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I am trying to compile a basic code in C++ using the Netbeans 11.1 IDE. For this I have installed Cygwin tools that incorporate the compiler, make tool and debugger. In Netbeans I installed the plugin to be able to develop in C/C++ and testing with C I have no problem. When writing the following code, I note that the IDE shows two errors: #include <iostream> int main(int argc, char** argv) { std::cout << "Hello world"; return 0; } 1) In the instruction #include the IDE indicates the message "Cannot find include file ". 2) The IDE also marks the std identifier as wrong saying "Unable to resolve identifier std" | What is the difference between g++ and gcc? Which one of them should be used for general c++ development? |
i need this as a Tikz drawing but im no able to do the back and forward arrows (1)&(2) and in total im not sure what im doing at all.: May somebody show me as an starter how to do Tikz drawings correctly? | What packages do you use and recommend for creating graphics in your LaTeX documents? As this is a community wiki post, please add your package to the accepted answer (or add a comment, and someone with >100 rep will add it to the CW answer), and include a brief description of what differentiates it from others and how it can be used (GUI drawing tool which generates code, type in raw text, or generates image for inclusion in document). We'll eventually sort these answers under headings. |
I had a flight ticket from Madrid (MAD, Spain) to Miami (MIA, US) to fly in March with AirEuropa. I got an email saying the flight was cancelled 13 days and 21 hours before the flight. Am I eligible to get a cash refund? Am I entitled to further compensation? The flight was cancelled the day after Donald Trump forbade the entrance of non-residents to the US because of COVID-19. The answer from an AirEuropa agent is no, I am not. They offer a voucher that has to be spent within 2020, which IMO is very limited. As I understand the EU rules, I can choose to get a refund unless the carrier can prove the cancellation was because of extraordinary circumstances. I guess COVID-19 is extraordinary, but Trump did not forbid flights to the US, but the entrance of some people, so AirEuropa could have flown that day. | Recently a flight was cancelled and I think I was mistreated. On the day, about 5 of the flights from the airport got cancelled, they claimed it was because of bad weather. I had to wait for two more hours after my estimated departure time only to get information that my flight was cancelled. However, 5 minutes from the information being anounced, another airlines plane departed from the same airport, and other departures were also succesful. I did not get any re-routing options and was told I can re-book or refund at their website. They did not have any available flights until after more than a week and therefore I am not able to get home for Easter. I cried all day as I am spending Easter alone now. Am I eligible for compensation? Shall I challenge the airline that the weather conditions were not to be considered as extreme circumstances? |
Note: Not a duplicate, for I need an answer for Windows Vista, 7, 8, 8.1, and 10. The solution for 8 and above does not work for Windows 7 or Vista. I often talk with naive users who have no idea what's in their system, and less interest, and who use Windows Vista, 7, 8, 8.1, or 10. Some maintenance processes for the software I support differ if an SSD is installed vs an HDD, i.e., defragmentation. I need a solution which works on every Vista or 7 machine, which means no third party apps, only native Microsoft 'ware. Asking the naive user to reboot, go into the BIOS, obtain the drive model, and then search for the drive by model and then parse out if SSD or HDD is too complex, so a suggestion of how to discover in Windows if an SSD is installed in lieu of an HDD is desired. Use of tools already in Windows is required; third party apps are not viable. Thank you. | I've recently received an assembled PC. I don't know if the disk is an SSD or old HDD (whether SATA or other technologies). I can't find a way to tell if the disk is SSD or not, apart from the size of the disk. However, now that the sizes of SSDs are getting close to that of HDDs, checking the size is not a good and robust way to distinguish drive type. Is there some other way to determine if the disk is an SSD? |
I've read on this site several times that it is better to say $i^2=-1$ as opposed to $i=\sqrt{-1}$. If we let $i^2=-1$, why doesn't $i=-\sqrt{-1}$? This makes sense since $(-\sqrt{-1})(-\sqrt{-1})=-1$. Does the property $x^2=4\Rightarrow x=\pm2$ not hold here? If so, could someone please explain? Note; This question is unique because I'm asking just about the fact that since $i^2=-1$, why isn't $i$ equal to $\pm\sqrt{-1}$. User64786 and Dietrich Burde's comment's reveal that what I am asking about is different than the tagged question. It seems that the answer is a matter of convention, not algebra. Thank you. | this is something that came up when working with one of my students today and it has been bothering me since. It is more of a maths question than a pedagogical question so i figured i would ask here instead of MESE. Why is $\sqrt{-1} = i$ and not $\sqrt{-1}=\pm i$? With positive numbers the square root function always returns both a positive and negative number, is it different for negative numbers? |
After installing Ubuntu 12.04 LTS , would i be able to update my system to 13.04 without losing my data? And how i will do it? Can Anyone Tell me? | I am currently using Ubuntu 10.04. I know there is a 10.10 release, but can I upgrade directly to 11.04? Could you walk me through the steps please? |
I am using the MAPE formula, ABS(actual-forecast)/actual *100, but this raises problems when the actual values are zero. Is it possible to add 1 to the denominator and calculate this way? Would I get accurate percent error data, as long as I am consistent with the formula? Any ideas are appreciated, thank you | How do I calculate relative error when the true value is zero? Say I have $x_{true} = 0$ and $x_{test}$. If I define relative error as: $\text{relative error} = \frac{x_{true}-x_{test}}{x_{true}}$ Then the relative error is always undefined. If instead I use the definition: $\text{relative error} = \frac{x_{true}-x_{test}}{x_{test}}$ Then the relative error is always 100%. Both methods seem useless. Is there another alternative? |
The problem is the following: $$ a_1 = \sqrt6 \ \text{ and } \ a_{n+1}=\sqrt{6 +a_n} \ \\ \ \\ \text{Find} \ \lim_{n\to \infty}a_n $$ I tried dividing $a_{n+1}$ by $a_n$, which is bigger than one. I assume one can use the comparison test to conclude that this limit goes to infinity? But how should I go about finding the limit if I don't have a calculator to see that $\dfrac{a_{n+1}}{a_n}$ = 1,18... ? | (Fitzpatrick Advanced Calculus 2e, Sec. 2.4 #12) For $c \gt 0$, consider the quadratic equation $x^2 - x - c = 0, x > 0$. Define the sequence $\{x_n\}$ recursively by fixing $|x_1| \lt c$ and then, if $n$ is an index for which $x_n$ has been defined, defining $$x_{n+1} = \sqrt{c+x_n}$$ Prove that the sequence $\{x_n\}$ converges monotonically to the solution of the above equation. Note: The answers below might assume $x_1 \gt 0$, but they still work, as we have $x_3 \gt 0$. This is being repurposed in an effort to cut down on duplicates, see here: . and here: . |
Let $a,b,c$ be positive real numbers such that $abc=1$. Prove that $$a^2+b^2+c^2\geq a+b+c$$. Also, state the condition for equality. My Attempt, $a,b,c$ are real and positive numbers, then $$(a-1)^2+(b-1)^2+(c-1)^2\ge 0$$ $$a^2-2a+1+ b^2-2b+1+c^2-2c+1\ge 0$$ $$a^2+b^2+ c^2-2(a+b+c)+3\ge 0$$. I have made a start in this way, but I am not sure if this works. Please help me, with any simple and beautiful method. | Let $a, b, c$ be positive real numbers such that $abc = 1$. Prove that $a^2 + b^2 + c^2 \ge a + b + c$. I'm supposed to prove this use AM-GM, but can't figure it out. Any hints? |
I've just finished watching the last episode of Naruto(220), and when I started watching Shippuden the first episode seemed odd, I have only watched the first 5 minutes of that episode and didn't think it was right, it was naruto and sakura running through some kind of dungeon trying to find Sasuke, they eventually heard an explosion and rushed there, they found Sasuke standing on top of a small crater. That's about as far as I got. My question is, am I on the correct episode or am I missing some episodes? Or perhaps did I start on the wrong one? | I watched all Naruto episodes on Netflix. I want to know if episode 220 leads right into Naruto Shippuden. I only watched a few minutes of episode 1 in Shippuden, but just watching it, I feel like I'm missing more episodes that lead into Shippuden. Is there anymore Naruto episodes after Episode 220? Like, do they show Pervy Sage actually training Naruto or does his path of training leads into Shippuden? |
I would like to use special characters as the german umlaute ä, ö, ü, etc. (also ß) in the source file in plain TeX as I may use them in LaTeX using \usepackage[utf8]{inputenc}. The use of \input utf8-pl and typesetting with plain TeX leads to the error message "The encTeX extension of TeX is not found“. Is there a way to circumvent this problem? I am using TeXShop Version 3.75 on a MacBook Air with macOS Sierra (Version 10.12.1) and encTeX is apparently part of TeXShop. | I'm using TeX with the plain format. On my keyboard there is the 'è' character (as well as é, ò, à, ù, ì). I'd like to make it work so that, when put è in the input file, TeX transforms it into \`e, i.e. the letter e with an accent. I think I have to change the character code of è and do something like that, but I don't know what to do exactly. Can you help me? |
