a sequence of output data, a realization of an underlying state-space or hidden Markov model is desired. The singular value decomposition of the Hankel matrix provides a means of computing the A, B, and C matrices which define the state-space realization. The Hankel matrix formed from the signal has been found useful for decomposition of non-stationary signals and time-frequency representation.\n\n### Method of moments for polynomial distributions\n\nThe method of moments applied to polynomial distributions results in a Hankel matrix that needs to be inverted in order to obtain the weight parameters of the polynomial distribution approximation."
] | [
null,
"https://wikimedia.org/api/rest_v1/media/math/render/svg/3de03113894a78b2c226c9cd556c74d2a05155c5",
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"https://wikimedia.org/api/rest_v1/media/math/render/svg/894ab6e9c9afcfea7d9370399cebe1557bdf9b2e",
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null,
"https://wikimedia.org/api/rest_v1/media/math/render/svg/d76572040aaa8196f0279a8029d75a2edb903696",
null,
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http://csundergrad.science.uoit.ca/courses/csci1061u/notes/static.html | [
"Static members and methods\n\nProgramming Workshop 2 (CSCI 1061U)\n\nFaculty of Science, UOIT\n\nhttp://vclab.science.uoit.ca\n\n`static` keyword is used to declares members and methods that are not bound to class instances.\n\nStatic members\n\nStatic members of a class are not associated with objects of the class. These are independent objects that are stored elsewhere, once, and these are accessible within class functions. We need to define the static member outside of class (see below). The static member is shared between all instances of the class. Meaning if its value is changed in one instance, the other instances will see it as well.\n\n``````class A\n{\nstatic int x; // declaration - use 'static'\n};\n\nint A::x = 0; // definition - doesn't use 'static'``````\n\nThe following piece of code where static member is used to count the total number of instances.\n\n``````#include <iostream>\nusing namespace std;\n\nclass X\n{\npublic:\nstatic int how_many;\n\nX() {\n++how_many;\n}\n};\n\nint X::how_many = 0;\n\nint main()\n{\nX instance1;\nX instance2;\nX instance3;\n\ncout << \"X has \" << X::how_many << \" instances.\" << endl;\n\nreturn 0;\n}``````\n\nWhen we run this program, the ouput is:\n\n``X has 3 instances``\n\nStatic methods\n\nStatic functions of the class are not associated with class instances. Consequently, this pointer is not available within static methods. Static methods can only directly access static members and other static methods of the class.\n\nIn the follwoing code, `void an_example_static_function()` is a static method of class X.\n\n``````using namespace std;\n\nclass X\n{\npublic:\nint x;\nstatic int how_many;\n\nX() {\n++how_many;\n}\n\nstatic void an_example_static_function();\n};\n\nint X::how_many = 0;\n\nvoid X::an_example_static_function()\n{\ncout << \"how_many = \" << how_many << endl;\n}\n\nint main()\n{\nX instance1;\nX instance2;\nX instance3;\n\ncout << \"X has \" << X::how_many << \" instances.\" << endl;\n\nX::an_example_static_function();\n\nreturn 0;\n}``````"
] | [
null
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https://www.chisel-lang.org/api/latest/chisel3/experimental/Interval$.html | [
"o\n\n# Interval \n\n### Companion class Interval\n\n#### object Interval extends NumObject\n\nFactory and convenience methods for the Interval class IMPORTANT: The API provided here is experimental and may change in the future.\n\nSource\nBits.scala\nLinear Supertypes\nOrdering\n1. Alphabetic\n2. By Inheritance\nInherited\n1. Interval\n2. NumObject\n3. AnyRef\n4. Any\n1. Hide All\n2. Show All\nVisibility\n1. Public\n2. All\n\n### Value Members\n\n1. final def !=(arg0: Any)\nDefinition Classes\nAnyRef → Any\n2. final def ##(): Int\nDefinition Classes\nAnyRef → Any\n3. final def ==(arg0: Any)\nDefinition Classes\nAnyRef → Any\n4. def Lit(value: BigInt, range: IntervalRange)\nAttributes\nprotected[chisel3]\n5. def Lit(value: BigInt, width: Width, binaryPoint: BinaryPoint)\nAttributes\nprotected[chisel3]\n6. val MaxBitsBigIntToBigDecimal: Int\nDefinition Classes\nNumObject\n7. val MaxBitsBigIntToDouble: Int\nDefinition Classes\nNumObject\n8. def Zero(range: IntervalRange)\n\nCreates an Interval zero that supports the given range Useful for creating a Interval register that has a desired number of bits\n\nCreates an Interval zero that supports the given range Useful for creating a Interval register that has a desired number of bits\n\n`val myRegister = RegInit(Interval.Zero(r\"[0,12]\")`\n9. def Zero\n\nCreates a Interval connected to a Interval literal with the value zero\n\n10. def apply(range: IntervalRange)\n\nCreate an Interval type with specified range.\n\nCreate an Interval type with specified range.\n\nrange\n\ndefines the properties\n\n11. def apply(width: Width, binaryPoint: BinaryPoint)\n\nCreate an Interval type with specified width and binary point\n\n12. def apply(width: Width)\n\nCreate an Interval type with specified width.\n\n13. def apply(binaryPoint: BinaryPoint)\n\nCreate an Interval type with specified width.\n\n14. def apply()\n\nCreate an Interval type with inferred width and binary point.\n\n15. final def asInstanceOf[T0]: T0\nDefinition Classes\nAny\n16. def clone()\nAttributes\nprotected[lang]\nDefinition Classes\nAnyRef\nAnnotations\n@throws( ... ) @native()\n17. final def eq(arg0: AnyRef)\nDefinition Classes\nAnyRef\n18. def equals(arg0: Any)\nDefinition Classes\nAnyRef → Any\n19. def finalize(): Unit\nAttributes\nprotected[lang]\nDefinition Classes\nAnyRef\nAnnotations\n@throws( classOf[java.lang.Throwable] )\n20. def fromBigDecimal(value: Double, dummy: PrivateType = PrivateObject, width: Width, binaryPoint: BinaryPoint)\n\nCreate an Interval literal with inferred width from Double.\n\nCreate an Interval literal with inferred width from Double. Use PrivateObject to force users to specify width and binaryPoint by name\n\n21. def fromBigInt(value: BigInt, width: Width = Width(), binaryPoint: BinaryPoint = 0.BP)\n\nMake an interval from this BigInt, the BigInt is treated as bits So lower binaryPoint number of bits will treated as mantissa\n\n22. def fromDouble(value: Double, dummy: PrivateType = PrivateObject, width: Width, binaryPoint: BinaryPoint)\n\nCreate an Interval literal with inferred width from Double.\n\nCreate an Interval literal with inferred width from Double. Use PrivateObject to force users to specify width and binaryPoint by name\n\n23. final def getClass(): Class[_]\nDefinition Classes\nAnyRef → Any\nAnnotations\n@native()\n24. def getLargestLegalLit(range: IntervalRange)\n\nThis returns the largest Interval literal that can legally fit in range, if possible If the upper bound or binary point is not known then return None\n\nThis returns the largest Interval literal that can legally fit in range, if possible If the upper bound or binary point is not known then return None\n\nrange\n\nuse to figure low number\n\n25. def getSmallestLegalLit(range: IntervalRange)\n\nThis returns the smallest Interval literal that can legally fit in range, if possible If the lower bound or binary point is not known then return None\n\nThis returns the smallest Interval literal that can legally fit in range, if possible If the lower bound or binary point is not known then return None\n\nrange\n\nuse to figure low number\n\n26. def hashCode(): Int\nDefinition Classes\nAnyRef → Any\nAnnotations\n@native()\n27. final def isInstanceOf[T0]\nDefinition Classes\nAny\n28. final def ne(arg0: AnyRef)\nDefinition Classes\nAnyRef\n29. final def notify(): Unit\nDefinition Classes\nAnyRef\nAnnotations\n@native()\n30. final def notifyAll(): Unit\nDefinition Classes\nAnyRef\nAnnotations\n@native()\n31. final def synchronized[T0](arg0: ⇒ T0): T0\nDefinition Classes\nAnyRef\n32. def toBigDecimal(value: BigInt, binaryPoint: BinaryPoint): BigDecimal\n\nconverts a bigInt with the given binaryPoint into the BigDecimal representation\n\nconverts a bigInt with the given binaryPoint into the BigDecimal representation\n\nvalue\n\na bigint\n\nbinaryPoint\n\nthe implied binaryPoint of @i\n\nDefinition Classes\nNumObject\n33. def toBigDecimal(value: BigInt, binaryPoint: Int): BigDecimal\n\nconverts a bigInt with the given binaryPoint into the BigDecimal representation\n\nconverts a bigInt with the given binaryPoint into the BigDecimal representation\n\nvalue\n\na bigint\n\nbinaryPoint\n\nthe implied binaryPoint of @i\n\nDefinition Classes\nNumObject\n34. def toBigInt(value: BigDecimal, binaryPoint: BinaryPoint): BigInt\n\nHow to create a bigint from a big decimal with a specific binaryPoint\n\nHow to create a bigint from a big decimal with a specific binaryPoint\n\nvalue\n\na BigDecimal value\n\nbinaryPoint\n\na binaryPoint that you would like to use\n\nDefinition Classes\nNumObject\n35. def toBigInt(x: BigDecimal, binaryPoint: Int): BigInt\n\nHow to create a bigint from a big decimal with a specific binaryPoint (int)\n\nHow to create a bigint from a big decimal with a specific binaryPoint (int)\n\nx\n\na BigDecimal value\n\nbinaryPoint\n\na binaryPoint that you would like to use\n\nDefinition Classes\nNumObject\n36. def toBigInt(x: Double, binaryPoint: BinaryPoint): BigInt\n\nHow to create a bigint from a big decimal with a specific binaryPoint\n\nHow to create a bigint from a big decimal with a specific binaryPoint\n\nx\n\na BigDecimal value\n\nbinaryPoint\n\na binaryPoint that you would like to use\n\nDefinition Classes\nNumObject\n37. def toBigInt(x: Double, binaryPoint: Int): BigInt\n\nHow to create a bigint from a double with a specific binaryPoint\n\nHow to create a bigint from a double with a specific binaryPoint\n\nx\n\na double value\n\nbinaryPoint\n\na binaryPoint that you would like to use\n\nDefinition Classes\nNumObject\n38. def toDouble(value: BigInt, binaryPoint: BinaryPoint)\n\nconverts a bigInt with the given binaryPoint into the double representation\n\nconverts a bigInt with the given binaryPoint into the double representation\n\nvalue\n\na bigint\n\nbinaryPoint\n\nthe implied binaryPoint of @i\n\nDefinition Classes\nNumObject\n39. def toDouble(i: BigInt, binaryPoint: Int)\n\nconverts a bigInt with the given binaryPoint into the double representation\n\nconverts a bigInt with the given binaryPoint into the double representation\n\ni\n\na bigint\n\nbinaryPoint\n\nthe implied binaryPoint of @i\n\nDefinition Classes\nNumObject\n40. def toString()\nDefinition Classes\nAnyRef → Any\n41. final def wait(): Unit\nDefinition Classes\nAnyRef\nAnnotations\n@throws( ... )\n42. final def wait(arg0: Long, arg1: Int): Unit\nDefinition Classes\nAnyRef\nAnnotations\n@throws( ... )\n43. final def wait(arg0: Long): Unit\nDefinition Classes\nAnyRef\nAnnotations\n@throws( ... ) @native()\n44. object\n\nContains the implicit classes used to provide the .I methods to create intervals from the standard numberic types.\n\nContains the implicit classes used to provide the .I methods to create intervals from the standard numberic types.\n\n```val x = 7.I\nval y = 7.5.I(4.BP)```"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.555826,"math_prob":0.91738206,"size":8181,"snap":"2020-34-2020-40","text_gpt3_token_len":1997,"char_repetition_ratio":0.20520973,"word_repetition_ratio":0.5965598,"special_character_ratio":0.22124435,"punctuation_ratio":0.12974203,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97379994,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-09-25T03:41:28Z\",\"WARC-Record-ID\":\"<urn:uuid:315d8f6e-843f-40c4-969e-565df8aedb08>\",\"Content-Length\":\"82549\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:6dd6c7f6-46e4-4ce4-b59c-3b93a03f169d>\",\"WARC-Concurrent-To\":\"<urn:uuid:7a99c611-d5cf-4abd-b144-d45a559f4815>\",\"WARC-IP-Address\":\"185.199.110.153\",\"WARC-Target-URI\":\"https://www.chisel-lang.org/api/latest/chisel3/experimental/Interval$.html\",\"WARC-Payload-Digest\":\"sha1:MWASK27ECOOMJB4J6D6EHF3WXHHOJKKB\",\"WARC-Block-Digest\":\"sha1:PDAQXHUES55RNXESZU3MKQL5VJGGKEUA\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-40/CC-MAIN-2020-40_segments_1600400221980.49_warc_CC-MAIN-20200925021647-20200925051647-00503.warc.gz\"}"} |
https://socratic.org/questions/how-do-you-find-the-zeros-of-y-9x-4-5x-2-4 | [
"# How do you find the zeros of y=9x^4+5x^2-4?\n\nJan 16, 2017\n\n$\\pm i \\mathmr{and} \\pm \\frac{2}{3}$.\n\n#### Explanation:\n\nSolving this quadratic in ${x}^{2}$,\n\n${x}^{2} = - 1 \\mathmr{and} \\frac{4}{9}$. So,\n\n$x = \\pm i \\mathmr{and} \\pm \\frac{2}{3}$.\n\nSee graphical depiction for real zeros, as x-intercepts $\\pm \\frac{2}{3}$.\n\ngraph{9x^4+5x^2-4 [-.8, .8, -1.25, 1.25]}"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6096669,"math_prob":0.99998486,"size":331,"snap":"2020-45-2020-50","text_gpt3_token_len":109,"char_repetition_ratio":0.103975534,"word_repetition_ratio":0.0,"special_character_ratio":0.32326284,"punctuation_ratio":0.14666666,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99984264,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-10-25T22:36:57Z\",\"WARC-Record-ID\":\"<urn:uuid:3dbd78d2-75c7-4ba1-8062-25e2ed086de8>\",\"Content-Length\":\"32317\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:1a2a3d9a-5d9e-4f45-9fbb-a2565f749f04>\",\"WARC-Concurrent-To\":\"<urn:uuid:0d1e71a8-c866-4580-b942-4735557d2acb>\",\"WARC-IP-Address\":\"216.239.34.21\",\"WARC-Target-URI\":\"https://socratic.org/questions/how-do-you-find-the-zeros-of-y-9x-4-5x-2-4\",\"WARC-Payload-Digest\":\"sha1:LDZ62VVSB223SCIU43JSELRNPEYOPK57\",\"WARC-Block-Digest\":\"sha1:GNYPSEYWR44AI6KNIZ2RC6ATAZXKRPDE\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-45/CC-MAIN-2020-45_segments_1603107890028.58_warc_CC-MAIN-20201025212948-20201026002948-00206.warc.gz\"}"} |
https://answers.everydaycalculation.com/divide-fractions/4-5-divided-by-10-42 | [
"Solutions by everydaycalculation.com\n\n## Divide 4/5 with 10/42\n\n4/5 ÷ 10/42 is 84/25.\n\n#### Steps for dividing fractions\n\n1. Find the reciprocal of the divisor\nReciprocal of 10/42: 42/10\n2. Now, multiply it with the dividend\nSo, 4/5 ÷ 10/42 = 4/5 × 42/10\n3. = 4 × 42/5 × 10 = 168/50\n4. After reducing the fraction, the answer is 84/25\n5. In mixed form: 39/25\n\nMathStep (Works offline)",
null,
"Download our mobile app and learn to work with fractions in your own time:"
] | [
null,
"https://answers.everydaycalculation.com/mathstep-app-icon.png",
null
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http://cindyphilips.com/t73wqwr0/33a8a1-divergent-transformations-ruling | [
"Automation In Manufacturing Ppt, Area Housing Authority Of The County Of Ventura Application, Recursive Backtracking - Python, 2006 Monte Carlo, Windows 10 64-bit 1gb Ram, Anthropology Thesis Statement Examples, A* Search Algorithm Python, Musée Carnavalet Reopening, King Size Hershey Bar Nutrition Facts, Lundberg Family Farms Accident, Native Honeysuckle For Sale, \" />\n\n# divergent transformations ruling\n\nnovember 30, 2020\n\nIn particular, if we consider the identity function Examples of such techniques are Padé approximants, Levin-type sequence transformations, and order-dependent mappings related to renormalization techniques for large-order perturbation theory in quantum mechanics. However, convergence is a stronger condition: not all series whose terms approach zero converge. {\\displaystyle d} }, Some conventions expect all local basis elements to be normalized to unit length, as was done in the previous sections. {\\displaystyle \\partial _{a}} For a vector expressed in local unit cylindrical coordinates as, where ea is the unit vector in direction a, the divergence is. 1 d You need two bodies on board to target. {\\displaystyle {\\hat {\\mathbf {e} }}^{i}} i {\\displaystyle \\nabla \\cdot \\mathbf {A} } C0 is ordinary summation, and C1 is ordinary Cesàro summation. . The use of local coordinates is vital for the validity of the expression. unit volume, i.e. Synopsis: Set in a futuristic dystopia where society is divided into five factions that each represent a different virtue, teenagers have to decide if they want to stay in their faction or switch to another - for the rest of their lives. Absolute convergence defines the sum of a sequence (or set) of numbers to be the limit of the net of all partial sums ak1 + ... + akn, if it exists. Hardy (1949, 4.17). The degree of failure of the truth of the statement, measured by the homology of the chain complex. 90-ENGLISH JOURNAL Another member of this school, Paul Postal, discusses in a recent monograph the inadequacies of traditional models of linguistic description.3 Taxonomic models, according to Postal, cannot ac-count for the intuitively-felt relation- ships among sentences such 2S active and passive, interrogative and declarative, assertive and negative, incorporated and In Einstein notation, the divergence of a contravariant vector Fμ is given by. {\\displaystyle g_{ab}} Once it resolves you will reveal cards from the top of your deck until you reveal a creature, put it onto the battlefield, and then repeat the process once more. The divergence of the harmonic series was proven by the medieval mathematician Nicole Oresme. A rtificial intelligence (AI) offers a transformational potential for both companies and public health authorities. z (A) Single–[Ir] site–catalyzed hydrogenation and dehydration reactions in this work (black arrows and red text) and the original Krebs cycle (blue ring and gray text/arrows).Dashed arrows are proposed partial pathways in the hydrogenation of each substrate with Ir-a. In the case of one dimension, F reduces to a regular function, and the divergence reduces to the derivative. , and The series a1 + ... is called Lambert summable to s if. x The Lindelöf sum is a powerful method when applied to power series among other applications, summing power series in the Mittag-Leffler star. The logarithm of the division of … The psu(2,2|4) integrable super spin chain underlying the AdS/CFT correspondence has integrable boundary states which describe set-ups where k D3-branes get dissolved in a probe D z Taking regularity, linearity and stability as axioms, it is possible to sum many divergent series by elementary algebraic manipulations. Show you… Divergent Transformations Abweichende Transformationen Transformations divergentes Trasformazioni Divergenti 分岐変容 Transformações Divergentes 趋异转化 Transformaciones divergentes ... Rules: Undaunted (This spell costs less to cast for each opponent.) ( The homologous sequences are based on a Phormidium lacuna open reading frame sequence sc_7_37, which is the 37 th open reading frame of DNA scaffold 7. sc_7_37 sequence encodes for a protein (Refseq ID: WP_087706519) that is annotated as … ^ a if this integral exists. Community. F If λn = n log(n), then (indexing from one) we have. However, the function of AcuK was previously unknown. We Are Divergent's & We Are Not The Problem We Are The Solution. Euler summation is essentially an explicit form of analytic continuation. ∂ Exile two target creatures. r = . Commander 2016 — Rare. The two classical summation methods for series, ordinary convergence and absolute convergence, define the sum as a limit of certain partial sums. 3 . Christianity and authoritarianism are commonly believed to be at opposite ends of the democratic-autocratic continuum. ) {\\displaystyle \\mathrm {div} } This fact is not very useful in practice, since there are many such extensions, inconsistent with each other, and also since proving such operators exist requires invoking the axiom of choice or its equivalents, such as Zorn's lemma. Γ ( again written in local unit coordinates, the divergence is. A summation method can be seen as a function from a set of sequences of partial sums to values. g The ) [a] = , and . ... We Are Born to Rule. a Riemannian or Lorentzian manifold. A is referred to as the codifferential. A counterexample is the harmonic series. The divergence of a vector field extends naturally to any differentiable manifold of dimension n that has a volume form (or density) μ, e.g. Expand the task list: Define Accounting Configuration for Rapid Implementation. = In this general setting, the correct formulation of the divergence is to recognize that it is a codifferential; the appropriate properties follow from there. i A system of strain-cued transformations in cell shape and motility, propagating across a population of cells that have wavelike response to density pe… = The determinant appears because it provides the appropriate invariant definition of the volume, given a set of vectors. … First, transformation could be achieved radically through measures such as If s = 0 is an isolated singularity, the sum is defined by the constant term of the Laurent series expansion. dissension. If, in a Euclidean coordinate system with coordinates x1, x2, ..., xn, define. ≠ For divergence of infinite series, see, The choice of \"first\" covariant index of a tensor is intrinsic and depends on the ordering of the terms of the Cartesian product of vector spaces on which the tensor is given as a multilinear map, del in cylindrical and spherical coordinates, Del in cylindrical and spherical coordinates, \"Numerical Investigation on the Effects of Obstruction and Side Ratio on Non-Newtonian Fluid Flow Behavior Around a Rectangular Barrier\", \"Divergence and curl: The language of Maxwell's equations, fluid flow, and more\", https://en.wikipedia.org/w/index.php?title=Divergence&oldid=989080190, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, This page was last edited on 16 November 2020, at 23:01. ∂ By dotting both sides of the last equality with the contravariant element where After substituting, the formula becomes: See § In curvilinear coordinates for further discussion. This partly explains why many different summation methods give the same answer for certain series. The square-root appears in the denominator, because the derivative transforms in the opposite way (contravariantly) to the vector (which is covariant). ) the political and social construction of poverty central and eastern european countries in transition Sep 30, 2020 Posted By Hermann Hesse Library TEXT ID 5101fb2a5 Online PDF Ebook Epub Library social transformations in eastern and central europe have produced outcomes that were hardly expected when the region emerged from communist rule yet these the A Cesàro sums are Nørlund means if k ≥ 0, and hence are regular, linear, stable, and consistent. It does not depend on the order of the elements of the sequence, and a classical theorem says that a sequence is absolutely convergent if and only if the sequence of absolute values is convergent in the standard sense. Here partial converse means that if M sums the series Σ, and some side-condition holds, then Σ was convergent in the first place; without any side-condition such a result would say that M only summed convergent series (making it useless as a summation method for divergent series). = i e However, some special cases are very important summation methods.\n\n#### About the Author",
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http://wyvilirasuwihype.billsimas.com/ac-network-theorem-7140571405.html | [
"# Ac network theorem\n\nA dependent or controlled source is that whose magnitude is governed by a current or voltage of the system in which it is situated.",
null,
"Nuclear physics, biology, geology, and chemistry professors would just love to be able to have their students apply advanced mathematics to real experiments posing no safety hazard and costing less than a textbook. A resistive circuit is a circuit containing only resistorsideal current sourcesand ideal voltage sources.\n\nTwo circuits are said to be equivalent with respect to a pair of terminals if the voltage across the terminals and current through the terminals for one network have the same relationship as the voltage and current at the terminals of the other network.\n\nThe solution principles outlined here also apply to phasor analysis of AC circuits. So, I suggest the following alternative approach: Component transfer function For a two-terminal component i. Equivalent impedance transforms A Ac network theorem procedure in network analysis is to simplify the network by reducing the number of components.\n\nThe difference is that in a. The diagrammatic representation of the dependent sources is similar to that we have shown in analyzing the d. Here are the lists of A.\n\nExploit the convenience inherent to your science, and get those students of yours practicing their math on lots of real circuits!",
null,
"A particular technique might directly reduce the number of components, for instance by combining impedances in series. These parameters can be impedances, but there is a large number of other approaches see two-port network.\n\nNodal Analysis Node voltage analysis of a. Most often, an input port and an output port are discussed and the transfer function is described as gain or attenuation.\n\nStudents will also develop real troubleshooting skills as they occasionally make circuit construction errors.",
null,
"This can be done by replacing the actual components with other notional Ac network theorem that have the same effect. An excellent way to introduce students to the mathematical analysis of real circuits is to have them first determine component values L and C from measurements of AC voltage and current.\n\nAnother reason for following this method of practice is to teach students scientific method: The simplest circuit, of course, is a single component connected to a power source!\n\nIt has been my experience that students require much practice with circuit analysis to become proficient. Analysis of a circuit consists of solving for the voltages and currents present in the circuit. In addition to application of mesh or nodal analysis in a.\n\nYou may find it necessary to discuss this circuit in detail with your students before they are ready to troubleshoot it. A circuit is, in this sense, a one-port network and is a trivial case to analyse.\n\nDiscuss these issues with your students in the same Socratic manner you would normally discuss the worksheet questions, rather than simply telling them what they should and should not do. This can be accomplished in the Ac network theorem manner as we do for d. A three or more terminal component effectively has two or more ports and the transfer function cannot be expressed as a single impedance.\n\nWhile this approach makes students proficient in circuit theory, it fails to fully educate them. To this end, instructors usually provide their students with lots of practice problems to work through, and provide answers for students to check their work against.\n\nThey also need real, hands-on practice building circuits and using test equipment. In the frequency domain network having n-principle nodes, one of them is designated as the reference node and we require n-1 node voltage equations to solve for the desired result.\n\nIn most sciences, realistic experiments are much more difficult and expensive to set up than electrical circuits. Small step-down power transformers work well for inductors at least two inductors in one package! If the sources are constant DC sources, the result is a DC circuit.\n\nSome calculators, though, are able to add, subtract, multiply, divide, and invert complex quantities as easy as they do scalar quantities, making this method of AC circuit analysis relatively easy. If there is any connection to any other circuits then a non-trivial network has been formed and at least two ports must exist.\n\nThis question is really a series of practice problems in complex number arithmetic, the purpose being to give you lots of practice using the complex number facilities of your calculator or to give you a lot of practice doing trigonometry calculations, if your calculator does not have the ability to manipulate complex numbers!\n\nIf your students will be working with real circuits, then they should learn on real circuits whenever possible. If your goal is to educate theoretical physicists, then stick with abstract analysis, by all means! Often, \"circuit\" and \"network\" are used interchangeably, but many analysts reserve \"network\" to mean an idealised model consisting of ideal components.Norton's theorem states that any two-terminal network can be reduced to an ideal current generator and a parallel impedance.\n\nThévenin's theorem states that any two-terminal network can be reduced to an ideal voltage generator plus a series impedance. In an electric network, the network theorems are derived from Kirchhoff’s law and ohms law and are useful in simplifying analysis of the basic circuits.\n\nIntroduction to Network Theorems in Electrical Engineering. by Tarun Agarwal at. This theorem is used in both AC and DC circuits wherein it helps to construct Thevenin and Norton. Solved Example on Maximum Power Transfer Theorem in AC Circuits Consider the below AC network to which we are going to determine the condition for maximum power transfer and the value of maximum power.\n\nNetwork Theorems - Alternating Current examples - J. R. Lucas In the previous chapter, we have been dealing mainly with direct current resistive circuits in order to the principles of the various theorems clear. to ac networks is very similar in content to that found in this chapter.\n\nThe first theorem to be introduced is the superposition theorem, followed by Thévenin’s theorem, Norton’s theorem, and the maximum power transfer theorem. Norton’s Theorem is the dual of Thevenin’s theorem, and states that any linear, active, bilateral network, considered across one of its ports, can be replaced by an equivalent current source (Norton’s current source) and an equivalent shunt admittance .\n\nAc network theorem\nRated 4/5 based on 28 review"
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https://books.google.co.nz/books?qtid=c97e7849&dq=editions:UOM39015065320957&lr=&id=kolUz5MZlVMC&output=html&sa=N&start=80 | [
"Search Images Maps Play YouTube News Gmail Drive More »\nSign in\n Books Books",
null,
"Multiply each payment by its term of credit, and divide the sum of the products by the sum of the payments ; the quotient will be the average term of credit.",
null,
"The Youth's Assistant in Theoretic and Practical Arithmetic: Designed for ... - Page 82\nby Zadock Thompson - 1838 - 164 pages\nFull view - About this book",
null,
"## INTRODUCTION TO THE NATIONAL ARITHMETIC, ON THE INDUCTIVE SYSTEM\n\nBEJAMIN GREENLEAF - 1860\n...payment of the whole. Hence the following RULE. -—Multiply each payment by its own time, of credit, and divide the sum of the products by the sum of the payments. NOTE 1. — This is the rule usually adopted by merchants, but it is not perfectly correct...\nFull view - About this book",
null,
"## Bryant and Stratton's Commercial Arithmetic: In Two Parts. Designed for the ...\n\nEmerson Elbridge White - Arithmetic (Commercial), 1861 - 1861 - 332 pages\n...quality of 1 oz. is 20. RULK. Multiply the value or quality of each article by'the number of articles, and divide the sum of the products by the sum of the articles. The quotient will be the average value or quality of the mixture. Ex.3. A grocer t mixed...\nFull view - About this book",
null,
"## Vermont School Journal and Family Visitor, Volumes 3-4\n\nEducation - 1861\n...starting point. The rule for Equation of Payments is, \" multiply each payment by its own time of credit, and divide the sum of the products by the sum of the payments,\" — another case in point. I have put down some of the more prominent faults in the books,...\nFull view - About this book",
null,
"## Davies' University Arithmetic: Embracing the Answers, and a Full Analysis ...\n\nCharles Davies - Arithmetic - 1861 - 336 pages\n...find the average time of payment : Rule. — Multiply each payment by the time before it becomes due, and divide the sum of the products by the sum of the payments: the Quotient will be the average time. Examples. 1. A merchant ows \\$1200, of which \\$200 is...\nFull view - About this book",
null,
"## Introduction to the National Arithmetic, on the Inductive System: Combining ...\n\nBenjamin Greenleaf - Arithmetic - 1861 - 324 pages\n...payment of the whole. Hence the following RULE. — Multiply each payment by its own time of credit. and divide the sum of the products by the sum of the payments. NOTE 1. — This is the rule usually adopted by merchants, but it is not perfectly correct...\nFull view - About this book",
null,
"## Practical Arithmetic: Embracing the Science and Applications of Numbers\n\nCharles Davies - Arithmetic - 1863 - 336 pages\n...\\$12 \" \" J_X 12 = 12. \\$6 \\$48 6 6)48. Rule. Multiply each payment by the time before it becomes due, and divide the sum of the products by the sum of the payments: the quotient will be the mean time. Examples. 2. A owes B \\$600 ; one-third is to be paid...\nFull view - About this book",
null,
"## Arithmetic, designed for the use of schools\n\n...the following Ordinary Rule. Multiply the several debts by their times in any uniform denomination, and divide the sum of the products by the sum of the debts. Thus, the above process is reduced to the following: — 651 x 5 = 3255 434x8 = 3472 10S5 )6727...\nFull view - About this book",
null,
"## A Practical Arithmetic: Upon the Basis of the Works of Geo. R. Perkins\n\nGeorge Payn Quackenbos - Arithmetic - 1872 - 336 pages\n...Go through Ex. 1. 434. RULE. — To equate two or more payments, multiply each payment by its time, and divide the sum of the products by the sum of the payments. The times of the several payments must be in the same denomina. tion, and this will be the...\nFull view - About this book",
null,
"## National arithmetic, adapted to the standards of the revised code. Adapted ...\n\nNational arithmetic - 1872\n...much as a woman, and a woman 5 times as much as a boy. (1.) Multiply 89 by 24, 94 by 36, and 56 by 20, and divide the sum of the products by the sum of the multipliers. (2.) How many more pence are there in 16 crowns than in 5 half-sovereigns ? (3.) How much...\nFull view - About this book",
null,
"## The Bryant and Stratton Business Arithmetic: A New Work, with Practical ...\n\nHenry Beadman Bryant, Emerson Elbridge White, C. G. Stowell - Business mathematics - 1872 - 564 pages\n...mos., making it equitable for both. 676. RULE. Multiply each payment or debt by its time of credit, and divide the sum of the PRODUCTS by the sum of the PAYMENTS. NOTES. — 1. By the term discount, as used above, is meant mercantile discount or simple...\nFull view - About this book"
] | [
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"https://books.google.co.nz/books/content",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.93398756,"math_prob":0.9019041,"size":2717,"snap":"2021-04-2021-17","text_gpt3_token_len":714,"char_repetition_ratio":0.20678216,"word_repetition_ratio":0.31163707,"special_character_ratio":0.30327567,"punctuation_ratio":0.20358306,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9803845,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-04-12T03:46:48Z\",\"WARC-Record-ID\":\"<urn:uuid:6a93e067-806e-4efa-93b5-e05f4f9af445>\",\"Content-Length\":\"35117\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:259b971f-97fd-49f1-b877-5da88e9c66ac>\",\"WARC-Concurrent-To\":\"<urn:uuid:80b3e588-dd77-4d04-b942-e779a10685ed>\",\"WARC-IP-Address\":\"142.250.73.238\",\"WARC-Target-URI\":\"https://books.google.co.nz/books?qtid=c97e7849&dq=editions:UOM39015065320957&lr=&id=kolUz5MZlVMC&output=html&sa=N&start=80\",\"WARC-Payload-Digest\":\"sha1:WF7T7TKCOEVHEQZIAX25YOYQIQI6PL5L\",\"WARC-Block-Digest\":\"sha1:NT7KMBSOAXNDEFVZJNLX7MNR7UOSGVAI\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-17/CC-MAIN-2021-17_segments_1618038066568.16_warc_CC-MAIN-20210412023359-20210412053359-00044.warc.gz\"}"} |
https://forum.arduino.cc/t/problem-including-if-statement-into-clock-code/689587 | [
"",
null,
"# problem including if statement into clock code\n\nI want my code to turn a servo when the serial monitor displays a certain time and I can’t seem to get my code to work…\n\nI would greatly appreciate any help!\nI’m really new to Arduino so this may be a pretty simple question.\nThanks so much!\n\n• Evan\n``````#include <Time.h>\n#include <TimeLib.h>\n#include <Servo.h>\nServo myservo;\n\nint pos;\n\nvoid setup()\n{\nmyservo.attach(9, 500, 2500);\nSerial.begin(9600);\nsetTime(9, 0, 1, 29, 12, 20);\n}\n\nvoid loop()\n{\ndigitalClockDisplay();\n\nif ( Serial.print(hour()) = 9 ) && (Serial.print(minute()) = 00) && (Serial.print(second()) = 00 ) ) {\n\nfor (pos = 0; pos <= 110; pos += 1) {\n// tell servo to go to position in variable 'pos'\nmyservo.write(pos);\n// wait 30 ms for servo to reach the position\ndelay(30);\n}\n\nfor (pos = 110; pos >= 0; pos -= 1) {\n// tell servo to go to position in variable 'pos'\nmyservo.write(pos);\n// wait 30 ms for servo to reach the position\ndelay(30);\n}\n}\n}\n}\n\ndelay(1000);\n\n}\n\nvoid digitalClockDisplay()\n{\nSerial.print(hour());\nprintDigits(minute());\nprintDigits(second());\nSerial.println();\n\n}\nvoid printDigits(int digits)\n{\nSerial.print(\":\");\nif (digits < 10)\nSerial.print('0');\nSerial.print(digits);\n}\n``````\n\nclock_and_servo.ino (1006 Bytes)\n\n``````if ( Serial.print(hour()) = 9 ) && (Serial.print(minute()) = 00) && (Serial.print(second()) = 00 ) )\n``````\n\nOops...\n\nAlso: the number of curly braces doesn't match!\n\n`````` }\n}\n}\n}\ndelay(1000);\n}\n``````\n\nah true the curly brackets were off!\n\nBut also I'm not sure what the problem is with the line you mentioned. That was the one I was having problems with but I'm not sure how to fix it...\nIf you could point me in the right direction that would be fantastic!\n\nThanks so much!\n\nevanbrorby:\nIf you could point me in the right direction\n\nYou need to use == not = in an if(), thus:\n\n``````if ( Serial.print(hour()) == 9 )\n``````\n\n... not:\n\n``````if ( Serial.print(hour()) = 9 )\n``````\n\nI count 9 ) and 10 (\n\nSerial.print() returns the number of bytes printed, so you are comparing 9 (from your example) to the number of bytes sent to the serial monitor, not to the hour. You need to do the comparison separately from the print:\n\n``````if (hour == 9) {\nSerial.print...\nEtc\n}\n``````\n\nThat's a good spot...."
] | [
null,
"https://aws1.discourse-cdn.com/arduino/original/3X/1/f/1f6eb1c9b79d9518d1688c15fe9a4b7cdd5636ae.svg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.54692245,"math_prob":0.9417928,"size":1180,"snap":"2021-31-2021-39","text_gpt3_token_len":343,"char_repetition_ratio":0.14370748,"word_repetition_ratio":0.22459893,"special_character_ratio":0.36610168,"punctuation_ratio":0.20588236,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9880278,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-07-31T16:40:17Z\",\"WARC-Record-ID\":\"<urn:uuid:ae19d7d3-e221-4fb0-a41a-a5060f2f7728>\",\"Content-Length\":\"29890\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:7588fc2c-f185-451e-845f-47ac5e8a1708>\",\"WARC-Concurrent-To\":\"<urn:uuid:d657fd29-7b0b-46be-ad5a-8d3999e8421a>\",\"WARC-IP-Address\":\"184.104.202.141\",\"WARC-Target-URI\":\"https://forum.arduino.cc/t/problem-including-if-statement-into-clock-code/689587\",\"WARC-Payload-Digest\":\"sha1:H6BKNEAYSWJHYO5ZTYKXSDATSQXK36XR\",\"WARC-Block-Digest\":\"sha1:J5F3DDE4QMBNVDOP347ADLOKAR6PZX35\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-31/CC-MAIN-2021-31_segments_1627046154089.68_warc_CC-MAIN-20210731141123-20210731171123-00452.warc.gz\"}"} |
https://circuitdigest.com/microcontroller-projects/interfacing-esp32-with-74hc595-for-7-segment-display | [
"# Interfacing ESP32 with 74HC595 for 7 Segment Display\n\nPublished July 10, 2020 0",
null,
"All microcontrollers have specific numbers of IO pins but in some applications, like in a 7-Segment Display, we will need more GPIO pins than what our controller could offer. For such cases, where multiple output pins are required but the microcontroller has a limited number of output pins, 74HC595 Shift Register would be a perfect choice. 74HC595 is a shift register that takes serial data as an input and provides parallel output. Other than the power pins, it requires only 3 pins that need to control multiple shift registers. We have previously this IC with other microcontrollers as well\n\nTherefore, one can use three output pins from the microcontroller unit and cascade two or more shift registers to get 16 or 24+ output pins. In this ESP32 74HC595 project, we will interface three 74HC595 using only three pins and connect three 7-Segment displays to see outputs using only three pins from the ESP32 which is a WiFi/BT enabled microcontroller device that is a popular choice for many IoT based projects. You can also check out other ESP32 Projects if you are interested in building more with this controller. Also, we will be using the Arduino IDE to program our ESP32 here, if you completely new, do check out the Getting started with ESP32 using Arduino before you proceed any further.\n\n### Required Components\n\n1. ESP32 Devkit v4.0\n2. 7-Seg displays common cathode - 3pcs\n3. 74HC595 - 3 pcs\n4. 680R resistor - 24pcs\n5. 5V power supply\n7. Lots of hook up wires\n8. Arduino IDE with ESP32 programming environment.\n9. A micro-USB cable",
null,
"### Schematic\n\nThe schematic diagram for ESP32 7 Segment Display is given below-",
null,
"The ESP32 is connected with the 74HC595. The data pin of the shift register is connected with the PIN14, the Clock pin is connected with the PIN12, and the Latch or strobe pin is connected with the PIN4. You can check out the basics of 7-Segment Display article to understand more about 7-segment displays and how they work.\n\n### 74HC595 Shift Register\n\n74HC595 is an 8-bit shift register. The pin diagram can be shown in the below image-",
null,
"The pin description can be seen in the below table-",
null,
"The QA to QH, from the starting pin 1 to 7 and the pin 15 is the 8-bit output from the shift register. The input pin is PIN14 that is serial data input that takes the data serially.\n\nOther input pins are PIN 11 and PIN12. Those two pins are SCK and RCK. SCK is the clock input and the RCK is the latch input. The truth table that is required to get the data and provide the data to the next shift register is given below\n\n74HC595 Truth Table",
null,
"However, PIN9 is the serial data output which will provide the data to the next cascaded shift register. Thus, PIN9 is connected with the PIN 14 of the next shift register. The data gets passed serially to the next shift register continuously.\n\n### Programming ESP32 for 7 Segment Display using 74HC595\n\nThe program to control all three 7-Segment Display can be found at the bottom of the page. You can directly use it for the above given circuit diagram and test it. The explanation of the code is as follows.\n\nBefore we get into the program, we declare the type of 7-Segment Display we are using.\n\nThis line will identify the ESP32 about the 7-Segment display type. If the common cathode is used, it needs to be true, otherwise, if the common anode is used, it requires to be false. Since depending on the common Cathode status, the output of the shift register will change.\n\n`const bool commonCathode = true;`\n\nThe next section is used to provide the supported digit and letters in an 8-bit format. This will provide the exact binary output from the shift register to light up the 7-Seg displays.\n\n```const byte digit_pattern =\n{\n// 74HC595 Outpin Connection with 7segment display.\n// Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7\n// a b c d e f g DP\n0b11111100, // 0\n0b01100000, // 1\n0b11011010, // 2\n0b11110010, // 3\n0b01100110, // 4\n0b10110110, // 5\n0b10111110, // 6\n0b11100000, // 7\n0b11111110, // 8\n0b11110110, // 9\n0b11101110, // A\n0b00111110, // b\n0b00011010, // C\n0b01111010, // d\n0b10011110, // E\n0b10001110, // F\n0b00000001 // .\n};```\n\nIn the below code lines, the shift register pins are defined.\n\n```//Pin connected to ST_CP of 74HC595\nint latchPin = 4;\n//Pin connected to SH_CP of 74HC595\nint clkPin = 12;\n//Pin connected to DS of 74HC595\nint dtPin = 14;\n// display value\nint dispVal = 0;\nbool increment = true;```\n\nThe setup code is done before the actual loop application. In the above code, the 74HC595 control pins are set as output and the serial output for UART communication is also done for the debugging purpose only.\n\n```void setup() {\n// put your setup code here, to run once:\n// set the serial port at 115200\nSerial.begin(115200);\ndelay(1000);\n// set the 74HC595 Control pin as output\npinMode(latchPin, OUTPUT); //ST_CP of 74HC595\npinMode(clkPin, OUTPUT); //SH_CP of 74HC595\npinMode(dtPin, OUTPUT); //DS of 74HC595\n}```\n\nIn the loop section or the actual application section, the code has two-part. At first, the digits are incremented and on the other part, the digits are decremented. However, writing into the shift register is always begging with the latch pin becoming LOW, and after the data is sent, it needs to be High.\n\n```void loop() {\n// put your main code here, to run repeatedly:\nint dispDigit1=dispVal/10;\nint dispDigit2=dispVal%10;\nif(increment==true){\nprintf(\"%d%d.\\n\", dispDigit1,dispDigit2);\ndigitalWrite(latchPin, LOW);\nif(commonCathode == true){\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit2]|digit_pattern); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit1]);\n}else{\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit2]|digit_pattern)); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit1]));\n}\ndigitalWrite(latchPin, HIGH);\ndispVal += 1;\nif (dispVal == 99){\nincrement=false;\n}\n}else{\nprintf(\"%d%d.\\n\", dispDigit1,dispDigit2);\ndigitalWrite(latchPin, LOW);\nif(commonCathode == true){\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit2]|digit_pattern); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit1]);\n}else{\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit2]|digit_pattern)); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit1]));\n}\ndigitalWrite(latchPin, HIGH);\ndispVal -= 1;\nif (dispVal == 0){\nincrement=true;\n}\n}\ndelay(250);\n}\ndigitalWrite(latchPin, LOW);```\n\nThe data that is sent in between this Low and High code.\n\n`digitalWrite(latchPin, HIGH);`\n\nThen, if the common cathode is used, it will print the digit in the 7-Seg display by using the below code -\n\n```shiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit2]|digit_pattern);\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit1]);```\n\nThese shift Out function uses the bitwise operator to shift the data serially along with the clock input at the same time. It will print the digit as well as the data point (DP). However, since it is an LSB First data, the LSB is first sent to the 74HC595 and shifted to the next 74HC595. The third 7-Segment is not programmed and connected to see that the first digit is transferred to the last 7-segment, i.e. 74HC595 unit. When the 7-Seg is a common anode, it will use an invert operator to invert the output. Thus,\n\n```shiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit2]|digit_pattern));\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit1]));```\n\n### Seven Segment Display with ESP32 – Working\n\nThe circuit is constructed in two breadboards and the output is checked. The digits are shown perfectly on the 7-Seg displays as you can see in the below image. The connections and debugging might get hard because of the number of wires, we build it on a breadboard and it did work as expected.",
null,
"The complete working can be found in the video linked at the bottom of this page. Hope you enjoyed the tutorial and learned something useful, if you have any questions, leave them in the comment section or use our forums for other technical questions and discussions.\n\nCode\n```/*\n* This program Print Numbers on 3, 7segment display\n* Hardware Connections (Breakoutboard to Arduino Nano):\n* Vin - 5V (3.3V is allowed)\n* GND - GNDs\n* 74HC595 ST_CP - 4 (ESP32)\n* 74HC595 SH_CP - 12 (ESP32)\n* 74HC595 DS - 14 (ESP32)\n*\n*/\n// set the 7segment type (common Cathode or Anode)\nconst bool commonCathode = true; // I'm using common Cathode 7segment if you use common Anode then change the value into false.\n// alpha-digit pattern for a 7-segment display\nconst byte digit_pattern =\n{\n// 74HC595 Outpin Connection with 7segment display.\n// Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7\n// a b c d e f g DP\n0b11111100, // 0\n0b01100000, // 1\n0b11011010, // 2\n0b11110010, // 3\n0b01100110, // 4\n0b10110110, // 5\n0b10111110, // 6\n0b11100000, // 7\n0b11111110, // 8\n0b11110110, // 9\n0b11101110, // A\n0b00111110, // b\n0b00011010, // C\n0b01111010, // d\n0b10011110, // E\n0b10001110, // F\n0b00000001 // .\n};\n//Pin connected to ST_CP of 74HC595\nint latchPin = 4;\n//Pin connected to SH_CP of 74HC595\nint clkPin = 12;\n//Pin connected to DS of 74HC595\nint dtPin = 14;\n// display value\nint dispVal = 0;\nbool increment = true;\nvoid setup() {\n// put your setup code here, to run once:\n// set the serial port at 115200\nSerial.begin(115200);\ndelay(1000);\n// set the 74HC595 Control pin as output\npinMode(latchPin, OUTPUT); //ST_CP of 74HC595\npinMode(clkPin, OUTPUT); //SH_CP of 74HC595\npinMode(dtPin, OUTPUT); //DS of 74HC595\n}\nvoid loop() {\n// put your main code here, to run repeatedly:\nint dispDigit1=dispVal/10;\nint dispDigit2=dispVal%10;\nif(increment==true){\nprintf(\"%d%d.\\n\", dispDigit1,dispDigit2);\ndigitalWrite(latchPin, LOW);\nif(commonCathode == true){\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit2]|digit_pattern); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit1]);\n}else{\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit2]|digit_pattern)); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit1]));\n}\ndigitalWrite(latchPin, HIGH);\ndispVal += 1;\nif (dispVal == 99){\nincrement=false;\n}\n}else{\nprintf(\"%d%d.\\n\", dispDigit1,dispDigit2);\ndigitalWrite(latchPin, LOW);\nif(commonCathode == true){\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit2]|digit_pattern); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, digit_pattern[dispDigit1]);\n}else{\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit2]|digit_pattern)); // 1. (Digit+DP)\nshiftOut(dtPin, clkPin, LSBFIRST, ~(digit_pattern[dispDigit1]));\n}\ndigitalWrite(latchPin, HIGH);\ndispVal -= 1;\nif (dispVal == 0){\nincrement=true;\n}\n}\ndelay(250);\n}```\nVideo\n\nTags"
] | [
null,
"https://circuitdigest.com/sites/default/files/projectimage_mic/Interfacing-ESP32-with-74HC595.jpg",
null,
"https://circuitdigest.com/sites/default/files/inlineimages/u2/ESP32-based-Devkit-V4.0_0.jpg",
null,
"https://circuitdigest.com/sites/default/files/circuitdiagram_mic/ESP32-7-Segment-Display-Schematic.png",
null,
"https://circuitdigest.com/sites/default/files/inlineimages/u2/74HC595-Shift-Register.jpg",
null,
"https://circuitdigest.com/sites/default/files/inlineimages/u2/74HC595-Shift-Register-Pin-Description.png",
null,
"https://circuitdigest.com/sites/default/files/inlineimages/u2/74HC595-Truth-Table.png",
null,
"https://circuitdigest.com/sites/default/files/inlineimages/u2/Seven-Segment-Display-with-ESP32.jpg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6441409,"math_prob":0.890121,"size":10557,"snap":"2023-40-2023-50","text_gpt3_token_len":2991,"char_repetition_ratio":0.16545059,"word_repetition_ratio":0.3229358,"special_character_ratio":0.3133466,"punctuation_ratio":0.15655278,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9632546,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14],"im_url_duplicate_count":[null,1,null,3,null,3,null,3,null,3,null,3,null,3,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-03T21:23:11Z\",\"WARC-Record-ID\":\"<urn:uuid:e7cab077-2950-4711-96e8-34eb9e287219>\",\"Content-Length\":\"86690\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:04b77241-4bfe-47b1-af62-ef0f406f2b63>\",\"WARC-Concurrent-To\":\"<urn:uuid:5e0ea3ed-3a9c-45b1-ab32-82ac070f2668>\",\"WARC-IP-Address\":\"72.14.191.42\",\"WARC-Target-URI\":\"https://circuitdigest.com/microcontroller-projects/interfacing-esp32-with-74hc595-for-7-segment-display\",\"WARC-Payload-Digest\":\"sha1:4IBQZK7FMSUPAVI7BE4GTRXCWJRVYMAT\",\"WARC-Block-Digest\":\"sha1:YJKNGIMOAJ43DMEY73FZQ6G3QOS4WHGY\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100508.53_warc_CC-MAIN-20231203193127-20231203223127-00187.warc.gz\"}"} |
http://blog.hudongdong.com/c/187.html | [
"请认准网站唯一域名: hudongdong.com, 其他域名都是违规的垃圾镜像,请勿访问\n\nC++的运算符\nC++的运算符十分丰富,使得C++的运算十分灵活方便。例如把赋值号(=)也作为运算符处理,这样,a=b=c=4就是...",
null,
"13\n2015/07\n\n# C++的运算符\n\nC++的运算符十分丰富,使得C++的运算十分灵活方便。例如把赋值号(=)也作为运算符处理,这样,a=b=c=4就是合法的表达式,这是与其他语言不同的。C++提供了以下运算符:\n\n+(加) -(减) *(乘) /(除) %(整除求余) ++(自加) --(自减)\n\n>(大于) <(小于) ==(等于) >=(大于或等于) <=(小于或等于) !=(不等于)\n\n&&(逻辑与) ||(逻辑或) !(逻辑非)\n\n<<(按位左移) >>(按位右移) &(按位与) |(按位或) ^(按位异或) ~(按位取反)",
null,
"Last modification:January 1st, 1970 at 08:00 am",
null,
""
] | [
null,
"http://blog.hudongdong.com/usr/themes/handsome/libs/GetCode.php",
null,
"http://blog.hudongdong.com/img/weixin.png",
null,
"https://cdn.v2ex.com/gravatar/d41d8cd98f00b204e9800998ecf8427e",
null
] | {"ft_lang_label":"__label__zh","ft_lang_prob":0.8977579,"math_prob":0.9988743,"size":562,"snap":"2021-04-2021-17","text_gpt3_token_len":453,"char_repetition_ratio":0.032258064,"word_repetition_ratio":0.0,"special_character_ratio":0.38434163,"punctuation_ratio":0.12195122,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98194367,"pos_list":[0,1,2,3,4,5,6],"im_url_duplicate_count":[null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-01-21T11:15:52Z\",\"WARC-Record-ID\":\"<urn:uuid:70fcf979-2966-4a0c-8201-7548e12aa96c>\",\"Content-Length\":\"86783\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:cce4496d-2933-4f28-b048-24d766595347>\",\"WARC-Concurrent-To\":\"<urn:uuid:2aa91588-753b-48df-b0db-cd465dc17ae2>\",\"WARC-IP-Address\":\"36.27.212.91\",\"WARC-Target-URI\":\"http://blog.hudongdong.com/c/187.html\",\"WARC-Payload-Digest\":\"sha1:XXJ262VLSTNQ7JOY44AKF7LD62FIV2SC\",\"WARC-Block-Digest\":\"sha1:OWK2VWWG4M4D3ME6D3RTYIF5O3ZHQFFD\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-04/CC-MAIN-2021-04_segments_1610703524743.61_warc_CC-MAIN-20210121101406-20210121131406-00545.warc.gz\"}"} |
http://sjce.journals.sharif.edu/article_20957.html | [
"# بررسی احتمالاتی جابهجایی شمع تحت اثر بار دینامیکی با استفاده از روش وینکلر\n\nنوع مقاله : یادداشت فنی\n\nنویسندگان\n\nدانشکده ی مهندسی عمران و محیط زیست، دانشگاه صنعتی شیراز\n\nچکیده\n\nدر طی زلزلههای پیشین، تعداد زیادی از شمعهای استفاده شده دچار آسیب شدهاند که متأسفانه در نمونههای کمی از آنها، اطلاعاتی قابل استفاده به ثبت رسیده است. هدف از پژوهش حاضر، مدلسازی شمع و خاک براساس روش وینکلر و آنالیز احتمالاتی آن تحت بار دینامیکی زلزله با اعمال عدم قطعیت در پارامترهای ورودی خاک و بتن است. برای این منظور با برنامهنویسی در محیط متلب، آنالیز دینامیکی در حوزهی زمان با استفاده از روش نیومارک و شبیهسازی مونتکارلو بهعنوان ابزاری جهت آنالیز احتمالاتی با یکدیگر ادغام شدند تا توزیع احتمالاتی جابهجایی، سرعت و شتاب هر نقطه از شمع تعیین شود. جهت صحتسنجی، نتایج جابهجایی شمع و طیف پاسخ شتاب ساختگاه در حالت قطعی مقایسه شده است. از جمله مهمترین دستاوردهای پژوهش حاضر، میتوان به تعیین تابع توزیع احتمال بیشینهی جابهجایی شمع و بررسی احتمالاتی تأثیر طول شمع در جابهجایی آن در یک آنالیز دینامیکی اشاره کرد.\n\nکلیدواژهها\n\nموضوعات\n\nعنوان مقاله [English]\n\n### DISPLACEMENT RELIABILITY ASSESSMENT OF DYNAMIC LOADED PILE USING WINKLER METHOD\n\nنویسندگان [English]\n\n• A. Johari\n• R. Shirvani\nDept. of Civil Engineering and Environment Shiraz University of Technology\nچکیده [English]\n\nDuring previous earthquakes, a large number of used piles have been damaged,\n\nwhich unfortunately have been recorded in a small sample of usable information.\n\nTherefore, it would be very useful to obtain close-to-realistic information on\n\ndesigning and determining the behavior of the piles. The purpose of this paper\n\nis the modeling of soil and pile using Winkler's method and its probabilistic\n\nanalysis under the dynamic load of the earthquake by applying uncertainty of\n\ninput parameters of soil and concrete. For this purpose, by programming in the\n\nMATLAB, dynamic analysis in the time domain is combined with the New Mark\n\nmethod and the Monte Carlo Simulation (MCS) as a tool for probabilistic\n\nanalysis to determine the probability distribution of the displacement velocity, and acceleration of each point of the pile. In this way, the plie is modeled as beam elements, stiffness and damping of the soil, by linear springs and dampers are modeled respectively, and optional earthquake force is considered on the bedrock. The MCS is a computational algorithm that involves building models of possible results by substituting a range of values for any variable with inherent uncertainty. To verify, the results of the displacement of the pile and the spatial response of the site are compared by the output of PLAXIS and Deepsoil deterministically. Using probabilistic analysis, it is possible to determine the probability of outputs of the model. Also, in this paper, the effect of the pile length on its probabilistic displacement in the dynamic analysis is assessed and the maximum displacement probability density functions of them are compared. The results indicate that with increasing the length of the piles, the average displacement of the pile head increase. Furthermore, with increasing the length of the piles the standard deviation of displacement of the pile head also increases. This means with increasing the length of the piles the uncertainties of pile displacement increase.\n\nکلیدواژهها [English]\n\n• Dynamic load\n• winkler method\n• uncertainty\n• pile displacement\n• monte carlo simulation"
] | [
null
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https://www.colorhexa.com/cd4982 | [
"# #cd4982 Color Information\n\nIn a RGB color space, hex #cd4982 is composed of 80.4% red, 28.6% green and 51% blue. Whereas in a CMYK color space, it is composed of 0% cyan, 64.4% magenta, 36.6% yellow and 19.6% black. It has a hue angle of 334.1 degrees, a saturation of 56.9% and a lightness of 54.5%. #cd4982 color hex could be obtained by blending #ff92ff with #9b0005. Closest websafe color is: #cc3399.\n\n• R 80\n• G 29\n• B 51\nRGB color chart\n• C 0\n• M 64\n• Y 37\n• K 20\nCMYK color chart\n\n#cd4982 color description : Moderate pink.\n\n# #cd4982 Color Conversion\n\nThe hexadecimal color #cd4982 has RGB values of R:205, G:73, B:130 and CMYK values of C:0, M:0.64, Y:0.37, K:0.2. Its decimal value is 13453698.\n\nHex triplet RGB Decimal cd4982 `#cd4982` 205, 73, 130 `rgb(205,73,130)` 80.4, 28.6, 51 `rgb(80.4%,28.6%,51%)` 0, 64, 37, 20 334.1°, 56.9, 54.5 `hsl(334.1,56.9%,54.5%)` 334.1°, 64.4, 80.4 cc3399 `#cc3399`\nCIE-LAB 51.104, 57.098, -3.743 31.589, 19.359, 23.191 0.426, 0.261, 19.359 51.104, 57.22, 356.25 51.104, 82.961, -15.517 43.999, 51.158, -0.452 11001101, 01001001, 10000010\n\n# Color Schemes with #cd4982\n\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #49cd94\n``#49cd94` `rgb(73,205,148)``\nComplementary Color\n• #cd49c4\n``#cd49c4` `rgb(205,73,196)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #cd5249\n``#cd5249` `rgb(205,82,73)``\nAnalogous Color\n• #49c4cd\n``#49c4cd` `rgb(73,196,205)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #49cd52\n``#49cd52` `rgb(73,205,82)``\nSplit Complementary Color\n• #4982cd\n``#4982cd` `rgb(73,130,205)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #82cd49\n``#82cd49` `rgb(130,205,73)``\n• #9449cd\n``#9449cd` `rgb(148,73,205)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #82cd49\n``#82cd49` `rgb(130,205,73)``\n• #49cd94\n``#49cd94` `rgb(73,205,148)``\n• #9e2b5d\n``#9e2b5d` `rgb(158,43,93)``\n• #b23169\n``#b23169` `rgb(178,49,105)``\n• #c63674\n``#c63674` `rgb(198,54,116)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #d25d90\n``#d25d90` `rgb(210,93,144)``\n• #d8719d\n``#d8719d` `rgb(216,113,157)``\n• #dd85ab\n``#dd85ab` `rgb(221,133,171)``\nMonochromatic Color\n\n# Alternatives to #cd4982\n\nBelow, you can see some colors close to #cd4982. Having a set of related colors can be useful if you need an inspirational alternative to your original color choice.\n\n• #cd49a3\n``#cd49a3` `rgb(205,73,163)``\n• #cd4998\n``#cd4998` `rgb(205,73,152)``\n• #cd498d\n``#cd498d` `rgb(205,73,141)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #cd4977\n``#cd4977` `rgb(205,73,119)``\n• #cd496c\n``#cd496c` `rgb(205,73,108)``\n• #cd4961\n``#cd4961` `rgb(205,73,97)``\nSimilar Colors\n\n# #cd4982 Preview\n\nThis text has a font color of #cd4982.\n\n``<span style=\"color:#cd4982;\">Text here</span>``\n#cd4982 background color\n\nThis paragraph has a background color of #cd4982.\n\n``<p style=\"background-color:#cd4982;\">Content here</p>``\n#cd4982 border color\n\nThis element has a border color of #cd4982.\n\n``<div style=\"border:1px solid #cd4982;\">Content here</div>``\nCSS codes\n``.text {color:#cd4982;}``\n``.background {background-color:#cd4982;}``\n``.border {border:1px solid #cd4982;}``\n\n# Shades and Tints of #cd4982\n\nA shade is achieved by adding black to any pure hue, while a tint is created by mixing white to any pure color. In this example, #030102 is the darkest color, while #fcf2f6 is the lightest one.\n\n• #030102\n``#030102` `rgb(3,1,2)``\n• #12050b\n``#12050b` `rgb(18,5,11)``\n• #210914\n``#210914` `rgb(33,9,20)``\n• #310d1d\n``#310d1d` `rgb(49,13,29)``\n• #401226\n``#401226` `rgb(64,18,38)``\n• #50162f\n``#50162f` `rgb(80,22,47)``\n• #5f1a38\n``#5f1a38` `rgb(95,26,56)``\n• #6e1e41\n``#6e1e41` `rgb(110,30,65)``\n• #7e234a\n``#7e234a` `rgb(126,35,74)``\n• #8d2753\n``#8d2753` `rgb(141,39,83)``\n• #9d2b5c\n``#9d2b5c` `rgb(157,43,92)``\n• #ac2f65\n``#ac2f65` `rgb(172,47,101)``\n• #bb336e\n``#bb336e` `rgb(187,51,110)``\n• #c93a77\n``#c93a77` `rgb(201,58,119)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #d1588d\n``#d1588d` `rgb(209,88,141)``\n• #d56897\n``#d56897` `rgb(213,104,151)``\n• #da77a2\n``#da77a2` `rgb(218,119,162)``\n• #de87ac\n``#de87ac` `rgb(222,135,172)``\n• #e296b7\n``#e296b7` `rgb(226,150,183)``\n• #e6a5c1\n``#e6a5c1` `rgb(230,165,193)``\n• #ebb5cc\n``#ebb5cc` `rgb(235,181,204)``\n• #efc4d7\n``#efc4d7` `rgb(239,196,215)``\n• #f3d3e1\n``#f3d3e1` `rgb(243,211,225)``\n• #f7e3ec\n``#f7e3ec` `rgb(247,227,236)``\n• #fcf2f6\n``#fcf2f6` `rgb(252,242,246)``\nTint Color Variation\n\n# Tones of #cd4982\n\nA tone is produced by adding gray to any pure hue. In this case, #8f878b is the less saturated color, while #fa1c7c is the most saturated one.\n\n• #8f878b\n``#8f878b` `rgb(143,135,139)``\n• #977f89\n``#977f89` `rgb(151,127,137)``\n• #a07688\n``#a07688` `rgb(160,118,136)``\n• #a96d87\n``#a96d87` `rgb(169,109,135)``\n• #b26486\n``#b26486` `rgb(178,100,134)``\n• #bb5b84\n``#bb5b84` `rgb(187,91,132)``\n• #c45283\n``#c45283` `rgb(196,82,131)``\n• #cd4982\n``#cd4982` `rgb(205,73,130)``\n• #d64081\n``#d64081` `rgb(214,64,129)``\n• #df3780\n``#df3780` `rgb(223,55,128)``\n• #e82e7e\n``#e82e7e` `rgb(232,46,126)``\n• #f1257d\n``#f1257d` `rgb(241,37,125)``\n• #fa1c7c\n``#fa1c7c` `rgb(250,28,124)``\nTone Color Variation\n\n# Color Blindness Simulator\n\nBelow, you can see how #cd4982 is perceived by people affected by a color vision deficiency. This can be useful if you need to ensure your color combinations are accessible to color-blind users.\n\nMonochromacy\n• Achromatopsia 0.005% of the population\n• Atypical Achromatopsia 0.001% of the population\nDichromacy\n• Protanopia 1% of men\n• Deuteranopia 1% of men\n• Tritanopia 0.001% of the population\nTrichromacy\n• Protanomaly 1% of men, 0.01% of women\n• Deuteranomaly 6% of men, 0.4% of women\n• Tritanomaly 0.01% of the population"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5215382,"math_prob":0.5953271,"size":3707,"snap":"2019-51-2020-05","text_gpt3_token_len":1649,"char_repetition_ratio":0.12449365,"word_repetition_ratio":0.011111111,"special_character_ratio":0.5578635,"punctuation_ratio":0.23634337,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9740013,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-01-26T05:36:51Z\",\"WARC-Record-ID\":\"<urn:uuid:8ca7c9a3-02ab-49eb-8944-577e495909aa>\",\"Content-Length\":\"36311\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:7b888128-c79c-4acd-b606-2d04f59238e6>\",\"WARC-Concurrent-To\":\"<urn:uuid:a22ab41e-b105-44ec-af92-cf8bb8dcb7ca>\",\"WARC-IP-Address\":\"178.32.117.56\",\"WARC-Target-URI\":\"https://www.colorhexa.com/cd4982\",\"WARC-Payload-Digest\":\"sha1:BLJD2MPZLBL663QHPF5NMVJBJFHC2V5U\",\"WARC-Block-Digest\":\"sha1:QB5WNENOQGGTKVVA5QCIRDNSPMQ43MZW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-05/CC-MAIN-2020-05_segments_1579251687725.76_warc_CC-MAIN-20200126043644-20200126073644-00378.warc.gz\"}"} |
https://math.stackexchange.com/questions/19132/characterizing-units-in-polynomial-rings/392604 | [
"# Characterizing units in polynomial rings\n\nI am trying to prove a result, for which I have got one part, but I am not able to get the converse part.\n\nTheorem. Let $R$ be a commutative ring with $1$. Then $f(X)=a_{0}+a_{1}X+a_{2}X^{2} + \\cdots + a_{n}X^{n}$ is a unit in $R[X]$ if and only if $a_{0}$ is a unit in $R$ and $a_{1},a_{2},\\dots,a_{n}$ are all nilpotent in $R$.\n\nProof. Suppose $f(X)=a_{0}+a_{1}X+\\cdots +a_{n}X^{n}$ is such that $a_{0}$ is a unit in $R$ and $a_{1},a_{2}, \\dots,a_{r}$ are all nilpotent in $R$. Since $R$ is commutative, we get that $a_{1}X,a_{2}X^{2},\\cdots,a_{n}X^{n}$ are all nilpotent and hence also their sum is nilpotent. Let $z = \\sum a_{i}X^{i}$ then $a_{0}^{-1}z$ is nilpotent and so $1+a_{0}^{-1}z$ is a unit. Thus $f(X)=a_{0}+z=a_{0} \\cdot (1+a_{0}^{-1}z)$ is a unit since product of two units in $R[X]$ is a unit.\n\nI have not been able to get the converse part and would like to see the proof for the converse part.\n\n• If $x$ is nilpotent then $1-x$ is a unit. – PrimeNumber Jan 26 '11 at 20:47\n• @Chandru1: $\\ u$ unit, $z^n = 0\\ \\Rightarrow\\ u-z\\ |\\ u^n - z^n = u^n,\\$ so $\\ u - z\\$ is a unit, being a divisor of the unit $u^n\\:.\\$ Thus $\\$ unit + nilpotent = unit. – Gone Jan 30 '11 at 19:16\n\nIf $$R$$ is a domain then easily $$f(X)$$ a unit implies that $$a_i = 0$$ for $$i>0$$. Now $$R\\to R/\\mathfrak p$$, for $$\\mathfrak p$$ prime, reduces to the domain case, yielding that the $$a_i$$, $$i>0$$ are in every prime ideal. But the intersection of all prime ideals is the nilradical, the set of all nilpotent elements - as you proved a few days ago.\n\nRemark This is a prototypical example of reduction to domains by factoring out prime ideals.\n\n• See here for units in the Laurent polynomial ring $R[x,x^{-1}]\\ \\$ – Gone Jun 28 '19 at 12:43\n\nLet $$f=\\sum_{k=0}^n a_kX^k$$ and $$g= \\sum_{k=0}^m b_kX^k$$. If $$f g=1$$, then clearly $$a_0,b_0$$ are units and:\n\n$$a_nb_m=0$$ $$a_{n-1}b_m+a_nb_{m-1}=0 \\Rightarrow (a_n)^2b_{m-1}=0$$ $$a_{n-2}b_m+a_{n-1}b_{m-1}+a_nb_{m-2}=0 \\Rightarrow (a_n)^3b_{m-2}=0$$ $$.....$$ $$.....+a_{n-2}b_2+a_{n-1}b_1+a_nb_0=0 \\Rightarrow (a_n)^{m+1}b_{0}=0$$\n\nSince $$b_0$$ is an unit, it follows that $$(a_n)^{m+1}=0$$.\n\nHence, we proved that $$a_n$$ is nilpotent, but this is enough. Indeed, since $$f$$ is invertible, $$a_nx^n$$ being nilpotent implies that $$f-a_nX^n$$ is unit and we can repeat (or more rigorously, perform induction on $$\\deg(f)$$).\n\n• Why does $a_{n-1}b_m+a_nb_{m-1}=0 \\Rightarrow (a_n)^2b_{m-1}=0$ ? – Nethesis Oct 3 '14 at 0:45\n• Wait, got it, though surely that is only true if $a_n \\in (Z)R$? – Nethesis Oct 3 '14 at 0:46\n• @Nethesis If by $Z$ you mean the center, it is probably because the ring is given commutative ;) – N. S. Oct 3 '14 at 1:15\n• Ah right, sorry, I was looking for an answer about a non commutative ring and din't see that in the question, my bad @N.S. – Nethesis Oct 5 '14 at 17:40\n• @zed111 In a commutative ring you have unit-nilpotent=unit. The proof is easy: if u is unit and v is nilpotent, then $v^n=0$ which means $$u^n=u^n-v^n=(u-v)(u^{n-1}+u^{n-2}v+...+v^{n-1})$$ This shows that $$(u-v)(u^{n-1}+u^{n-2}v+...+v^{n-1})(u^{-1})^n=1$$ – N. S. Apr 20 '15 at 15:47"
] | [
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https://studysoup.com/tsg/math/168/elementary-differential-equations-and-boundary-value-problems/chapter/18948/10-4 | [
"×\n\n×\n\n# Solutions for Chapter 10.4: Even and Odd Functions",
null,
"## Full solutions for Elementary Differential Equations and Boundary Value Problems | 10th Edition\n\nISBN: 9780470458310",
null,
"Solutions for Chapter 10.4: Even and Odd Functions\n\nSolutions for Chapter 10.4\n4 5 0 251 Reviews\n27\n3\n##### ISBN: 9780470458310\n\nThis textbook survival guide was created for the textbook: Elementary Differential Equations and Boundary Value Problems, edition: 10. This expansive textbook survival guide covers the following chapters and their solutions. Elementary Differential Equations and Boundary Value Problems was written by and is associated to the ISBN: 9780470458310. Chapter 10.4: Even and Odd Functions includes 40 full step-by-step solutions. Since 40 problems in chapter 10.4: Even and Odd Functions have been answered, more than 18249 students have viewed full step-by-step solutions from this chapter.\n\nKey Math Terms and definitions covered in this textbook\n\nA sequence of steps (end of Chapter 9) to solve positive definite Ax = b by minimizing !x T Ax - x Tb over growing Krylov subspaces.\n\n• Covariance matrix:E.\n\nWhen random variables Xi have mean = average value = 0, their covariances \"'£ ij are the averages of XiX j. With means Xi, the matrix :E = mean of (x - x) (x - x) T is positive (semi)definite; :E is diagonal if the Xi are independent.\n\n• Dot product = Inner product x T y = XI Y 1 + ... + Xn Yn.\n\nComplex dot product is x T Y . Perpendicular vectors have x T y = O. (AB)ij = (row i of A)T(column j of B).\n\n• Eigenvalue A and eigenvector x.\n\nAx = AX with x#-O so det(A - AI) = o.\n\n• Ellipse (or ellipsoid) x T Ax = 1.\n\nA must be positive definite; the axes of the ellipse are eigenvectors of A, with lengths 1/.JI. (For IIx II = 1 the vectors y = Ax lie on the ellipse IIA-1 yll2 = Y T(AAT)-1 Y = 1 displayed by eigshow; axis lengths ad\n\n• Gauss-Jordan method.\n\nInvert A by row operations on [A I] to reach [I A-I].\n\n• Graph G.\n\nSet of n nodes connected pairwise by m edges. A complete graph has all n(n - 1)/2 edges between nodes. A tree has only n - 1 edges and no closed loops.\n\n• Hermitian matrix A H = AT = A.\n\nComplex analog a j i = aU of a symmetric matrix.\n\n• Incidence matrix of a directed graph.\n\nThe m by n edge-node incidence matrix has a row for each edge (node i to node j), with entries -1 and 1 in columns i and j .\n\n• Inverse matrix A-I.\n\nSquare matrix with A-I A = I and AA-l = I. No inverse if det A = 0 and rank(A) < n and Ax = 0 for a nonzero vector x. The inverses of AB and AT are B-1 A-I and (A-I)T. Cofactor formula (A-l)ij = Cji! detA.\n\n• Linear transformation T.\n\nEach vector V in the input space transforms to T (v) in the output space, and linearity requires T(cv + dw) = c T(v) + d T(w). Examples: Matrix multiplication A v, differentiation and integration in function space.\n\n• Orthonormal vectors q 1 , ... , q n·\n\nDot products are q T q j = 0 if i =1= j and q T q i = 1. The matrix Q with these orthonormal columns has Q T Q = I. If m = n then Q T = Q -1 and q 1 ' ... , q n is an orthonormal basis for Rn : every v = L (v T q j )q j •\n\n• Right inverse A+.\n\nIf A has full row rank m, then A+ = AT(AAT)-l has AA+ = 1m.\n\n• Singular Value Decomposition\n\n(SVD) A = U:E VT = (orthogonal) ( diag)( orthogonal) First r columns of U and V are orthonormal bases of C (A) and C (AT), AVi = O'iUi with singular value O'i > O. Last columns are orthonormal bases of nullspaces.\n\n• Subspace S of V.\n\nAny vector space inside V, including V and Z = {zero vector only}.\n\n• Sum V + W of subs paces.\n\nSpace of all (v in V) + (w in W). Direct sum: V n W = to}.\n\n• Triangle inequality II u + v II < II u II + II v II.\n\nFor matrix norms II A + B II < II A II + II B II·\n\n• Unitary matrix UH = U T = U-I.\n\nOrthonormal columns (complex analog of Q).\n\n• Vector space V.\n\nSet of vectors such that all combinations cv + d w remain within V. Eight required rules are given in Section 3.1 for scalars c, d and vectors v, w.\n\n• Volume of box.\n\nThe rows (or the columns) of A generate a box with volume I det(A) I."