I have written Longest Common SubSequence in Python using recursion with memoization: def print2d(table): print '\n'.join([''.join(['{:4}'.format(item) for item in row]) for row in table]) a="123" b="213" m = [[-1]*len(b)]*len(a) def lcs(i,j): print i, j print2d(m) if i== -1 or j == -1: return 0; if m[i][j] != -1: return m[i][j] res = 0 res = max(res, lcs(i, j-1)) res = max(res, lcs(i-1, j)) if a[i] == b[j]: res = max(res, 1 + lcs(i-1,j-1)) m[i][j]=res return res print lcs(len(a)-1,len(b)-1) print2d(m) All those print statements are there because I didn't get the correct result and decided to take a look at how the algorithm works. What I found surprised me. If you run it yourself you can see the tables printed and they look ok until: 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 -1 0 -1 -1 0 -1 -1 0 -1 -1 1 1 1 -1 -1 1 -1 -1 1 -1 -1 1 0 1 -1 -1 1 -1 -1 1 -1 -1 0 1 1 -1 -1 1 -1 -1 1 -1 -1 Why all of a sudden on the step 0 -1 the whole first column became 0 ? So, I quickly created C++ program doing exactly the same thing the same way: #include <iostream> #include <iomanip> #include <string> #include <cstring> using namespace std; string a = "123", b = "213"; int mem[1000][1000]; int lcs(int i, int j) { cout << i << " " << j << "\n"; for(auto i = 0; i < a.length(); i++){ for(auto j = 0; j < b.length(); j++){ cout << setw(4) << right << mem[i][j]; } cout << "\n"; } if (i == -1 || j == -1) { return 0; } if (mem[i][j] != -1) { return mem[i][j]; } int res = 0; res = max(res, lcs(i, j - 1)); res = max(res, lcs(i - 1, j)); if (a[i] == b[j]) { res = max(res, 1 + lcs(i - 1, j - 1)); } mem[i][j] = res; return res; } int main(){ memset(mem, -1, sizeof mem ); int r = lcs(a.length()-1, b.length()-1); cout << r << "\n"; return 0; } And it works as expected. Corresponding tables look like this: 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 0 -1 0 -1 -1 -1 -1 -1 -1 -1 -1 1 1 0 -1 -1 1 -1 -1 1 -1 -1 1 0 0 -1 -1 1 -1 -1 1 -1 -1 0 1 0 -1 -1 1 -1 -1 1 -1 -1 I am puzzled why Python and C++ code that are not that different produce such drastically different results. Am I missing something about how recursive functions in Python work? Or is it because in Python I use list of lists and not 2D array as in C++? | I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3 The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]] Then I changed one of the innermost values: my_list[0][0] = 5 Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]] which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it? |
I have an option clash between package xcolor and another package, but I don't know which. Here is my MWE \documentclass[10pt]{beamer} \setbeamertemplate{navigation symbols}{} \usepackage{caption} \usepackage{subcaption} \usepackage{url} \usepackage{color} \usepackage[usenames]{xcolor} \author{The author} \title{Package conflicts} \date{October 3rd, 2012} \begin{document} This is supposed to be \textcolor{olivegreen}{olivegreen} \end{document} And the error message is : This is pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian) entering extended mode (./error_xcolor.tex LaTeX2e <2009/09/24> <blablabla> ! LaTeX Error: Option clash for package xcolor. I hope this is enough log for you guys. At this time of the day, I'm hoping for America to save my french ass ... again : ) | I'm writing a report, and have a rather large table in my appendix. I'd like to emphasize some specific values by coloring some single cells. I'm trying to do it with xcolor. But receiving the error: ! LaTeX Error: Option clash for package xcolor. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.17 The package xcolor has already been loaded with options: [] There has now been an attempt to load it with options [table] My preamble looks as follows \documentclass[a4paper,oneside,article]{memoir} \usepackage[latin1]{inputenc} \usepackage[T1]{fontenc} \usepackage[danish]{babel} \usepackage{lmodern} \usepackage{graphicx} \graphicspath{{Figures/}} \usepackage{fullpage} \usepackage{modroman} \usepackage{float} \usepackage{caption} \usepackage[numbers]{natbib} \usepackage{url} \usepackage{pgfplots} \usepackage{mathtools} \usepackage[table]{xcolor} And take out of my table \begin{table} \centering \begin{tabular}{|c|c|c|} \hline \cellcolor{green!25}D & x & D/$L_0$ \\ \hline 65 & 2600 & 0,417\\ \hline 60 & 2400 & 0,385\\ \end{tabular} \caption{Bestemmelse af bølgehøjde} \label{tab:Q1} \end{table} Read some other questions asking more or less the same. And the answer to them seems to be a "collision" between packages. I have no idea how to find the problem. So my question is: Where is the "collision"? How on earth would I have found it without help ? |
I'd like to clear recent inputs in terminal not cls or clear but when you press up or down. How do I clear this list so that when I rename sudo to nodood or something you cannot press up to view the new sudo perhaps my script will read input. EDIT: Note pressing Ctrl + R in terminal will let you search history like history | grep searchQueryString Another useful tip is sudo !! which re-executes last command with sudo prefixed | I want to clear all previous commands from the history of my server. I used history -c and it seems all things are cleared but when I ssh to the server, all the commands are still there. How can I clear them permanently? |
Let me get one thing straight first. I am not saying that fundamental constants like the speed of light don't have the value that we know they have today. What I am asking is whether the value of a constant could change with time. For example, we measure today that the speed of light is almost $300000000\,m/s$, but this measurement was made over the last century. But what if a long time ago (billions of years ago) that constant had a different value? So, it's always the limit of how fast something can move, but that limit slowly changes with time. To conclude,i am asking if there is any kind of evidence that any of the fundamental constants like the speed of light remain constant in time or if we just took that for granted. | Cavendish measured the gravitation constant $G$, but actually he measured that constant on the Earth. What’s the proof that the value of the gravitation constant if measured on Neptune would remain the same? What’s the guarantee of its being a constant? There are many such constants; I just took one example so that you can understand what I intended to ask. Is the value of the speed of light really a constant? Who knows that it wouldn’t change its value on other planets, or, more precisely, what’s the guarantee that the speed of light remains the same even near a black hole? If no one can ever reach a black hole, then how can a scientist claim the value of the speed of light? |
Everyone. Help me. This script at the above URL is very useful to create another object symmetrically (in Blender 2.7) import bpy import re import mathutils scn = bpy.context.scene objs = bpy.context.selected_objects for obj in objs: new_obj = obj.copy () new_obj.data = obj.data.copy () scn.objects.link (new_obj) new_obj.name = re.sub (r '\. l \. \ d \ d \ d', '.r', new_obj.name) for m, n in zip (new_obj.modifiers, obj.modifiers): if m.type == "MIRROR": axes = [m.use_x, m.use_y, m.use_z] dir = [(1,0,0), (0,1,0), (0,0,1)] for axis, direction in zip (axes, dir): if axis: new_obj.data.transform (mathutils.Matrix.Scale (-1, 4, direction)) new_obj.data.flip_normals () obj.modifiers.remove (n) new_obj.modifiers.remove (m) I want to use this with Blender 2.8, but I don't know how to modify it. Does anyone have a way to modify it? Please tell me. Thank you. フィードバックを送信 履歴 保存済み コミュニティ | I've created a humanoid model that I'm exporting as an FBX for use in Unity. The model is composed of many sub-meshes, because I want the model to "explode" in the game, and send the individual pieces flying. So, for example, I have individual "Hand", "LowerArm", "UpperArm", etc objects in my model. Currently each object has an unapplied Mirror modifier to keep the model symmetrical. The issue is that when exporting this model as an FBX, the "Hands" object contains both the left and right hands as a single object, as opposed to being separate objects. A very manual way to address this is to apply all of my Mirror modifiers, then manually separate the vertices on one half of the model to a new object. The obvious downside to that is that it's destructive, and I can't easily edit the model anymore after doing that. I was hoping there might exist a "separation" modifier, which could intelligently separate a mesh into two pieces depending on whether the vertices are on one side of the model or another. That way, the modifier would be applied on export, but I wouldn't need to apply my Mirror modifiers in Blender. So, in short: Is there a way to export an FBX of my model that separates my current "Hand" object into "LeftHand" and "RightHand", without having to manually apply the Mirror modifiers, and manually separate the vertices? Thanks, -Dan |
Is it possible to get generic type arguments from within the executed generic method without directly referencing them (i.e. typeof(T0))? For example: public static List<(T0?, T1?, T2?, T3?, T4?)> ParseParameter<T0, T1, T2, T3, T4>(this JArray array, params string[] columnCodesCaseIndependent) { var genericArgs = MethodBase.GetCurrentMethod()!.GetGenericArguments(); // ... return result; } Testing the above in debugger I see: {Name="T0", FullName=null} same as above for the rest So the types are not the ones actually used. net5.0 | Let's say I have a generic member in a class or method, like so: public class Foo<T> { public List<T> Bar { get; set; } public void Baz() { // get type of T } } When I instantiate the class, the T becomes MyTypeObject1, so the class has a generic list property: List<MyTypeObject1>. The same applies to a generic method in a non-generic class: public class Foo { public void Bar<T>() { var baz = new List<T>(); // get type of T } } I would like to know what type of objects the list of my class contains. So what type of T does the list property called Bar or the local variable baz contain? I cannot do Bar[0].GetType(), because the list might contain zero elements. How can I do it? |
I have a spreadsheet with 2 columns. These columns have telephone numbers in them. I need a list of where the same telephone numbers exists in both columns. These need to be listed in column C as the matching telephone number. Excel 2010. Regards | In Excel I have two columns, one with about 3000 rows and one with about 100. I need to find all of the matches between the two columns and put them in a separate column. I have to do this every morning so if there is a way to do so, I'd like to make it as automated as possible. |