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https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1252-9 | [
"# Multicell multiuser massive MIMO channel estimation and MPSK signal block detection applying two-dimensional compressed sensing\n\n## Abstract\n\nFor the uplink multicell massive multiple-input multiple-output (MIMO) block fading systems, a two-dimensional smoothed l0 channel estimation method (2D-SL0-CE) with the aid of virtual channel representation is firstly exploited in this paper, which can jointly estimate the desired multiuser channels of the target cell and the interference links from neighbor cells without inducing pilot contamination. Then, a 2D-SL0 signal detection method (2D-SL0-SD) with the aid of sparse decomposing and the modified 2D sl0 recovery algorithm is proposed, which can jointly decode M-ary phase-shift keying (MPSK) signal block for whole desired users. Moreover, an improved 2D-SL0-SD is also proposed to remove multiuser interference of neighbor cells in high SNR scenario. Simulation results show that the 2D-SL0-CE method can remove performance floor induced by pilot contamination and need less pilot overhead than the conventional least square (LS) method. When detecting QPSK signal blocks at 12 dB SNR, the 2D-SL0-SD method with perfect channel state information (CSI) can obtain 10−2 BER. Moreover, in the case of 8PSK signals, the 2D-SL0-SD joining with the 2D-SL0-CE can obtain 10−2 BER at 20 dB SNR.\n\n## Introduction\n\nThe high energy and spectrum efficiency of massive multiple-input multiple-output (MIMO) systems heavily build on the premise that the base stations (BS) obtain channel state information (CSI) with reasonable quality, which is generally estimated via pilot sequences . However, in the uplink massive MIMO systems, the pilot overhead demanded should be proportional to the number of users and would be prohibitively large as the number of users increase. In the uplink multicell massive MIMO, this results in pilot contamination as the same pilot sequences have to be reused by neighbor cells to serve a large number of users . Moreover, the pilot contamination is a major limiting factor to system performance . Hence, the massive MIMO urgently needs efficient channel estimation scheme without producing pilot contamination and requiring too much pilot overhead. Based on the estimated CSI, the signals received at base stations are typically detected through linear methods with low complexity, such as zero-forcing and matched filter [7, 8]. However, the performances of linear detector are typically far inferior to the optimal maximum likelihood (ML) detector whose computational complexity exponentially scales up with the signal constellation size and the number of antennas . Thus, the development of computationally efficient and reliable detector for massive MIMO also needs to be thoroughly addressed .\n\nIn the past few years, several types of schemes have been exploited to mitigate or reduce the impact of pilot contamination in multicell massive MIMO systems. (1) Semi-blind or blind approaches, such as —the eigenvalue decomposition-based method with a short training sequence was proposed in . Hu et al. proposed a semi-blind method without requiring the statistical information of channels. Another low-complexity semi-blind approach was proposed in , which the received signal are firstly projected onto the subspace with minimal interference, then alternatively refined the channel estimation and detected the data symbols. Applying the theory of large random matrices, proposed a blind pilot decontamination with subspace projection. (2) Optimization design of non-orthogonal pilot signals, such as —when training slots are not large enough to construct the orthogonal pilot signals, exploits a pilot design criterion and shows that the line packing on a complex Grassmannian manifold is the optimization scheme, which is based on minimal mean square error (MMSE) estimator. A generalized Welch-bound equality-based pilot signal design method is proposed in , which has low correlation coefficients and ensures the network to satisfy the requirement of user capacity. For a given pilot length, proposes an alternating minimization-based pilot design algorithm. (3) The precoding-based approaches, such as —a MMSE-based precoding is exploited in to alleviate the impact of pilot contamination. A pilot contamination mitigation method along with zero-forcing precoding is proposed in , which can generate orthogonal pilot signals across neighboring cells through multiplying the Zadoff-Chu sequences element-wise with a specific orthogonal variable spreading factor code.\n\nSome significant efforts have been made to reduce the pilot overhead for massive MIMO systems, which can be divided into two broad categories. (1) Low-rank channel covariance matrices based methods, such as —the finite scattering environment and small angular spread result in high correlation of different paths between the user and the BS and low-rank channel covariance matrix. Through exploiting the correlation characteristic of channel vectors, the joint spatial division and multiplexing (JSDM) was proposed in which significantly reduced the overhead of downlink training and uplink feedback for frequency division duplexing (FDD) massive MIMO systems. When the number of pilot signals is no less than the rank of channel covariance matrix and the noise interference disappear, proves that the MMSE estimator can recovery channel vectors exactly. (2) Compressed channel sensing method—exploiting the channel sparsity and applying the compressed sensing (CS) to reduce the overhead of CSI feedback has been investigated in . A spare channel estimation method applying Gaussian-mixture Bayesian learning has been proposed in to estimate the whole channel parameters including the desired and interference links, which can mitigate pilot contamination and reduce pilot overhead, but every time, the approach just can estimate the channel response at one beam.\n\nAn iterative MIMO detector with relaxed ML constraints using sparse decomposition has been proposed to preserve a low computational cost even increase the signal size, but the method just suit to detect a vector . In block fading systems, the detection target at the BS usually is a multiuser data frame, i.e., a two-dimensional (2D) signal block. To detect the 2D signals, the method in should run the decoding process many times or convert the 2D signal detection problem to a vector detection problem. However, the converting method will substantially increase the required memory and processing load which would make it become non-competitive when applied to massive MIMO block fading systems. For example, the converting approach can be represented as:\n\n$$\\mathbf{Y}=\\mathbf{AXB}^{T} \\Longleftrightarrow \\mathbf{y}=\\Phi \\mathbf{x}$$\n(1)\n\nwith AR60×200, BR30×100, x=vec(X), and y=vec(Y), which results in Φ=BA with dimensions 1800×20,000. The signs of vec() and $$\\bigotimes$$ denote vectorization of a matrix and Kronecker product, respectively.\n\nIn this paper, the multiuser channel estimation problem and the multiuser signal decoding problem in uplink massive MIMO systems are modelled as two-dimensional sparse signal recovery problems in compressed sensing, respectively. Although [35, 36] researched the 2D compressed sensing channel estimation schemes for massive MIMO, it is the FDD model discussed in [35, 36] which is different from the time division duplexing (TDD) multicell multiuser system model considered in this paper. The main contributions of this paper are summarized as follows:\n\n• We propose a channel estimation method named as 2D-SL0-CE applying the two-dimensional smoothed l0-norm compressed sensing recovery algorithm [37, 38], which are able to jointly estimate multiuser CSI. Using virtual channel representation, the 2D-SL0-CE formulates the joint channel estimation problem, comprising both the target and interference channels, as a 2D sparse signal reconstruction problem in CS, which not only can mitigate the pilot contamination but also can significantly reduce pilot overhead.\n\n• We propose a signal detection method named as 2D-SL0-SD using our modified 2D-SL0 algorithm, which can decode multiuser M-ary phase-shift keying (MPSK) signal block. Applying sparse decomposition, the 2D-SL0-SD models the detection problem of multiuser signal block as a 2D sparse signal reconstruction problem whose elements are binaries {0,1}. Moreover, in the high SNR scenario, through exploiting the estimated CSI of interference links, an improved 2D-SL0-SD is also proposed to remove the decoding bottleneck induced by interference from neighboring cells.\n\nThe remaining paper is organized as follows. The system model and the least square (LS) channel estimation methods are described in Section 2. Section 3 models the multicell multiuser channel estimation problem as a two-dimensional compressed sensing problem and describes the proposed channel estimation algorithm. Section 4 models the signal decoding problem of multiuser as a 2D sparse signal recovery problem and presents the steps of the proposed 2D-SL0-SD method. Section 5 gives and analyzes the numerical results. Section 6 draws a conclusion of the whole paper.\n\nNotations: diag(x) represents a diagonal matrix with diagonal elements being the vector x. Superscripts T and denote the transpose and pseudo-inverse, respectively. CN(0,1) denotes complex Gaussian variables with zero mean and unit variance. $$\\bigotimes$$ denotes Kronecker product. Vectors and matrices are denoted by boldface lowercase and uppercase letters, respectively.\n\n## System model\n\nConsider a multicell massive MIMO system in which each target cell shares the same frequency band with L−1 adjacent cells. Each cell has one BS with a uniform linear array (ULA) of M antennas that serves K (K<<M) single antenna users. The uplink channel vector from the kth terminal in ith cell to jth BS is modelled as:\n\n$$\\mathbf{h}_{jik}=\\sqrt{\\beta_{jik}}\\mathbf{g}_{jik},$$\n(2)\n\nwhere gjik is the fast fading vector, and large-scale fading factor βjik describes the quasi-static shadow fading and the path loss. Different channel vectors are assumed to be independent. Consequently, the channel matrix between the K users in ith cell and the jth BS can be represented as:\n\n$$\\mathbf{H}_{ji}\\mathbf{=G}_{ji}\\mathbf{D}_{ji}$$\n(3)\n\nwith Hji=[hji1,,hjiK], Gji=[gji1,,gjiK] and $$\\mathbf {D}_{ji}=\\text {diag}\\left (\\sqrt {\\beta _{ji1}},\\cdots,\\sqrt {\\beta _{jiK}}\\right)$$.\n\nIn a block fading channel, the training signal received at the jth BS becomes:\n\n$$\\mathbf{Y}_{j}^{tr}=\\sqrt{P_{tr}}\\sum\\limits_{i=1}^{L}\\mathbf{H}_{ji}\\mathbf{X}_{i}^{tr}+\\mathbf{N}_{j}^{tr},$$\n(4)\n\nwhere Ptr denotes the training signal-to-noise ratio (SNR), the rows of $$\\mathbf {X}_{i}^{tr}\\in C^{K\\times T_{tr}}$$ are the pilot sequences of ith cell, and $$\\mathbf {N}_{j}^{tr}$$ is the noise with i.i.d. elements distributed as CN(0,1).\n\nThe jth cell is assumed as the target cell. One natural choice to find a channel estimate based on the training signal without employing any prior information is the LS method which is given by:\n\n$$\\begin{array}{*{20}l} \\hat{\\mathbf{H}}_{jj}^{LS}&=\\frac{1}{\\sqrt{P_{tr}}}\\mathbf{Y}_{j}^{tr}\\left(\\mathbf{X}_{j}^{tr}\\right)^{\\dag} \\\\ &= \\mathbf{H}_{jj}+\\sum\\limits_{i=1,i\\neq j}^{L} \\mathbf{H}_{ji}+\\frac{1}{\\sqrt{P_{tr}}}\\mathbf{N}_{j}^{tr}, \\end{array}$$\n(5)\n\nwhere the second term denotes pilot contamination resulting in the same orthogonal pilots reused by adjacent cells.\n\n## 2D-SL0-CE channel estimation method\n\nThe key idea of our exploited channel estimation is to explore the sparsity in the virtual channel representation, which applies spatial beams at fixed virtual directions to characterize the physical channel matrix. The virtual channel matrix $$\\mathbf {G}_{ji}^{v}$$ can be linked to the above described physical channel matrix Gji by the following transformation:\n\n$$\\mathbf{G}_{ji}=\\mathbf{A}_{R}\\mathbf{G}_{ji}^{v},$$\n(6)\n\nwhere AR=[aR(θ1),,aR(θM)] with the receiver response vectors given by:\n\n$$\\mathbf{a}_{R}(\\theta_{m})=\\frac{1}{\\sqrt{M}}\\left[1, e^{-j2\\pi \\theta_{m}}, \\cdots, e^{-j2\\pi(M-1)\\theta_{m}}\\right]^{T}.$$\n(7)\n\nThe direction θm is related to the physical angle ϕm[−π/2,π/2] as θm=dsin(ϕm)/λ with λ being the carrier wavelength and d being the antenna spacing . We uniformly sample the principal θ period to set the virtual spatial angles, i.e., θm=m/M, and resulting in an M×M unitary discrete Fourier transform matrix AR. The element $$\\mathbf {G}_{ji,mk}^{v}$$ of M×K matrix $$\\mathbf {G}_{ji}^{v}$$ represents the coupling gain from the kth terminal to the mth virtual receive angle θm. Therefore, the element will be zero when there is no corresponding coupling, and the $$\\mathbf {G}_{ji}^{v}$$ will be a sparse matrix when the number of non-zero elements is much smaller than that of the total elements.\n\nSubstituting (6) into (4) yields the following received training signal at the jth BS:\n\n$$\\mathbf{Y}_{j}^{tr}=\\sqrt{P_{tr}}\\sum_{i=1}^{L}\\mathbf{A}_{R}\\mathbf{G}_{ji}^{v} \\mathbf{D}_{ji}\\mathbf{X}_{i}^{tr}+\\mathbf{N}_{j}^{tr}.$$\n(8)\n\nFurthermore, taking the transpose operation to (8), we can obtain:\n\n{{} \\begin{aligned} \\underbrace{\\frac{1}{\\sqrt{P_{tr}}}(\\mathbf{Y}_{j}^{tr})^{T}}_{=\\mathbf{Y}} \\,=\\,\\sum\\limits_{i=1}^{L}\\left(\\mathbf{X}_{i}^{tr}\\right)^{T}\\mathbf{D}_{ji}\\left(\\mathbf{G}_{ji}^{v}\\right)^{T}\\mathbf{A}_{R}\\,+\\,\\frac{1}{\\sqrt{P_{tr}}}\\left(\\mathbf{N}_{j}^{tr}\\right)^{T}\\\\ =\\![\\underbrace{\\left(X_{1}^{tr}\\right)^{T},\\!\\cdots\\!,\\left(X_{L}^{tr}\\right)^{T}}_{=\\mathbf{X}}] \\underbrace{\\left[\\begin{array}{l} \\mathbf{D}_{j1}\\left(\\mathbf{G}_{j1}^{v}\\right)^{T} \\\\ \\vdots\\\\ \\mathbf{D}_{jL}\\left(\\mathbf{G}_{jL}^{v}\\right)^{T} \\end{array}\\right]}_{=\\mathbf{G}} \\!\\mathbf{A}_{R}\\,+\\,\\underbrace{\\frac{1}{\\sqrt{P_{tr}}}\\left(\\mathbf{N}_{j}^{tr}\\right)^{T}}_{=\\mathbf{N}}. \\end{aligned}}\n(9)\n\nNow, based on the linear model Y=XGAR+N, the channel estimation problem is modelled as a 2D sparse signal reconstruction problem in compressed sensing. Then, we estimate Hj=[Hj1,,HjL] based on Y, X, and AR, using the 2D-SL0 sparse reconstruction algorithm . The proposed channel estimation method 2D-SL0-CE is summarized in Algorithm 1. Different from other types of compressed sensing recovery algorithms, the SL0 and 2DSL0 applied the following function to approximate the l0-norm of b, i.e., ||b||0.\n\n$$\\left \\{ \\begin{array}{lr} \\mathbf{F}_{\\sigma}(\\mathbf{b})=\\sum_{i=1}^{M} \\text{exp}\\left(\\frac{-b_{i}^{2}}{2\\sigma^{2}}\\right),\\\\ ||\\mathbf{b}||_{0}\\approx M-\\mathbf{F}_{\\sigma}(\\mathbf{b}),\\sigma\\rightarrow 0, \\end{array} \\right.$$\n(10)\n\nwhere bRM×1 is a sparse vector, and the parameter σ determines the quality of the approximation and how smooth the function Fσ(b). Consequently, the minimum l0-norm solution can be found by maximizing Fσ(b). In Algorithm 1, steps 2–9 gradually decrease the value of σ and maximize the objective function for each value of σ.",
null,
"## 2D-SL0-SD signal detection method\n\nIn a block fading scenario, the received data signal at the jth BS can be written as:\n\n$$\\mathbf{Y}_{j}=\\sqrt{P_{\\text{data}}}\\mathbf{H}_{jj}\\mathbf{X}_{j}+\\underbrace{\\sqrt{P_{\\text{data}}}\\sum\\limits_{i=1,i\\neq j}^{L}\\mathbf{H}_{ji}\\mathbf{X}_{i}+\\mathbf{N}_{j}}_{=\\mathbf{W}_{j}},$$\n(11)\n\nwhere $$\\mathbf {Y}_{j}\\in \\mathcal {C}^{M\\times N}$$ is the received data, $$\\sqrt {P_{\\text {data}}}$$ denotes the uplink SNR, Xi denotes the transmitted data matrix of the ith cell whose element is selected from a finite alphabet constellation defined as {s1,,sQ} with Q being the finite alphabet cardinal, Nj is the noise with elements distributed as CN(01), and Wj represents the noise plus interference faced by the received data of jth BS.\n\nThe transmitted symbol of the ith cell can be sparse represented as (12) through exploiting the prior knowledge that each transmitted element Xi,mn belongs to a discrete and finite alphabet constellation:\n\n$$X_{i,mn}=\\mathbf{s e}_{i,mn},$$\n(12)\n\nwhere Xi,mn denotes the nth symbol of mth user in ith cell, s=[s1,,sQ] is the discrete and finite constellation vector, and ei,mn=[ei,mn(s1),,ei,mn(sQ)]T with ei,mn(sq) being equal to 1 if Xi,mn=sq or 0 otherwise (1≤qQ). Applying this sparse representation into all symbols, the transmitted data matrix in the ith cell can be expressed in function of a sparse matrix as:\n\n$$\\mathbf{X}_{i}=\\mathbf{B}_{s}\\mathbf{E}_{i},$$\n(13)\n\nwhere $$\\mathbf {B}_{s}=\\mathbf {I}_{K} \\bigotimes \\mathbf {s}$$ is a block diagonal matrix of size K×KQ, and the nth column of the matrix Ei is [(ei,1n)T,,(ei,Kn)T]T.\n\nSubstituting (13) into (11) generates\n\n$$\\mathbf{Y}_{j}=\\sqrt{P_{\\text{data}}}\\mathbf{H}_{jj}\\mathbf{B}_{s}\\mathbf{E}_{j}+\\mathbf{W}_{j}=\\mathbf{A}_{j}\\mathbf{E}_{j}\\mathbf{I}_{N}+\\mathbf{W}_{j}$$\n(14)\n\nwith $$\\mathbf {A}_{j}=\\sqrt {P_{\\text {data}}}\\mathbf {H}_{jj}\\mathbf {B}_{s}$$. The detection problem of signal block has been modelled as a 2D sparse binary {0,1} reconstruction problem in CS, then based on Yj, Aj, and IN, the signal block Xj can be detected using the modify 2D-SL0 algorithm which suits to reconstruct 2D sparse binary {0,1} signal. The process of 2D-SL0-SD is summarized in Algorithm 2. Because the elements of Ej needed to be recovered are 0 or 1, but the elements recovered by the original 2D-SL0 algorithm are not exactly 0 or 1, step 10 of Algorithm 2 is added to find which element of $$\\hat {\\mathbf {e}}_{j,mn}$$ maybe 1 with highest probability and reset such element to 1 and others to 0.",
null,
"In the high SNR scenario, such as Nj→0, it can be observed from (11) that the main factor restricting the decoding performance is not the noise but the interference from neighboring cells. Thus, the performance of 2D-SL0-SD will meet floor as the SNR increases. In order to resolve this problem, the CSI of interference links are exploited and an improved 2D-SL0-SD method is proposed, which does not treat the signals from neighbor cells as interference, moreover, decodes them jointly with the desired signals. Specifically, exploiting the CSI of whole links estimated by the above proposed 2D-SL0-CE method, the received data signal at the jth BS in (11) can be rewritten as:\n\n$$\\small \\mathbf{Y}_{j}=\\sqrt{P_{\\text{data}}}[\\mathbf{H}_{j1},\\!\\cdots\\!, \\mathbf{H}_{jL}][(\\mathbf{X}_{1})^{T},\\!\\cdots\\!, (\\mathbf{X}_{L})^{T}]^{T}+\\mathbf{N}_{j}.$$\n(15)\n\nMoreover, substituting (13) into (15) can generate:\n\n\\begin{aligned} \\mathbf{Y}_{j}\\,=\\, &\\underbrace{\\sqrt{P_{\\text{data}}}[\\mathbf{H}_{j1}\\mathbf{B}_{s},\\cdots\\!, \\mathbf{H}_{jL}\\mathbf{B}_{s}]}_{=\\mathbf{A}}\\underbrace{[(\\mathbf{E}_{1})^{T},\\cdots\\!, (\\mathbf{E}_{L})^{T}]^{T}}_{=\\mathbf{E}}\\!\\mathbf{I}_{N} \\\\ &+\\mathbf{N}_{j}. \\end{aligned}\n(16)\n\nNow, the decoding problem without multiuser interference has also been modelled as a 2D sparse {0,1} signal reconstruction problem, which has the same form as that of (14), and can be solved through the processes of Algorithm 2 whose Aj needs to be replaced by A. Hereafter, the improved 2D-SL0-SD with interference cancel is named as 2D-SL0-SD-IC. Comparing (16) with (14), it can be observed that the recovery object of the 2D-SL0-SD-IC is E, including not only the Ej of the objective cell but also the Ei of the L−1 neighbor cells (i=1,L,ij), and the noise is the only interference source.\n\nIt is worth noting that the proposed 2D-SL0-SD is only suitable to decode constant modulus signal, such as MPSK. Since there is only one element of ei,mn in (12) equaling to 1 and the others are zeros, Algorithm 2 needs a ruler to reset the values of the estimated $$\\hat {\\mathbf {e}}_{i,mn}$$. In step 10 of Algorithm 2, the ruler is that the element of $$\\hat {\\mathbf {e}}_{j,mn}$$ with the largest real part is viewed as such element whose value is 1 with the highest probability. Such ruler requires that the elements of s in (12) have the same modulus.\n\n## Numerical results and discussion\n\nThe spectral efficiency and estimation accuracy of the proposed 2D-SL0-CE sparse channel estimation method and the decode performance of the proposed 2D-SL0-SD are investigated. A multicell scenario with L cells sharing the same frequency band is considered. The fading coefficient is modelled as βjik=zjik/(rjik/rh)α, in which $$z_{jik}\\thicksim ln N\\left (0,\\sigma _{\\text {shadow}}^{2}\\right)$$ is a lognormal random variable, rjik denotes the distance between the BS and the corresponding terminal, and rh is the cell-hole radius. The number of non-zero elements in each column of $$G_{ji}^{v}$$, which means the number of multipath, is assumed to S, whose positions are randomly selected and values are generated through CN(0,1). The pilot sequence of each user is randomly generated using the complex normal distribution and then is normalized to unity. The normalized mean square error (NMSE) defined as $$\\frac {1}{N_{\\text {MC}}}{\\sum \\nolimits }_{i=1}^{N_{\\text {MC}}}\\frac {\\|\\hat {H_{i}}-H_{i}\\|_{F}^{2}}{\\|H_{i}\\|_{F}^{2}}$$ is used to evaluate the estimation accuracy, where NMC means the number of Monte-Carlo simulations, Hi and $$\\hat {H_{i}}$$ are the actual and estimated channel impulse response of ith Monte-Carlo trial, respectively. The parameters of the system and the 2D-SL0 algorithm are summarized in Table 1.\n\nFirstly, at the scenario of S=5, the NMSE of the 2D-SL0-CE and the bit error rate (BER) of the 2D-SL0-SD detection QPSK signals with various CSI, including perfect and estimated CSI, are investigated. The whole number of multicell users is 20×7=140; thus, the LS method should require orthogonal pilot sequences with length being not less than 140 to avoid pilot contamination. Figure 1 shows that the 2D-SL0-CE method applying random pilot sequences with a length of 12 can outperform LS with 140 pilots nearly 5 dB. Moreover, the NMSE of 2D-SL0-CE is approximate linear reducing with the SNR increasing when the pilot length is not less than 12. While in the case that 20 orthogonal pilot sequences are reused by the objective cell and neighbor cells, Fig. 1 also shows that the LS method will meet a performance floor caused by pilot contamination. In a block fading scenario with signal length N=200, Fig. 2 plots the BER performance of the 2D-SL0-SD detection QPSK signal block using various CSIs. Applying perfect CSI at 10 dB SNR, the 2D-SL0-SD can approach near to 10−2 BER. Moreover, its BER is approximate linear reducing with the SNR increasing, which shows its reliable detection ability. Using the CSI estimated through the 2D-SL0-CE, where each user applies random non-orthogonal pilot sequence with length being 32, the obtained BER of 2D-SL0-SD at 15 dB SNR is slightly better than 10−2, which shows joint the 2D-SL0-CE with 2D-SL0-SD for channel estimation and decoding QPSK signals is a feasible scheme.\n\nThen, applying perfect CSI and estimated CSI through 2D-SL0-CE, respectively, Figs. 3 and 4 show the BER of 2D-SL0-SD and its improved version 2D-SL0-SD-IC detecting various PSK data block with length N=200. In both cases, the BER of 2D-SL0-SD is better than 2D-SL0-SD-IC within a SNR threshold value. This is because the received energy of interference data is usually smaller than that of target data, which induces more difficult to decode interference data. The decoding object in 2D-SL0-SD-IC includes the target and interference data, which means the decoding result of two parts will affect each other. Thus, in the low-SNR scenario, the low correct decoding probability of interference data leads to 2D-SL0-SD-IC has higher BER than 2D-SL0-SD. With the SNR increasing and exceeding a threshold value, the 2D-SL0-SD will gradually meet a performance bound induced by interference. However, the BER of 2D-SL0-SD-IC will be still approximately linear reducing owing to gradually high correct decoding probability of interference data. In theory, with the distance of the two neighbor signal points in constellation diagram gradually reducing, it will be more difficult to decode the signals correctly. In Figs. 3 and 4, it can be observed that the BERs of QPSK, 8PSK, and 16PSK are gradually increasing at the same SNR.\n\nFinally, the NMSE of 2D-SL0-CE method with fixed pilot length at various scenarios, including various sparsity and number of users in each cell, is studied in Figs. 5 and 6, respectively. In the case of each cell having 20 users, applying random pilot sequences with fixed length of 26, Fig. 5 shows that the NMSE is approximately linear reducing with the SNR increasing when the S is not larger than 20. In the case of S=5 and pilot length being 26, Fig. 6 shows that the NMSE is approximately linear reducing with the SNR increasing when the number of users in each cell is not larger than 50. In order to recovery a 1D E-sparse F-length vector successfully with high probability, presents that the number of measurements needed is of order $$\\mathcal {O}(E\\text {log}(F/E))$$. In the 2D cases, from the best performance plots in Figs. 5 and 6, it can be obtained that the number of measurements are 2.15 and 2.23 times of KLSlog(M/S), respectively, where the value of KLS is the number of non-zero elements in 2D signals. Thus, ensuring the original 2D signal can be recovered with high probability, the number of measurements needed is also of order $$\\mathcal {O}(E\\text {log}(F/E))$$, where the E and F denote the numbers of non-zero elements and whole elements in the 2D signal, respectively. In practical, the above ruler can be used to guide for setting pilot length.\n\n## Conclusions\n\nThis paper has investigated the two challenging problems for block fading massive MIMO systems. The one is to exploit efficient uplink channel estimation method that requires acceptable pilot overhead and can mitigate pilot contamination. The other one is to jointly decode multiuser data block. The joint multiuser channel estimation and data block detection problems have both been modelled and solved as a 2D sparse signal reconstruction problem in the CS framework. More specifically, through using a linear virtual channel representation for ULA, the 2D-SL0-CE compressed channel sensing method is proposed, which needs less pilot overhead than LS method, and can jointly estimate the desired and interference uplinks. Through sparse representation in a finite alphabet set for each transmitted data symbol, the 2D-SL0-SD data decoding method is proposed which can simultaneously decode a MPSK data block for multiuser. Simulation results demonstrate that joint the 2D-SL0-CE with 2D-SL0-SD to estimate channel and decode MPSK data for multiuser massive MIMO is a feasible scheme.\n\n## Abbreviations\n\n2D-SL0:\n\nTwo-dimensional smoothed l0\n\n2D-SL0-CE:\n\nTwo-dimensional smoothed l0-norm channel estimation\n\n2D-SL0-SD:\n\nTwo-dimensional smoothed l0-norm signal detection\n\n2D-SL0-SD-IC:\n\nTwo-dimensional smoothed l0-norm signal detection with interference cancel\n\nBER:\n\nBit error rate\n\nBS:\n\nBase station\n\nCS:\n\nCompressed sensing\n\nCSI:\n\nChannel state information\n\nFDD:\n\nFrequency division duplexing\n\nJSDM:\n\nJoint spatial division and multiplexing\n\nLS:\n\nLeast square\n\nMIMO:\n\nMultiple-input multiple-output\n\nML:\n\nMaximum likelihood\n\nMMSE:\n\nMinimal mean square error\n\nMPSK:\n\nM-ary phase-shift keying\n\nNMSE:\n\nNormalized mean square error\n\nQPSK:\n\nSNR:\n\nSignal-to-noise ratio\n\nTDD:\n\nTime division duplexing\n\nULA:\n\nUniform linear array\n\n## References\n\n1. 1\n\nN. Shariati, E. Bjornson, M. Bengtsson, M. Debbah, Low-complexity polynomial channel estimation in large-scale MIMO with arbitrary statistics. IEEE J. Sel. Top. Signal Proc.8(5), 815–830 (2014).\n\n2. 2\n\nO. Elijah, C.Y. Leow, T.A. Rahman, S. Nunoo, S.Z. Iliya, A comprehensive survey of pilot contamination in massive MIMO 5G system. IEEE Commun. Surv. Tutor.18(2), 905–923 (2016).\n\n3. 3\n\nH.Q. Ngo, E.G. Larsson, T.L. Marzetta, The multicell multiuser MIMO uplink with very large antenna arrays and a finite-dimensional channel. IEEE Trans. Commun.61(6), 2350–2361 (2013).\n\n4. 4\n\nW. Tan, M. Matthaiou, S. Jin, X. Li, Spectral efficiency of DFT-based processing hybrid architectures in massive MIMO. IEEE Wirel. Commun. Lett.6(5), 586–589 (2017).\n\n5. 5\n\nW. Tan, G. Xu, E.D. Carvalho, L. Fan, C. Li, Low cost and high efficiency hybrid architecture massive MIMO systems based on DFT processing. Wirel. Commun. Mob. Comput.2018:, 1–11 (2018).\n\n6. 6\n\nC. Li, K. Song, Y. Li, L. Yang, Energy efficient design for multiuser downlink energy and uplink information transfer in 5G. Sci. China Inf. Sci.59(2), 1–8 (2016).\n\n7. 7\n\nW. Tan, D. Xie, J. Xia, W. Tan, L. Fan, S. Jin, Spectral and energy efficiency of massive MIMO for hybrid architectures based on phase shifters. IEEE Access.6:, 11751–11759 (2018).\n\n8. 8\n\nW. Tan, S. Jin, C.K. Wen, J. Tao, Spectral efficiency of multi-user millimeter wave systems under single path with uniform rectangular arrays. EURASIP J. Wirel. Commun. Netw.181:, 458–472 (2017).\n\n9. 9\n\nA. Elghariani, M. Zoltowski, Low complexity detection algorithms in large-scale MIMO systems. IEEE Trans. Wirel. Commun.15(3), 1689–1702 (2016).\n\n10. 10\n\nL. Bai, T. Li, J. Liu, Q. Yu, J. Choi, Large-scale MIMO detection using MCMC approach with blockwise sampling. IEEE Trans. Wirel. Commun.64(9), 3697–3707 (2016).\n\n11. 11\n\nH.Q. Ngo, E.G. Larsson, EVD-based channel estimation in multicell multiuser MIMO systems with very large antenna arrays (IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Kyoto, 2012).\n\n12. 12\n\nD. Hu, L. He, X. Wang, Semi-blind pilot decontamination for massive MIMO systems. IEEE Trans. Wirel. Commun.15(1), 525–536 (2016).\n\n13. 13\n\nC.Y. Wu, W.J. Huang, W.H. Chung, Low-complexity semiblind channel estimation in massive MU-MIMO systems. IEEE Trans. Wirel. Commun.16(9), 6279–6290 (2017).\n\n14. 14\n\nR.R. Muller, L. Cottatellucci, M. Vehkapera, Blind pilot decontamination. IEEE J. Sel. Top. Sign. Process.8(5), 773–786 (2014).\n\n15. 15\n\nH. Wang, W. Zhang, Y. Liu, Q. Xu, P. Pan, On design of non-orthogonal pilot signals for a multi-cell massive MIMO system. IEEE Wirel. Commun. Lett.4(2), 129–132 (2015).\n\n16. 16\n\nN. Akbar, N. Yang, P. Sadeghi, R.A. Kennedy, Multi-cell multiuser massive MIMO networks: user capacity analysis and pilot design. IEEE Trans. Commun.64(12), 5064–5077 (2016).\n\n17. 17\n\nY. Han, J. Lee, Uplink pilot design for multi-cell massive MIMO networks. IEEE Commun. Lett.20(8), 1619–1622 (2016).\n\n18. 18\n\nC. Li, K. Song, D. Wang, F. Zheng, L. Yang, Optimal remote radio head selection for cloud radio access networks. Sci. China Inf. Sci.59(10), 1–12 (2016).\n\n19. 19\n\nJ. Jose, A. Ashikhmin, T.L. Marzetta, S. Vishwanath, Pilot contamination and precoding in multi-cell TDD systems. IEEE Trans. Wirel. Commun.10(8), 2640–2651 (2011).\n\n20. 20\n\nS. Ali, Z. Chen, F. Yin, Eradication of pilot contamination and zero forcing precoding in the multi-cell TDD massive MIMO systems. IET Commun.11(13), 2027–2034 (2017).\n\n21. 21\n\nC. Li, P. Liu, C. Zou, F. Sun, J.M. Cioffi, L. Yang, Spectral-efficient cellular communications with coexistent one- and two-hop transmissions. IEEE Trans. Veh. Technol.65(8), 6765–6772 (2016).\n\n22. 22\n\nH. Xie, F. Gao, S. Jin, An overview of low-rank channel estimation for massive MIMO systems. IEEE Access. 4:, 7313–7321 (2016).\n\n23. 23\n\nA. Adhikary, J. Nam, J.Y. Ahn, G. Caire, Joint spatial division and multiplexing the large-scale array regime. IEEE Trans. Inf. Theory.59(10), 6441–6463 (2013).\n\n24. 24\n\nJ. Fang, X. Li, H. Li, F. Gao, Low-rank covariance-assisted downlink training and channel estimation for FDD massive MIMO systems. IEEE Trans. Wirel. Commun.16(3), 1935–1947 (2017).\n\n25. 25\n\nL. Fan, R. Zhao, F. Gong, N. Yang, G.K. Karagiannidis, Secure multiple amplify-and-forward relaying over correlated fading channels. IEEE Trans. Commun.65(7), 2811–2820 (2017).\n\n26. 26\n\nR. Zhao, Y. Yuan, L. Fan, Y. He, Secrecy performance analysis of cognitive decode-and-forward relay networks in Nakagami-m fading channels. IEEE Trans. Commun.65(2), 549–563 (2017).\n\n27. 27\n\nL. Fan, X. Lei, N. Yang, T.Q. Duong, G.K. Karagiannidis, Secrecy cooperative networks with outdated relay selection over correlated fading channels. IEEE Trans. Veh. Technol.66(8), 7599–7603 (2017).\n\n28. 28\n\nX. Wang, H. Zhang, L. Fan, Y. Li, Performance of distributed switch-and-stay combining for cognitive relay networks with primary transceiver. Wirel. Pers. Commun.97(2), 3031–3042 (2017).\n\n29. 29\n\nJ. Yuan, S. Jin, W. Xu, W. Tan, M. Matthaiou, K.K. Wong, User-centric networking for dense C-RANS: high-SNR capacity analysis and antenna selection. IEEE Trans. Commun.65(11), 5067–5080 (2017).\n\n30. 30\n\nZ. Gao, L. Dai, Z. Wang, S. Chen, Spatially common sparsity based adaptive channel estimation and feedback for FDD massive MIMO. IEEE Trans. Signal Process.63(23), 6169–6183 (2015).\n\n31. 31\n\nV.K.N. Lau, S. Cai, A. Liu, Closed-loop compressive CSIT estimation in FDD massive MIMO systems with 1 bit feedback. IEEE Trans. Signal Process.64(8), 2146–2155 (2016).\n\n32. 32\n\nC. Li, K. Song, L. Yang, Low computational complexity design over sparse channel estimator in underwater acoustic OFDM communication system. IET Commun.11(7), 1143–1151 (2017).\n\n33. 33\n\nC.K. Wen, S. Jin, K.K. Wong, J.C. Chen, P. Ting, Channel estimation for massive MIMO using Gaussian-mixture Bayesian learning. IEEE Trans. Wirel. Commun.14(3), 1356–1368 (2015).\n\n34. 34\n\nY. Fadlallah, A. Aissa-El-Bey, K. Amis, D. Pastor, R. Pyndiah, New iterative detector of MIMO transmission using sparse decomposition. IEEE Trans. Veh. Technol.64(8), 3458–3464 (2015).\n\n35. 35\n\nW. Kai, L. Jingzhi, X. Lin, H. Le, Two-dimensional compressed sensing of channel state information in massive MIMO system (IEEE International Conference on Electronics Information and Emergency Communication (ICEIEC), Macau, 2017).\n\n36. 36\n\nY. Wang, H. Wang, Y. Fu, Modified two-dimensional compressed sensing scheme for massive MIMO channel estimation (IEEE International Conference on Wireless Communications & Signal Processing (WCSP), Yangzhou, 2016).\n\n37. 37\n\nH. Mohimani, M. Babaie-Zadeh, C. Jutten, A fast approach for overcomplete sparse decomposition based on smoothed l 0 norm. IEEE Trans. Signal Process.57(1), 289–301 (2009).\n\n38. 38\n\nA. Ghaffari, M. Babaie-Zadeh, C. Jutten, Sparse decomposition of two dimensional signals (IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Taipei, 2009).\n\n39. 39\n\nN. Kolomvakis, M. Matthaiou, M. Coldrey, Massive MIMO in sparse channels (IEEE International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), Toronto, 2014).\n\n40. 40\n\nD.L. Donoho, Compressed sensing. IEEE Trans. Inf. Theory. 52(4), 1289–1306 (2006).\n\n### Funding\n\nThis work was partly supported by the National Natural Science Foundation of China (Grant Nos. 61601005, 61801114), Natural Science Foundation of Anhui Province (Grant Nos. 1808085MF164, 1608085QF138), Key Projects of the Outstanding Young Talents Program in the Universities of Anhui Province (Grant No. gxyqZD2016027), the Natural Science Foundation of Jiangsu Province (Grant No. BK20170688) and Doctoral Scientific Research Foundation of Anhui Normal University (Grant Nos. 2014bsqdjj38, 2018XJJ40).\n\n### Availability of data and materials\n\nMostly, I got the writing material from different journals as presented in the references. A MATLAB tool has been used to simulate my concept.\n\n## Author information\n\nAuthors\n\n### Contributions\n\nXY conceived and designed the methods. XY performed the experiments and wrote the paper. AZ analyzed the simulation data. GZ and XG gave valuable suggestions on the structure of the paper. LY revised the original manuscript. All authors read and agreed the manuscript.\n\n### Corresponding author\n\nCorrespondence to Xinrong Ye.\n\n## Ethics declarations\n\n### Competing interests\n\nThe authors declare that they have no competing interests.\n\n### Publisher’s Note\n\nSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\n\n## Rights and permissions",