This code used to work fine with java 6 and 7, but running it with a jre 1.8 method getMajorJavaVersion returns 2. Is it a bug, or are we doing something wrong? public static void validateJavaVersion() { // check whether the current JVM version is at least Java 6 if (JdkVersion.getMajorJavaVersion() < JdkVersion.JAVA_16) { throw new APIException("OpenMRS requires Java 6, but is running under " + JdkVersion.getJavaVersion()); } } getJavaVersion gives the version as 1.8.0_20 Note that JdkVersion belongs to Spring, not to the JRE itself. Another question: is there any API to compare two java versions? Preferably native but we can use Apache commons and Spring too. | Is there a standard idiom for comparing version numbers? I can't just use a straight String compareTo because I don't know yet what the maximum number of point releases there will be. I need to compare the versions and have the following hold true: 1.0 < 1.1 1.0.1 < 1.1 1.9 < 1.10 |
I'm a bit stuck on this... my only thought was to use second induction on $n$, which works well enough for the case where $n$ is composite and has two or more distinct prime factors, but if $n$ is prime or a prime power the induction hypothesis does nothing, so I'm thinking there must be another way. Any ideas? | Let $(a_n)$ be a strictly increasing sequence of positive integers such that: $a_2 = 2$ and $a_{mn} = a_m a_n$ for $m, n$ relatively prime. Show that $a_n = n$, for every positive integer $n$. This is a result apparently due to Paul Erdős, and has a proof by induction. I tried like this, $a_{10}=a_2a_5$. After this what we can do? [Editor's comment] Possibly due to the apparent simplicity of the conditions it may be difficult to appreciate the subtleties of this question. If we try and construct a counterexample like $a_3=4$, $a_4=5$, $a_5=6$, then the requirements dictate $a_6=8$, $a_{10}=12$, $a_{15}=24$. At this point we realize that we have been speeding. For monotonicity forces $a_9\le 11$, and therefore $a_{18}\le22<a_{15}$, violating the requirements. It is not obvious why something similar ruins all the modifications to the sequence $a_n=n$. [/comment, JL] |
Setting $h=c=1$ the familiar Wikipedia result is that the Gravitational constant, $G$ goes like $$ G = \frac{1}{m_{Planck}^2}$$ However, I suspect that this is only true in 4 or (3+1) dimensions? Or just 3 spatial dimensions. But how would this change if I work in d-dimensions? I guess I would have $$ G_d = \frac{1}{m_{Planck}^{f(d)}}$$ where $f(d)$ is a dimensional dependent number. But then what is $f(d)$? | From Newton's law of gravitation we know that $$F=G\frac{m_1m_2}{r^2}$$ where $G$ is gravitational constant. We can also see that it has dimensions $$[G]=\frac{[L]^3}{[M][T]^2}$$ and we have a good numerical estimate of its value ($G\simeq 6.67\times 10^{-11} N(m/kg)^2$). I've read (for instance in the paper I'm currently mostly interested in, Kerr/CFT correspondence) that in higher dimensions, there are 4 dimensional gravitational constant, and in the search for explanation of it, I've also found that in string theory we have gravitational constants of higher dimensions. But I haven't seen any formula that would give me mean to calculate it in higher dimensions. Is there such a thing, or is the definition of it theory dependent? |
Is there any chance to get the exact coordinatas of the voronoi polygons? I am using Qgis software and I have the "center" (redpoint) of the polygons and I would like to export the polygons corners coordinates. | I want to convert polygons into points using QGIS. I know how it's done in ArcGIS Desktop. |
How do I know which of the following questions is grammatically correct? On/In/At what sites will this product be able to be sold? On/In/At which sites will this product be able to be sold? What/Which sites will this product be able to be sold? And does it make sense to write "will this product be able to be sold"? Thank you! | Possible Duplicate: Which is best in your opinion? "You can find this content on the X website." "You can find this content in the X website." "I posted the comment on FB." "I posted the comment in FB." Thanks for your opinions and advice! |
I am trying to write a program where the names of some functions are dependent on the value of a certain macro variable with a macro like this: #define VARIABLE 3 #define NAME(fun) fun ## _ ## VARIABLE int NAME(some_function)(int a); Unfortunately, the macro NAME() turns that into int some_function_VARIABLE(int a); rather than int some_function_3(int a); so this is clearly the wrong way to go about it. Fortunately, the number of different possible values for VARIABLE is small so I can simply do an #if VARIABLE == n and list all the cases separately, but I was wondering if there is a clever way to do it. | As mentioned in many of my previous questions, I'm working through K&R, and am currently into the preprocessor. One of the more interesting things — something I never knew before from any of my prior attempts to learn C — is the ## preprocessor operator. According to K&R: The preprocessor operator ## provides a way to concatenate actual arguments during macro expansion. If a parameter in the replacement text is adjacent to a ##, the parameter is replaced by the actual argument, the ## and surrounding white space are removed, and the result is re-scanned. For example, the macro paste concatenates its two arguments: #define paste(front, back) front ## back so paste(name, 1) creates the token name1. How and why would someone use this in the real world? What are practical examples of its use, and are there gotchas to consider? |
Is there a way to trigger code when my class is subclassed? class SuperClass: def triggered_routine(subclass): print("was subclassed by " + subclass.__name__) magically_register_triggered_routine() print("foo") class SubClass0(SuperClass): pass print("bar") class SubClass1(SuperClass): print("test") Should output foo was subclassed by SubClass0 bar test was subclassed by SubClass1 | In Python, what are metaclasses and what do we use them for? |
So, I've been tasked with solving the above. I've gone up to the general solution which wasn't too tricky: $$U(x,y)=e^{-x}(\frac{R_1e^{4x}}{4}+f(y-x))$$ However, it gets a bit strange for me when I'm equipped with any initial/boundary data alongside it. So doing the obvious thing and just inputting the respective values gives me $$U(x,0)=e^{-x}(\frac{R_1e^{4x}}{4}+f(-x))=0,$$ but then what does that tell me and how do I get the overall solution from it? Do I just solve for $f(-x)$? If so, then $$\frac{R_1e^{4x}}{4}+f(-x)=0,$$ or equivalently $$R_1e^{4x}+4f(-x)=0,$$ then $$4f(-x)=-R_1e^{4x},$$ so $$f(-x)=\frac{-R_1e^{4x}}{4} \Rightarrow f(-x)=Ce^{4x}.$$ So then what? Do I then try to apply this to when $f$ takes $y-x$ as its argument? So then we'll have $$U(x,y)=f(y-x)=Ce^{4x-4y},$$ and conclude that as our solution? I realise that something has gone wrong here, because when I do compute the partial derivatives and substitute them back into my original question, the left hand side and right hand side don't quite equal each other? Or, do I end up keeping the general solution that I obtained and then substitute my $f(y-x)$ expression that I obtained when putting in the initial data? | It is asked to solve the PDE $$u_x + u_y + u = e^{x+2y}$$ My attempt: We have that $$\frac{dx}{1}=\frac{dy}{1}=\frac{du}{e^{x+2y}-u} $$ $\Rightarrow \frac{dy}{dx}=1 \Rightarrow y=x+C_1 \iff C_1=y-x$ $\Rightarrow \frac{du}{dx}= e^{x+2y}-u \iff \dot{u}+u=e^{x+2y} \iff \\ \frac{d}{dx}(e^x u) = e^{2x+2y} \iff u = e^{-x} ( \frac{1}{2}e^{2x+2y} + C_2)$ As $u$ is constant along its characteristics: $$u(x,y)=\frac{e^{-x}}{2}(e^{2x+2y} + 2C_2(y-x))$$ where $C_2$ is any function of one variable. But wolfram gave the following answer $$u(x,y)=\frac{e^{-x}}{4}(e^{2x+2y} + 4C_2(y-x))$$ as you can check What am I doing wrong? |
I'm answering a question with a suggestion to use rename, and I realize I don't know what package it comes from (as part of the answer, I imagine saying something like "if you don't have rename, it's installed as part of [package]"). man rename tells me to SEE ALSO: mv(1), perl(1) - so my first thought is that it was installed with perl. A related answer, , helps me figure out that the perl package includes prename but not rename - and it turns out that my /usr/bin/rename points to /etc/alternatives/rename which points to /usr/bin/prename So this is still kind of confusing. Did /etc/alternatives/rename point somewhere else before I installed perl? Is there a general way to tell which package something comes from? | Simple enough question: is there some shell command (or GUI method) I can use that, given the path to a file on my system, tells me what package put it there? Assuming the file did in fact come from a package, that is. Bonus question: what if it's a file that isn't installed on my system? Is there, say, a website that will let me look up a file and see what packages, if any, provide it? |
I am reading through this article about the special case of the positive mass theorem in general relativity. I do not understand the section below: In particular what does it mean to isometrically embed an $n$-dimensional Riemannian manifold $(M,g)$ in a higher dimensional space, and where does the embedding given for the $n=3$ Schwarzschild metric come from? I assume we are referring to the standard definition of isometric embeddings using pullbacks of covariant tensor fields. I assume the author refers to the map between Riemannian manifolds $f: \mathbb{R}^3-B_{2m}\to\mathbb{R}^4$ given by $f(x,y,z)=(x,y,z,\sqrt{8m(r-2m)})$. I have tried to check if the Schwarzchild metric on $\mathbb{R}^3$ is the pullback of the flat metric on $\mathbb{R}^{4}$, however this doesn't appear to be true... | I am reading through this article about the special case of the positive mass theorem in general relativity. I do not understand the section below: In particular what does it mean to isometrically embed an $n$-dimensional Riemannian manifold $(M,g)$ in a higher dimensional space, and where does the embedding given for the $n=3$ Schwarzschild metric come from? I assume we are referring to the standard definition of isometric embeddings using pullbacks of covariant tensor fields. I assume the author refers to the map between Riemannian manifolds $f: \mathbb{R}^3-B_{2m}\to\mathbb{R}^4$ given by $f(x,y,z)=(x,y,z,\sqrt{8m(r-2m)})$. I have tried to check if the Schwarzchild metric on $\mathbb{R}^3$ is the pullback of the flat metric on $\mathbb{R}^{4}$, however this doesn't appear to be true... |
If I open a question and the question title is too long, then the back button doesn't work and the only way to use the app again is to restart it. App Version: 1.4.5 Device: iPhone 5s (Global) OS Version: Version 10.0.2 (Build 14A456) | The bug displayed in the attached screenshot occurs consistently for me while running the developer beta of iOS 10 using v1.5.2 of the Stack Exchange app on an iPhone 6. I was able to recreate this by simply tapping on any question or answer in my feed with a long title. This doesn't appear to be a bug with iOS 10 itself since I haven't seen it in other apps, but I could be wrong. |
The Functional Equation satisfied by the exponential $f(x)=e^{kx}$ is of the form: $$ f(x+y)=f(x)f(y), \quad f(0)=1, f'(0)=k $$ Show that $f'(x) = kf(x)$. Attempt I tried applying Chain Rule to the functional equation but it doesnt work. $$ [f(x+y)]'=f'(x)f(y)+f(x)f'(y) $$ Let $y=0$, then $f'(x)=f'(x)\cdot 1+k\cdot f(x)$, which is absurd because it is saying $$ [e^{kx}]' = [e^{kx}]'+ke^{kx} $$ So I was wondering why we cannot apply chain rule directly to the Cauchy Functional Equation? It seems that I need to show directly $$ [f(x+0)]' = f'(0)f(x) $$ but I cannot see how to obtain this from the definition of the functional equation. | Problem: A function $f: \mathbb R \to \mathbb R$ satisfies equation $f(x+y)=f(x)f(y)$ for all $x,y\in \mathbb R$ and $f(x)\neq 0$ for all $x \in \mathbb R$. If $f'(0)=2$, find $f'(x)$ in terms of $f(x)$ Solution: $f(x+y)=f(x)f(y)$ Differentiating partially w.r.t $x$ we get $f'(x+y)=f'(x)f(y)$ At x=0 $f'(y)=f'(0)f(y)$ $f'(y)= 2f(y)$ $f'(x)= 2f(x)$ Can we solve question like above ? I mean,$f'(x)$ represent ordinary diff. while I used it for partial diff. |
How to find the sum $$\frac {1}{6} + \frac {5}{6.12} + \frac {5. 8}{6.12.18} + \frac {5.8.11}{6.12.18.24} + \cdots.$$ I have tried to make this series in the form $1 + n x + \frac {n (n + 1) x^2}{2!} + \frac {n (n+1) (n+2)x^3}{3!} + \cdots$. But I failed to do so. Can anyone please help me | How to find infinite sum How to find infinite sum $$1+\dfrac13+\dfrac{1\cdot3}{3\cdot6}+\dfrac{1\cdot3\cdot5}{3\cdot6\cdot9}+\dfrac{1\cdot3\cdot5\cdot7}{3\cdot6\cdot9\cdot12}+\dots? $$ I can see that 3 cancels out after 1/3, but what next? I can't go further. |
import javax.sound.sampled.AudioInputStream; import javax.sound.sampled.AudioSystem; import javax.sound.sampled.Clip; public class Test13 { public Test13() { ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); System.out.println(classLoader.getResourceAsStream("audio1.wav")); try{ Clip clip = AudioSystem.getClip(); AudioInputStream inputStream = AudioSystem.getAudioInputStream(classLoader.getResourceAsStream("audio1.wav")); clip.open(inputStream); clip.start(); clip.close(); } catch (Exception e) { System.out.println("something failed"); } } } //When I click on Run, at Console window there showed : //<terminated> Test13 [java application]C:\Program Files\java\jdk1.8.0_221\bin\javaw.exe | I am using the following code to play a sound file using the java sound API. Clip clip = AudioSystem.getClip(); AudioInputStream inputStream = AudioSystem.getAudioInputStream(stream); clip.open(inputStream); clip.start(); The method call to the Clip.start() method returns immediately, and the system playbacks the sound file in a background thread. I want my method to pause until the playback has completed. Is there any nice way to do it? EDIT: For everyone interested in my final solution, based on the answer from Uri, I used the code below: private final BlockingQueue<URL> queue = new ArrayBlockingQueue<URL>(1); public void playSoundStream(InputStream stream) { Clip clip = AudioSystem.getClip(); AudioInputStream inputStream = AudioSystem.getAudioInputStream(stream); clip.open(inputStream); clip.start(); LineListener listener = new LineListener() { public void update(LineEvent event) { if (event.getType() != Type.STOP) { return; } try { queue.take(); } catch (InterruptedException e) { //ignore this } } }; clip.addLineListener(listener ); } |
The electrostatic repulsion between me and the chair keeps me hovering above the chair at all times. What is the average distance that exists between any two everyday object due to electrostatic repulsion and gravity? How can this distance be determined? | What is the distance between, say, a cup of coffee and the table it rests on? What is the distance between two touching hands? |
var a:Double = 7599 var b:Double = 7598 var x = a / 100 (75.98999999999999) var y = b / 100 (75.98) Can anyone tell me why y is calculating to 2 decimal places and more importantly why x isn't? I basically use this function in a RoundUp and RoundDown function but it doesn't work for certain numbers. | Consider the following code: 0.1 + 0.2 == 0.3 -> false 0.1 + 0.2 -> 0.30000000000000004 Why do these inaccuracies happen? |
var Person = function(name){ this.name = name; this.sayName = function () { console.log("My Name is "+ this.name); } } var nitin = new Person("Nitin"); nitin.sayName(); // My Name is Nitin // Codebreak var Person = function(name){ this.name = name; } Person.prototype.sayName = function (){ console.log("My Name is "+ this.name); } var nitin = new Person("Nitin"); nitin.sayName(); // My Name is Nitin I was going though inheritance in JS, but for both the approaches above result is same. So I am confused here which approach to follow and why? | What's the difference between var A = function () { this.x = function () { //do something }; }; and var A = function () { }; A.prototype.x = function () { //do something }; |
I'm trying to install on my Ubuntu 16.04 server. I've found tutorial online on how to install it. The problem is I'm stuck at step 3: I'm getting the following error: sudo dpkg -i wkhtmltox-0.12.2.1_linux-trusty-amd64.deb dpkg: error processing archive wkhtmltox-0.12.2.1_linux-trusty-amd64.deb (-- install): package architecture (amd64) does not match system (armhf) Errors were encountered while processing: wkhtmltox-0.12.2.1_linux-trusty-amd64.deb Anybody can help me install this? | I am trying to install current stable version 0.12.1, but it only installs 0.9.9. Any chance to install latest version with apt-get install? It seems that 0.9.9 is very old :( |
I need to prepare presentation about calculus, paying special attention for examination of function of one variable. I am not very advances in the topic, but I'm looking for book which contains interesting, not fundamental, examples from fields like continuity of functions, limits, differentiability. Unfortunately, I didn't learn from english book (english isn't my national language), so books, from which I learned, contained examples for beginners, which could show just problem. According to differentiability there was just mention that, for example, function y=|x| is not differentiable in x=0, and I'm looking for examples not so obvious. For example Weierstrass function is interesting example in that field. I didn't find book more complicated, different than basics for students. This could be student's book or notebook. I ask for help because I have no experience with foreign books for analysis, calcus. I will be grateful, if someone decides to help me and to recommend a book | This question is a of the common question asking for calculus references. It is here to away the repetition, and give a canonical resource for calculus references. I'm looking for a resources to learn single-variable calculus. |
I came across this error while installing cpusim3.9.0: Exception in thread "main" java.lang.NoClassDefFoundError: cpusim.util.CPUSimConstants at cpusim.Main.main(Main.java:135) I followed this installation process: Open a Terminal with Ctrl + Alt + T. Download the CPUSim-Zipfile: wget http://www.cs.colby.edu/djskrien/CPUSim/CPUSim3.9.0.zip Install unzip sudo apt-get install unzip Unzip the CPUSim3.9.0.zip-file unzip CPUSim3.9.0.zip Go into the newly created folder cd CPUSim3.9.0/ If you haven't install a Java JRE or JDK yet, you need to install it now. If you are unsure write java -version. if this results with an error you must install it. You need to first enable the universe repository. Then you can install the Java Runtime Environment (JRE). sudo apt-get install openjdk-7-jre Create an executable start script cat <<'EOF' > cpusim #!/bin/bash java -cp CPUSim3.9.jar:jhall.jar:CPUSimHelp3.9.jar cpusim.Main -m SampleAssignments/Wombat1.cpu -t SampleAssignments/W1-0.a EOF chmod +x cpusim the error came after I pressed ./cpusim (also I'm using ubuntu on virtual box) | I'm going according to the steps mentioned on the cs colby . First, I installed java on my system by typing the following commands- sudo add-apt-repository ppa:linuxuprising/java sudo apt-get update sudo apt-get install oracle-java10-set-default sudo apt install oracle-java10-set-default Then, according to the instructions, I downloaded the .zip file, extracted it and then in the terminal typed java -cp .:richtextfx-fat-0.6.10.jar:reactfx-2.0-MR.jar -jar CPUSim-4.0.11.jar But this didn't work. of command 1 terminal. Here is a screenshot of all the files that are there in the CPUSim folder, On observing the names of the folders present, I thought that the previous command was wrong. So I tried the following ones, java -cp .:richtextfx-fat-0.6.10.jar:reactfx-2.0-M4.jar -jar CPUSim-4.0.11.jar java -cp .:richtextfx-0.6.10.jar:reactfx-2.0-M4.jar -jar CPUSim-4.0.11.jar But none of them seems to work. Now when I click on the CPUSim-4.0.11.jar file, nothing happens. I have just switched to Ubuntu from Windows 10, and have a very little knowledge about how things work here. Please tell me how I could install and run CPUSim 4.0.11 on Ubuntu 18.04 LTS. |