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https://deepai.org/publication/computing-the-testing-error-without-a-testing-set | [
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"Computing the Testing Error without a Testing Set\n\nDeep Neural Networks (DNNs) have revolutionized computer vision. We now have DNNs that achieve top (performance) results in many problems, including object recognition, facial expression analysis, and semantic segmentation, to name but a few. The design of the DNNs that achieve top results is, however, non-trivial and mostly done by trail-and-error. That is, typically, researchers will derive many DNN architectures (i.e., topologies) and then test them on multiple datasets. However, there are no guarantees that the selected DNN will perform well in the real world. One can use a testing set to estimate the performance gap between the training and testing sets, but avoiding overfitting-to-the-testing-data is almost impossible. Using a sequestered testing dataset may address this problem, but this requires a constant update of the dataset, a very expensive venture. Here, we derive an algorithm to estimate the performance gap between training and testing that does not require any testing dataset. Specifically, we derive a number of persistent topology measures that identify when a DNN is learning to generalize to unseen samples. This allows us to compute the DNN's testing error on unseen samples, even when we do not have access to them. We provide extensive experimental validation on multiple networks and datasets to demonstrate the feasibility of the proposed approach.\n\nAuthors\n\n04/10/2021\n\nUse of Metamorphic Relations as Knowledge Carriers to Train Deep Neural Networks\n\nTraining multiple-layered deep neural networks (DNNs) is difficult. The ...\n01/20/2021\n\nA Search-Based Testing Framework for Deep Neural Networks of Source Code Embedding\n\nOver the past few years, deep neural networks (DNNs) have been continuou...\n10/06/2021\n\nGeneralizing Neural Networks by Reflecting Deviating Data in Production\n\nTrained with a sufficiently large training and testing dataset, Deep Neu...\n08/13/2019\n\nLearning Credible Deep Neural Networks with Rationale Regularization\n\nRecent explainability related studies have shown that state-of-the-art D...\n11/28/2019\n\nComparing Offline and Online Testing of Deep Neural Networks: An Autonomous Car Case Study\n\nThere is a growing body of research on developing testing techniques for...\n01/26/2021\n\nCan Offline Testing of Deep Neural Networks Replace Their Online Testing?\n\nWe distinguish two general modes of testing for Deep Neural Networks (DN...\n12/09/2020\n\nEntropy Maximization and Meta Classification for Out-Of-Distribution Detection in Semantic Segmentation\n\nDeep neural networks (DNNs) for the semantic segmentation of images are ...\nThis week in AI\n\nGet the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday.\n\n1 Introduction\n\n11footnotetext: Let and be the performance of an algorithm computed using a training and testing set, respectively; is the estimated testing error computed without any testing data. The performance metric may be classification accuracy, F1-score, Intersection-over-Union (IoU), etc.\n\nDeep Neural Networks (DNNs) are algorithms capable of identifying complex, non-linear mappings, , between an input variable and and output variable , i.e., \n\n. Each DNN is defined by its unique topology and loss function. Some well-known models are\n\n[24, 14, 17], to name but a few.\n\nGiven a well-curated dataset with samples, , we can use DNNs to find an estimate of the functional mapping . Let us refer to the estimated mapping function as . Distinct estimates, , will be obtained when using different DNNs and datasets. Example datasets we can use to this end are [9, 12, 10], among many others.\n\nUsing datasets such as these to train DNNs has been very fruitful. DNNs have achieved considerable improvements in a myriad of, until recently, very challenging tasks, e.g., [17, 26].\n\nUnfortunately, we do not generally know how the estimated mapping functions will perform in the real world, when using independent, unseen images.",
null,
"Figure 1: (a) We compute the test performance of any Deep Neural Network (DNN) on any computer vision problem using no testing samples (top); neither labelled nor unlabelled samples are necessary. This in sharp contrast to the classical computer vision approach, where model performance is calculated using a curated test dataset (bottom). (b) The persistent algebraic topological summary (λ∗, μ∗) given by our algorithm (x-axis) against the performance gap Δρ between training and testing performance (y-axis).\n\nThe classical way to address this problem is to use a testing dataset, Figure 1(a, bottom). The problem with this approach is that, in many instances, the testing set is visible to us, and, hence, we keep modifying the DNN topology until it works on this testing dataset. This means that we overfit to the testing data and, generally, our algorithm may not be the best for truly unseen samples.\n\nTo resolve this issue, we can use a sequestered dataset. This means that a third-party has a testing dataset we have never seen and we are only able to know how well we perform on that dataset once every several months. While this does tell us how well our algorithm performs on previously unseen samples, we can only get this estimate sporadically. And, importantly, we need to rely on someone else maintaining and updating this sequestered testing set. Many such sequestered datasets do not last long, because maintaining and updating them is a very costly endeavour.\n\nIn the present paper, we introduce an approach that resolves these problems. Specifically, we derive an algorithm that gives an accurate estimate of the performance gap between our training and testing error, without the need of any testing dataset, Figure 1(a, top). That means we do not need to have access to any labelled or unlabelled data. Rather, our algorithm will give you an accurate estimate of the performance of your DNN on independent, unseen sample.\n\nOur key idea is to derive a set of topological summaries measuring persistent topological maps of the behavior of DNNs across computer vision problems. Persistent topology has been shown to correlate with generalization error in classification , and as a method to theoretically study and explain DNNs’ behavior [5, 8, 27]. The hypothesis we are advancing is that the generalization gap is a function of the inner-workings of the network, here represented by its functional topology and described through topological summaries. We propose to regress this function and use it to estimate test performance based only on training data.\n\nFigure 1(b) shows an example. In this plot, the -axis shows a linear combination of persistent topology measures of DNNs. The -axis in this plot is the value of the performance gap when using these DNNs on multiple computer vision problems. As can be seen in this figure, there is a linear relationship between our proposed topological summaries and the DNN’s performance gap. This means that knowing the value of our topological summaries is as good as knowing the performance of the DNN on a sequestered dataset, but without any of the drawbacks mentioned above – no need to depend on an independent group to collect, curate, and update a testing set.\n\nWe start with a set of derivations of the persistent topology measures we perform on DNNs (Section 2), before using this to derive our algorithm (Section 3). We provide a discussion of related work (Section 4) and extensive experimental evaluations on a variety of DNNs and computer vision problems, including object recognition, facial expression analysis, and semantic segmentation (Sections 5 and 6).\n\n2 Topological Summaries\n\nA DNN is characterized by its structure (i.e., the way its computational graph is defined and trained), and its function (i.e, the actual values its components take in response to specific inputs). We focus here on the latter.\n\nTo do this, we define DNNs on a topological space. A set of compact descriptors of this space, called topological summaries, are then calculated. They measure important properties of the network’s behaviour. For example, a summary of the functional topology of a network can be used to detect overfitting and perform early-stopping .\n\nLet be a set. An abstract simplicial complex is a collection of vertices denoted , and a collection of subsets of called simplices that is closed under the subset operation, i.e., if and , then .\n\nThe dimension of a simplex is , where denotes cardinality. A simplex of dimension is called a -simplex. A -simplex is realized by a single vertex, a -simplex by a line segment (i.e., an edge) connecting two vertices, a -simplex is the filled triangle that connects three vertices, etc.\n\nLet be a metric space – the association of the set with a metric . Given a distance , the Vietoris-Rips complex is an abstract simplicial complex that contains all the simplices formed by all pairs of elements with\n\n ν(ai,aj)<ϵ, (1)\n\nfor some small , and .",
null,
"Figure 2: Given a metric space, the Vietoris-Rips filtration creates a nested sequence of simplicial complexes by connecting points situated closer than a predefined distance ϵ. Varying ϵ, we compute persistent properties (cavities) in these simplices. We define a DNN in one such topological space to compute informative data of its behaviour that correlates with its performance on testing data.\n\nBy considering a range of possible distances, , where , a Vietoris-Rips filtration yields a collection of simplicial complexes, , at multiple scales, Figure 2 .\n\nWe are interested in the persistent topology properties of these complexes across different scales. For this, we compute the persistent homology groups and the Betti numbers , which gives us the ranks of those groups . This means that the Betti numbers compute the number of cavities of a topological object.222Two objects are topologically equivalent if they have the same number of cavities (holes) at each of their dimensions. For example, a donut and a coffee mug are topologically equivalent, because each has a single 2D cavity, the whole in the donut and in the handle of the mug. On the other hand, a torus (defined as the product of two circles, ) has two holes because it is hollow. Hence, a torus is topologically different to a donut and a coffee mug.\n\nIn DNNs, we can, for example, study how its functional topology varies during training as follows (Fig. 3\n\n). First, we compute the correlation of every node in our DNN to every other node at each epoch. Nodes that are highly correlated (i.e., their correlation is above a threshold) are defined as connected, even if there is no actual edge or path connecting them in the network’s computational graph. These connections define a simplicial complex, with a number of cavities. These cavities are given by the Betti numbers. We know that the dynamics of low-dimension Betti numbers (i.e.,\n\nand\n\n) is informative over the bias-variance problem (i.e., the generalization vs. memorization problem)\n\n. Similarly, it has been shown that these persistence homology measures can be used to study and interpret the data as points in a functional space, making it possible to learn and optimize the estimates defined on the data .",
null,
"Figure 3: An overview of computing topological summaries from DNNs. We first define a set of nodes A in the network. By computing the correlations between these nodes we project the network into a metric space (A,ν) from which we obtain a set of simplicial complexes in a topological space through Vietoris-Rips filtration. Persistent homology on this set of simplicial complexes results in a persistence diagram from which topological measures can be computed directly.\n\n3 Algorithm\n\nRecall is the set of labeled training samples, with the number of samples.\n\nLet be the activation value of a particular node in our DNN for a particular input\n\n. Passing the sample vectors\n\nthrough the network (), allows us to compute the correlation between the activation of each pair of nodes which defines the metric of our Vietoris-Rips complex. Formally,\n\n νpq=n∑i=1(api−¯¯¯¯¯ap)(aqi−¯¯¯¯¯aq)ςapςaq, (2)\n\nwhere and\n\nindicate the mean and standard deviation over\n\n.\n\nWe represent the results of our persistent homology using a persistence diagram. In our persistence diagram, each point has as coordinates a set of pairs of real positive numbers , where the subscripts and in indicate the birth and death distances of a cavity in the Vietoris-Rips filtration, and is the total number of cavities.\n\nA filtration of a metric space is a nested subsequence of complexes that abide by the following rule: . Thus, this filtration is in fact what defines the persistence diagram of a -dimensional homology group. This is done by computing the creation and deletion of -dimensional homology features. This, in turn, allows us to compute the lifespan homological feature .\n\nBased on this persistence diagram, we define the life of a cavity as the average time (i.e., persistence) in this diagram. Formally,\n\n λ=1CC∑i=1(ϵid−ϵib). (3)\n\nSimilarly, we define its midlife as the average density of its persistence. Formally,\n\n μ=1CC∑i=1ϵid+ϵib2. (4)\n\nFinally, we define the linear functional mapping from these topological summaries to the gap between the training and testing error as,\n\n g(λ,μ;c)=ˆΔρ, (5)\n\nwhere is our estimate of the gap between the training and testing errors, and , with , and , Figure 1(b).\n\nWith the above result we can estimate the testing error without the need of any testing data as,\n\n ^ρtest=ρtrain−ˆΔρ, (6)\n\nwhere is the training error computed during training with .\n\nGiven an actual testing dataset , we can compute the accuracy of our estimated testing error as,\n\n Error=|ρtest−^ρtest|, (7)\n\nwhere is the testing error computed on .\n\nThe pseudo-code of our proposed approach is shown in Alg. 1.333Code available at https://github.com/cipriancorneanu/dnn-topology.\n\n3.1 Computational Complexity\n\nLet the binomial coefficient be the number of -simplices of a simplicial complex (as, for example, would be generated during the Vietoris-Rips filtration illustrated in Fig. 2). In order to compute persistent homology of order on S, one has to compute , with , the number of -simplices, and the number of -simplices. This has polynomial complexity , .\n\nFortunately, in Alg. 1, we only need to compute persistent homology of the first order. Additionally, the simplicial complexes generated by the Vietoris-Rips filtration are generally extremely sparse. This means that for typical DNNs, the number of -simplices is way lower than the binomial coefficient defined above. In practice, we have found 10,000 to be a reasonable upper bound for the cardinality of . This is because we define nodes by taking into account structural constraints on the topology of DNNs. Specifically, a node\n\nis a random variable with value equal to the mean output of the filter in its corresponding convolutional layer. Having random variables allows us to define correlations and metric spaces in Alg.\n\n1. Empirically, we have found that defining nodes in this way is robust, and similar characteristics, e.g. high correlation, can be found even if a subset of filters is randomly selected. For smaller, toy networks there is previous evidence that supports that functional topology defined in this way is informative for determining overfitting in DNNs.\n\nFinally, the time it takes to compute persistent homology, and consequently, the topological summaries, and , is 5 minutes and 15 seconds for VGG16, one of the most extended networks in our analysis. This corresponds to a single iteration of Alg. 1 (the for-loop that iterates over ), excluding training, on a single 2.2 GHz Intel Xeon CPU.\n\n4 Related Work\n\nTopology measures have been previously used to identify over-fitting in DNNs. For example, using lower dimensional Betti curves (which calculates the cavities) of the functional (binary) graph of a network , which can be used to perform early stopping in training and detect adversarial attacks. Other topological measures, this time for characterizing and monitoring structural properties, have been used for the same purpose .\n\nOther works tried to address the crucial question of how the generalization gap can be predicted from training data and network parameters [2, 1, 22, 15]. For example, a metric based on the ratio of the margin distribution at the output layer of the network and a spectral complexity measure related to the network’s Lipschitz constant has been proposed . In , the authors developed bounds on the generalization gap based on the product of norms of the weights across layers. In , the authors developed bounds based on noise stability properties of networks showing that more stability implies better generalization. And, in \n\n, the authors used the notion of margin in support vector machines to show that the normalized margin distribution across a DNN’s layers is a predictor of the generalization gap.\n\n5 Experimental Settings\n\nWe have derived an algorithm to compute the testing accuracy of a DNN that does not require access to any testing dataset. This section provides extensive validation of this algorithm. We apply our algorithm in three fundamental problems in computer vision: object recognition, facial action unit recognition, and semantic segmentation, Figure 4.",
null,
"Figure 4: We evaluate the proposed method on three different vision problems. (a) Object recognition is a standard classification problem consisting in categorizing objects. We evaluate on datasets of increasing difficulty, starting with real world digit recognition and continuing towards increasingly challenging category recognition. (b) AU recognition involves recognizing local, sometimes subtle patterns of facial muscular articulations. Several AUs can be present at the same time, making it a multi-label classification problem. (c) In semantic segmentation, one has to output a dense pixel categorization that properly captures complex semantic structure of an image.\n\n5.1 Object Recognition\n\nObject recognition is one of the most fundamental and studied problems in computer vision. Many large scale databases exist, allowing us to provide multiple evaluations of the proposed approach.\n\nTo give an extensive evaluation of our algorithm, we use four datasets: CIFAR10 , CIFAR100 , Street View House Numbers (SVHN) \n\n, and ImageNet\n\n. In the case of ImageNet, we have used a subset with roughly images split in 200 object classes.\n\nWe evaluate the performance of several DNNs by computing the classification accuracy, namely the number of predictions the model got right divided by the total number of predictions, Figure 5 and Tables 1 & 2.\n\n5.2 Facial Action Unit Recognition\n\nFacial Action Unit (AU) recognition is one of the most difficult tasks for DNNs, with humans significantly over-performing even the best algorithms [2, 4].\n\nHere, we use BP4D , DISFA , and EmotionNet \n\n, of which, in this paper, we use a subset of 100,000 images. And, since this is a binary classification problem, we are most interested in computing precision and recall, Figure\n\n6 and Tables 3 & 4.\n\n5.3 Semantic Segmentation\n\nSemantic segmentation is another challenging problem in computer vision. We use Pascal-VOC and Cityscapes . The version of Pascal-VOC used consists of 2,913 images, with pixel based annotations for 20 classes. The Cityscapes dataset focuses on semantic understanding of urban street scenes . It provides 5,000 images with dense pixel annotations for 30 classes.\n\nSemantic segmentation is evaluated using union-over-intersection (IoU444\n\nAlso known as the Jaccard Index., which counts the number of pixels common between the ground truth and prediction segmentation masks divided by the total number of pixels present across both masks.\n\n), Figure 7 and Table 5.",
null,
"Figure 5: Topology summaries against performance (accuracy) gap for different models trained to recognize objects. Each disc represents mean (centre) and standard deviation (radius) on a particular dataset. Linear mapping and the corresponding standard deviation of the observed samples are marked.\n\n5.4 Models\n\nWe have chosen a wide range of architectures (i.e., topologies), including three standard and popular models [17, 24, 14] and a set of custom-designed ones. This provides diversity in depth, number of parameters, and topology. The custom DNNs are summarized in Table 6.\n\nFor semantic segmentation, we use a custom architecture called Fully Convolutional Network (FCN) capable of producing dense pixel predictions \n\n. It casts classical classifier networks\n\n[14, 24] into an encoder-decoder topology. The encoder can be any of the networks previously used.\n\n5.5 Training\n\nFor all the datasets we have used, if a separate test set is provided, we attach it to the train data and perform a cross validation on all available data. For object recognition , and for the other two problems . Each training is performed using a learning rate with random initialization. We also train each model on , and of the available folds. This increases the generalization gap variance for a specific dataset. In the results presented below, we show all the trainings that achieved a performance metric above . We skip extreme cases of generalization gaps either close to maximum ().\n\nFor object recognition the input images are resized to color images, unless explicitly stated. Also they are randomly cropped and randomly flipped. In the case of semantic segmentation all input images are\n\ncolor images. No batch normalization (except for ResNet which follows the original design), dropout, or other regularization techniques are used during training. We train with a sufficient fixed number of epochs to guarantee saturation in both training and validation performance.\n\nWe use a standard stochastic gradient descent (SGD) optimizer for all training with momentum\n\nand learning rate and weight decay as indicated above. The learning rate is adaptive following a plateau criterion on the test performance, reducing to a quarter every time the validation performance metric does not vary outside a range for a fixed number of epochs.\n\n6 Results and Discussion",
null,
"Figure 6: Topology summaries against performance (F1-score) gap for different models trained for AU recognition. Each disc represents mean (centre) and standard deviation (radius) for a 10-fold cross validation. Linear mapping and the corresponding standard deviation of the observed samples are marked.",
null,
"Figure 7: Topology summaries against performance (IoU) gap for different models trained for semantic segmentation. Each disc represents mean (centre) and standard deviation (radius) on a particular dataset. Linear mapping and the corresponding standard deviation of the observed samples are marked.\n\nTopological summaries are strongly correlated with the performance gap. This holds true over different vision problems, datasets and networks.\n\nLife , the average persistence of cavities in the Vietoris-Rips filtration, is negatively correlated with the performance gap, with an average correlation of . This means that the more structured the functional metric space of the DNN (i.e., larger wholes it contains), the less it overfits.\n\nMidlife is positively correlated with the performance gap, with an average correlation of . Midlife is an indicator of the average distance about which cavities are formed. For DNNs that overfit less, cavities are formed at smaller which indicates that fewer connections in the metric spaces are needed to form them.\n\nWe show the plots of topological summaries against performance gap for object recognition, AU recognition and semantic segmentation in Figures 5-7, respectively. The linear mapping between each topological summary, life and midlife (Eqs. 3 & 4), and the performance gap are shown in the first and second rows of these figures, respectively. In all these figures rows represent DNN’s results.\n\nThe results of each dataset are indicated by a disc, where the centre specifies the mean and the radius the standard deviation. We also mark the linear regression line\n\nand the corresponding standard deviation of the observed samples from it.\n\nFinally, Tables 1, 3 & 5 show the , namely the absolute value of the difference between the estimate given by Alg. 1 and that of a testing set, computed with Eq. (7) by leaving-one-sample-out. A different way of showing the same results can be found in Tables 2 and 4 where mean and standard deviation of the same error is computed by leaving-one-dataset-out.\n\nIt is worth mentioning that our algorithm is general and can be applied to any DNN architecture. In Table 6 we detail the structure of the networks that have been used in this paper. These networks range from simple (with only a few hundred of nodes, i.e., ), to large (e.g., ResNet) nets with many thousands of nodes.\n\nThe strong correlations between basic properties of the functional graph of a DNN and fundamental learning properties like the performance gap also makes these networks more transparent. Not only do we propose an algorithm capable of computing the performance gap, but we show that this is linked to a simple law of the inner-workings of that networks. We consider this to be a contribution to make deep learning more explainable.\n\nBased on these observations we have chosen to model the relationship between the performance gap and the topological summaries through a linear function. Figures 5-7 show a simplified representation of the observed pairs and the regressed lines.\n\nWe need to mention that choosing a linear hypothesis for is by no means the only option. Obviously, using a non-linear regressor for in Alg. 1 leads to even more accurate predictions of the testing error. However, this improvement comes at the cost of being less flexible when studying less common networks/topologies – overfitting.\n\nTable 1-5 further evaluate the algorithm proposed.\n\nCrucially, an average error between and is obtained across computer vision problems, which is as accurate as computing a testing error with a labelled dataset .\n\n7 Conclusions\n\nWe have derived, to our knowledge, the first algorithm to compute the testing classification accuracy of any DNN-based system in computer vision, without the need for the collection of any testing data.\n\nThe main advantages of the proposed evaluation method versus the classical use of a testing dataset are:\n\n1. there is no need for a sequestered dataset to be maintained and updated by a third-party,\n\n2. there is no need to run costly cross-validation analyses,\n\n3. we can modify our DNN without the concern of overfitting to the testing data (because it does not exist), and,\n\n4. we can use all the available data for training the system.\n\nWe have provided extensive evaluations of the proposed approach on three classical computer vision problems and shown the efficacy of the derived algorithm.\n\nAs a final note, we would like to point out the obvious. When deriving computer vision systems, practitioners would generally want to use all the testing tools at their disposal. The one presented in this paper is one of them, but we should not be limited by it. Where we have access to a sequestered database, we should take advantage of it. In combination, multiple testing approaches should generally lead to better designs.\n\nAcknowledgments. NIH grants R01-DC-014498 and R01-EY-020834, Human Frontier Science Program RGP0036/2016, TIN2016-74946-P (MINECO/FEDER, UE), CERCA (Generalitat de Catalunya) and ICREA (ICREA Academia). CC and AMM defined main ideas and derived algorithms. CC, with SE, and MM ran experiments. CC and AMM wrote the paper.\n\nReferences\n\n• S. Arora, R. Ge, B. Neyshabur, and Y. Zhang. Stronger generalization bounds for deep nets via a compression approach. arXiv preprint arXiv:1802.05296, 2018.\n• L. F. Barrett, R. Adolphs, S. Marsella, A. M. Martinez, and S. D. Pollak. Emotional expressions reconsidered: Challenges to inferring emotion from human facial movements. Psychological Science in the Public Interest, 20(1):1–68, 2019.\n• P. L. Bartlett, D. J. Foster, and M. J. Telgarsky. Spectrally-normalized margin bounds for neural networks. In Advances in Neural Information Processing Systems, pages 6240–6249, 2017.\n• C. F. Benitez-Quiroz, R. Srinivasan, Q. Feng, Y. Wang, and A. M. Martinez. Emotionet challenge: Recognition of facial expressions of emotion in the wild. arXiv preprint arXiv:1703.01210, 2017.\n• M. G. Bergomi, P. Frosini, D. Giorgi, and N. Quercioli.\n\nTowards a topological–geometrical theory of group equivariant non-expansive operators for data analysis and machine learning.\n\nNature Machine Intelligence, 1(9):423–433, 2019.\n• F. Chazal, D. Cohen-Steiner, L. J. Guibas, F. Mémoli, and S. Y. Oudot. Gromov-hausdorff stable signatures for shapes using persistence. In Computer Graphics Forum, volume 28, pages 1393–1403. Wiley Online Library, 2009.\n• M. Cordts, M. Omran, S. Ramos, T. Rehfeld, M. Enzweiler, R. Benenson, U. Franke, S. Roth, and B. Schiele.\n\nThe cityscapes dataset for semantic urban scene understanding.\n\nIn\n\nProc. of the IEEE Conference on Computer Vision and Pattern Recognition (CVPR)\n\n, 2016.\n• C. A. Corneanu, M. Madadi, S. Escalera, and A. M. Martinez. What does it mean to learn in deep networks? and, how does one detect adversarial attacks? In Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, pages 4757–4766, 2019.\n• J. Deng, W. Dong, R. Socher, L.-J. Li, K. Li, and L. Fei-Fei. Imagenet: A large-scale hierarchical image database. In Computer Vision and Pattern Recognition, 2009. CVPR 2009. IEEE Conference on, pages 248–255. Ieee, 2009.\n• M. Everingham, S. A. Eslami, L. Van Gool, C. K. Williams, J. Winn, and A. Zisserman. The pascal visual object classes challenge: A retrospective. International journal of computer vision, 111(1):98–136, 2015.\n• M. Everingham, L. Van Gool, C. K. I. Williams, J. Winn, and A. Zisserman. The PASCAL Visual Object Classes Challenge 2012 (VOC2012) Results.\n• C. Fabian Benitez-Quiroz, R. Srinivasan, and A. M. Martinez. Emotionet: An accurate, real-time algorithm for the automatic annotation of a million facial expressions in the wild. In Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, pages 5562–5570, 2016.\n• A. Hatcher. Algebraic Topology. Cambridge University Press, 2002.\n• K. He, X. Zhang, S. Ren, and J. Sun. Deep residual learning for image recognition. In Proceedings of the IEEE conference on computer vision and pattern recognition, pages 770–778, 2016.\n• Y. Jiang, D. Krishnan, H. Mobahi, and S. Bengio. Predicting the generalization gap in deep networks with margin distributions. arXiv preprint arXiv:1810.00113, 2018.\n• A. Krizhevsky and G. Hinton. Learning multiple layers of features from tiny images. Technical report, Citeseer, 2009.\n• A. Krizhevsky, I. Sutskever, and G. E. Hinton.\n\nImagenet classification with deep convolutional neural networks.\n\nIn Advances in neural information processing systems, pages 1097–1105, 2012.\n• Y. LeCun, Y. Bengio, and G. Hinton. Deep learning. nature, 521(7553):436, 2015.\n• J. Long, E. Shelhamer, and T. Darrell. Fully convolutional networks for semantic segmentation. In Proceedings of the IEEE conference on computer vision and pattern recognition, pages 3431–3440, 2015.\n• S. M. Mavadati, M. H. Mahoor, K. Bartlett, P. Trinh, and J. F. Cohn. Disfa: A spontaneous facial action intensity database. IEEE Transactions on Affective Computing, 4(2):151–160, 2013.\n• Y. Netzer, T. Wang, A. Coates, A. Bissacco, B. Wu, and A. Y. Ng. Reading digits in natural images with unsupervised feature learning. Journal, 2011.\n• B. Neyshabur, S. Bhojanapalli, D. McAllester, and N. Srebro. Exploring generalization in deep learning. In Advances in Neural Information Processing Systems, pages 5947–5956, 2017.\n• B. Rieck, M. Togninalli, C. Bock, M. Moor, M. Horn, T. Gumbsch, and K. Borgwardt. Neural persistence: A complexity measure for deep neural networks using algebraic topology. arXiv preprint arXiv:1812.09764, 2018.\n• K. Simonyan and A. Zisserman. Very deep convolutional networks for large-scale image recognition. ICLR, 2015.\n• L. Vietoris. Über den höheren zusammenhang kompakter räume und eine klasse von zusammenhangstreuen abbildungen. Mathematische Annalen, 97(1):454–472, 1927.\n• O. Vinyals, A. Toshev, S. Bengio, and D. Erhan. Show and tell: A neural image caption generator. In Proceedings of the IEEE conference on computer vision and pattern recognition, pages 3156–3164, 2015.\n• A. M. Zador. A critique of pure learning and what artificial neural networks can learn from animal brains. Nature communications, 10(1):1–7, 2019.\n• X. Zhang, L. Yin, J. F. Cohn, S. Canavan, M. Reale, A. Horowitz, P. Liu, and J. M. Girard. Bp4d-spontaneous: a high-resolution spontaneous 3d dynamic facial expression database. Image and Vision Computing, 32(10):692–706, 2014.\n• A. Zomorodian and G. Carlsson. Computing persistent homology. Discrete & Computational Geometry, 33(2):249–274, 2005."
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https://elmprogramming.com/list.html | [
"# 3.16\n\n## List\n\nSo far we have only seen how to store a single value in a data structure. To store multiple values, we can use one of the following collections Elm provides: `List`, `Array`, `Tuple`, or `Record`. This section covers list. The rest will be covered in successive sections.\n\n### Creating a List\n\nIn Elm, a list is a data structure for storing multiple values of the same kind. List is one of the most used data structures in Elm. A list is created with square bracket literals. Each element in a list must be separated by a comma. Here are some examples:\n\nNote: Elm style guide recommends using a space after `[` and a space before `]`, but when `elm repl` prints a list, it doesn’t include those spaces because the style guide was created to improve the readability of code for humans.\n\nWhat happens when we try to put values of different types in a list?\n\nElm doesn’t like that. We can also create a numeric list by specifying a range.\n\nA range is created by specifying the first and last numbers in a sequence. It’s a nice shortcut that saves you from having to type out a long list of numbers. As of this writing, Elm can only use a range to create a list of numbers, but not other types such as character or string.\n\nThe Elm Platform also comes pre-loaded with the `List` module. Like the `String` module, it’s also automatically loaded by `elm repl`. That’s why we don’t need to explicitly import it. The `List` module contains many more functions for working with lists. Let’s go through some of them.\n\n### Checking Membership\n\nThe `member` function determines whether or not an item is present in a given list.\n\n### Checking Length\n\nThe `isEmpty` function determines whether or not a list is empty, whereas the `length` function returns the number of elements in a list.\n\n### Reversing a List\n\nThe `reverse` function returns a new list that contains elements from the original list in reverse order.\n\n### Combining Lists\n\nThe `List` module provides multiple functions for putting lists together. Let’s start with something we’re already familiar with: `++` operator.\n\nWe can also combine more than two lists with `++` operator.\n\nJust like the `String` module, `List` also provides the `append` function for combining two lists.\n\nUnlike `++`, combining more than two lists with `append` is a bit tedious.\n\nIf we have a bunch of lists buried inside another list, we can use the `concat` function to flatten it like this:\n\nFinally, we can add an element to the front of a list using the `::` (pronounced cons) operator.\n\n### Splitting a List\n\n#### Partitioning a List\n\nUnlike strings, we can’t use a separator to split a list. What we can do is partition a list based on some criteria. The elements that satisfy the criteria will be put into one list and the ones that don’t into another. A predicate function is the perfect place to store our criteria. As a reminder, a predicate is a function that takes a value as an input and returns a boolean as an output. Here’s an example that partitions a list using an anonymous function as a predicate.\n\nHere’s another example that uses a normal function as a predicate to partition a list.\n\nElements that satisfy the predicate are placed in the first list, the rest go into the second list. Notice how the partitioned lists are contained inside a tuple?\n\nTuple\nA tuple is a container like a list, but we can put values of different types into it like this: `( 1, \"Sobchak\", [ 't', 'd' ] )`. Tuples are quite useful for returning multiple results from a function. We will cover it in much more detail later in the Tuple section.\n\nYou may be wondering why the `partition` function didn’t return a list instead of a tuple. After all a list can also hold multiple lists in it. That’s because lists must contain values of the same kind, but tuples don’t have to. In the future, if `partition` decides to also return the number of elements in each list like this: `(3, [1,2,3], 3, [4,5,6])`, it won’t be able to do that with a list. Tuples on the other hand are perfect for a situation like this.\n\n#### Unzipping a List\n\nLet’s say we have a list of tuples each containing two elements.\n\nHow can we split it into two lists? We can use the `unzip` function to accomplish that.\n\nThe first list contains the first item from each tuple in the original list and the second list contains the second item. Notice that `unzip` also returns a tuple instead of a list. You will see this pattern of functions returning multiple values in a tuple in most Elm code.\n\n### Sorting a List\n\n#### Ascending order\n\nBelow is a list of top seven highest scores from regular season games in NBA history.\n\nBut they aren’t sorted in any particular order. How can we sort them in ascending order? We can do that by using the `sort` function.\n\n#### Descending order\n\nThe `sort` function sorts a list only in ascending array. It doesn’t allow us to pass an argument specifying in what order we want the list to be sorted. What a let-down. If we want to sort a list in descending order, Elm makes us jump through a couple of hoops. Let’s try the next example in the `src/Playground.elm` file as the code we’re about to type is a bit too long for the repl. Define a function called `descending` right above `main`.\n\nNow change `main` to this:\n\nRun `elm reactor` from the `beginning-elm` directory in terminal if it’s not running already and go to `http://localhost:8000/src/Playground.elm` in your browser. You should see the original list sorted in descending order:\n\nLet’s go through the above code step-by-step. Not sure if you noticed, but in `main` we used the `sortWith` function instead of our stubborn friend `sort` to sort the list of scores in descending order. `sortWith` accepts two arguments:\n\n• A comparison function\n• A list that needs sorting\n\nGiven two values, a comparison function tells us whether the first value is equal, less than, or greater than the second value. As it happens, Elm provides a function called `compare` which does just that. If the first value is less than the second, `compare` returns `LT`. But if the first value is greater, it returns `GT`. And if they both are equal, it returns `EQ`.\n\nNote: `compare` is defined in the Basics module. Elm puts generic values and functions that can operate on different types of data such as strings, lists, records, etc. into the `Basics` module. Like `String` and `List`, the `Basics` module is also loaded automatically by the repl. That’s why we don’t need to explicitly import it.\n\nWe can also compare strings with the `compare` function.\n\nStrings are compared based on alphabetical order. This is how words are ordered in an English dictionary. For example, the word “Thomas” is considered less than “Thompson” because the letter ‘a’ comes before the letter ‘p’ in the alphabet.\n\nWhen we want to sort a list in descending order, we need the `compare` function to behave in opposite manner. How can we make it do that? By creating another function that pulls a switcheroo on `compare` like this:\n\n`descending` returns `GT` when `compare` actually meant `LT` and `LT` when it meant `GT`. Now we can give this function to `sortWith` and our list will get sorted in descending order.\n\nThe sorted list is then passed to the `Debug.toString` function, which generates a string representation of the list. Finally, the `Html.text` function renders the sorted list on a browser.\n\n#### Converting a Value to a String\n\nEarlier, in the Backward Function Application section, we used the `String.fromFloat` function to convert a float to a string before rendering it on a browser with `Html.text` like this:\n\nIn Elm, there are three ways to convert a value to a string:\n\n• `String.fromInt` — Converts an `Int` to a `String`.\n\n• `String.fromFloat` — Converts a `Float` to a `String`.\n\n• `Debug.toString` — Converts any kind of value to a string. This function is not meant to be used in production code. If you need to show a string representation of a value other than `Int` or `Float` in production, you need to use localization. Similarly to the `Basics`, `String`, and `List` modules, `Debug` is also included in the Elm Platform and is automatically loaded.\n\nLocalization\n“Localization is the process of translating software user interfaces from one language to another and adapting it to suit a foreign culture.” - MDN\n\nNote: Unfortunately, as of this writing Elm doesn’t provide an elegant approach to localization. Therefore, we won’t be covering it in this book.\n\n#### Arbitrary order\n\n`sortWith` actually opens a door for comparing values using any order we want, not just ascending or descending. Let’s say we want to sort certain characters from Game of Thrones based on how evil they are. Add the following function definition right above `main` in `Playground.elm`.\n\nNow let’s use `evilometer` in `main` to sort a list of evil characters.\n\nRefresh the page at `http://localhost:8000/src/Playground.elm` and you should see `[\"Joffrey\",\"Ramsay\",\"Night King\"]`.\n\nAll `sortWith` expects from a comparing function is one of these values: `LT`, `GT`, or `EQ`. It doesn’t care how those values are computed. The `sort` function is actually a specialized case of `sortWith`. Internally, it just calls the `compare` function directly to compare values. So if we write `sortWith` like this, we get the behavior of `sort` function:\n\n### Filtering a List\n\nJust like `String.filter` `List.filter` also takes a predicate and a list of items. It then creates a new list containing all items from the original list that pass the test implemented by the predicate. Here are some examples:\n\nThe `isOdd` function is a predicate that determines whether a given number is odd. We divide the number by `2` and check if the remainder is `0`. If yes, it’s not an odd number. The `remainderBy` function divides the second argument by the first and returns the remainder. It’s defined in the `Basics` module.\n\nThe `isHost` function is also a predicate that determines whether someone is a host from ever fascinating Westworld. It uses the `List.member` function we used earlier to determine whether a given name is in a list of hosts.\n\n### Mapping a List\n\nProgramming is all about data transformation. We take an input and apply a sequence of functions to it until we arrive at a result that can be returned as an output. Let’s say we have a list of strings:\n\nAnd we want to find out how many strings have lengths less than six. How can we accomplish that? Well, first we need to find out a length of each string in the list. How about we generate another list that contains just lengths, but not the strings themselves? We can do that easily with the `map` function.\n\n`List.map` applies the given function to each element in the original list and puts the result in a new list. Here we gave it `String.length` which takes a string and returns its length. Next, we need to remove lengths that are greater than or equal to 6. We already know a function that knows how to do it — `List.filter`.",
null,
"Let’s work through one more problem to solidify our understanding of `List.map`. Let’s say we want to find out whether any of the guardians have hyphen in their name. We can use `String.contains` to check for a hyphen like this:\n\nAfter a while, typing an anonymous function starts to get a little tiresome. What if we apply `map` like this instead:\n\nWhoa! That works too. Previously, we applied `String.contains` with both arguments (`\"-\"` and `x`) it needed to return a boolean. However, if we call it without the second argument (`x`), we get back a partially applied function instead of a boolean value. `List.map` then passes each string from the `guardians` list, one at a time, to this partially applied function as the last argument. This results in a boolean value.",
null,
"An anonymous function like `(\\param -> someFunction x param)` can always be rewritten as `(someFunction x)` as long as `param` is the last argument. Here’s one more example that checks if a guardian’s name starts with `Dr`.\n\nThe partial application technique also works with operators. Let’s rewrite one of our earlier examples that contained an operator using the partial application technique.\n\nNotice that we had to flip the `<` operator in order to achieve the same result. That’s because the partial application technique requires us to use operators in prefix style, which places an operator before the operands. If we hadn’t flipped the `<` operator, we would have gotten a list of numbers that are greater than `6`.\n\n### Folding a List\n\nWe have created numerous lists with numbers in them, but we haven’t tried to add all the elements up yet. Let’s do that.\n\nWhat we have done here is fold (or reduce) a list into a number that represents the sum of all elements in the list. The `foldl` function takes three arguments: combining function, initial value, and a list. The combining function in turn takes two arguments: an element from the list and an accumulator. The following diagram illustrates various components of the `foldl` function.",
null,
"During the first application of the combining function, the initial value is passed to the accumulator as shown in the diagram below.",
null,
"After the first application, `foldl` repeatedly passes the accumulator (sum thus far) back to the combining function as the second argument until there are no more elements left in the original list. The figure below shows the step-by-step application of the combining function.",
null,
"Since we are calculating a sum here, we used the `+` operator inside our combining function. But if we were calculating a product, our combining function would use the `*` operator instead.\n\nWhy is it returning zero as the product? Oops… We forgot to change the initial value. `foldl` passes the initial value (zero in our case) as the first argument to the combining function. The result of multiplying a number by zero is zero. If we change the initial value to `1`, we get the expected result.\n\nRemember, `+` and `*` operators are also functions. And all `foldl` expects is a function as the first argument. It doesn’t care whether it’s an anonymous function or a normal function or an operator. Therefore, we can re-write the above examples in a much more succinct way like this:\n\nIn case of addition and multiplication, you can think of replacing the commas in the list with the `+` and `*` operators respectively. `foldl` is capable of reducing a list in many different ways, but if all you want to do is calculate sum or product, Elm already provides those functions as a convenience.\n\nThat was pretty anticlimactic, wasn’t it? I showed you in detail how to use `foldl` to calculate the sum and product of a list only to find out later there already exist functions to do exactly that much more easily. To make it up to you, I’ll show you one more example that’s actually useful. Let’s say we want to calculate the total number of characters in this list:\n\nWe can use `foldl` to easily reduce this entire list of strings to a single number.\n\n### Folding a List from Right\n\n`foldl` folds a list from left as its name indicates. What that means is it begins its operation starting from the beginning of the list, but sometimes we need to fold a list starting from the end. The `List` module provides another function called `foldr` for that.\n\nThe structure of `foldr` looks very similar to that of `foldl`.",
null,
"For sum and product it doesn’t matter whether we start from the beginning or end of a list, but there are operators that produce different results depending on where we start. Let’s use one that we are already familiar with: power operator (`^`).\n\nEarlier, we learned that `^` is right-associative whereas `+` and `*` are left-associative. What that means is if we write an expression as shown below, `^` will start evaluating it from the right.\n\nThere are two reasons why `^` is right-associative in Elm:\n\n1. `^` is also right-associative in mathematics and Elm tries to follow the rules from mathematics as much as possible.\n\n2. If `^` was left-associative, the end result could simply be computed by just multiplying the exponents. Let’s see some examples to understand what this means.\n\nWe applied parentheses to force `^` to evaluate from left. We were then able to simply multiply all the exponents on the right and use `^` only once to get the same result. Therefore, to make the `^` operator more meaningful, we need to evaluate an expression from the right. Now let’s see how `foldr` behaves with `^`.\n\nIt can be hard to understand how `foldr` works just by looking at the code above. The figure below illustrates what exactly happens when we apply `foldr`.",
null,
"Just like `foldl`, `foldr` also repeatedly passes the accumulator (result thus far) back to the combining function as the second argument until there are no more elements left in the original list. The figure below shows the step-by-step application of the combining function given to `foldr`.",
null,
"What happens if we use `^` with `foldl`? It starts applying the `^` operator from the left resulting in a different value which is not what we want.\n\nHere is how we arrived at the final result in the example above:\n`(4 ^ 1) = 4`\n`(2 ^ 4) = 16`\n`(3 ^ 16) = 43046721`\n\nLastly, we can rewrite the above expressions more succinctly just by specifying the operator instead of the entire anonymous function as shown below.\n\n#### Are they all evil?\n\nEarlier we partitioned a list containing characters from Game of Thrones into two lists. The first list was infested with evil people whereas the second list was full of kind souls.\n\nWhat if we want to find out if any one of the characters is evil? The `any` function is designed to do just that.\n\nThere’s certainly evil lurking in that list. Just like the `partition` function, `any` takes a predicate that tells whether a given character is evil or not. We can also find out if all characters are evil by using the `all` function instead.\n\nHow can Hodor be evil, right? If you think about it, `any` and `all` are also folding a list. They both reduce a list to a single boolean value. There are a few more of these functions that perform a special kind of fold. You can learn all about them here.\n\n### Take it or Drop it\n\nRemember those annoying bouncers at famous night clubs who tend to let only good looking people in? If those bouncers were Elm programmers, they’d love the `drop` function.\n\nThe `drop` function drops the specified number of elements from the beginning of a list and returns a new list with remaining elements. Once in a while, we get a nice bouncer who lets people on a first come first serve basis. They would definitely prefer `take` to `drop`.\n\nWatch out! The bouncer just let Freddy into the club. `take` returns a new list containing the specified number of elements from the beginning of a list.\n\nConceptually speaking, a list is divided into two parts: head and tail. The first element is called the head and tail represents the rest of the elements.",
null,
"The `List` module provides functions for getting the head and tail of a list as shown below.\n\nElm cannot guarantee that it can return a value when asked for the head (or tail) of a list. If the list is empty there is no value to return. Therefore, it returns a `Maybe`.\n\n### How List Works Behind the Scenes\n\nList is sometimes also called a linked list as it is a linear collection of data elements, each pointing to the next element. An element in a list is called a node.",
null,
"Even if there is no data in it, the last (empty) node does exist. If you don’t believe me check this out:\n\nWe started with an empty list and added `9` in-front of it using the cons (`::`) operator. We then continued to add the rest of the elements to that list one at a time. When we create a list in this way, it starts to look like a recursive data structure meaning a list consists of nodes which themselves are lists. Because a node isn’t required to contain a value, an empty node is also considered a list.",
null,
"In fact, `List` in Elm is actually defined as a recursive data structure. In the Recursive Types section, we will create our own implementation of a linked list that will work similarly to Elm’s implementation of `List` to better understand how a recursive data structure works.\n\nWe covered quite a few functions from the `List` module in this section, but there are still more included in that module. You can learn all about them here."
] | [
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https://en.wikisource.org/wiki/Page:BatemanElectrodynamical.djvu/10 | [
"# Page:BatemanElectrodynamical.djvu/10\n\n282\n[March 11,\nMr. H. Bateman\n\nlimited by the condition that the total charge on a system of particles is invariant. This is expressed analytically by the equation\n\n ${\\begin{array}{l}\\rho w_{x}dy\\ dz\\ dt+\\rho w_{y}dz\\ dx\\ dt+\\rho w_{z}dx\\ dy\\ dt-\\rho dx\\ dy\\ dz\\\\\\qquad =\\rho 'w'_{x}dy'dz'dt'+\\rho 'w'_{y}dz'dx'dt'+\\rho 'w'_{z}dx'dy'dt'-\\rho 'dx'dy'dz',\\end{array}}$",
null,
"(1)\n\nprovided the axes form a right-handed system in each case.\n\nIf the transformation is such that the integral equations of the theory of electrons are invariant, we must have\n\n ${\\begin{array}{l}E_{x}dy\\ dz+E_{y}dz\\ dx+E_{z}dx\\ dy-H_{x}dx\\ dt-H_{y}dy\\ dt-H_{z}dz\\ dt\\\\\\qquad =E'_{x}dy'\\ dz'+E'_{y}dz'\\ dx'+E'_{z}dx'\\ dy'-H'_{x}dx'\\ dt'-H'_{y}dy'\\ dt'-H'_{z}dz'\\ dt',\\end{array}}$",
null,
"${\\begin{array}{l}H_{x}dy\\ dz+H_{y}dz\\ dx+H_{z}dx\\ dy+E_{x}dx\\ dt+E_{y}dy\\ dt+E_{z}dz\\ dt\\\\\\qquad =\\theta \\left[H'_{x}dy'\\ dz'+H'_{y}dz'\\ dx'+H'_{z}dx'\\ dy'+E'_{x}dx'\\ dt'+E'_{y}dy'\\ dt'+E'_{z}dz'\\ dt'\\right],\\end{array}}$",
null,
"(2)\n\nwhere $\\theta$",
null,
"is a constant.\n\nThese relations give two sets of equations connecting the quantities $E_{x},\\dots ,H_{x},\\dots$",
null,
"with $E'_{x},\\dots ,H'_{x},\\dots$",
null,
"viz.,\n\n ${\\begin{array}{rl}E_{x}=E'_{x}{\\frac {\\partial (y',z')}{\\partial (y,z)}}+E'_{y}{\\frac {\\partial (z',x')}{\\partial (y,z)}}&+E'_{z}{\\frac {\\partial (x',y')}{\\partial (y,z)}}-H'_{x}{\\frac {\\partial (x',t')}{\\partial (y,z)}}\\\\\\\\&-H'_{y}{\\frac {\\partial (y',t')}{\\partial (y,z)}}-H'_{z}{\\frac {\\partial (z',t')}{\\partial (y,z)}}\\\\\\\\-H_{x}=E'_{x}{\\frac {\\partial (y',z')}{\\partial (x,t)}}+E'_{y}{\\frac {\\partial (z',x')}{\\partial (x,t)}}&+E'_{z}{\\frac {\\partial (x',y')}{\\partial (x,t)}}-H'_{x}{\\frac {\\partial (x',t')}{\\partial (x,t)}}\\\\\\\\&-H'_{y}{\\frac {\\partial (y',t')}{\\partial (x,t)}}-H'_{z}{\\frac {\\partial (z',t')}{\\partial (x,t)}}\\end{array}}$",
null,
"${\\mathsf {and}}\\ {\\begin{array}{rr}H_{x}=&\\theta \\left[H'_{x}{\\frac {\\partial (y',z')}{\\partial (y,z)}}+H'_{y}{\\frac {\\partial (z',x')}{\\partial (y,z)}}+H'_{z}{\\frac {\\partial (x',y')}{\\partial (y,z)}}\\right.\\\\\\\\&\\left.+E'_{x}{\\frac {\\partial (x',t')}{\\partial (y,z)}}+E'_{y}{\\frac {\\partial (y',t')}{\\partial (y,z)}}+E'_{z}{\\frac {\\partial (z',t')}{\\partial (y,z)}}\\right],\\\\\\\\E_{x}=&\\theta \\left[H'_{x}{\\frac {\\partial (y',z')}{\\partial (x,t)}}+H'_{y}{\\frac {\\partial (z',x')}{\\partial (x,t)}}+H'_{z}{\\frac {\\partial (x',y')}{\\partial (y,t)}}\\right.\\\\\\\\&\\left.+E'_{x}{\\frac {\\partial (x',t')}{\\partial (x,t)}}+E'_{y}{\\frac {\\partial (y',t')}{\\partial (x,t)}}+E'_{z}{\\frac {\\partial (z',t')}{\\partial (x,t)}}\\right].\\end{array}}$",
null,
"(3)\n\nIn order that these equations may be equivalent to one another we must\n\n1. It is assumed here that the equations of transformation are independent of $E_{x},E_{y,}E_{z},H_{x},H_{y},H_{z}$",
null,
"",
null,
""
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https://getcalc.com/math-fraction-decimal-47by50.htm | [
"# 47/50 as a Decimal",
null,
"47/50 as a decimal expansion provides the detailed information about what is 47/50 in decimal form, and the answer with steps help students to easily understand how it is being calculated.\n\n47/50 as a Decimal Expansion\n47/50 = 0.94\nHence,\n47/50 as a decimal equals to 0.94\nwhere,\n47/50 is a given fraction,\nThe decimal expansion of 47/50 is 0.94\n\n47/50 as a Mixed Number\nThe given fraction 47/50 can't be represented as a mixed number since the numerator 47 of the given fraction is smaller than the denominator 50.\n\nFor values other than 47/50, use this below tool:\n\n## How-to: 47/50 as a Decimal\n\nThe below work with steps provide the detailed information about how to convert fraction 47/50 as a decimal equivalent.\nstep 1 Address the input parameters and observe what to be found:\nInput values:\nThe fraction = 47/50\n\nWhat to be found:\nFind the decimal expansion of fraction 47/50.\n\nstep 2 Multiply both numerator and denominator by 2 to make the denominator as powers of 10:\n= 47/50 x 2/2\n= 94/100\n\nstep 3 The numerator 94 of fraction 94/100 can also be expressed as 94.00. Being 100 as the denominator, move the decimal point 2 decimal places from right to left in the numerator to write the fraction as decimal number.\n= 94/100\n= 0.94\n\nHence,\n47/50 as a decimal is 0.94",
null,
""
] | [
null,
"https://getcalc.com/calculator-images/math/fraction-decimal-calculator.png",
null,
"https://getcalc.com/cdn/graphics/getcalc-logo.png",
null
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http://channelflow.org/dokuwiki/doku.php?id=gibson:teaching:spring-2018:math445:lecture:pendulum&rev=1524747532&do=diff | [
"#",
null,
"channelflow.org\n\n### Site Tools\n\ngibson:teaching:spring-2018:math445:lecture:pendulum\n\n# Differences\n\nThis shows you the differences between two versions of the page.\n\n — gibson:teaching:spring-2018:math445:lecture:pendulum [2018/04/26 05:58] (current)gibson created 2018/04/26 05:58 gibson created 2018/04/26 05:58 gibson created Line 1: Line 1: + ====== The plane pendulum ====== + + ==== Mathematical models==== + + In class we derived four different mathematical models of the plane pendulum, listed here in order of decreasing mathematical complexity. + + ** Nonlinear damped pendulum.** This is the most physically realistic model. It includes a linear model of air resistance the $\\alpha/m \\; d\\theta/dt$ term and is accurate for large displacement angles $\\theta$. + \\begin{eqnarray*} + \\frac{d^2\\theta}{dt^2} + \\frac{\\alpha}{m} \\frac{d\\theta}{dt} + \\frac{g}{\\ell} \\sin \\theta = 0 + \\end{eqnarray*} + + ** Nonlinear undamped pendulum.** This model neglects air resistance. It is derived from the previous model by setting the air resistance constant $\\alpha$ to zero. + \\begin{eqnarray*} + \\frac{d^2\\theta}{dt^2} + \\frac{g}{\\ell} \\sin \\theta = 0 + \\end{eqnarray*} + + ** Linear damped pendulum.** This is valid only for small oscillations. You can derive it from the nonlinear damped pendulum model by substituting the //small angle approximation// $\\sin \\theta \\approx \\theta$ for small $\\theta$. + \\begin{eqnarray*} + \\frac{d^2\\theta}{dt^2} + \\frac{\\alpha}{m} \\frac{d\\theta}{dt} + \\frac{g}{\\ell} \\theta = 0 + \\end{eqnarray*} + + ** Linear undamped pendulum.** The simplest pendulum model. It neglects air resistance and employs the small-angle approximation. + \\begin{eqnarray*} + \\frac{d^2\\theta}{dt^2} + \\frac{g}{\\ell} \\theta = 0 + \\end{eqnarray*} + + In each of these, the variables are + + * $\\theta(t)$: the unknown function that describes the angle of the pendulum away from vertical as a function of time. + * $m$: the mass of the pendulum bob. + * $\\ell$: the length of the pendulum string + * $g$: the acceleration of gravity + * $\\alpha$: an air resistance constant + + + In class we showed that the linear undamped pendulum has a solution of the form $\\theta(t) = \\theta_0 \\cos \\omega t$ where $\\omega = \\sqrt{g/\\ell}$ and $\\theta_0$ is an arbitrary initial angular displacement. (Note that $\\theta_0$ must be small for the small-angle approximation to be valid!) + + + + ---- + + ==== Changing a second-order ODE into a system of first-order ODEs ==== + + A 2nd-order ordinary differential equation in the scalar variable $\\theta(t)$ can be transformed into a 1st order equation in the vector variable $\\vec{x}(t)$, using the substitution + + \\begin{eqnarray*} + \\vec{x} = \\left(\\begin{array}{l} x_1\\\\ x_2 \\end{array} \\right) = \\left(\\begin{array}{l} \\theta \\\\ d\\theta/dt \\end{array} \\right) + \\end{eqnarray*} + + For example, to transform the linear undamped pendulum equation $d^2\\theta/dt^2 + (g/\\ell) \\theta = 0$, + let $x_1 = \\theta$ and $x_2 = d\\theta/dt$. Differentiate those two equations to get + $d x_1/dt = d\\theta/dt = x_2$ and $d x_2/dt = d^2\\theta/dt^2$. Now note that, according to the linear undamped pendulum equation, $d^2\\theta/dt^2 = -(g/\\ell) \\theta = -(g/\\ell) x_1$. Putting all this together, we can write + + \\begin{eqnarray*} + \\frac{d\\vec{x}}{dt} = \\left(\\begin{array}{l} dx_1/dt\\\\ dx_2/dt \\end{array} \\right) = \\left(\\begin{array}{cc} 0 & 1 \\\\ -g/\\ell & 0 \\end{array} \\right) \\left(\\begin{array}{c} x_1 \\\\ x_2 \\end{array} \\right) + \\end{eqnarray*} + + This equation is now of the form $d\\vec{x}/dt = \\vec{f}(\\vec{x})$, so it can be solved numerically with Matlab's ''ode45'' function.\ngibson/teaching/spring-2018/math445/lecture/pendulum.txt · Last modified: 2018/04/26 05:58 by gibson\n\n### Page Tools",
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] | [
null,
"http://channelflow.org/dokuwiki/lib/exe/fetch.php",
null,
"http://channelflow.org/dokuwiki/lib/exe/indexer.php",
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https://www.excellup.com/class_12/chemistry_12/12-chemistry-chemical-kinetics-molecularity-reaction.aspx | [
"Class 12 Chemistry\n\n# Chemical Kinetics\n\n## Molecularity of Reaction\n\nThe number of reacting species taking part in an elementary reaction, which must collide simultaneously to bring about a chemical reaction is called molecularity of a reaction.\n\nExample of unimolecular reaction: NH_4NO_2→N_2+2H_2O\n\nExample of bimolecular reaction: 2HI→H_2+I_2\n\nExample of trimolecular reaction: 2NO+O_2→2NO_2\n\nThe probablity of more thatn three molecules to collide and react simultaneously is very small. So, reactions with the molecularity three are very rare. Such reactions are slow to proceed. So, complex reactions involving more than three molecules in the stoichiometric equation must take place in more than one step.\n\nLet us take example of following reaction:\n\nKC\\lO_3+6Fe\\SO_4+3H_2SO_4→KCl+3Fe_2(SO_4)_3+3H_2O\n\nThis reaction appears to be of tenth order. But in reality, it is a second order reaction because the reaction takes place in several steps. The overall rate of such a reaction is controlled by the slowest step in the reaction. Such a step is called the rate determining step.\n\nOrder of a reaction is applicable to elementary as well as complex reactions. But molecularity is applicable only to elementary reactions. Molecularity has no meaning for complex reaction.\n\n### Integrated Rate Equations\n\n#### Zero Order Reactions:\n\nLet us consider following reaction:\n\nR→P\n\nRate =-(d[R])/(dt)=k[R]^0\n\nOr, =-(d[R])/(dt)=k\\xx1\n\nOr, d[R}=-k dt\n\nIntegrating both sides\n\n[R]=-kt+I ……….. (1)\n\nHere, I the constant of integration\n\nAt t=0, the concentration of reactant R=[R]_0\n\nSubstituting in equation (1)\n\n[R]_0=-k\\xx0+I\n\nOr, [R]_0=I\n\nSubstituting in equation (1)\n\n[R]=-kt+[R]_0……..(2)\n\nOn further simplifying the equation, we get the rate constant k as follows:\n\nk=([R]_0-[R])/t …………. (3)\n\n#### First Order Reactions\n\nLet us consider following reaction:\n\nR→P\n\nRate =-(d[R])/(dt)=k[R]\n\nOr, =-(d[R])/([R]=kdt ……….(1)\n\nIntegrating this equation, we get\n\nIn[R]=-kt+I …………(2)\n\nWhen t = 0, R = [R]0\n\nSo, equation (2) can be written as follows:\n\nIn[R]_0=-k\\xx0+I\n\nOr, In[R]_0=I\n\nSubstituting the value of I in equation (2), we get:\n\nIn[R]=-kt+In[R]_0 ………….(3)\n\nRearranging this equation, we get the following:\n\nIn([R])/([R]_0)=-kt\n\nOr, k=1/tIn([R]_0)/([R])\n\nAt time t1, equation (2) can be written as follows:\n\nIn[R]_1=kt_1-In[R]_0 ……..(4)\n\nAt time t1, we get:\n\nIn[R]_2=kt_2-In[R]_0 ………….(5)\n\nSubtracting equation (5) from (4) we get\n\nIn[R]_1-In[R]_2=-kt_1-(-kt_2)\n\nOr, In([R]_1)/([R]_2)=k(t_2-t_1)\n\nEquation (3) can also we written as follows:\n\nTaking antilog of both sides\n\n[R]=[R]_0e^(-kt)\n\n### Half Life of a Reaction\n\nThe time in which concentration of a reactant is reduced to one halg of its initial concentration is called half life of the reaction.\n\nWe know, for zero order reaction:\n\nk=([R]_0-[R])/(t)\n\nWhen t=1/2 the rate constant is givne as follows:\n\nk=([R]_o-1/2[R]_0)/(t_(1/2))\n\nOr, t_(1/2)=([R]_0)/(2k)\n\nFor First order reaction,\n\nk=(2.303)/t\\lo\\g([R]_0)/([R])\n\nAt t_(1/2), the above equation becomes\n\n[R]=([R]_0)/([R])\n\nOr, k=(2.303)/(t_(1/2))\\lo\\g\\([R]_0)/([R]/2)\n\nOr, t_(1/2)=(2.303)/(k)\\lo\\g2\n\nOr, t_(1/2)=(2.303)/k\\xx0.301\n\nOr, t_(1/2)=(0.693)/k\n\nFor zero order reaction t_(1/2)∝[R]_0\n\nFor first order reaction t1/2 is independent of [R]0\n\nPseudo First Order Reaction: When one reactant is present in large excess, its concentration remains more or less constant throughout the reaction. In this case, the reaction behaves as first order reaction. Such reactions are called pseudo first order reaction. Following reaction shows an example of pseudo first order reaction.\n\nCH_3CO\\OC_2H_5+H_2O→CH_3CO\\OH+C_2h_5OH\n\nIn this reaction, water is present in excess amount. So, the concentration of water does not change much throughout the reaction. So, rate of the equation can be given as follows:\n\nRate =k’[CH_3CO\\OC_2H_5][H_2O]\n\nSince we are taking the concentration of H2O as constant\n\nSo, k-k’[H_2]\n\nSo, the rate equation can be written as follows:\n\nRate =k[CH_3CO\\OC_2H_5]"