I wrote this code: double sums = Math.round(sum) * 100.00 / 100.00; I am only getting one 0 after the decimal (e.g. 10.0) but I want 10.00. Is there something wrong ? | What I would like is a method to convert a double to a string which rounds using the half-up method - i.e. if the decimal to be rounded is 5, it always rounds up to the next number. This is the standard method of rounding most people expect in most situations. I also would like only significant digits to be displayed - i.e. there should not be any trailing zeroes. I know one method of doing this is to use the String.format method: String.format("%.5g%n", 0.912385); returns: 0.91239 which is great, however it always displays numbers with 5 decimal places even if they are not significant: String.format("%.5g%n", 0.912300); returns: 0.91230 Another method is to use the DecimalFormatter: DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385); returns: 0.91238 However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this: 0.912385 -> 0.91239 0.912300 -> 0.9123 What is the best way to achieve this in Java? |
I am running long program on server, which is basically Jar file of java program. I want to keep this program running even if SSH terminal is closed, how I can keep this program running on server? | I sometimes have long running processes that I want to kick off before going home, so I create a SSH session to the server to start the process, but then I want to close my laptop and go home and later, after dinner, I want to check on the process that I started before leaving work. How can I do that with SSH? My understanding is that if you break your SSH connection you will also break your login session on the server, therefore killing the long running process. |
Okay so I have Ubuntu command prompt and I've done sudo apt-get install ubuntu-desktop sudo apt-get install build-essential and many other things, but I still cant get Ubuntu GUI (on my desktop). Can someone help me? | Trying to run a Ubuntu server for the first time... But everything is in a terminal. Is there a way to switch to a GUI? |
I have been very lucky and have been able to travel this year. However, now that I am preparing to go back to the US, I realize that I have collected various small amounts of money (usually equivalent to $20–30) in a variety of world currencies. It is great to have such a 'coin collection', but since I'm travelling and living on a budget, I really would like to be able to actually use the money. What's the best strategy for changing various world currencies (e.g. Swiss francs, Thai baht, rupees, etc.) into dollars? If I go to a US bank where I have an account (e.g. Bank of America, Citibank) with foreign currency, will they be able to change it back into dollars? | Tonight I just cleaned my room and while doing this I found some money. I counted it and I found out that there are a lot of coins from 25 different countries. I know that normally banks don't exchange foreign currencies in coins, but is there a way so that I can still get some money for my foreign coins? |
I try to make an atlas for a big map. Is there the possibility to insert a textfield on the diffrent pages of the atlas pages to see wich name the neighbouring pages have? | I was asked in a recent training course if QGIS could automatically calculate the next/previous and above/below page numbers for a map book created using the atlas generator. I managed to work out a fairly reasonable label expression for a regular grid if you know the width and height of the grid. But we then started to think of realistic examples where we don't want to draw pages that don't contain our district of interest, such as this one of my home county: So this afternoon I had a play at a python script to work out the 4 neighbours I was interested in for each grid cell and added those values to my grid (this is heavily based on Ujaval Gandhi's ): for f in feature_dict.values(): print 'Working on %s' % f[_NAME_FIELD] geom = f.geometry() # Find all features that intersect the bounding box of the current feature. # We use spatial index to find the features intersecting the bounding box # of the current feature. This will narrow down the features that we need # to check neighboring features. intersecting_ids = index.intersects(geom.boundingBox()) # Initalize neighbors list and sum neighbors = [] neighbors_sum = 0 for intersecting_id in intersecting_ids: # Look up the feature from the dictionary intersecting_f = feature_dict[intersecting_id] int_geom = intersecting_f.geometry() centroid = geom.centroid() height = geom.boundingBox().height() width = geom.boundingBox().width() # For our purpose we consider a feature as 'neighbor' if it touches or # intersects a feature. We use the 'disjoint' predicate to satisfy # these conditions. So if a feature is not disjoint, it is a neighbor. if (f != intersecting_f and not int_geom.disjoint(geom)): above_point = QgsGeometry.fromPoint(QgsPoint(centroid.asPoint().x(), centroid.asPoint().y()+height)) below_point = QgsGeometry.fromPoint(QgsPoint(centroid.asPoint().x(), centroid.asPoint().y()-height)) left_point = QgsGeometry.fromPoint(QgsPoint(centroid.asPoint().x()-width, centroid.asPoint().y())) right_point = QgsGeometry.fromPoint(QgsPoint(centroid.asPoint().x()+width, centroid.asPoint().y())) above = int_geom.contains(above_point) below = int_geom.contains(below_point) left = int_geom.contains(left_point) right = int_geom.contains(right_point) if above: print "setting %d as above %d"%(intersecting_f['id'],f['id']) f['above']=intersecting_f['id'] if below: print "setting %d as below %d"%(intersecting_f['id'],f['id']) f['below']=intersecting_f['id'] if left: print "setting %d as left of %d"%(intersecting_f['id'],f['id']) f['left']=intersecting_f['id'] if right: print "setting %d as right of %d"%(intersecting_f['id'],f['id']) f['right']=intersecting_f['id'] # Update the layer with new attribute values. layer.updateFeature(f) layer.commitChanges() This works just fine. But to be honest the whole creating a test point to the North and then testing all the possible neighbours seems wrong. However after an afternoon of wracking my brain I can't think of a better way to determine what is a particular grid cell's northern neighbour? Ideally I'd like something simple enough to put in a print composer text box, but I suspect that's too much to ask for. |
I do listen stuff before falling asleep and for that I set the native timer on my iPhone to stop playing after ~30 minutes. When I cook something I ask Siri to set timer for let's say 5 minutes, but after the 5 minutes, my iPhone just stops playing (there is nothing playing at that moment actually). How do I tell Siri I want to be notified after the timer runs out? | I normally use the iPhone timer to sleep the device after I've dozed off to some music or podcast. Unfortunately this means that when I ask Siri to set a timer for some cooking, Siri waits the allotted time and turns off the phone rather than notify me that the time is up. Any solutions to this? |
My codes are follows: \documentclass{book} \usepackage[natbib,authordate,backend=biber]{biblatex-chicago}% \addbibresource{bibsamp.bib} \begin{document} \citet{baker_tenenbaum_saxe06} and \citet{baker_saxe_tenenbaum09} \printbibliography \end{document} Content of test.bib @inproceedings{baker_tenenbaum_saxe06, Author = {C. L. Baker and J. Tenenbaum and R. Saxe}, Booktitle = {Advances in Neural Information Processing Systems}, Date-Added = {2014-01-30 12:16:28 +0100}, Date-Modified = {2014-02-01 00:11:49 +0100}, Publisher = {Cambridge, MA: MIT Press}, Title = {Bayesian Models of Human Action Understanding}, Volume = {18}, Year = {2006}} @article{baker_saxe_tenenbaum09, Author = {C. L. Baker and J. Tenenbaum and R. Saxe}, Date-Added = {2014-01-30 12:11:35 +0100}, Date-Modified = {2014-02-05 23:44:19 +0100}, Journal = {Cognition}, Number = {3}, Pages = {329--349}, Title = {Action Understanding as Inverse Planning}, Volume = {113}, Year = {2009}} Output I need to repeat the author names instead of three em dash rule even though the author names are same. Please suggest... | for my seminar paper, I have to quote a scientific paper. This is the corresponding .bib entry: @article{hochreiter1991untersuchungen, title={Untersuchungen zu dynamischen neuronalen Netzen}, author={Sepp Hochreiter}, journal={Diploma, Technische Universit{\"a}t M{\"u}nchen}, volume={91}, number={1}, year={1991} } In my bibliography, however, the scientific paper appears as follows — . 1991. „Untersuchungen zu dynamischen neuronalen Netzen“. Diploma, Technische Universität München 91 (1). The problem is that the author is replaced by a dash. Does anyone know where the error in my bibtext is? |
I have a type ‘C’ Schengen visa valid from June 9 2019 - June 8 2020. In September, I will be going to Thessaloniki in Greece to observe in a hospital (I work in healthcare), supposedly for 6 months. The Greek consul in my country advised me to use my current Schengen visa for this trip. However, I know the maximum length of stay is 90 days. My question is, while in Greece, can I apply for an extension to the 90-day stay? I know you can apply to extend if your visa is expiring, but mine is not. I just want to extend the length of stay. | My daughter applied at the Italian Consulate in Philadelphia, and they gave her two entries for 20 days (we thought it was for 20 days each entry). She was in Italy 12 days, then went to England for 1 week and flew to Venice to take a 10-day cruise. She couldn't make it because they said she has only 8 remaining days, but she still has a land tour already paid this week. What can she do? Can she extend the Schengen visa for 12 more days? Right now, she is in Madrid, but next week she has to fly from Barcelona to Paris to start with the tour. What would happen if she decides to take the tour with the expired visa? She is a US permanent resident. |
I really don't understand why this code #include <map> template<typename T, typename U> std::ostream& operator<<(std::ostream& o, const std::map<T,U>& input) { for (std::map<typename T,typename U>::iterator it=input.begin(); it!=input.end(); ++it) { o << it->first << " => " << it->second << '\n'; } return o; } returns this compilation error: error: wrong number of template arguments (1, should be 4) error: provided for ‘template<class _Key, class _Tp, class _Compare, class _Alloc> class std::map’ can anyone help me please?? | In templates, where and why do I have to put typename and template on dependent names? What exactly are dependent names anyway? I have the following code: template <typename T, typename Tail> // Tail will be a UnionNode too. struct UnionNode : public Tail { // ... template<typename U> struct inUnion { // Q: where to add typename/template here? typedef Tail::inUnion<U> dummy; }; template< > struct inUnion<T> { }; }; template <typename T> // For the last node Tn. struct UnionNode<T, void> { // ... template<typename U> struct inUnion { char fail[ -2 + (sizeof(U)%2) ]; // Cannot be instantiated for any U }; template< > struct inUnion<T> { }; }; The problem I have is in the typedef Tail::inUnion<U> dummy line. I'm fairly certain that inUnion is a dependent name, and VC++ is quite right in choking on it. I also know that I should be able to add template somewhere to tell the compiler that inUnion is a template-id. But where exactly? And should it then assume that inUnion is a class template, i.e. inUnion<U> names a type and not a function? |
I'm new to R and I'm trying to find the correlation between a numeric variable and a factor one. I have a data frame with the following 3 columns: 1. nr of clicks (range 0:14) 2. response (1= "YES", 0="NO") 3. Frequencies - no of counts (how many clients responded "YES" with X no of clicks) So, the no of rows of the table is 28. How can I measure the correlation between the dependent variable, response, and the numeric one? Thanks! Rodica | I have a dataframe with many observations and many variables. Some of them are categorical (unordered) and the others are numerical. I'm looking for associations between these variables. I've been able to compute correlation for numerical variables (Spearman's correlation) but : I don't know how to measure correlation between unordered categorical variables. I don't know how to measure correlation between unordered categorical variables and numerical variables. Does anyone know how this could be done? If so, are there R functions implementing these methods? |
I want to transfer Blender scene with cloth simulation to Maya and Houdini. The solution of this problem involves answers to two questions: - How to "bake" the animation, so it does not depend on the cloth modifier (how to bake cloth simulation into shape key animation, if this is what I need to do)? - In what format it is better to save the final result for future transfer to Maya (fbx?)? | I'm simulating a cloth. How can I bake the cloth simulation into keyframed vertices or shape keyed vertices? |
I want to make cookies thicker looking can i add some yeast into cookies dough to make them thicker. | I've never seen anything with both yeast and baking powder. What's the reason for that? Shouldn't e.g. muffins get even more fluffy by adding some yeast? Or bread by adding baking powder? I know there are differences in flavor, but there are cakes with yeast as also non-sweet things with baking powder. So that shouldn't be the problem... |
In a paper I am reading, the author wrote as "The problem does exhibit the property, ..." However, I learned that exhibit is a verb, so I think that "The problem exhibits the property, ..." is correct. What is different between them? In a similar way, I saw "do exist" instead of just "exist" many time. | It is possible to use do as an auxiliary verb to denote emphasis: I do like ice cream Is it also possible to use it when do is the main verb as well? E.g.: I did do (it). He does do (it). I do do (it). Are the sentences above acceptable? Do they sound unnatural? |
How do I Show that for $t \in \mathbb{R}$ $$ \mid e^{it} - 1 \mid\leq \mid t \mid $$ Is it enough to show that $\mid e^{it} \mid = 1$? | Prove $|e^{i\theta} - 1| \leq |\theta|$, for all real numbers $\theta$. |
I am working with python 3.5 lists on a very performance dependent application. After searching for I wondered about the colon [:] in that solution. I am aware that it creates a copy (theoretically), but in this example see no purpose for it. Does it maybe save memory? Or does it have to do with shallow/deep copies? Will python behave differently for the cases of an existing mylist = ... versus mylist[:] = ...? I've found some similar questions but none with how python behaves given such a assignment. | I need a good explanation (references are a plus) on Python's slice notation. To me, this notation needs a bit of picking up. It looks extremely powerful, but I haven't quite got my head around it. |
Considering there are icons for the tag, the tag, the tag, and some other ones, won't it be possible to have an icon for the tag too? | What does an icon on the tag mean, for example the "rg" before the sql-server tag as pictured below? |
I accidentally created a file with the name - (eg, seq 10 > -). Then I tried to use less to view it, but it just hangs. I understand that this is happening because less - expects input from stdin, so it does not interpret the - as a file name. I tried less \- but it does not work either. So, is there any way to indicate less that - is a file and not stdin? The best I could get is: find -name '-' -exec less {} + | How do you remove a file whose filename begins with a dash (hyphen or minus) -? I'm ssh'd into a remote OSX server and I have this file in my directory: tohru:~ $ ls -l total 8 -rw-r--r-- 1 me staff 1352 Aug 18 14:33 --help ... How in the world can I delete --help from a CLI? This issue is something that I come across in different forms on occasion, these files are easy to create, but hard to get rid of. I have tried using backslash rm \-\-help I have tried quotes rm "--help" How do I prevent the minus (dash or hyphen) character to be interpreted as an option? |
We know that Gauss has shown that the sum $S$ of the first $n$ natural numbers is given by the relation: $$S=\frac{n(n+1)}{2} \tag{*}$$ The proof that I remember most frequently is as follows: Let be $S=1+2+\dotsb+(n-1)+n \tag{1}$ We can write $S$ it also as: $\tag{2} S=n+(n-1)+\dotsb+2+1.$ By adding up member to member we get: $\tag{3} 2S=\underbrace{(n+1)+(n+1)+\dotsb+2+1}_{n-\mathrm{times}}.$ Hence we obtain the $(^\ast)$. How many other simple methods exist to calculate the sum of the first natural numbers? | Apparently $1+2+3+4+\ldots+n = \dfrac{n\times(n+1)}2$. How? What's the proof? Or maybe it is self apparent just looking at the above? PS: This problem is known as "The sum of the first $n$ positive integers". |
Can i asked for a text book recommendation to study time series analysis if i don't have a strong background in Probability? My background is in Pure Mathematics and my probability background is only as good as the basic understanding of discrete and continuous random variables. I tried many text but all of them requires a strong probability background. | I started by Time Series Analysis by Hamilton, but I am lost hopelessly. This book is really too theoretical for me to learn by myself. Does anybody have a recommendation for a textbook on time series analysis that's suitable for self-study? |
Prove: $$ \text{lcm}(x,y)=\frac{|x\cdot y|}{\text{gcd}(x,y)}$$ I used many ways to do it, all failed. One of them was to represent $|x\cdot y|$ as a sum of primes then $\text{gcd}(x,y)$ as a sum of primes and do the operation but I ended up with a false result since some prime factors were left. So what is the simplest proof for the gcd to lcm relation? | I was reading a text book and came across the following: Important Results (This comes immediately after LCM:) If 2 [integers] $a$ and $b$ are given, and their $LCM$ and $HCF$ are $L$ and $H$ respectively, then $L \times H = a \times b$ Can some please help me understand why the above result is true? Thanks in advance. |
I use the Stack Exchange Combined flair on my personal website. I understand the criterion of inclusion for a SE network in this list, and also that the participating sites are shown listed in the decreasing order of total reputation. I noticed that recently my Combined flair started displaying 6 instead of 5 sites. I am curious to know if there is a maximum number of sites that can be displayed in the Combined flair? Also, does setting a site as hidden removes it from the Combined flair? | Somewhat related to ... It appears the combined flair has space for about 7 Stack Exchange sites (I'm estimating, I've only got 4 on there now).The combined flair can fit 7 different Stack Exchange sites. What happens if a user has more than 200 rep on more sites than the seven sites that fit on the flair? Does the flair Use what first went on and ignore anything beyond what fits? (Mine currently seems to be ordered based on how old the profiles are) Use the top-repped accounts, and order them by rep? (Mine may be doing this, but I can't tell at this time, since rep order and age order are the same) Break? Randomly select some sites? Has anyone encountered this before, or is it unusualy to have 200+ rep on that many different Stack Exchange sites? |
I've have this socket on my laptop (Lenovo Z570). What is this port and what is it used for? And what does that symbol mean (I expected a LOCK symbol)? | When I inspected my monitor I found a hole with a lock symbol (pictured below). What is this? What is the function of this hole? My monitor is a Samsung Syncmaster SA100. |
I'm practicing on camera movements based on a tutorial by polyjord and I noticed that my keyframes are missing in the timeline at some point: Q: How do I get my keyframes back? | Soo, I think I accidentally pressed something and I don't know how to fix that. The thing is that keyframes in the timeline are know hidden behind the numbers The animation still works, I can add new keyframes, but I cannot select any of them as they're hidden... does anyone know how to get back to default settings? |
Kinda like if you were to wake up and just know that something is wrong, the only thing I can think of is maybe "Avant vu" which means (directly translated) "Before seen" and is a word like deja vu but other than that I can't think of anything. | It may be something that will happen to the person who is having the feeling but it may also be to several persons, as might occur with a highly destructive earthquake, for instance. The word or phrase would be used in the following sentence: “I’m no spiritualist but I have a feeling of ___. I hope it’s just a feeling." EDIT - The phrase I'm looking for conveys a much stronger feeling than "I have a bad hunch". It is about something catastrophic which the person feels is "going to happen in a few minutes". |