] | [
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https://cosmolearning.org/topics/differential-equations/ | [
"",
null,
"",
null,
"# Topics: Calculus - Differential Equations\n\n### Differential Equations\n\nA differential equation is a mathematical equation for an unknown function of one or several variables that relates the values of the function itself and of its derivatives of various orders. Differential equations play a prominent role in engineering, physics, economics and other disciplines.",
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http://www.psencik.cz/outlook-macros/set-birthday-anniversary-reminders | [
"Outlook Macros > \n\n### Set Birthday/Anniversary Reminders\n\n Following macro changes (it does not set reminder if it is not set already) reminders for birthday/anniversary events to configured number of hours before event (because by default it is 15 minutes before midnight and one does not want to be woken by Android at that time). This macro is useful for situation when birthday event is not synchronized with reminder time (which can happen rarely on specific conditions). License: GPL `Sub SetSpecEventReminders()`` Dim ns As NameSpace`` Dim f As Folder`` Dim t As AppointmentItem`` Dim rp As RecurrencePattern`` Dim istr As String`` Dim remtime As Integer`` Dim n As Integer`` `` Set ns = Application.GetNamespace(\"MAPI\")`` Set f = ns.GetDefaultFolder(olFolderCalendar)`` `` istr = InputBox(\"Number of hours before event\")`` `` If Not IsNumeric(istr) Then`` MsgBox \"Input is incorrect, macro will not continue.\"`` Exit Sub`` End If`` `` remtime = CInt(istr) * 60`` n = 0`` `` For Each i In f.Items`` If i.Class = olAppointment Then`` Set t = i`` `` If t.IsRecurring And t.ReminderSet And t.AllDayEvent Then`` Set rp = t.GetRecurrencePattern()`` `` If rp.RecurrenceType = olRecursYearly And rp.Interval = 12 And rp.NoEndDate Then`` If (t.ReminderMinutesBeforeStart <> remtime) Then`` t.ReminderMinutesBeforeStart = remtime`` t.Save`` n = n + 1`` End If`` End If`` End If`` End If`` Next`` `` MsgBox \"Changed \" & n & IIf(n = 1, \" event\", \" events\")``End Sub`"
] | [
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http://warp.povusers.org/EfficientLZW/part2.html | [
"# An efficient LZW implementation\n\n## 2. Optimizing the dictionary\n\nIt should be noted that each time a new string is added to the dictionary the prefix part of that new string already exists in the dictionary. It never happens that such a prefix is not in the dictionary.\n\nThus instead of storing the entire byte string at the new dictionary position it's enough to store the last byte of the new string and an index to the prefix for that string. This way even very large strings will only require one byte and one index value in the dictionary.\n\nThus instead of containing `[prefix]`-`B` pairs, each dictionary item can simply contain `<index>`-`B` pairs, greatly decreasing memory usage. Typically the index takes 4 bytes and thus each string in the dictionary can be made to take only 5 bytes.\n\n(In practice this requires the indices and the bytes to be stored in separate arrays, else the compiler will most probably allocate 4 bytes for the byte value for memory alignment reasons. Often this extra memory usage is not so critical, though, and a simple LZW implementation may well just put the indices and the bytes in the same array.)\n\nThis also makes comparing dictionary elements faster because only the index-byte pairs need to be compared instead of the full strings.\n\nNote that also the first 256 elements in the dictionary, which had empty prefixes, have now index values instead of prefixes as well. However, these index values should still mean \"empty prefix\". This can be achieved by assigning an invalid index value to these prefix indices (eg. -1). Each time this invalid value is found as prefix index, it's simply interpreted as \"empty prefix\".\n\nWhen this is done, the algorithm has to be changed to do the same thing as well. That is, in the same way as the dictionary, instead of using a prefix-byte pair, it should use an index-byte pair. The fundamental difference comes in step 5 in the previous algorithm: The `[prefix]` part should be assigned with the index of the string in the dictionary. This index is automatically found when the string is searched in the dictionary, so this is not a problem.\n\nIf we rewrite the algorithm using this system, using the notation `<index>` for a dictionary index and `<index to empty>` as the invalid index value denoting an empty prefix, it becomes:\n\n1. Initialize the dictionary (with the first 256 entries).\n2. `<index>``<index to empty>`\n3. `B` ← next byte in the input.\n4. Is the string `<index>B` in the dictionary?\n• Yes:\n1. `<index>` ← index of `<index>B` in the dictionary.\n• No:\n1. Add the string `<index>B` to the dictionary.\n2. Output `<index>` to the result.\n3. `<index>``B`\n5. If there are bytes left in the input, jump to step 3.\n6. Else output `<index>` to the result.\n\nNote that \"index of `[prefix]` in the dictionary\" becomes simply \"`<index>`\" because that's precisely what \"`<index>`\" is.\n\nSpeedwise the main issue is step 4, ie. searching the string in the dictionary. A naive solution would be to perform a linear search throughout the entire dictionary. However, this is a very slow and inefficient solution. A very efficient algorithm for this will be discussed in part 4.\n\nCopyright 2007: Juha Nieminen"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.83649707,"math_prob":0.8460555,"size":2964,"snap":"2019-13-2019-22","text_gpt3_token_len":657,"char_repetition_ratio":0.18885136,"word_repetition_ratio":0.019455252,"special_character_ratio":0.2182861,"punctuation_ratio":0.09440559,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.96019936,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-03-24T17:26:03Z\",\"WARC-Record-ID\":\"<urn:uuid:18bc09d8-20df-45bb-8d9d-279779cd5e28>\",\"Content-Length\":\"4661\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5cddf737-169f-47a8-a0f5-ff2c084402d2>\",\"WARC-Concurrent-To\":\"<urn:uuid:9d68a277-7d13-4017-92ea-aa324cbbc696>\",\"WARC-IP-Address\":\"203.29.75.52\",\"WARC-Target-URI\":\"http://warp.povusers.org/EfficientLZW/part2.html\",\"WARC-Payload-Digest\":\"sha1:A2IJLEWYUA5QMNZTEPHNJI6VXW4D35PA\",\"WARC-Block-Digest\":\"sha1:NDJZ473LULCFVDRWTGF4N7DE7FMFUSYX\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-13/CC-MAIN-2019-13_segments_1552912203464.67_warc_CC-MAIN-20190324165854-20190324191854-00446.warc.gz\"}"} |
http://fpgacpu.org/usenet/render.html | [
"3-D Rendering Acceleration\n\nHome\n\nLFSR Design >>\n<< Rambus for FPGAs\n\n```Newsgroups: comp.graphics.algorithms,comp.arch.fpga\nSubject: Re: FPGA accelerated engines for volume rendering\nDate: 22 Mar 1995 05:47:46 GMT\n\nIn <[email protected]>\[email protected] (Arrigo Benedetti) writes:\n\n>I'm looking for references to implementations of hardware accelerators for\nvolume\n>rendering algorithms (or other computationally intensive graphics\nalgorithm)\n>based on FPGA's.\n\nI suspect this is not the volume rendering you mean, but maybe you'll find\nit interesting anyway, a kind of software/hardware practice and\nexperience, if you will.\n\nA while back, I did a design for a Gouraud shaded Z-buffered rendering\naccelerator, whose datapath is compiled into a Xilinx XC4003A. Sure, it's\nprobably the most well understood graphics rendering problem, and my\nimplementation is simple at best (e.g. no blending, no textures), but I\nwanted to see how far one could get, at home, on a hobbyist scale.\n\nThe inner loop (one scan line) of this simple polygon rendering algorithm\nis:\n// interpolate left to right, in (r,g,b) and z, and update\n// pixels for which z is closer than zbuf[x]:\n... set up fixed point z, dz, r, dr, g, dg, b, db ...\nfor (x = xleft; x < xright; x++) {\nif (z < zbuf[x]) { // Z-buffer check\nzbuf[x] = z; // update Z-buffer\nbuf[x] = pixel(r,g,b); // update image\n}\nz += dz; r += dr; g += dg; b += db;\n}\n\nWhen attached to 32-bits of DRAM or VRAM, and assuming a 16-bit Z-buffer,\nthis design required three passes, fast page mode streaming over memory, to\nrender a span of pixels across one scan line of a polygon. That is, I\nimplement the above as three passes :-\n\nbit closer[];\n// Pass 1: (check two Z-values per iteration)\n// initialize z0, z1, dz0, dz1\nfor (x = xleft; x < xright; x += 2) {\ncloser[x] = (z0 < zbuf[x]);\ncloser[x+1] = (z1 < zbuf[x+1]);\nz0 += dz0; z1 += dz1;\n}\n// Pass 2: (update up to two Z-values per iteration)\n// reinitialize z0, z1, dz0, dz1\nfor (x = xleft; x < xright; x += 2) {\nif (closer[x]) zbuf[x] = z0;\nif (closer[x+1]) zbuf[x+1] = z1;\nz0 += dz0; z1 += dz1;\n}\n// Pass 3: (update zero or one pixel value per iteration)\n// initialize r, g, b, dr, dg, db\nfor (x = xleft; x < xright; x++) {\nif (closer[x]) buf[x] = pixel(r,g,b);\nr += dr; g += dg; b += db;\n}\n\n.. in hardware, in each case doing one loop iteration per clock (50 ns\nclock).\n\n((I separated passes 1 and 2 because I thought it would be easier to do\nseparate read and write passes on the Z-buffer memory, pipelined, rather\nthan one pass with lots of back to back read/modify/write traffic.))\n\nAmortized cost: 100 ns/pixel, several times faster than an R4000 software\napproach, even assuming packing several 8.8 bit fixed point interpolants\nper 64-bit register.\n\nBesides address sequencing and DRAM/VRAM control, the hardware to do the\nabove is only two 24-bit accumulators (for the 16.8 bit fixed point\ninterpolations of z0 and z1, and reused for 'r' and 'g' interpolation), one\n16-bit accumulator (for the 8.8 bit fixed point interpolation of 'b'), and\ntwo 16-bit magnitude comparators (for comparing zbuf[i] and zbuf[i+1] with\nz0 and z1), plus a 64-by-2 bit SRAM to buffer closer/farther values (wider\npolygons would be divided into abutting narrow ones). All of which fits\nnicely in a \"3000-gate\" XC4003A.\n\n((An \"accumulator\" in Xilinx-speak is an adder whose output is captured in\na register \"sum\", and whose inputs are sum and another register \"delta\", so\nthat \"sum += delta\" is formed each clock.))\n\nI also considered using 16-bits/pixel (565 RGB) and adding error\ndistribution \"dithering\" to propagate the error at each pixel to later\npixels on the same line. This would require another adder at each\naccumulator.\n\nIn my first couple of nights using ViewLogic, XBLOX, and XACT\n1.4-something, I was able to design and compile the datapath of the above.\nUnfortunately at that point I got stuck, trying to determine how to\ninterface an R3081 and then an R4000 to the FPGA, and so never did get the\ndarn rendering engine built. (The R4000 bus protocols are nontrivial,\nespecially when trying to interface to an FPGA with its own, nontrivial\ninput setup/hold times and output delays.) Now, when time permits, I am\ndesigning a 32-bit RISC in the left half of an XC4010, and I hope to use\nthe right half for a rendering accelerator as described above. Here\n\"interpolate\" (one iteration of one of the above passes) will be a machine\ninstruction.\n\nJan Gray\n```"
] | [
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https://www.arxiv-vanity.com/papers/0905.1699/ | [
"# Lorentz Breaking Massive Gravity in Curved Space\n\nD.Blas, D. Comelli, F. Nesti, L. Pilo\nFSB/ITP/LPPC, École Polytechnique Fédérale de Lausanne,\nCH-1015, Lausanne, Switzerland\nINFN, Sezione di Ferrara, I-35131 Ferrara, Italy\nDipartimento di Fisica, Università di L’Aquila, I-67010 L’Aquila, and\nINFN, Laboratori Nazionali del Gran Sasso, I-67010 Assergi, Italy\nFebruary 4, 2021\n###### Abstract:\n\nA systematic study of the different phases of Lorentz-breaking massive gravity in a curved background is performed. For tensor and vector modes, the analysis is very close to that of Minkowski space. The most interesting results are in the scalar sector where, generically, there are two propagating degrees of freedom (DOF). While in maximally symmetric spaces ghost-like instabilities are inevitable, they can be avoided in a FRW background. The phases with less than two DOF in the scalar sector are also studied. Curvature allows an interesting interplay with the mass parameters; in particular, we have extended the Higuchi bound of dS to FRW and Lorentz breaking masses. As in dS, when the bound is saturated there is no propagating DOF in the scalar sector. In a number of phases the smallness of the kinetic terms gives rise to strongly coupled scalar modes at low energies. Finally, we have computed the gravitational potentials for point-like sources. In the general case we recover the GR predictions at small distances, whereas the modifications appear at distances of the order of the characteristic mass scale. In contrast with Minkowski space, these corrections may not spoil the linear approximation at large distances.\n\n## 1 Introduction\n\nMassive gravity has recently received a lot of attention mainly due to its relation to large distance modifications of the gravitational force (for recent reviews, see e.g. [1, 2]). Even if the addition of a Lorentz-invariant mass term to the standard action for the graviton in a flat background accomplishes the desired modification, it also implies the appearance of new problems, such as the vDVZ discontinuity and the strong coupling of the scalar mode of the massive graviton [3, 4, 5, 6]. It was realized in (see also ) that some of these problems may be softened if the mass term breaks the Lorentz invariance to rotational invariance.\n\nIt is also known that some of the features of Lorentz breaking massive gravity are peculiar to Minkowski space and do not hold in other backgrounds (see also [10, 11]). In this note, we will study the behavior of the gravitational perturbations in a curved background with a mass term breaking linearized general covariance.\n\nA caveat to this restriction has to do with the choice of action for the graviton fluctuations in curved spacetime. Normally, one considers the perturbations of the General Relativity (GR) action to second order around a background which solves the equations of motion (EOM). This ensures gauge invariance under linearized diffeomorphisms (diff) at the quadratic level. In this work, we modify GR by adding a mass term which breaks explicitly gauge invariance, but other diff-breaking corrections are possible. In particular, also the kinetic term may be modified once one relaxes the constraint of general covariance.111Recently, there has been some interest in the modifying the kinetic structure of GR as a way to improve its UV behavior . The motivation for considering only mass terms is that we want to focus on large distance (infrared) modifications of gravity. Besides, there are known physical examples generating this kind of mass terms for gravitational perturbations.\n\nA first example is a model where the matter sector includes four scalar fields that condense, breaking spontaneously the symmetry of the background metric (see also for related previous work and for some cosmological implications). In the gauge where those scalar modes are frozen (unitary gauge), the spectrum of the perturbations reduces to the gravitational modes with a mass term that violates the symmetry of the background. In this sense, the scalars are the Goldstones modes of the broken diff invariance. Another interesting example is bigravity, where a second rank-2 tensor interacts with the metric . In this case, there are exact flat backgrounds where the metrics do not share the whole group of invariance, but preserve a common . The spectrum of fluctuations around these backgrounds includes a Lorentz breaking massive graviton which is a combination of both metrics [17, 18] (see also for some phenomenology and [20, 21] for spherically symmetric solutions).\n\nInspired by the previous models222Other related models include theories with extra dimensions and theories with condensing vector fields . we will consider the presence in the action of a generic mass term (function of the metric) which breaks general covariance. This term both allows for FRW backgrounds (see e.g. [24, 25]) and generates the LB mass terms for the gravitational perturbations. Thus, the analysis of just the gravitational degrees of freedom is consistent in this setup where diff-invariance is broken, while in a diff-invariant context this is possible only in a de Sitter (dS) space.333We leave the analysis of gravitational perturbations coupled to additional fields in a FRW background for a forthcoming publication .\n\nThe paper is organized as follows: In section 2 we introduce our notations and the setup of our investigations. Then we analyze the perturbations with LB terms in curved backgrounds for the tensor (section 4), vector (section 5) and scalar modes (section 6 and appendix A). In section 7 we study the generalized Newton-like potentials and their deviations from GR. We present the conclusions in section 8.\n\n## 2 Action, background and perturbations\n\nOur starting point is the Einstein-Hilbert (EH) Lagrangian with the addition of mass terms for the gravitational perturbations, breaking general covariance. In the flat limit these terms also break Lorentz invariance, and we will refer to them as Lorentz-breaking (LB) terms.\n\nThis setup describes, at quadratic level, infrared modifications of gravity where only gravitational degrees of freedom are present. At full nonlinear level these deformations of the EH theory may be parametrized by adding to the lagrangian a nonderivative function of the metric components, breaking general covariance:\n\n S=∫d4x√−gM2P[R−2F(gμν)]. (1)\n\nGeneral covariance can be restored [4, 8] by introducing extra (Stückelberg) fields,444This implies the addition of (at most) four scalar fields, but invariant actions can also be found by adding vector or tensor fields. which in the equivalent of the unitary gauge yield the form (1).\n\nIt is clear that the term will contribute to the background EOM, and exact solutions are known for certain functions. For example, when constant, the homogeneous and isotropic (FRW) background will be maximally symmetric and the theory will be gauge (diff) invariant. For constant, FRW solutions can be found, which can modify the standard cosmological solutions of GR. For certain classes of , solutions that exhibit late-time cosmic acceleration were studied in (see also ).\n\nAccordingly, we assume that the dynamics of modified gravity admits a spatially flat isotropic and homogeneous background (FRW henceforth)\n\n ¯gμν=a(η)2ημνwith ημν=diag(−1,1,1,1), (2)\n\nwhere is the conformal time. We will use and , where is the derivative with respect to (therefore ).\n\nWe define the metric perturbations as\n\n gμν=a2(ημν+hμν). (3)\n\nThe second-order expansion of can then be written as:\n\n S=S(2)GR+S(2)LB, (4)\n\nwhere555We stress that in this expression, depends only on the background.\n\n SGR=∫d4x√−gM2P(R−6H2) (5)\n\nand the term gives rise also to LB masses for . Assuming rotations are preserved, these can be parametrized as\n\n S(2)LB=M2P4∫d4x√−¯g[m20h200+2m21h20i−(m22−4H′a−1)h2ij+(m23−2H′a−1)h2ii−2m24h00hii]. (6)\n\nHere spatial indices are contracted with , and represent effective time dependent masses. The terms proportional to in (6) are conveniently chosen to cancel similar contributions coming from the expansion of (5) in backgrounds different from dS. Notice that the parametrization in (6) is completely general as the mass parameters are arbitrary functions of the conformal time.\n\nDiff gauge invariance is restored taking the limit , and it corresponds to the case constant. On the other hand, for FRW background and vanishing masses the action is invariant only under longitudinal spatial diffs. This is a consequence of the fact that a generic FRW background is never a consistent background for GR without matter. A non maximally symmetric background breaks the time diffs, and accordingly in the limit of vanishing masses one recovers the invariance under spatial diffs.\n\nIn the Lorentz-invariant case the masses can be expressed in terms of two parameters ,\n\n m20=α+β,m21=−α,m22−4a−1H′=−α,m24=β,m23−2a−1H′=β, (7)\n\nand the mass term (6) can be written in terms of contractions of with . The Fierz-Pauli (FP) choice, free of ghosts in flat space, corresponds to . In curved space also the “non-Fierz-Pauli” case can be free of ghosts (see section 6).\n\nThe setup introduced here is suitable to describe a rather general class of massive gravity theories, and exhibits a rich set of phases, depending on the masses and . In general we can have the following scenarios:\n\n• The term in the action (1) does not affect neither the background (dS limit) nor the propagation of the perturbations. This is the case for and and is realized, e.g., when .\n\n• Only the perturbations are modified. This corresponds to and . Writing , this happens when the scale of is much larger than the scale related to .\n\n• Only the background is modified. This happens for and . As we will see, it can also be realized in less trivial situations.\n\n• Finally, in general both the background and the perturbations are modified by .\n\nIn order to study the dynamics of the perturbations, it is convenient to decompose the metric fluctuations as irreducible representations of the rotation group:666Here, we follow the notation of .\n\n h00=ψ,h0i=ui+∂iv,∂iui=0,hij=χij+∂isj+∂jsi+∂i∂jσ+δijτ,∂isi=∂jχij=δijχij=0. (8)\n\nFrom those fields one can define two scalar and one vector gauge invariant quantities\n\n Ψ≡τ+H(2v−σ′),Φ≡ψ−2v′+σ′′−H(2v−σ′),Wi=ui−s′i, (9)\n\nwhile the transverse-traceless spin two field is already gauge invariant. It is also convenient to define the field .\n\nWe will couple the gravitational fields to a conserved777EMT conservation is not strictly required in massive gravity. A study of non-conserved EMT in FP can be found in . energy-momentum tensor ,\n\n ST=−∫d4xa2hμνημαηνβTαβ=−∫d4x a2(χijTij+ΦT00−2T0iWi+ΨTii), (10)\n\nwith , where is the covariant derivative associated to the background metric. The field is the generalization of Newtonian potential around the source in the linearized approximation. For FRW, the EMT conservation is equivalent to\n\n T′00=∂iT0i−H(T00+Tijδij),∂jTij=T′i0+2HTi0=a−2(a2Ti0)′. (11)\n\n## 3 Stable perturbations in curved backgrounds?\n\nOur goal is to study the dynamics of perturbations in curved backgrounds and determine when one can get a theory free of instabilities. These instabilities can be of ghost or Jeans type. The ghost-like instabilities are related to an infinite phase-space volume. If they are present, the decay rate of the perturbative vacuum will be infinite unless a cutoff is introduced in the theory (see also ). In the Lorentz breaking case, the different masses provide a natural energy scale to place the cutoff. If we admit a hierarchy inside the mass scales we may freeze the non-stable degrees of freedom, while still keeping some of the masses below the cutoff. In an expanding universe, there is also another important dimensional parameter, . We will focus on modifications such that at least some of the mass scales are inside the horizon scale . In this case, there is a natural hierarchy inside the set of dimensional parameters, which allows to define a large momentum cutoff keeping the masses small,\n\n |Δ|≤m2(mH)α∼Λ2c, (12)\n\nwith . Even if the addition of a cutoff may unveil phenomenologically acceptable phases, to keep the discussion simple we will consider theories free from ghost-like instabilities in the quadratic Lagrangian (see however [2, 17]).\n\nJeans-like instabilities can be also present. By this we mean instabilities that appear in a certain finite range of momenta. They are the signature of the growth with time of the perturbation at certain scales, and may even be interesting phenomenologically as a contribution to the clustering of matter at large distances (see, e.g. ). Furthermore, in an expanding universe, they may be settled beyond the horizon, where they are presumably frozen. Again, we leave the study of this possibility for future research , and concentrate on lagrangians with a stable spectrum.\n\nIt is also important to recall that in a FRW universe, energy is not a conserved quantity, and its positivity does not guarantee stability. Nevertheless, for scales smaller than the horizon, we can still use the positivity of the energy associated to the conformal time as a necessary requirement for stability (see also [31, 32]). As we will focus on these length scales, we will not discuss any global issue.\n\nFinally, there are two concerns for massive gravity beyond the linear theory . The first one is the strong coupling that emerges when one or more propagating states have their kinetic terms suppressed by a small parameter. In this case, the range of validity of the linear theory is drastically reduced. Furthermore, if we consider the action (1) as an effective action with a cutoff, one expects the contributions of higher order operators to become important at much lower energies than the initial cutoff scale. To study this behaviour one should analyze the scaling of relevant interaction terms which is beyond the scope of this paper. Here we just point out that when Lorentz invariance is violated, the strong coupling cutoff can be present in energy and/or momentum independently. We will accordingly speak of time and space cutoff , , by making canonical the relative quadratic terms in the action.\n\nBesides, when the functions satisfy certain conditions, there is a reduction of the phase-space, i.e. not all the six DOF of the gravitational perturbations propagate. It turns out that in Minkowski those are the only ghost-free possibilities . In general, unless there exists a symmetry that enforces them (see for example the case of bigravity , or the case described in ) these conditions are only satisfied for the quadratic Lagrangian in very finely tuned backgrounds. This means that the analysis is very sensitive to small changes in the background and probably to the interaction terms and higher order operators [1, 8, 10]. In the following we show how the generalization of LB massive gravity to curved backgrounds is useful to circumvent both concerns.\n\nIn the next sections we analyze the spectrum of tensor, vector and scalar perturbations, that at linearized level are not coupled, by SO(3) symmetry.\n\n## 4 Tensor Modes\n\nThe action for the tensor perturbations is\n\n S(T)=M2P4∫d4x a2[−ημν∂μχij∂νχij−a2m22χijχij], (13)\n\n ημν∂μ∂νχij−2Hχ′ij−a2m22χij=0. (14)\n\nThe absence of tachyonic instabilities requires\n\n m22≥0. (15)\n\nOne can also readily check from (13) that there are no ghost or gradient instabilities.888In an expanding universe, the friction term appearing in (14) implies that the perturbation is frozen at large distance. When imposing , we are assuming that the mass scale is well inside the horizon and unless otherwise stated, we will assume this to be the case.\n\n## 5 Vector Modes\n\nExtracting the vector part from (4) we get\n\n S(v)=M2P2∫d4x a2{−(ui−s′i)Δ(ui−s′i)+a2[m21uiui+m22sjΔsj]}. (16)\n\nThe field is not dynamical and it can be integrated out through its equation of motion,\n\n Δ(ui−s′i)−a2m21ui=0, (17)\n\nto yield\n\n S(v)=M2P2∫d4x a4[m21s′iΔΔ−a2m21s′i+m22siΔsi]. (18)\n\nTherefore, the dispersion relation of the vector field breaks Lorentz invariance at any scale (provided ). The action is free from instabilities for\n\n m21≥0andm22≥0, (19)\n\nin complete analogy to what happens in Minkowski space.\n\nThe case is particularly interesting, as it implies the cancellation of the time-derivative term in (18), so that there is no propagating vector mode. As we will see in section 6.3, this case is also important for the scalar sector.\n\nThe canonically normalized field can be defined by a rescaling:\n\n sci≡Λv(η)2si,Λv(η)2=a2m1MP√ΔΔ−a2m21, (20)\n\nwith the action\n\n S(v)=12∫d4x {(sci)′(sci)′+m22m21sciΔsci−[a2m22+Λ2v(Λ−2v)′′]scisci}. (21)\n\nTherefore the canonical field has a LB dispersion relation and a time dependent mass.\n\nFrom (20) we can also read the naive temporal strong coupling scale of the vectors, that is momentum (and time) dependent. At large momenta, , we expect the physical strong coupling scale to be given by , that is also the expected cutoff for a gauge theory explicitly broken by a mass term . This implies that the theory can be trusted only if the horizon scale does not exceed the cutoff, . In section 8 we will comment on some physical consequences of this bound. A similar spatial strong coupling scale can be defined by making canonical the spatial gradients.\n\n## 6 Scalar Modes\n\nThe scalar sector of the theory is the most interesting one. In flat space with the FP Lorentz invariant mass term it is a scalar mode which has the lowest strong coupling scale, and it is this sector that shows crucial differences when Lorentz symmetry is violated or spacetime is curved [7, 9]. As we will see later, it is also here that the difference between the maximally symmetric spacetimes and generic FRW spaces arises. The analysis will show that generically there are two scalar degrees of freedom, while the only possibilities with less degrees of freedom are or .\n\nThe scalar part of (4) can be written as (modulo total derivatives)\n\n S(s) = M2P4∫d4xa2{−6(τ′+Hψ)2+2(2ψ−τ)Δτ+4(τ′+Hψ)Δ(2v−σ′) +a2[m20ψ2−2m21vΔv−m22(σΔ2σ+2τΔσ+3τ2) +m23(Δσ+3τ)2−2m24ψ(Δσ+3τ)]},\n\nwhere the , terms have canceled as promised.\n\nIn the de Sitter background (dS), when all masses are set to zero, the action reduces to the first line of (6) and it is gauge invariant.999The first line of (6) differs from the standard action of the graviton in a FRW background by a term proportional to which cancels in dS (cf. ). As previously remarked, for a FRW background and vanishing masses the action is invariant only under longitudinal spatial diffs (only is undetermined).\n\nFrom (6) it is clear that and are Lagrange multipliers enforcing the following constraints\n\n ψ=m21m24(Σ+3τ)a3+2Hm21(Σ′+3τ′)a2−2Δm21τa−8HΔτ′8H2aΔ+(m20−6H2)m21a3,v=2Ha2m24(Σ+3τ)+4H2aΣ′+2m20aτ′−4HΔτ8H2aΔ+(m20−6H2)m21a3. (23)\n\nNotice that the behavior of these fields in FRW is qualitatively different from Minkowski space. In particular, whereas in flat space, the cases and are singular and must be treated separately, in curved spacetime, and are always determined by equations (23). After integrating out and we are left with a Lagrangian for :\n\n LΣ,τ=12φ′tKφ′+φtBφ′−12φtAφ, (24)\n\nwhere\n\n K=−M2Pa28H2Δ+(m20−6H2)m21a2(2H2a2m21a2m20m21a2m20m21m20(3a2m21−4Δ)), (25) (26)\n\nWe will first study the dynamics of (24) through the Hamiltonian, for which the explicit expression of the matrix is not needed101010As the form of this matrix in the general case is quite cumbersome and not particularly illuminating, we will not write it explicitly in this work.. The conjugate momenta are\n\n πi=∂L∂φ′i=Kijφ′j−Bijφj. (27)\n\nThus, two DOF will propagate when the matrix is non-degenerate, i.e. when\n\n det||K||∝m0m1≠0. (28)\n\nIn this case one can express the velocities in terms of momenta, and the resulting Hamiltonian is:\n\n HΣ,τ=12πtK−1π+12φtMφ,M=(A+BK−1B), (29)\n\nwith a rather simple kinetic term:\n\n K−1=1M2Pa2⎛⎜ ⎜ ⎜ ⎜⎝3−4Δa2m21−2−22H2m20⎞⎟ ⎟ ⎟ ⎟⎠. (30)\n\nThe theory is free of ghosts when the kinetic energy matrix is positive definite, that translates into the following conditions:\n\n m21>0,0\n\nTherefore contrary to the flat space case, we can still have a well defined kinetic term with two propagating degrees of freedom. In fact a window for opens up, and this allows even for a “non-FP” Lorentz-invariant mass term free of ghosts (and vDVZ discontinuity, see section 7).111111Recently, non-Fierz-Pauli lagrangians with scale dependent masses were also considered in . Notice, though, that in that case Lorentz invariance made the masses depend on both space and time, whereas in this work we are dealing only with time dependent masses.\n\nIt is also instructive to look at the no-ghost conditions in the low and high momentum regimes. We find,\n\n no ghost{at large momenta:m21>0,m20>0at small momenta:m21>0,0\n\nTherefore a nonzero curvature allows the scenario where the theory is free of ghosts in the ultraviolet but there is one ghost mode at large wavelengths; this happens for and . Such a ghost mode at very large distances would not necessarily render the theory phenomenologically sick, but would indicate a large scale instability of backgrounds with curvature smaller than , including the limiting case of Minkowski (Jeans-like instability, in the language of the section 3).\n\nFrom (30) one can find when the scalar sector suffers from strong coupling due to a small kinetic term. As happens for the vector modes, one of the strong coupling scales is related to the smallness of , whereas the other one depends on the ratio . When this ratio is not small (and compatible with the ghost-free condition (31)), both the scalar and vector sector become strongly coupled at the same time scale .