let $x_0 = a$ and $x_1 = b $ , $x_{n+1} = ( 1- \frac{1}{2n}) x_n + \frac{1}{2n} x_{n-1}$, $n\ge 1$ find $\lim_{n \to \infty}x_n$? My attempt: I take $x_n = a + (b-a) + \dots + (x_n - x_{n-1})$ after that that I am not able to proceed further. Please help me or any hints/solution will be appreciated. Thank you and thanks in advance for giving hints/solutions | Consider the following sequence : $x_{0}=a$ , $x_{1}=b$ , $x_{n+1}=\bigl(1-\frac{1}{2n}\bigr)x_{n}+\frac{1}{2n}x_{n-1}.$ Find $\displaystyle \lim_{n\to \infty}x_{n}.$ I calculate $x_{2}$ , $x_{3}$ ,$x_{4}$ ,but I could not find any relationship between any two consecutive pair. But I found that the sum of the coefficients of $a$ & $b$ is equal to the term in denominator in each $x_{i}$. How we find this limit...? |
Why am I getting a black spot in the cylinder. The scene is nothing special consists of few objects with no materials except for the cylinder, and lighting comes from the environment map. The cylinder is smooth shaded and simply using a glossy material with the default settings. Could this possibly have to do with render settings. I have tried re-adding the cylinder and creating a new glossy material but with the same results. | How do I remove them? They don't appear when using flat shading. Nothing in the scene can cause this. |
It seems the syntax highlighter is not able to handle Java. Any idea how to help fix this? A sample code is below, and and in stackoverflow. try (Statement stmt = con.createStatement()) { ResultSet rs = stmt.executeQuery(query); while (rs.next()) { String coffeeName = rs.getString("COF_NAME"); int supplierID = rs.getInt("SUP_ID"); float price = rs.getFloat("PRICE"); int sales = rs.getInt("SALES"); int total = rs.getInt("TOTAL"); System.out.println(coffeeName + ", " + supplierID + ", " + price + ", " + sales + ", " + total); } } EDIT: Well, it seems syntax highlighter doesn't work in stackexchange, but in stackoverlow instead. For the same case: most of the times, it doesn't work, e.g. And now it does | I noticed that sometimes my code gets highlighted in different colors when rendered. What is syntax highlighting? How does it work? Why isn't my code being highlighted correctly? How do I report a bug or request a new language? How do I use syntax highlighting? What languages are currently available on Stack Exchange? |
I see two kinds of equal signs in different resources in regards to defining sets. One is := and the other is = An example : S = {1, 2, 3} or S := {1, 2, 3} I realized that resources concerned with mathematical analysis uses the latter whereas others use the former. Is there any difference in the meaning of both notations? | I am sorry if this is quite elementary question. But I always think, that why we use $:=$ at some places, instead of $=$. Is there any fundamental difference between these two? Before reading Terry Tao's blog (4 months ago), I had never seen a symbol like this (:=). |
I don't understand at all what the time operators are in quantum mechanics. I thought that given a wave function, because it's a function of time, we could simple put in any time in the future to find it's time evolution. What is this time operator, why is it unitary, and how does it work? | Is there one central reason why there is no "Time" operator in QM? I know this question has been asked before, but I thought I would try to stimulate some fresh thinking. |
I have a sequence that is defined recursively by $a_1=1, a_{n+1}=\frac{1}{1+a_n}$ and it is increasing for $n>1$ and bounded above. How would I find the limit to the recursive sequence? | We define $$a_{n+1}=\frac{1}{1+a_n}, a_0=c> 0$$ I stumbled across that sequence and Mathematica gives me that it converges against $\frac{1}{2} \left(\sqrt{5}-1\right)$ which doesn't even depend on $a_0$. Normally I show that sequences converge by seeing that they are monotonic and then the limit can be easily found by setting $a_n=a_{n+1}$, but this one seems to be alternating. Also by checking OEIS I noticed that $a_n=1/g(n)$ where $g(n)$ gives the $n+1$'th . I would be glad if someone can show me how to show that such sequences converge and how to find the limit, also maybe this is a well known sequence, as it has a quite simple form, too bad that google is very bad for looking for sequences and OEIS doesn't mention anything. |
I have an HP Pavilion dv7-6135dx. This morning, the power supply/AC adapter started making squealing noises for a few seconds at a time. I had it plugged in during a storm that happened while I was sleeping. As soon as I got up and realized, I put it in a surge protector. As I type this, it seems to have stopped for the moment, but it was going on and off almost constantly a couple of minutes ago. I'm assuming this means I need to replace the supply, but not sure if it actually means anything at all. Running Ubuntu 15.04, it that's relevant. EDIT: I should also mention that I had the laptop powering 4 usb devices (Keyboard, mouse, gaming controllers) for several hours yesterday. Again, don't know if this is relevant. EDIT 2: As I start to use the laptop, I'm noticing that it seems to squeak a little bit when I pick up the mouse or start typing. | I have many different AC adapters and power supplies for a variety of devices, ranging from small 5V/1A USB chargers to laptop power adapters and desktop PSUs. However, I often hear a whining noise from some of these power supplies. This happens most often when they are not connected to a device or otherwise in use, and stop making noise when I connect a load to it such as by plugging in a device that is not fully charged. Why do some AC adapters and power supplies make this whining noise? Why do some not make this noise? Is there anything I can do to suppress it? |
I have a .deb file in my downloads folder than i need to install with a bunch of dependencies. What is a command that will install the package with the dependencies. I know this is probably a duplicate but i just want the command to install the package from the downloads folder and automaticly install dependencies, because i don't know much about the terminal | Say, I have foo-1.2.3.deb which depends on perl and python, however, running command: dpkg -i ./foo-1.2.3.deb won't install these dependencies. So I must apt-get install perl python by hand. How to make dpkg -i install these dependencies for me automatically? |
Since a 32bit system can't manage a 2^33 number (because the obvious 32-bit limit), how can manage a number? It should require "80-bit"... | 32-bit computers can only store signed integers up to 231 - 1. This is why we have run out of IPv4 addresses and have entered the 64-bit era. However, the number 231 - 1 (2,147,483,647) is not as large as the number 1 trillion (1,000,000,000,000) which I seem to be able to display fine without my machine crashing. Can someone explain why this is? |
I have a tex document with math formula, figure, tikz drawings. What is the best way to convert tex to doc format. I tried with latex2rtf, pandoc, ... but nothing works. Can someone write step by step tutorial to convert tex to doc? Thanks. Edit main.tex \documentclass[a4paper, 12pt, oneside]{article} \usepackage [utf8]{inputenc} \usepackage[slovene]{babel} \usepackage[a4paper,left=3cm,right=2.5cm,top=3.5cm,bottom=3cm]{geometry} \usepackage[pdftex]{color,graphicx, hyperref} \usepackage{times} %\usepackage{a4wide} \usepackage{mathtools} \usepackage{subcaption} \usepackage{longtable} \usepackage{booktabs} \usepackage{natbib} \usepackage[T1]{fontenc} \usepackage[parfill]{parskip} \usepackage{lmodern} \usepackage[final]{pdfpages} \usepackage{graphicx} \usepackage{tikz} \usepackage{tkz-berge} \usetikzlibrary{arrows,% shapes,positioning} \usepackage{standalone} \begin{document} \section{Objave} \input{grafi} \bibliographystyle{apa} \bibliography{viri} \end{document} grafi.tex \documentclass[a4paper, 12pt, oneside]{standalone} \usepackage [utf8]{inputenc} \usepackage[slovene]{babel} \usepackage[a4paper,left=3cm,right=2.5cm,top=3.5cm,bottom=3cm]{geometry} \usepackage[pdftex]{color,graphicx, hyperref} \usepackage{times} %\usepackage{a4wide} \usepackage{mathtools} \usepackage{subcaption} \usepackage{subfig} \usepackage{longtable} \usepackage{booktabs} \usepackage{natbib} \usepackage[T1]{fontenc} \usepackage[parfill]{parskip} \usepackage{lmodern} \usepackage[final]{pdfpages} \usepackage{graphicx} \usepackage{tikz} \usepackage{tkz-berge} \usetikzlibrary{arrows,% shapes,positioning} \usepackage{standalone} \begin{document} \subsection{Teorija grafov} bla bla $(G)$ bla $V(G)$ bla $E(G)$.bla aaaaaaaaaaa $v,u$ $\epsilon$ $V(G)$ aaaaaaaa $(u,v)$ $\epsilon$ $E(G)$ aaa $u~v$. \begin{figure}[h] \def\tkzH{130pt} \def\tkzV{130pt} \input{graf} \caption{aaaaaaaaaaaaaaa $V(G) = \left\{1,2,3,4,5,6\right\}$ aaaaaaaa $ E(G) = \{ \{1,2\}, \{1,5\}, \{2,3\}, \{2,5\},\{3,4\}, \{4,5\}, \{4,6\}\}$.} \label{graf} \end{figure} \end{document} graf.tex \documentclass{standalone} \usepackage[utf8]{inputenc} \usepackage{fullpage} \usepackage{fourier} \usepackage{tikz} \usetikzlibrary{arrows,% shapes,positioning} \begin{document} \begin{center} \resizebox{\tkzH}{\tkzV}{ \begin{tikzpicture}[node distance = 30pt] \tikzset{VertexStyle} = [shape = circle, draw, %ball color = white, text = black, inner sep = 2pt, outer sep = 0pt, minimum size = 24 pt] \tikzset{EdgeStyle} = [black, double = black, double distance = 0.5pt] \tikzset{LabelStyle} = [%draw, %fill = yellow, %text = red, sloped, anchor=center, above] \node[VertexStyle](1){1}; \node[VertexStyle, below right =30pt of 1](2){2}; \node[VertexStyle, above right = 30pt of 1](5) {5}; \node[VertexStyle, right = of 5](4) {4}; \node[VertexStyle, right = of 2] (3) {3}; \node[VertexStyle, above right = 30pt of 4] (6) {6}; \foreach \from/\to in {1/2, 1/5, 5/4, 2/3, 3/4, 4/6, 2/5} \draw[EdgeStyle] (\from) -- (\to); \end{tikzpicture} } \end{center} \end{document} | I often have to write up reports based on the analysis of some data. I use R to analyse the data and export tables, figures, and text. This is then included into a LaTeX document either using input or Sweave (). However, when I collaborate with others, I sometimes need to provide a document in Open Office / MS Word format. Question: Thus, assume the simplest scenario I have a LaTeX document with text, tables, and figures I need to export this reliably into Open Office or MS Word format: this includes mathematical formulas, table formatting, and quality figures) I don't need to go back from MS Word to LaTeX What is a reliable, efficient, and preferably free process? Initial Thoughts: Export to HTML, LaTeX - LyX - ODF Use odfWeave that deals with some specific issues associated with LaTeX to Open Office conversion I was hoping that there is an expert out there who has worked out a good system already. |