\n\nThe analysis of the positivity of the “mass” term is rather cumbersome and we will consider just the high momentum limit (larger than the rest of the scales: , and ). In this case, requiring that the mass matrix in (29) is positive definite gives\n\n m23−m22<(m21−2m24)216m20,H′a−1<−⎡⎣m214+(m21−2m24)216m21⎤⎦, (33)\n\n(where we have used and .) When the previous conditions are satisfied there is no gradient instability at small distances. Notice that the r.h.s. in the last condition is always negative, meaning that only a FRW background with an expanding horizon can be stable. Besides, one can easily check that the previous conditions are inconsistent in the Lorentz-invariant case.\n\nTo summarize, in the non degenerate case of , we found two DOF where\n\n• there is no ghost provided ,\n\n• there is no gradient instability when (33) are satisfied (so is negative).\n\nThe difference that we found with the maximally symmetric case, where there is necessarily a gradient instability, implies the presence of a spatial strong coupling problem in this limit. In fact in approaching the dS background the spectrum of the Hamiltonian must pass through the case in which one of the modes is frozen, because the determinant of vanishes and accordingly the ‘‘spatial’’ part of its dispersion relation will vanish.121212See for a discussion of the modifications to these dispersion relations coming from higher order operators.\n\nIn the degenerate cases, when or vanish, there are less DOF and a separate analysis is given in the following sections. The case is related to the Fierz-Pauli case , whereas the case appears naturally in the ghost condensate and bigravity theories [13, 17, 18].\n\n### 6.1 The phase m0=0\n\nFor , the field is an auxiliary field as one can check from the action (24). Even if there is only one remaining DOF, the general treatment is quite involved and it is presented in appendix A. In this section we will just state the results and study some particular cases.\n\nThe EOM for yield the constraint (75), which once once substituted in the action gives a (quite complicated) effective Lagrangian for . Its kinetic part is\n\n Ka4M2P=3a3m21[a(m24)2+2(am2μH2−H(m24)′+m24H′)]−4[am24(m21−m24)+m21H′]Δam21(2Δ−3a2m24)2−2(4Δ−3a2m21)[3a2H(aHm2μ−(m24)′)−(2Δ−3a2m24)H′], (34)\n\nwhere . The positivity of the kinetic energy (no ghost) for large momenta gives\n\n am24(m21−m24)+m21H′am21+4H′>0. (35)\n\nOn the other hand at small momenta the kinetic term reduces to\n\n K|Δ=0=a2M2P/3,\n\nwhich is, remarkably, always positive.\n\nOne can show (cf. appendix A) that is positive also at any intermediate momenta in the variable provided that, in addition to (35), one has\n\n m21≥0,(a(m44+2H2m2μ)+2m24H′−2H(m24)′am24(m21−m24)+m21H′)>0. (36)\n\nWhen these conditions are saturated we are led to a case with a vanishing kinetic term, as discussed below (see (45)). Due to its analogy with the special case discussed in , we will refer to this case as partially massless.\n\nThe condition (36) refers to modes at large distances (eventually outside the horizon) and is not present in the Minkowski spacetime. In dS, taking the Lorentz-invariant FP limit (7) with , the previous conditions reduce to the Higuchi bound ,\n\n 2H2≤m2. (37)\n\nContrary to this case, the LB mass terms allow for a unitary massless limit. In fact, if the mass is an appropriate function of the conformal time, this limit can be free from ghosts also in the Lorentz-invariant case (see section 6.2.3).\n\nFrom the same kinetic term we can also estimate the strong coupling scale of the field , since the canonical field is defined at high momentum by the rescaling\n\n Σc=ΛΣΣ,ΛΣ=aMPm1√−Δ[am21x(1−x)+H′am21+4H′]12, (38)\n\nwhere .\n\nConcerning the potential term , it can be written as\n\n M=m22b2+cΔ+dΔ2+eΔ3+(m22−m23)Δ4q2 (39)\n\nwhere , , , are functions of and , whereas is a second order polynomial in .\n\nThe absence of gradient instabilities, equivalent to the positivity of , requires in the ultraviolet and infrared regimes the following simple conditions:\n\n {at large momentam22>m23at small momentam22>0. (40)\n\nWe see that for the potential is free from gradient instabilities that would be as dangerous as ghost instabilities as they would imply an infinitely fast instability . Notice also that at zero momentum, the condition required for the stability of tensors and vectors, enforces positivity of the potential. This implies, together with the stability of the kinetic term, that at small momentum the theory is always stable.\n\nAt intermediate scales, the analysis becomes very technical, and a method to check for the positive definiteness is presented in the appendix A.\n\n### 6.2 Particular cases with m0=0\n\nSome interesting subcases of the dynamics can be found looking at the numerator and denominator of eq (34). When the denominator vanishes, the field disappear from the EOM and the constraint (75) does not hold anymore. The analysis of this situation is presented in section 6.2.1.\n\nWhen the mass parameters are fine tuned in such a way that the numerator of (34) vanishes, the field does not propagate and it becomes an auxiliary field. This possibility is examined in section 6.2.2, where we also show its relation to a gauge invariance related to conformal invariance. Finally, the Fierz-Pauli Lagrangian in dS is a subcase of the phase where this fine tuning can occur. We study this possibility in section 6.2.3.\n\n#### 6.2.1 Time diffeomorphisms in FRW\n\nFrom the constraint (75) for as a function of , we see that it is singular for specific values of the masses. This happens when\n\n m21=2m24=−4a−1H′,m2μ=a(H2)′−2H′′a2H. (41)\n\n(If only the first condition holds, the constraint for (75) reduces to .)\n\nIn this case, and away from dS (we are assuming ), the field does not appear at all in the action. This corresponds to a restoration of the gauge symmetry corresponding to time diffeomorphisms, .\n\nThe final Lagrangian in terms of is then given by\n\n L=M2pa22{aH′Δ+3aH′Σ′2−13[m22+Δ3(aH′)2+(2aH′+H′′/H)Δ(Δ+3aH′)2]Σ2}. (42)\n\nNotice that in Minkowski this phase has and features an enhanced gauge invariance mentioned in . In contrast to the case of Minkowski, and to the case of dS, in FRW background the field propagates. It is also clear from (42) that the kinetic term is positive definite provided that . Concerning the potential term, let us consider scales well inside the horizon. The requirement of positive energy at these scales gives the condition\n\n m22≥−(2aH′+H′′/H), (43)\n\nWhen inequality (43) is exactly saturated, the scalar degree of freedom has vanishing speed in the at high momenta. Its dispersion relation is then .\n\nFinally, let us note that if for the scalar mode is well behaved, the limit of vanishing leads to a vanishing kinetic term and thus to strong coupling once interactions are taken into account. The resulting time strong coupling scale can be estimated as\n\n Λs=aMP√aH′Δ+3aH′. (44)\n\nthat is clearly more dangerous at short distances , where it may become sensibly lower than .\n\n#### 6.2.2 Partially massless\n\nAnother particular case appears when, after integrating out , the kinetic term of cancels. This happens when the inequalities (35) and (36) are saturated,\n\n m21=am44am24+H′,a(m44+2H2m2μ)+2m24H′−2H(m24)′=0. (45)\n\nIn the Fierz-Pauli limit this expression reduces to the partially massless case of de Sitter space(cf. ) and corresponds to a situation without propagating scalar degrees of freedom. In the Lorentz invariant case with constant masses in de Sitter space, this fact is related to a conformal invariance . In the most general case, one can prove that the system is invariant under the transformation\n\n δψ=−2(ξ′+Hξ)+ϕt,δv=−ξ+ζ′,δτ=2Hξ+ϕs,δσ=2ζ, (46)\n\nwith\n\n ξ=−a24(am24ζ+H′ζ+Hζ′)H(am24+2H′),ϕs=m24ζϕt=ζm2(am4(m24−4H2)+2m4H′−4Hm′4)2aH2, (47)\n\nonly when the extra condition\n\n a[m44+2H2(2m22−3m24)]+2[m24H′−H(m24)′]=0 (48)\n\nis satisfied. The previous condition implies the cancellation of the potential part once (45) is satisfied. In the Lorentz-invariant limit with constant masses and dS background (48) is always satisfied when (45) holds. Notice also that the existence of this sort of scale invariance is general even if the kinetic term is not invariant under diff away from de Sitter.\n\n#### 6.2.3 Lorentz-invariant FP limit with time dependent masses\n\nIn the Fierz-Pauli limit ((7) with ) the mode propagates. However, the conditions (45) can be still be satisfied in dS (and only for this background) provided that satisfies the differential equation\n\n 4Hm′=(a2m2−2H2)m. (49)\n\nThis equation can be integrated to yield\n\n m2(η)=2H2m2Im2I+(2H2−m2I)a(η), (50)\n\nwhere is the value of the mass at the time corresponding to . The resulting mass runs from to when runs from 0 to 1. Notice that choosing the initial conditions corresponding to a constant mass, , we recover the partially massless case discussed in . A similar situation could be studied for the non-Fierz-Pauli (Lorentz-invariant) case (, ).\n\n### 6.3 The phase m1=0\n\nThe case is particularly interesting in the Minkowski background, as only the tensor modes propagate. As we will show, there is a corresponding effect in dS, while one scalar mode starts to propagate in a FRW background. When the fields is not dynamical as one can check in action (24). Accordingly, its EOM is\n\n H(m22−m23)Σ=m24τ′−H(m22−3m23)τ. (51)\n\nNotice that again the Minkowski space limit is peculiar and the degree of freedom associated to is not present131313Also, the case should be treated differently.. In curved space, generically is determined by (51) and when it is substituted back in the action, after integration by parts, yields the Lagrangian\n\n L = M2Pa2H2{m4η2(m22−m23)τ′2−[H′aΔ+m22[H2(m22−3m23+3m24)−m24H′a]m22−m23 −H[m24(m23(m22)′−m22(m23)′)+m22(m23−m22)(m24)′](m22−m23)2⎤⎦τ2⎫⎬⎭.\n\nwhere . From the previous expression we discover that in dS, the phase has no propagating degrees of freedom (in the sense that the action is independent so that there is no dynamics in space), even if, in comparison to the Minkowski case, the scalar sector has a kinetic term from which we expect a ghost condensate like dispersion relation coming from higher derivatives . Besides, the potential strong coupling scales and are easily read out from the previous expression.\n\nThus, in general the phase is quite rich, and particularly simple. Ghostlike instabilities are avoided imposing . To get rid of gradient instabilities in this case, it is enough to impose , whereas the tachyon free condition can also be read from (6.3). For the case with constant masses, it reduces to .\n\n### 6.4 Particular cases with m1=0\n\nA direct inspection of (6.3) and (51) shows some interesting subcases for the mass parameters. First, when the r.h.s. of eq. (51) cancels, this equation is no longer a constraint for . Besides, for , the kinetic term for cancels in the action. We devote the rest of this section to the analysis of these possibilities.\n\n#### 6.4.1 The case m22=m23\n\nWhen the kinetic term of is zero. In this case is non-dynamical and can be eliminated from the action. The only degree of freedom now is with a Lagrangian\n\n L=a4M2P2(6m22m44−9m64+4m20m42)m44(2m22−3m24)(2m20m22−3m44)2[m442(2m22−3m24)H2Σ′2+m22Σ2]. (53)\n\nAgain, this mode has no dynamics in space. From direct inspection we can derive the strong coupling scale, and the region of parameters where this mode disappears.\n\n#### 6.4.2 The case mη=0\n\nFinally, for we are back to a situation without scalar propagating degrees of freedom but still with a potential part at the linear level. In Minkowski also this part vanishes and the field is not determined (indeed, there is an additional gauge invariance). In dS, this happens when\n\n mη=0,H(m22−3m23+3m24)−(m24)′m24=m23(m22)′−m22(m23)′m22(m22−m23), (54)\n\nand outside this region of the parameter space, the EOM gives .\n\n## 7 Coupling to matter and vDVZ discontinuity\n\nThough the vDVZ discontinuity is one of the main phenomenological difficulties of FP massive gravity in flat space, it is known that it may be circumvented in curved backgrounds or when one considers Lorentz violating mass terms . For AdS or dS, the vDVZ discontinuity is avoided by hiding the effects of the mass at distances larger than the horizon, and as a consequence there is no modification of gravity at scales smaller than the Hubble radius. In this section we will see that some of the massive gravity phases we have studied allow for a modification of gravity at scales shorter than the horizon scale and still compatible with GR at linear order. We will focus on the gravitational potentials produced by a “point-like” conserved source.\n\nThe tensor part is described by a massive graviton with mass given by . Phenomenologically, this mass is constraint by cosmological and astrophysical observations (see e.g. [39, 13]), and has no impact on the gravitational potentials for point-like sources. Also vectors modes do not affect these potentials (for cosmological constraints see ). For our purposes only scalar perturbations are relevant.\n\nLet us briefly review the situation of standard GR in presence of “point like” conserved sources, in Minkowski or dS background:\n\n T00=ρ(r)a,T0i=Tij=0. (55)\n\nIn GR, there is no scalar propagating DOF and the gauge invariant potentials are determined from the sources as\n\n ΦGR = ΨGR=1M2PΔT00. (56)\n\nRecall that the perturbations are defined with respect to a non-flat metric. Thus, both the background and the perturbations play a role in the gravitational dynamics around local sources.\n\nAs described in section 6, the generic massive gravity case has two propagating DOF in the scalar sector. In this section we are interested in static solutions in the presence of static sources. More concretely, we will consider time scales short enough such that we can consider the background metric constant141414In this limit the standard Fourier analysis is well suited to analyze the EOM and energy is a conserved quantity. It is also clear that if the limit is not singular the results are equivalent to those of Minkowski space considered in [8, 7].. By inspecting the EOM’s in this limit, time derivatives can be neglected provided that ; and where is the typical time scale for the variation of the gravitational perturbations and is the energy scale of the sources.\n\nOnce that time derivatives of the two dynamical fields and are neglected, and in the regime , the EOM can be solved in a straightforward though lengthy way. The generalization of the Newtonian potential is the quantity and we get\n\n Φ=n2Δ2+n1Δ+n0d3Δ3+d2Δ2+d1Δ+d0, (57)\n\nwhere the and are polynomials in the masses. The physics relevant for the vDVZ discontinuity is captured by expanding in powers of , e.g. .\n\n Φ=Tii+T00M2PΔ−uT00+vTii2M2pΔ2(m22−m23)+O(1Δ3),u=a2[m4η+m22(6m23−4m24−2m22)],v=a2[m4η−2m22m24]. (58)\n\nThus, at small distances we get the GR result plus corrections.151515The expression (58) is valid for distances smaller than the inverse of mass. For distances of the order of the inverse of the mass, the appearance of a pole in (57) makes the series ill defined. The exact solution can be easily found and one can see that the perturbations acquire a Yukawa tail. Thus, this modification of Newtonian potential has the desirable feature of keeping the perturbations small at large distances. Also , that is important for post-Newtonian tests, has the same structure:\n\n Ψ=T00M2PΔ−a22M2PΔ2[T00m4η−2m22m24m22−m23+Tiim4ηm22−m23]+O(1Δ3). (59)\n\nClearly, no discontinuity is present at small distances provided that (notice also that has disappeared from the previous expression). When , the previous expressions are not valid and a discontinuity is present, as it can be established by noting that in the UV the EOM imply\n\n 2m23Ψ=m24Φ, (60)\n\nwhich does not hold in GR.\n\n### 7.1 Coupling to matter for m1=0\n\nThe case is of particular interest, as in flat space there is no scalar DOF and the potential features a correction linear with , invalidating the linearized approximation at large distances. In a curved space the scalar propagates and the gauge invariant potentials and can be written as a combination of the source, and its time derivatives as\n\n Ψ=ΨGR+a(2aHm22m24τ+m4ητ′2ΔH(m22−m23)),Φ=Ψ+am22(2aH(m22−3m23)τ−m44τ′ΔH(m22−m23)). (61)\n\nHere we have used the expression for obtained from the EOM, namely:\n\n τ′′=2(m22−m23)H′am4ηM2P(T00−M2PΔτ)+q1(mi,H)τ+q2(mi,H)τ′, (62)\n\nwhere are functions of the background and the masses, finite in the limit . From these expressions one can study the behavior of potentials in the limit"
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"益民居委会财经\n\n2019-06-25 23:07 来源:中国新闻采编网\n\n光听菜名,就叫人垂涎三尺,况且实在在敦煌这种贫瘠的地方,他能做出这些美食,的确让人难以想象。桂林市旅发委的工作人员阐述,他们已经得知游客用餐时监控视频被曝光一事,但目前投诉中心旅游监察所还在进一步调查当中,具体调查结果还未得出。\n\n步骤二:用瑞士军刀减掉睫毛根部,减淡假睫毛打造的眼线效果。岛上各式各样的鱼餐厅,友情提示哦,记得选择一家座无虚席的餐厅,保证你不会后悔!一条美味的鱼下肚后,一杯本土酸奶当然也必不可少,心里美滋滋的。\n\n。为什么能够做到如此的布施,因为菩萨真能照见五蕴皆空,即人我已尽,得生忍智,依摩诃般若而度生,以无我相布施自己的身命、资财等,不会有任何的吝惜之心。\n\n不过依我之见,外观工艺再强,也无法掩盖处理器的缺陷。然而有媒体爆料称她在川普家却被当作“二等公民”,不受尊重。\n\n难道我这样真的不开阔吗?我相信换成任何一个男人,面对这样一个奇葩,没有自知之明的闺密第三者,谁都受不了,我并不觉得自己有什么不对。这接连的大戏也惊动了唐宁街的一位高级官员,他也担心CambridgeAnalytica毁尸灭迹。\n\n此后,蒋兆和开始把自己友人的脸画到古代的名人身上去,还把自己的脸安到了杜甫的脸上。后来从今年四月初开始,她便找到了工作。\n\n宇宙飞船过了一百二十亿公里,往太阳系外观看却是一片漆黑。搭载一款古董处理器的手机,不会有太大影响力的。\n\n。2015年2月,凤凰新媒体宣布再度增资新闻客户端APP一点资讯,成为后者第一大股东。\n\n二、大庄严,即福、智两足尊之谓。为什么能够做到如此的布施,因为菩萨真能照见五蕴皆空,即人我已尽,得生忍智,依摩诃般若而度生,以无我相布施自己的身命、资财等,不会有任何的吝惜之心。\n\n从20世纪20年代到30年代这十年里,为了让犯罪嫌疑人说实话,除了东莨菪碱,美国警方还尝试着使用喷妥撒和阿米妥、巴比妥酸盐等药物,都是通过消弱一部分大脑活性,消除其抑制作用,让人不自主地开口而达到效果。嘉琪的爸爸今年25岁,南阳打工当服务员月工资在2000-2500元左右工资不稳定。\n\n惠能圆寂后其真身至今供奉在南华禅寺,该寺因此被尊奉为禅宗祖庭。惠能大师是中国古代著名的思想家,哲学家和改革家,是东方和世界文化名人,他将佛教中国化、平民化、现世化,开创了极具中国特色的佛教禅宗,在中国思想史上产生了重大影响,对韩国、日本及东南亚国家的信仰和文化也影响深远。\n\n千赢官网-千赢登录 火石寨以丹霞地貌之称,是我国北方发育最为典型的丹霞地貌群。走进去,走到街头巷尾;走进去,走到古老的大巴扎;走进去,走到神秘的咖啡占卜屋;走进去,走到人群中去…|现任首都在哪儿?如果说伊斯坦布尔是历史的首都,那安卡拉就是土耳其现今的首都、政治经济文化中心,它是土耳其的心脏。\n\n“看三年 晒变化” 拿起手机相机无人机记录\n\n“看三年 晒变化” 拿起手机相机无人机记录身边之变今年是习近平总书记视察山东三周年...[查看详细]\n\n媒体报道",
null,
"• 林秀勇\n• 张殿芳\n• 吴文峰\n• 刘洪军\n• 刘洪军\n• 李玉新\n• 王朝新\n• 侯丙玉\n• 王 兰\n• 王锋\n• 郭英\n• 李友良\n• 段文志\n\n• 姜德志\n• 王长伟\n• 刘明星\n• 周厚庆\n• 高先堂\n\n• 孟利\n• 刑文强\n• 崔利英\n• 王京宝\n• 张华\n• 马德刚\n\n• 夏晓民\n• 宫鲁迅\n• 李树新\n• 金刚\n• 刘宏\n• 荆晓\n• 冀冠宇\n• 陈贵国\n• 张晶\n• 徐军\n• 李富农\n• 王伟\n• 袁袤翔\n• 立友\n• 徐汉勇\n• 宋道学\n• 张立友\n\n• 曹立山\n• 耿安峰\n• 王玉成\n• 王玉冬\n• 郭南\n• 段印平\n• 姜永福\n• 郑跃光\n• 毕东祥\n• 张保利\n• 李玮\n• 郑旭东\n• 王丰海\n• 孙金利\n• 蒋庆东\n• 马树刚\n• 孙浩伟\n• 于俊东\n• 黄鹏\n• 杨士文\n• 李峰\n• 王洪涛\n• 贾全忠\n• 任吉祥\n• 商国红\n• 王永刚\n• 李刚\n• 王喜\n• 张洪伟\n\n• 于海涛\n• 李若祥\n• 于文强\n• 薄恩岐\n• 李君\n• 祝良英\n• 孙兴鑫\n• 车志强\n• 赵兵\n• 邢思乐\n• 于华\n• 刘淑芹\n• 于文强\n• 吴永才\n• 贺长江\n• 张林\n• 吴朋飞\n• 马兴才\n• 秦明\n• 徐建波\n• 冀武\n• 慕世松\n• 徐岩妮\n• 赵杰\n• 李庆盛\n\n• 曹生成\n• 李希阳\n• 许文晓\n• 申燕翔\n• 金志远\n• 刘春山\n• 王世金\n• 鞠瑞俭\n• 杨德平\n• 马凤兆\n• 窦相富\n• 王树海\n• 赵洪志\n• 王明志\n• 张成军\n• 张欣\n• 刘述华\n• 张磊\n• 崔成业\n• 王德金\n• 陈树庆\n• 张德胜\n• 宋欣禄\n\n• 傅元彬\n• 王淼\n• 王宣旺\n• 陈远志\n• 夏辉\n• 司加斌\n• 祝贺\n• 王宪金\n• 陈军\n• 马广峰\n• 郑冰\n• 王渊成\n• 魏东风\n• 孙建涛\n• 李广淼\n• 杨斌\n• 王鹏\n• 徐炳书\n• 张凯\n• 董兴刚\n• 徐希\n• 张斌\n• 韩彦\n• 王敏\n• 王海龙\n• 张元光\n• 桑恺\n• 陈雷\n• 穆居华\n• 高月芹\n• 马迎春\n• 刘刚\n• 李海军\n• 陈善军\n• 孙士东\n• 韩明新\n• 赵成伟\n• 颜强\n• 郭纪军\n• 任守帅\n• 刘建飞\n• 杨忠敏\n\n• 康克\n• 李明峰\n• 张兴朋\n• 陈宁\n• 曲吉磊\n• 刘耕\n• 玄甲明\n• 徐强\n• 王建英\n• 刘元\n\n• 宫明泉\n• 赵学军\n• 王奉信\n• 董永利\n• 赵顺德\n• 孙雨静\n\n• 尹衍华\n• 乔祥明\n• 陈兆强\n• 李锋\n• 董玲\n• 相振海\n• 李国华\n• 丁斌\n• 李明\n• 刘加祥\n• 丁连相\n• 李东\n• 王文兆\n• 于春江\n• 许家建\n• 王洪国\n• 秦红英\n• 杜光勤\n• 徐修国\n• 侯庆松\n• 葛均贵\n• 闫风水\n• 牟兰江\n• 安佰哲\n• 董玲\n• 王文俊\n• 吕丽丽\n\n• 任忱远\n• 李健生\n• 李敬刚\n• 李涛\n• 李鹏\n• 吕怀德\n• 刘青\n• 单国兴\n• 司德明\n• 李华俊\n• 王瑞涛\n• 江三郎\n• 王玉博\n• 李新刚\n• 朱云俊\n• 李敬刚\n• 李洪武\n• 李钟毅\n• 孙宏君\n• 王明月\n• 李金刚\n• 杨基明\n• 王建华\n• 霍向锋\n• 徐广海\n\n• 刘金池\n• 杨岸瑛\n• 贺芮\n• 李本辉\n• 张宏琳\n• 刘洪霞\n• 王道彬\n• 李伶伶\n• 陈永健\n• 马志豪\n• 单玉森\n• 陈永健\n• 张志国\n• 郭宗勤\n• 王勇\n• 李本晖\n• 高庆虎\n• 傅宗清\n• 张新燕\n• 赵子祯\n• 于帆\n• 韩伟\n• 刘任举\n• 韦明浩\n• 冯鲁宁\n• 张志国\n• 刘宝芳\n• 郭详然\n• 许新亮\n• 岳明华\n• 李赵明\n• 刘宝芳\n• 李保卫\n• 张宝鑫\n• 杨岸瑛\n• 袁珊珊\n• 谢洪祥\n• 张长东\n\n• 梁立山\n• 史奎华\n• 张志栋\n• 邢先进\n• 刘风良\n• 李祖超\n• 刘明华\n• 王金云\n• 栾学运\n• 徐春青\n• 燕超善\n• 李建波\n• 陈建福\n• 汪广军\n• 李子敏\n• 马强\n• 吕绪宏\n• 司明阳\n• 孙中华\n• 黄圣奎\n• 靳宪亮\n• 张士久\n• 周美超\n\n• 马高峰\n• 苏明坤\n• 刘树松\n• 秦丕山\n• 张道勇\n• 徐爱国\n• 杨东\n• 杨永真\n• 马现华\n• 葛祥金\n• 王官华\n• 高荣菊\n• 钟卫国\n• 朱林\n• 李兆敏\n• 高春升\n• 孙富强\n• 刘杰松\n• 宋庆峰\n• 孙金玲\n• 武玉明\n• 王哲\n• 张京卫\n• 周久全\n• 公丕凯\n• 季纬忠\n• 任崇阳\n• 房怀宝\n• 刘玉涛\n• 李建\n• 陆勇\n• 刘超\n• 孙成功\n• 高荣菊\n• 雷云岭\n• 孔庆文\n• 杨广伟\n• 刘玉涛\n• 王凤军\n• 刘忠堂\n• 梁照军\n• 宋树安\n• 苏万金\n• 梁照军\n• 孙昌营\n• 王成平\n• 赵海燕\n• 代磊\n• 辛疆\n• 王成亮\n\n• 宋晓\n• 杨科\n• 张文欣\n• 田冉\n• 杨青雷\n• 王泽斌\n• 王桂林\n• 宋华君\n• 洪常良\n• 王国强\n• 翟效思\n• 周庆杉\n• 王刚军\n• 许志健\n• 张文峰\n• 郑杰\n• 李继民\n• 吕卫国\n• 张海玲\n• 侯昌杰\n• 董建华\n• 丁玉品\n• 杜学兵\n• 刘军\n• 刘建伟\n• 李继文\n• 刘昌森\n• 崔 鹤\n• 李春光\n• 张健\n• 张民\n• 王昭龙\n• 刘芳\n• 许常哲\n• 曲兆军\n• 王录良\n• 王晓新\n• 邵光勇\n• 郭玲\n• 刘培强\n• 魏中庭\n• 杜少华\n• 付巧莲\n• 闫秀菊\n• 牛桂华\n• 岳彩军\n• 周松柏\n• 邹爱武\n• 张英良\n• 张国强\n• 刘认银\n\n• 王胜军\n• 田茂广\n• 吕东升\n\n• 王保成\n• 储华杰\n• 鲁丽娇"
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https://learn.careers360.com/school/question-need-solution-for-rd-sharma-maths-class-12-chapter-determinants-exercise-multiple-choise-question-23/?question_number=23.0 | [
"",
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"#### Need solution for RD Sharma maths class 12 chapter Determinants exercise multiple choise question 23\n\nCorrect option (c)\n\nHint:\n\nIf all the element in a diagonal of determinant is zero, then determinant must be zero.\n\nGiven:\n\nGiven that,\n\nWe have to find\n\nSolution:\n\nHere\n\nPut X=0,\n\nExpanding along R1\n\n#### infoexpert25",
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https://books.google.no/books?qtid=207e78dc&dq=editions:UOM39015067252117&lr=&id=P_BJAAAAMAAJ&hl=no&sa=N&start=60 | [
"Søk Bilder Maps Play YouTube Nyheter Gmail Disk Mer »\nLogg på\n Bøker Bok",
null,
"ANY two angles of a triangle are together less than two right angles.",
null,
"The Elements of Euclid: The Errors, by which Theon, Or Others, Have Long Ago ... - Side 20\nav Euclid, Robert Simson - 1838 - 416 sider\nUten tilgangsbegrensning - Om denne boken",
null,
"## Euclid's Elements of geometry, books i. ii. iii. iv\n\nEuclides - 1862\n...that the angle BCG (or Us equal ACD), is greater than the angle ABC. PROPOSITION 17.— THEOREM. A ny two angles of a triangle are together less than two right angles. (References— Prop. I. 13, 16; ax. 4.) Hypothesis. — Let ABC be any triangle. Sequence. — Any...\nUten tilgangsbegrensning - Om denne boken",
null,
"## Euclid's plane geometry, practically applied; book i, with explanatory notes ...\n\nEuclides - 1863\n...Therefore if one side of a triangle be produced, &e. QED Pitop. 17. — THEOE. (converse of Ax. 12.) Any two angles of a triangle are together less than two right angles. Con.— Pst. 2, DEJI.— P. 10, Ax. 4, P. 18. Let ABC be a triangle ; then any two /.s in it, as A...\nUten tilgangsbegrensning - Om denne boken",
null,
"## Responsions\n\nUniversity of Oxford - 1863\n...line perpendicular to a given straight line of an unlimited length, from a given point without it. 3. Any two angles of a triangle are together less than, two right angles. 4. At a given point in a given straight line make a rectilineal angle equal to a given rectilineal...\nUten tilgangsbegrensning - Om denne boken",
null,
"## Euclid's Elements of geometry, the first four books, by R. Potts. Corrected ...\n\nEuclides - 1864\n...greater than the angle ABC. Therefore, if one side of a triangle, &c. QED PROPOSITION XVII. THEOREM. Any two angles of a triangle are together less than two right angles. Let ABC be any triangle. Then any two of its angles together shall be less than two right angles. Produce any side BC to D....\nUten tilgangsbegrensning - Om denne boken",
null,
"## The school edition. Euclid's Elements of geometry, the first six books, by R ...\n\nEuclides - 1864\n...greater than the angle ABC. Therefore, if one side of a triangle, &c. QED PROPOSITION XVII. THEOREM. Any two angles of a triangle are together less than two right angles. Let ABC be any triangle. Then any two of its angles together shall be less than two right angles. Produce any side BC to D....\nUten tilgangsbegrensning - Om denne boken",
null,
"## Elements of plane geometry, book i, containing nearly the same propositions ...\n\nEuclides - 1865\n...demonstrated that the angle BCG, that is (7) the angle ACD, is greater than the angle ABC. PROPOSITION XVH. THEOR. Any two angles of a triangle are together less...angles. Let ABC be any triangle, any two of its angles are together less than two right angles. Produce BC to D, and because ACD is the exterior angle of...\nUten tilgangsbegrensning - Om denne boken",
null,
"## The college Euclid: comprising the first six and the parts of the eleventh ...\n\nEuclides - 1865\n...prodnced, the exterior angle is greater than either of the interior opposite angles . . .1. 16. 7. Any two angles of a triangle are together less than two right angles . . . . . . . . . I. 17. 8. If a side of any triangle be prodnced, the exterior angle is equal to the...\nUten tilgangsbegrensning - Om denne boken",
null,
"## Loftus's inland revenue officer's manual\n\nWilliam Harris Johnston - 1865\n...right angle ¡ it cannot have more than one, as it is proved in Euclid, Book I., Prop. 17, that « Any two angles of a triangle are together less than two right angles. An obtuse-angled triangle has one of its angles an obtuse angle. An acute-angled triangle has all its...\nUten tilgangsbegrensning - Om denne boken",
null,
"## The Elements of Euclid for the Use of Schools and Colleges: Comprising the ...\n\nEuclid, Isaac Todhunter - 1867 - 400 sider\n...ACD, is greater than the angle ABC. [I. 15. Wherefore, if one side &c. QED PROPOSITION 17. THEOREM. Any two angles of a triangle are together less than two right angles. Let ABC be a triangle : any two of its angles are together less than two right angles. Produce BC to D. Then because...\nUten tilgangsbegrensning - Om denne boken",
null,
"## The Elements of Euclid for the Use of Schools and Colleges: Comprising the ...\n\nEuclid, Isaac Todhunter - 1867 - 400 sider\n...or theorem; as for example, To describe an equilateral triangle on a given finite straight line, or Any two angles of a triangle are together less than two right angles. After the general enunciation follows the discussion of the proposition. First, ,the enunciation is...\nUten tilgangsbegrensning - Om denne boken"
] | [
null,
"https://books.google.no/googlebooks/quote_l.gif",
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"https://books.google.no/books/content",
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"https://books.google.no/books/content",
null,
"https://books.google.no/books/content",
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"https://books.google.no/books/content",
null,
"https://books.google.no/books/content",
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"https://books.google.no/books/content",
null,
"https://books.google.no/books/content",
null,
"https://books.google.no/books/content",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8215534,"math_prob":0.9331185,"size":3089,"snap":"2021-04-2021-17","text_gpt3_token_len":823,"char_repetition_ratio":0.22009724,"word_repetition_ratio":0.39285713,"special_character_ratio":0.278731,"punctuation_ratio":0.24965706,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.996419,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-01-16T12:28:04Z\",\"WARC-Record-ID\":\"<urn:uuid:419a96d4-428d-4149-bd69-ffc5d68a5ed4>\",\"Content-Length\":\"33372\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:350b6955-530c-49fe-bfa0-7597c7377f49>\",\"WARC-Concurrent-To\":\"<urn:uuid:47a2a8ea-11e8-4f71-96f9-26bc4687d9b5>\",\"WARC-IP-Address\":\"172.217.2.110\",\"WARC-Target-URI\":\"https://books.google.no/books?qtid=207e78dc&dq=editions:UOM39015067252117&lr=&id=P_BJAAAAMAAJ&hl=no&sa=N&start=60\",\"WARC-Payload-Digest\":\"sha1:V2SJQ2VPY7OFI4VCSDWOBEJBBLHOE3MV\",\"WARC-Block-Digest\":\"sha1:CYK4I47OCGXUT4ETMARS6TJGIWWK6E5R\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-04/CC-MAIN-2021-04_segments_1610703506640.22_warc_CC-MAIN-20210116104719-20210116134719-00343.warc.gz\"}"} |
https://fomaa.net/money-word-problems-worksheets/ | [
"# 75 Ripping Money Word Problems Worksheets\n\nfree printable money math worksheets canadian first worksheet adding 3rd grade rounding word problems worksheets math best money word problems worksheets money math worksheets middle school for kids printable word problems math in the movies worksheet money word problems worksheets fun money worksheets second grade math worksheet addition worksheets grade math grade kindergarten word problems new money math worksheets pdf identify word problems for fourth grade – coffeejournalub money word problems 2nd grade mon core worksheets algebra coin",
null,
"Money Worksheets 3rd Grade New Money Word Problems 3rd Grade from money word problems worksheets , source:ajihle.org",
null,
"Word Problems Fractions Multiplication With Mixed Numbers 6th Grade from money word problems worksheets , source:pular.info",
null,
"Gallery Word Problems With Money New Worksheets Fresh Addition from money word problems worksheets , source:emersonsapps.co",
null,
"Multi Step Word Problems Multiple Problem Worksheets 3rd Grade from money word problems worksheets , source:scanvac.info",
null,
"â 2nd Grade Word Problems Worksheets Ideas 6th Grade Math Word from money word problems worksheets , source:sukakucing.info"
] | [
null,
"https://fomaa.net/wp-content/uploads/2019/05/money-word-problems-worksheets-luxury-money-worksheets-3rd-grade-new-money-word-problems-3rd-grade-of-money-word-problems-worksheets.jpg",
null,
"https://fomaa.net/wp-content/uploads/2019/05/money-word-problems-worksheets-awesome-word-problems-fractions-multiplication-with-mixed-numbers-6th-grade-of-money-word-problems-worksheets.jpg",
null,
"https://fomaa.net/wp-content/uploads/2019/05/money-word-problems-worksheets-beautiful-gallery-word-problems-with-money-new-worksheets-fresh-addition-of-money-word-problems-worksheets.jpg",
null,
"https://fomaa.net/wp-content/uploads/2019/05/money-word-problems-worksheets-new-multi-step-word-problems-multiple-problem-worksheets-3rd-grade-of-money-word-problems-worksheets.jpg",
null,
"https://fomaa.net/wp-content/uploads/2019/05/money-word-problems-worksheets-beautiful-ac288c29a-2nd-grade-word-problems-worksheets-ideas-6th-grade-math-word-of-money-word-problems-worksheets.jpg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.78093,"math_prob":0.45979124,"size":2365,"snap":"2019-35-2019-39","text_gpt3_token_len":403,"char_repetition_ratio":0.38373572,"word_repetition_ratio":0.1257485,"special_character_ratio":0.15729387,"punctuation_ratio":0.04225352,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9581135,"pos_list":[0,1,2,3,4,5,6,7,8,9,10],"im_url_duplicate_count":[null,1,null,1,null,1,null,1,null,1,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-09-17T10:38:52Z\",\"WARC-Record-ID\":\"<urn:uuid:d398c701-2c21-4ac2-9719-df7624715caf>\",\"Content-Length\":\"141376\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:95958771-8229-427a-b804-2e3aeec21933>\",\"WARC-Concurrent-To\":\"<urn:uuid:61d4e679-0bd3-4f8c-90bb-36e45b8dec12>\",\"WARC-IP-Address\":\"104.28.29.231\",\"WARC-Target-URI\":\"https://fomaa.net/money-word-problems-worksheets/\",\"WARC-Payload-Digest\":\"sha1:F5L7ODTVH6ERBRJA32GHJ5MLSWFULFCR\",\"WARC-Block-Digest\":\"sha1:7YQKIUSOKWDKGCUMEW2CQ57C3LR2OV3X\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-39/CC-MAIN-2019-39_segments_1568514573070.36_warc_CC-MAIN-20190917101137-20190917123137-00315.warc.gz\"}"} |
https://eprints.maths.manchester.ac.uk/316/ | [
"# Numerical analysis of a quadratic matrix equation\n\nHigham, Nicholas J and Kim, Hyun-Min (2000) Numerical analysis of a quadratic matrix equation. IMA Journal of Numerical Analysis, 20. pp. 499-519. ISSN 1464-3642",
null,
"PDF 499.pdf Restricted to Repository staff only Download (167kB)\n\n## Abstract\n\nThe quadratic matrix equation AX2+ BX + C = 0in n x nmatrices arises in applications and is of intrinsic interest as one of the simplest nonlinear matrix equations. We give a complete characterization of solutions in terms of the generalized Schur decomposition and describe and compare various numerical solution techniques. In particular, we give a thorough treatment of functional iteration methods based on Bernoulli’s method. Other methods considered include Newton’s method with exact line searches, symbolic solution and continued fractions. We show that functional iteration applied to the quadratic matrix equation can provide an efficient way to solve the associated quadratic eigenvalue problem ({lambda}2A + {lambda}B + C)x = 0.\n\nItem Type: Article quadratic matrix equation; solvent; generalized Schur decomposition; scaling; functional iteration; Bernoulli’s method; Newton’s method; exact line searches; continued fractions; quadratic eigenvalue problem MSC 2010, the AMS's Mathematics Subject Classification > 15 Linear and multilinear algebra; matrix theoryMSC 2010, the AMS's Mathematics Subject Classification > 65 Numerical analysis Ms Lucy van Russelt 27 Jun 2006 20 Oct 2017 14:12 https://eprints.maths.manchester.ac.uk/id/eprint/316",
null,
"View Item"
] | [
null,
"https://eprints.maths.manchester.ac.uk/style/images/fileicons/application_pdf.png",
null,
"https://eprints.maths.manchester.ac.uk/style/images/action_view.png",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7630717,"math_prob":0.93329436,"size":1629,"snap":"2023-40-2023-50","text_gpt3_token_len":375,"char_repetition_ratio":0.11938462,"word_repetition_ratio":0.027272727,"special_character_ratio":0.2295887,"punctuation_ratio":0.14492753,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9964052,"pos_list":[0,1,2,3,4],"im_url_duplicate_count":[null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-09T02:04:29Z\",\"WARC-Record-ID\":\"<urn:uuid:e956acf0-9f2c-42ab-bec5-0b64d1998126>\",\"Content-Length\":\"31143\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2d9f997d-e97b-475d-82fc-fd7d3426c672>\",\"WARC-Concurrent-To\":\"<urn:uuid:7b2e3e54-fc0a-4156-a5fb-bc840750113a>\",\"WARC-IP-Address\":\"130.88.96.130\",\"WARC-Target-URI\":\"https://eprints.maths.manchester.ac.uk/316/\",\"WARC-Payload-Digest\":\"sha1:UID6GYD76C42BJ57PZUWKMV5DV6NSHXE\",\"WARC-Block-Digest\":\"sha1:X2VLT3GWCE7BY5LBYD4Z3L7BX3MWMTSH\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100781.60_warc_CC-MAIN-20231209004202-20231209034202-00300.warc.gz\"}"} |
http://ejournal.unmus.ac.id/index.php/ekosos/article/view/1867 | [
"# PENGARUH DISIPLIN TERHADAP EFEKTIFITAS KERJA KARYAWAN PT. MITRA ANIM HA SEJAHTERA MERAUKE\n\n• Elisabeth Pruwo Gebze Universitas Musamus\n\n### Abstract\n\nStudy aims to determine the effect of discipline on the work effectiveness of employees of PT. Mitra Anim Merauke Prosperous Justice. The sample in this study were 33 respondents, the sampling method used was the technique of total sampling and sampling was done using a Likert Scale, then the data was processed using SPPS version 20 with a simple linear regression analysis technique. From the regression analysis obtained by the equation Y = 2,588 + 0,784 (X). Hypothesis testing using the t test shows that the discipline variable (X) is proven to have a significant effect on work effectiveness, this is evidenced by the value of t count, (X) = 0.784 with a significant level of 0,000 <0.05 so ha is accepted and h0 is rejected. R Square number of 57.1% shows that work effectiveness can be explained by disciplinary variables, while 42.9% is explained by other variables not examined in this study.\nPublished\n07-08-2019\nSection\nArtikel"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8962191,"math_prob":0.74567,"size":1284,"snap":"2020-10-2020-16","text_gpt3_token_len":313,"char_repetition_ratio":0.0921875,"word_repetition_ratio":0.0,"special_character_ratio":0.22040498,"punctuation_ratio":0.09322034,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9648951,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-04-08T11:15:09Z\",\"WARC-Record-ID\":\"<urn:uuid:ed1c5524-4633-467d-8f82-eba1a1ea826f>\",\"Content-Length\":\"17805\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:d6740e9a-2f04-4cf9-a8b9-62a6b621c2eb>\",\"WARC-Concurrent-To\":\"<urn:uuid:6276605d-33a9-489e-a81e-75d739919f2b>\",\"WARC-IP-Address\":\"103.247.10.83\",\"WARC-Target-URI\":\"http://ejournal.unmus.ac.id/index.php/ekosos/article/view/1867\",\"WARC-Payload-Digest\":\"sha1:ZFXDMZVY5WWA6ZS7SCHZNQKU52GTK4CH\",\"WARC-Block-Digest\":\"sha1:K4BMYEEL4ILLUPP5ID3NZOO63LJXD4TB\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-16/CC-MAIN-2020-16_segments_1585371813538.73_warc_CC-MAIN-20200408104113-20200408134613-00154.warc.gz\"}"} |
https://imat.entermedschool.com/t/yield-of-reactions/7725 | [
"# Yield of reactions\n\ni have a question, i cant understand how the answer is 20%\n35g of molecular chlorine is reduced to 13,5g of zinc chloride using metallic zinc in excess\nZn+Cl2->ZnCl2\n\nWhat is the question?\n\n35g of molecular chlorine is reduced to 13,5g of zinc chloride using metallic zinc in excess\nZn+Cl2->ZnCl2\n\nThis is not the question. This is the information before the question. What is it that has been asked?!\n\nyhe question is what is the yield of the reaction\n\nYou start with 35 g chlorine which is equal to 1 mole.\nYou produce 13.5 g zinc chloride which is equal to 13.5 g / 65+(2 . 35) g/mol = 0,1 mol. But chlorine atoms in the ZnCl2 is double in terms of mole. It means you have 0.2 mole chlorine.\nSo, from 1 mole of chlorine, you have reached to 0.2 mole chlorine. The yield will be:\nn(product)/n(reactant).100%=0.2/1.0=20%\n\nthe product isnt 0,1 mol and the reactant 0,2mol?\nim confused\nthe yield is n product/n reactant or n reactant/n product ?\n\n35g of molecular chlorine (Cl2) is 0.5mol. (MM of Cl x 2 = 35x2 = 70g/mol)\n13.5g zinc chloride is 0.1 mol.\n%yield rxn = 0.1/0.5 x 100 = 0.2 x 100 = 20%"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8861137,"math_prob":0.9933095,"size":1220,"snap":"2023-40-2023-50","text_gpt3_token_len":390,"char_repetition_ratio":0.14144737,"word_repetition_ratio":0.18666667,"special_character_ratio":0.32213116,"punctuation_ratio":0.13605443,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9861547,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-08T17:05:26Z\",\"WARC-Record-ID\":\"<urn:uuid:bd984211-925a-4dc5-90de-6287980fb2c1>\",\"Content-Length\":\"29322\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:9566dd48-c16d-4166-a600-cac7bd843ff9>\",\"WARC-Concurrent-To\":\"<urn:uuid:b366dc3b-c94c-4290-a148-13185e329e0c>\",\"WARC-IP-Address\":\"159.69.118.250\",\"WARC-Target-URI\":\"https://imat.entermedschool.com/t/yield-of-reactions/7725\",\"WARC-Payload-Digest\":\"sha1:GPTDTJUIG7LVZEDCSZWALND7BDU2B5FV\",\"WARC-Block-Digest\":\"sha1:DD5Y6O3QONRUX27OHT4GRNLGCOFJ2X7T\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100762.64_warc_CC-MAIN-20231208144732-20231208174732-00746.warc.gz\"}"} |
https://s3.amazonaws.com/Media4MathPlus/Videos/VideoTutorials/DistributivePropertyGr5-11_timesheet.html | [
"Video Tutorial Captions: Using the Distributive Property to Evaluate Expressions 11\n\nThe distributive property allows you to multiply a factor across multiple terms of an expression.\n\nIn this video we will look at the case where a is negative, b is positive, the coefficient of x is negative, and the expression in parentheses involves subtraction.\n\nIn this video we will look at the case where a is negative, b is positive, the coefficient of x is negative, and the expression in parentheses involves subtraction.\n\nA number is multiplied by -1, the product is decreased by 8, and the difference is multiplied by -5.\n\nUse the distributive property to write the expression.\n\nEvaluate the expression for x = 3.\n\nThis is an example of converting words into an algebraic expression.\n\nLet's start with this part, \"A number is multiplied by -1, the product is decreased by 8.\"\n\nLet's start with this part, \"A number is multiplied by -1, the product is decreased by 8.\"\n\nSince we don't know which number, we designate it as -x.\n\nThis number is decreased by 8, so we write -x - 8.\n\nThis difference, or the entire expression, is multiplied by -5, so we enclose the expression in parentheses and multiply the whole expression by -5, as shown here.\n\nThis difference, or the entire expression, is multiplied by -5, so we enclose the expression in parentheses and multiply the whole expression by -5, as shown here.\n\nThis is the mathematical equivalent of this verbal expression.\n\nWe now distribute the -5 to both terms, as shown here.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nWe get 5x + 40.\n\nWe evaluate this expression for x = 3, as shown here.\n\nWe get 15 + 40, which is 55.\n\nLet's look at another example.\n\nA number is multiplied by -1, the product is decreased by 15, and the difference is multiplied by -12.\n\nUse the distributive property to write the expression.\n\nEvaluate the expression for x = -7.\n\nThis is an example of converting words into an algebraic expression.\n\nLet's start with this part, \"A number is multiplied by -1, the product is decreased by 15.\"\n\nSince we don't know which number, we designate it as -x.\n\nThis number is decreased by 15, so we write -x - 15.\n\nThis difference, or the entire expression, is multiplied by -12, so we enclose the expression in parentheses and multiply the whole expression by -12, as shown here.\n\nThis difference, or the entire expression, is multiplied by -12, so we enclose the expression in parentheses and multiply the whole expression by -12, as shown here.\n\nThis is the mathematical equivalent of this verbal expression.\n\nWe now distribute the -12 to both terms, as shown here.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nWe get 12x + 180.\n\nWe evaluate this expression for x = -7, as shown here.\n\nWe get -84 + 180, which is 96.\n\nLet's look at a final example.\n\nA number is multiplied by -1, the product is decreased by 28, and the difference is multiplied by -32.\n\nUse the distributive property to write the expression.\n\nEvaluate the expression for x = -1.\n\nThis is an example of converting words into an algebraic expression.\n\nLet's start with this part, \"A number is multiplied by -1, the product is decreased by 28.\"\n\nLet's start with this part, \"A number is multiplied by -1, the product is decreased by 28.\"\n\nSince we don't know which number, we designate it as -x.\n\nThis number is decreased by 28, so we write -x - 28.\n\nThis difference, or the entire expression, is multiplied by -32, so we enclose the expression in parentheses and multiply the whole expression by -32, as shown here.\n\nThis difference, or the entire expression, is multiplied by -32, so we enclose the expression in parentheses and multiply the whole expression by -32, as shown here.\n\nThis is the mathematical equivalent of this verbal expression.\n\nWe now distribute the -32 to both terms, as shown here.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nThe product of these two negative terms is positive, and the negative sign here changes subtraction to addition.\n\nWe get 32x + 896.\n\nWe evaluate this expression for x = -1, as shown here.\n\nWe get -32 + 896, or 864."
] | [
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https://tellmeanumber.hostcoder.com/839704 | [
"# Question Is 839,704 a prime number?\n\nThe number 839,704 is NOT a PRIME number.\n\n#### How to check if the number 839,704 is a prime number\n\nA prime number can be divided, without a remainder, only by itself and by 1. For example, 13 can be divided only by 13 and by 1. In this case, the number 839,704 that you looked for, is NOT a PRIME number, so it devides by 1,2, 4, 8, 43, 86, and of course 839,704.\n\n# Question Where is the number 839,704 located in π (PI) decimals?\n\nThe number 839,704 is at position 132679 in π decimals.\n\nSearch was acomplished in the first 100 milions decimals of PI.\n\n# Question What is the roman representation of number 839,704?\n\nThe roman representation of number 839,704 is DCCCXXXIXDCCIV.\n\n#### Large numbers to roman numbers\n\n3,999 is the largest number you can write in Roman numerals. There is a convencion that you can represent numbers larger than 3,999 in Roman numerals using an overline. Matematically speaking, this means means you are multiplying that Roman numeral by 1,000. For example if you would like to write 70,000 in Roman numerals you would use the Roman numeral LXX. This moves the limit to write roman numerals to 3,999,999.\n\n# Question How many digits are in the number 839,704?\n\nThe number 839,704 has 6 digits.\n\n#### How to get the lenght of the number 839,704\n\nTo find out the lenght of 839,704 we simply count the digits inside it.\n\n# Question What is the sum of all digits of the number 839,704?\n\nThe sum of all digits of number 839,704 is 31.\n\n#### How to calculate the sum of all digits of number 839,704\n\nTo calculate the sum of all digits of number 839,704 you will have to sum them all like fallows:\n\n# Question What is the hash of number 839,704?\n\nThere is not one, but many hash function. some of the most popular are md5 and sha-1\n\n#### Here are some of the most common cryptographic hashes for the number 839,704\n\nCriptographic function Hash for number 839,704\nmd5 b692b75cdcb6318c93a2c816f1e718c3\nsha1 6299998d24c76c1eebb035cd57eba6616950c425\nsha256 241b00b2358824107f91467224c1d763080efcc4404ce5a31746d74520daaa3a\nsha512 b1d24af164e5925418a91db3657451fcffd62d2545f15a1dedf8e05fc29c21498b5835cdbc9d71f93684aee263a5d7dfb68bfece80b9dedd63394069a8b4af79\n\n# Question How to write number 839,704 in English text?\n\nIn English the number 839,704 is writed as eight hundred thirty-nine thousand, seven hundred four.\n\n#### How to write numbers in words\n\nWhile writing short numbers using words makes your writing look clean, writing longer numbers as words isn't as useful. On the other hand writing big numbers it's a good practice while you're learning.\n\nHere are some simple tips about when to wright numbers using letters.\n\n Numbers less than ten should always be written in text. On the other hand numbers that are less then 100 and multiple of 10, should also be written using letters not numbers. Example: Number 839,704 should NOT be writed as eight hundred thirty-nine thousand, seven hundred four, in a sentence Big numbers should be written as the numeral followed by the word thousands, million, billions, trillions, etc. If the number is that big it might be a good idea to round up some digits so that your rider remembers it. Example: Number 839,704 could also be writed as 839.7 thousands, in a sentence, since it is considered to be a big number\n\n#### What numbers are before and after 839,704\n\nPrevious number is: 839,703\n\nNext number is: 839,705"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8955299,"math_prob":0.96165025,"size":372,"snap":"2021-43-2021-49","text_gpt3_token_len":119,"char_repetition_ratio":0.18478261,"word_repetition_ratio":0.0,"special_character_ratio":0.35752687,"punctuation_ratio":0.1980198,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9876822,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-25T09:32:12Z\",\"WARC-Record-ID\":\"<urn:uuid:21119258-3d52-4d64-a8b2-6a786b178347>\",\"Content-Length\":\"16668\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:3c934f94-a848-432d-8df3-254b64c9d03c>\",\"WARC-Concurrent-To\":\"<urn:uuid:c447e9ae-0718-4581-830d-6ada9ad12cce>\",\"WARC-IP-Address\":\"51.254.201.96\",\"WARC-Target-URI\":\"https://tellmeanumber.hostcoder.com/839704\",\"WARC-Payload-Digest\":\"sha1:I6RYQLE75NKHBR6GNGARQLVRLVLV4KSV\",\"WARC-Block-Digest\":\"sha1:BBLFZBNKOXEI3WGTJTBYWKRFU2TEZZ2X\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323587659.72_warc_CC-MAIN-20211025092203-20211025122203-00121.warc.gz\"}"} |
https://scicomp.stackexchange.com/questions/3004/termination-criterion-of-golden-section-search/3005 | [
"# Termination Criterion of Golden Section Search\n\nReading an implementation of the golden section search, I came across the following termination test:\n\n$$| a - d | < \\varepsilon ( |b| + |c| )$$\n\nwhere $a < b < c < d$ are four points at which the function has been probed and $\\varepsilon$ is a user-provided tolerance. Why is this a good termination criterion? If I take a function and an initial bracket and translate them along the abscissa, the algorithm should probe the function in the same fashion, but this test will terminate the runs at different iterations...\n\nCheers!\n\n$|b|+|c|$ has the same order of magnitude as the extrema. Therefore, however many significant digits you have in $|b|+|c|$ is as accurately as you can calculate the location of the extrema. By ensuring your bracket is some fraction of this, you are ensuring you have a reachable condition while still getting as much accuracy as you can.\nFor example, let's say that your extrema is at $10^9$ and you are working in single precision. With 7 sig. figs. in single precision, you can only hope to get an answer to within $100$ of the actual value (single precision simply doesn't have the accuracy to do any better). In this case you would have to set your error tolerance (the r.h.s. of the inequality) to at least $100$ or your algorithm would never converge. In another case you could have a function with an extrema at $10^{-3}$. If you used the parameters from the last run, you would find a number somwhere between -100 and 100, and be nowhere close.\nHowever, if you set epsilon to $10^{-7}$, you will measure your extrema to an accuracy of about $100$ in the first case and an accuracy of about $10^{-10}$ in the second case before convergence. This is using the exact same parameters in both cases."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9561014,"math_prob":0.9743547,"size":1461,"snap":"2022-27-2022-33","text_gpt3_token_len":335,"char_repetition_ratio":0.12216884,"word_repetition_ratio":0.0,"special_character_ratio":0.24572212,"punctuation_ratio":0.08934708,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99136513,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-08-16T13:54:11Z\",\"WARC-Record-ID\":\"<urn:uuid:713b2a9d-ca31-4992-b556-8a3d69dd2f71>\",\"Content-Length\":\"221377\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:f7955261-bf26-40d9-99fc-58d6db39cd2b>\",\"WARC-Concurrent-To\":\"<urn:uuid:3f4eb084-aba0-41cf-b7a6-2fa6c86f49f3>\",\"WARC-IP-Address\":\"151.101.65.69\",\"WARC-Target-URI\":\"https://scicomp.stackexchange.com/questions/3004/termination-criterion-of-golden-section-search/3005\",\"WARC-Payload-Digest\":\"sha1:S4KPCHKT7VLZVTTSNP42KNNYQA6XNIQX\",\"WARC-Block-Digest\":\"sha1:UWVGYDJZDFCF4U6V3HUQP7NPQ64U2KUA\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-33/CC-MAIN-2022-33_segments_1659882572304.13_warc_CC-MAIN-20220816120802-20220816150802-00505.warc.gz\"}"} |
https://www.esaim-m2an.org/articles/m2an/ref/2015/02/m2an140036/m2an140036.html | [
"Subscriber Authentication Point\nFree Access\n Issue ESAIM: M2AN Volume 49, Number 2, March-April 2015 331 - 347 https://doi.org/10.1051/m2an/2014036 05 February 2015\n1. A. Aziz and P. Monk, Continuous finite elements in space and time for the heat equation. Math. Comput. 52 (1989) 255–274. [CrossRef] [Google Scholar]\n2. E. Bänsch, P. Morin and R.H. Nochetto, Preconditioning a class of fourth order problems by operator splitting. Numer. Math. 118 (2011) 197–228. [CrossRef] [MathSciNet] [Google Scholar]\n3. R.D. Falgout, J.E. Jones and U.M. Yang, The design and implementation of hypre, a library of parallel high performance preconditioners. In Numerical solution of partial differential equations on parallel computers. Springer (2006) 267–294. [Google Scholar]\n4. S. Hussain, F. Schieweck and S. Turek, Higher order galerkin time discretizations and fast multigrid solvers for the heat equation. J. Numer. Math. 19 (2011) 41–61. [CrossRef] [MathSciNet] [Google Scholar]\n5. J.L. Lions and E. Magenes, Non-homogeneous Boundary Value Problems and Applications. Vol. I. Springer, New York (1972). [Google Scholar]\n6. A. Logg, K.-A. Mardal and G. Wells, Automated solution of differential equations by the finite element method: The fenics book. Vol. 84. Springer (2012). [Google Scholar]\n7. P. Lesaint and P.A. Raviart, On a Finite Element Method for Solving the Neutron Transport Equation. Analyse Numérique. University Paris VI, Labo (1974). [Google Scholar]\n8. T. Richter, A. Springer and B. Vexler, Efficient numerical realization of discontinuous galerkin methods for temporal discretization of parabolic problems. Numer. Math. (2012) 1–32. [Google Scholar]\n9. F. Schieweck, A-stable discontinuous Galerkin–Petrov time discretization of higher order. J. Numer. Math. 18 (2010) 25–57. [CrossRef] [MathSciNet] [Google Scholar]\n10. F. Schieweck and G. Matthies, Higher order variational time discretizations for nonlinear systems of ordinary differential equations. Preprint 23/2011, Otto-von-Guericke-Universität Magdeburg (2011). [Google Scholar]\n11. D. Schötzau and C. Schwab, Time discretization of parabolic problems by the hp-version of the discontinuous galerkin finite element method. SIAM J. Numer. Anal. 38 (2000) 837–875. [CrossRef] [MathSciNet] [Google Scholar]\n12. D. Schötzau and C. Schwab, hp-discontinuous galerkin time-stepping for parabolic problems. C. R. Acad. Sci. Ser. I Math. 333 (2001) 1121–1126. [Google Scholar]\n13. V. Thomée, Galerkin Finite Element Methods for Parabolic Problems. Number 1054 in Springer Lect. Notes Math. 2nd edition. Springer (1984). [Google Scholar]\n14. T. Werder, K. Gerdes, D. Schötzau and C. Schwab, hp-discontinuous galerkin time stepping for parabolic problems. Comput. Methods Appl. Mech. Eng. 190 (2001) 6685–6708. [Google Scholar]\n\nCurrent usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.\n\nData correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.68643594,"math_prob":0.6162362,"size":3201,"snap":"2023-40-2023-50","text_gpt3_token_len":911,"char_repetition_ratio":0.14044416,"word_repetition_ratio":0.0372807,"special_character_ratio":0.28397375,"punctuation_ratio":0.22544283,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9715167,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-11-30T10:35:20Z\",\"WARC-Record-ID\":\"<urn:uuid:897daa29-aa89-410e-be18-d3889e8fd5a3>\",\"Content-Length\":\"47673\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0a335761-4de6-4c7c-82ec-1d15776674fa>\",\"WARC-Concurrent-To\":\"<urn:uuid:d73bb8de-c0f1-4787-94a3-c4328b2f3bd6>\",\"WARC-IP-Address\":\"167.114.155.65\",\"WARC-Target-URI\":\"https://www.esaim-m2an.org/articles/m2an/ref/2015/02/m2an140036/m2an140036.html\",\"WARC-Payload-Digest\":\"sha1:K5ZXT7DSSRYC4LLM6XQBYJJKH6ZDYEXO\",\"WARC-Block-Digest\":\"sha1:DFLIA6PSEAWLGBFDOTWM5BGMGZIHFGTV\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100184.3_warc_CC-MAIN-20231130094531-20231130124531-00459.warc.gz\"}"} |
https://buyassignment.us/category/programming/ | [
"# Your Homework Done For You\n\nWe will provide you with a paper that’s not only original but one that will get you an A or an A-.",
null,
"## needing a 10-page paper to compare Java and a non-imperative programming languag\n\nneeding a 10-page paper to compare Java and a non-imperative programming language. article attached to use as comparison and reference. appendix needed to solve chessboard problem provided.\n\n## While many program languages are compiled, Python is interpreted. This means tha\n\nWhile many program languages are compiled, Python is interpreted. This means that each line of code is converted to a machine-level language and then executed immediately. In your initial post, explain the difference between an interpreted language and a compiled...\n\n## The purpose of the final project is to combine everything from previous programm\n\nThe purpose of the final project is to combine everything from previous programming assignments and lecture into a practical implementation of a finite element method. The task is to write a matlab script (m-file) that solves linear heat conduction in 1D with a...\n\n## ***THE ESSAY MUST BE ON THE PROGRAMMING LANGUAGE CALLED ELM*** The purpose of th\n\n***THE ESSAY MUST BE ON THE PROGRAMMING LANGUAGE CALLED ELM*** The purpose of this essay is to: a. Undertake some research into a programming language related topic and present it in a report. b. Undertake some research into a programming language related topic and...\n\n## Consider the 3-node wireless network shown in the above figure, which consists o\n\nConsider the 3-node wireless network shown in the above figure, which consists of three nodes a, b, and c. Each node has a power constraint P. AWGN is added on each transmission with variance No. Consider two different scenarios (Uplink or downlink), first use Matlab...\n\n## Write a program which adds 1 + 2 + 3 + up to a number that the user chooses. I\n\nWrite a program which adds 1 + 2 + 3 + up to a number that the user chooses. If the user said to add the number up to 5 the addition would look like this 1 + 2 + 3 + 4 + 5. You will need to create a loop to add these numbers. When the loop is completed, use an if..."
] | [
null,
"https://buyassignment.us/wp-content/uploads/2021/11/nerd-final-rgb.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9050637,"math_prob":0.6059917,"size":1801,"snap":"2022-27-2022-33","text_gpt3_token_len":420,"char_repetition_ratio":0.13466889,"word_repetition_ratio":0.12140575,"special_character_ratio":0.24764019,"punctuation_ratio":0.14124294,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9538143,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-06-30T17:29:03Z\",\"WARC-Record-ID\":\"<urn:uuid:44fe6e60-474d-4189-a1a8-462e52780e39>\",\"Content-Length\":\"509573\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5659bd18-668a-40a6-90b9-e08b8dd773cc>\",\"WARC-Concurrent-To\":\"<urn:uuid:cbf3d42a-e9f3-4058-8a89-55f4f86e5f30>\",\"WARC-IP-Address\":\"66.29.156.23\",\"WARC-Target-URI\":\"https://buyassignment.us/category/programming/\",\"WARC-Payload-Digest\":\"sha1:S257ZGI5G3RWL4KT6QOXMQKV77E6NYPX\",\"WARC-Block-Digest\":\"sha1:ZQ4DOC4YWBO3MCJLLFTBFG6WGHQ66N7O\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-27/CC-MAIN-2022-27_segments_1656103850139.45_warc_CC-MAIN-20220630153307-20220630183307-00641.warc.gz\"}"} |
https://euclideanspace.com/prog/scratchpad/mycode/topology/simplex/join/index.htm | [
"Join, Star and Link are important operations on simplectical complexes. This page discusses a FriCAS implementation of these.\n\n## Join\n\nThe code includes a join operation like this:\n\n `simplicialJoin : (a : %, b : %) -> %`\n\nThe simplectial join of A and B is a simplectical complex with the vertices and simplexes defined as follows:\n\n##### Vertices\n\nAre disjoint union of vertices of A and vertices of B\n\nvertexSet(simplicialJoin(A,B)) = vertexSet(A)",
null,
"vertexSet(B)\n\nIf A and B have common vertices then the vertices of B will be renamed to make then different from A.\n\n##### simplexes\n\nA subset of A",
null,
"B is a simplex of simplicialJoin(A,B) if and only if it is:\n\n• a simplex of A or\n• a simplex of B or\n• the union of a simplex of A and a simplex of B\n\n#### Properties of simplicialJoin\n\nMay be geometrically thought of as a cone over A with tip of shape B.\n\nsimplicialJoin is commutative and associative.\n\ndim(simplicialJoin(A,B)) = dim(A) + dim(B) + 1\n\n### Example 1\n\n Here is an example of the join of 2 lines: [1, 2] and [3, 4] This gives 4 points and the following simplexes: [1, 2] [3, 4] [1, 2 , 3, 4]",
null,
"but each simplex contains all its sub simplexes so the join is just:\n\n(1, 2, 3, 4)\n\nWe can calculate this using FriCAS like this:\n\nNote: the implementation of simplicialJoin refactors the indices of the second operand, if necessary, to make sure the points being joined are disjoint.\n\n ```(1) -> line := line()\\$SimplicialComplexFactory(Integer) (1) points 1..2 (1,2) Type: FiniteSimplicialComplex(Integer) (2) -> simplicialJoin(line,line,true) (2) points 1..4 (1,2,3,4) Type: FiniteSimplicialComplex(Integer)```\n The above example is just one simplex so here is an example where the operands have multiple simplexes.",
null,
"Each operand has two simplexes. The result has all 4 combinations of these simplexes.\n\n ```(3) -> ASIMP := FiniteSimplicialComplex(Integer) (3) FiniteSimplicialComplex(Integer) Type: Type (4) -> v1:List(List(NNI)) := [[1::NNI,2::NNI],[2::NNI,3::NNI]] (4) [[1,2],[2,3]] Type: List(List(NonNegativeInteger)) (5) -> sc1 := simplicialComplex([],v1)\\$ASIMP (5) points 1..3 (1,2) (2,3) Type: FiniteSimplicialComplex(Integer) (6) -> simplicialJoin(sc1,sc1,true) (6) points 1..6 (1,2,4,5) (1,2,5,6) (2,3,4,5) (2,3,5,6) Type: FiniteSimplicialComplex(Integer)```\n\n## Star\n\nWe can calculate this using FriCAS like this:\n\n `x`\n\nWe can calculate this using FriCAS like this:\n\n `x`"
] | [
null,
"https://euclideanspace.com/maths/standards/notation/union.png",
null,
"https://euclideanspace.com/maths/standards/notation/union.png",
null,
"https://euclideanspace.com/prog/scratchpad/mycode/topology/simplex/join/join1.png",
null,
"https://euclideanspace.com/prog/scratchpad/mycode/topology/simplex/join/join2.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8319957,"math_prob":0.997564,"size":1625,"snap":"2022-27-2022-33","text_gpt3_token_len":420,"char_repetition_ratio":0.16594695,"word_repetition_ratio":0.05821918,"special_character_ratio":0.24061538,"punctuation_ratio":0.106583074,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9989804,"pos_list":[0,1,2,3,4,5,6,7,8],"im_url_duplicate_count":[null,3,null,3,null,1,null,1,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-08-07T18:49:45Z\",\"WARC-Record-ID\":\"<urn:uuid:1ed81a62-f540-4394-b4f7-5081bfc2d72d>\",\"Content-Length\":\"23957\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:1fc0e66e-0420-471c-baeb-ea90976e2f92>\",\"WARC-Concurrent-To\":\"<urn:uuid:55ae41c8-d485-4483-86fe-48cfce14b93b>\",\"WARC-IP-Address\":\"217.160.0.191\",\"WARC-Target-URI\":\"https://euclideanspace.com/prog/scratchpad/mycode/topology/simplex/join/index.htm\",\"WARC-Payload-Digest\":\"sha1:KPUSUVHGMZL3363GIACBE6JUO4KJYQTB\",\"WARC-Block-Digest\":\"sha1:TAEJEXUIUZF742GX4HO65SI4HXRWUPCZ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-33/CC-MAIN-2022-33_segments_1659882570692.22_warc_CC-MAIN-20220807181008-20220807211008-00696.warc.gz\"}"} |
https://www.transtutors.com/questions/let-h-t-and-x-t-be-two-periodic-signals-with-the-same-fundamental-period-t-0-and-fou-1236650.htm | [
"# Let h ( t ) and x ( t ) be two periodic signals with the same fundamental period T 0 and Fourier 1 answer below »\n\n1. Let h ( t ) and x ( t ) be two periodic signals with the same fundamental period T 0 and Fourier coefficients a k and b k , respectively. Show that the Fourier coefficients c k of y ( t ) = h ( t ) x ( t ) are given by the convolution sum\n\nc k =\n\n)'\n\n£ =−∞\n\na £ b k £ .\n\n## 1 Approved Answer\n\nshaik n\n4 Ratings, (9 Votes)\nhes, Fourier Series representation selts of and follous y its with priad To are as beta Ž...\n\n## Plagiarism Checker\n\nSubmit your documents and get free Plagiarism report\n\nFree Plagiarism Checker\n\n## Recent Questions in Mechanical Engineering",
null,
"Looking for Something Else? Ask a Similar Question\n\nAsk Now"
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null,
"https://files.transtutors.com/resources/images/similar_ques_art.png",
null
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https://www.codingame.com/playgrounds/14589/how-to-play-with-pointers-in-c/pointer-arithmetic-part-1 | [
"# How to play with pointers in C\n\nDonotalo\n111.3K views\n\nGiven an array arr[ARRAY_SIZE] we can get the address of the i-th element by arr + i as arr works as a pointer to the first element of the array. This is true for any pointer pointing any element of arr array.\n\nIn the example above, p points to the 4th element of array by the assignment p = arr + 3. The statement *p = 55; modifies the contents of the memory location pointed to by p, essentially arr.\n\nIn the following example, all array elements are modified by pointer:\n\nThis is what happens in the example above. arr is initialized as follows:\n\narr: 1 2 3 4\n\n\nThe address is hypothetical here. p points to the first element of arr by int32_t *p = arr;:\n\narr: 1 2 3 4\n^\n|\np\n\n\nA loop iterates ARRAY_SIZE times. In each iteration *p is multiplied by *p - the dereferenced value of p is squared - and stored in the memory location pointed to by p by the statement *p *= *p;. This modifies one array element in every iteration. The next statement, p++;, increments the pointer p, not by 1, but by sizeof(*p), equivalently sizeof(int32_t) - in this case 4 at a time.\n\nbefore 1st iteration: p = 10\nafter 1st iteration : p = 14\nafter 2nd iteration : p = 18\nafter 3rd iteration : p = 22\nafter 4th iteration : p = 26\n\n\nThis can be verified by the following example with 16 bit integer:\n\nNotice that p is incremented by 2, or sizeof(int16_t), at every iteration.\n\nWarning: When the loop exits in the above example, p points to one past the last element of arr. That area is outside the declared variables in the program. Accessing that location is undefined behaviour.\n\nint16_t arr[ARRAY_SIZE] = { 0 };\nint16_t *p = arr;\n\nfor (int i = 0; i < ARRAY_SIZE; i++)\n{\nprintf(\"%p\\n\", p);\np++;\n}\n\n/* printf(\"%d\\n\", *p); */ /* Fatal: p points to outside location of declared variable - undefined behaviour */",
null,
"",
null,
"",
null,
""
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null,
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https://prowriters.firstclassessaywriters.com/2018/11/28/solutionanalyze-the-cash-flows-for-two-proposed-projects/ | [
"# [Solution]Analyze the cash flows for two proposed projects\n\nAnalyze the cash flows for two proposed projects, Project A and Project B. Each project has a cost of \\$10,000, and the desired rate of…\n\nAnalyze the cash flows for two proposed projects, Project A and Project B. Each project has a cost of \\$10,000, and the desired rate of return for each project is 12%. Expected cash flows are:YearProject AProject B0(\\$10,000)(\\$10,000)1\\$6,500\\$3,5002\\$3,000\\$3,5003\\$3,000\\$3,5004\\$1,000\\$3,500The IRR for Project A is 18% while for Project B is 15%.After analyzing the cash flow data for both projects, assess the following:1. Calculate each projectAcâ¬?cs Net Present Value (NPV)2. Identify the project that is the best option, if only one project can be selected. Give reasons for your choice.Please include detailed calculations when identifying the NPV.\n\nThe post Analyze the cash flows for two proposed projects\n\nAssignment status: Solved by our experts\n\n>>>Click here to get this paper written at the best price. 100% Custom, 0% plagiarism.<<<",
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"",
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"Posted on"
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null,
"http://ift.tt/2h3Rxhz",
null,
"http://ift.tt/2h4hMUS",
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