Please, help to understand the meanings of two sentences. 1) I found the rule about the usage of this pattern. The only rule I found at all was about this pattern ? About this pattern I found only one rule ? 2) I found a rule about the usage of this pattern. One of the rules I found was about this pattern ? About this pattern I found at least one rule ? Thanks in advance. | I can’t for the life of me figure out where to use a and where to use the — and where there is no article at all. Is there a simple rule of thumb to memorize? The standard rule you always hear: “If a person knows which item you are talking about then use "the" . . . doesn’t clear things up for me, as I have no idea whether or not they know. |
I'm using Skydrive to host files for my blog, such as zip files of source code. I'm trying to provide direct links that users on my blog can click to immediately download the file in question, without being confronted with a Skydrive page filled with all the files related to all posts on my blog. Is there a way to do this? I've tried getting a link to the file, shortening it et cetera, but visiting this link always shows the Skydrive page. Here is . At this point I can only assume Skydrive is doing this on purpose and am also wondering whether there's another provider I can switch to that will yield a better user experience. | I want to make a direct link to a document at SkyDrive, so that I'll see only the PDF at the browser, not any of the SkyDrive chrome. For example, if you click , you will go automatically to the PDF file. Is there any way to do this? |
In standard least squares regression, we find constants $\beta_1$ and $\beta_2$ such that the square of the average error, $\epsilon = y_i - (\beta_1 + \beta_2x_i)$, is minimized, and so the 'line of best fit' is given as: $$y_{\textrm{avg}}(x)=\beta_1 + \beta_2x$$ Now, my question is, if you had to put associated error terms for each of the obtained terms (i.e. $\Delta\beta_1$ & $\Delta\beta_2$), what would they be? My guess is that for $\beta_1$, the 'error term' that I'm looking for would be the standard deviation $\sigma$, and so for the 'error term' for $\beta_2$ we would get the upper and lower bounds for the slope of the line within the 'wiggle room' defined by $\sigma$. [See picture] Please give me some direction on this problem of mine if you can. | For my own understanding, I am interested in manually replicating the calculation of the standard errors of estimated coefficients as, for example, come with the output of the lm() function in R, but haven't been able to pin it down. What is the formula / implementation used? |
I typically run my program with: perl -e 'print "A"x200' | ./vuln_prog The stdin is consumed by a gets() function in C++. If this were just a command argument, I could open gdb by doing: gdb ./vuln_prog run $(perl -e 'print "A"x200') However, my scenario is not a command argument, but rather input (STDIN?). How would I debug this in gdb? I've tried a bunch of options, but nothing seems to really work. I would normally just run gdb on the process, and when it prompts for user input, type it in, however I'm not wanting to type just "A". I want to type all chars from \x00-\xff, which I can't type. | I have a program that takes input from stdin and also takes some parameters from command line. It looks like this: cat input.txt > myprogram -path "/home/user/work" I try to debug the code with gdb inside emacs, by M-x gdb, I try to load the program with the command: gdb cat input.txt > myprogram -path "/home/user/work" However, gdb does not like it. Question cribbed from . Unfortunately I don't understand the solution and am not sure what to do beyond compiling with the -g option and running the command M-x gdb. |
I have a dev machine that I use npm and node on. I have been having trouble with permissions issues and repeatedly tried uninstalling and working with nvm and other stuff. I'm not really looking for ways to solve that issue and would prefer to start from a clean slate. Is there a way to wipe everything from my system? | I've had a lot of problems lately and now I'm having problems logging in at the login screen. I'm giving up and just want to reset and start over. How can I "factory reset" Ubuntu, in this situation, or, for future reference, in general? |
I am seeing http get requests in my servers access log for a site that is not hosted on my server and also the dns records of the site do not point to my server the domain points to 3 ip addresses in china. Anyone have any ideas as to why this would happen? | When looking at my Apache2 access logs, I occasionally see GET requests asking my server for a page on a completely different server. For example: xx.xx.xx.xx - - [18/Jan/2012:07:12:10 -0500] "GET http://someotherserver.com/?sometimesmorestuff=likethis HTTP/1.1" 200 389 "-" "Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.8.1.12) Gecko/20080201 Firefox/2.0.0.12" I remembered reading something about that in the past, but at the time I had never seen that on my server, so I didn't worry about it. Now that I am seeing it on my server, I just ran a test and it appears that my site does indeed serve requests for content from other servers. This seems like a bad thing. So, two questions: A) Is this something I should be worrying about? B) How can I fix it? I've tried a little Googling, but I don't even know what this sort of thing is called, and that makes it difficult. |
I am not able to create a bibliography with biblatex and can't figure out what the problem might be. Below are the steps I have taken which I thought would work. What am I doing wrong? I am using: MiKTeX 2.9 TeXnicCenter 2.0 Beta 1 (64 bit) JabRef 2.10 I and copied manually biber.exe to my MiKTeX directory: this step was advised C:\Program Files\MiKTeX 2.9\miktex\bin\x64\biber.exe I created a new project in TeXnixCenter and a reference.bib file in JabRef (both in utf-8): LaTeX \documentclass{article} \usepackage[backend=biber]{biblatex} \addbibresource{reference.bib} \begin{document} \cite{ref1} \printbibliography \end{document} Bib-File % This file was created with JabRef 2.10. % Encoding: UTF8 @Article{ref1, Title = {Title}, Author = {Phil}, Journaltitle = {Journal}, Year = {2014}, Owner = {Phil}, Timestamp = {2014.05.03} } I set up the output profile in TeXnicCenter: I compiled several times in order to create the document but I only recived these warnings: ... ... | I'm trying to use biblatex and when I compile my document I get an error like the following: Windows data source C:\Users\<username>\AppData\Local\Temp\par-5061756c\ cache-890efc00b3ca6b775c7d44a325c1349fb2a3a3bd\inc\lib/Biber/LaTeX/recode_data.xml not found in . Mac data source /var/folders/v2/rld0ls7d2935gkvqv5hfr1x00000gn/T/par-616c616e/ cache-cdd483146f82a9655ce063f848d5139480fbf872/inc/lib/Biber/LaTeX/recode_data.xml not found in . Linux data source /tmp/par-6963617269756d/cache-f37ab610b7d79b2720a8ee3732849c6821705520 /inc/lib/Biber/LaTeX/recode_data.xml not found in . |
I am using graphicx to typeset the figures for my PhD thesis. I have large files in .eps format. However, whenever I try to typeset the file (using pdfTeX), the console says "LaTeX error: File 'Figure' not found" It is in the same directory as my .tex file, and the file will typeset if I create it as a .dvi and then convert it to .pdf. I would rather not do this though, because I want to use hyperref. | When I run in MikTeX I get an error message saying that the image file is not found: ! LaTeX Error: File `chick' not found. See the LaTeX manual or LaTeX Companion for explanation. Type H <return> for immediate help. ... l.21 \includegraphics{chick} ? I have put the image file (in this case chick.eps) in the same folder as import.tex. |
This year I am doing some travelling above what I would normally do. I am planning on a trip to the USA in April for about 30 days. After this I am returning to England for over a month. Subsequently I will fly to Canada at the end of June, spend about 20 days there, before flying into the USA for 10 days and crossing the border back to Canada. My re-entry to the USA will be after my 90-day limit is up from the original admission. After that I will most likely fly back to England again. Will this be deemed acceptable by the border control, and how will they know I have left and haven't just gone to Canada to try and get around the 90-day stay rule? | What are all the ineligible countries that do not restart the 90-day Visa Waiver into the USA? |
There're over 7 billion people in the world and every one of them is different from everyone else. Is it possible that there are two people so different that they belong to different species (in the sense that they cannot reproduce to produce fertile offspring)? This doesn't have to mean that there's someone in the world who's completely unable to reproduce with everyone else, just that these two individuals are so different that they can't reproduce with each other (they can still reproduce with other people who can reproduce with the other individual - a ring species system). I'm particularly interested in an answer based on how much the genome varies between people vs. how much they vary against our closest relatives (such as Neanderthals). For example if humans and Neanderthals share 99% of their genes, and the largest variation among current humans is 0.001% of genes, then the answer to this question would be "no". | For what biological reasons do we consider that all human beings belong to the same species? A Thai and a Nigerian share a common ancestor that is 140,000 years old (see and ). Would, for example, a mixed Thai - Nigerian baby suffer from any outbreeding depression? |
I have an MSI 2QE Ghost Pro laptop with 2 hard disks, 1 SSD and 1 SATA. I have Windows 10 installed on the SSD and Ubuntu 14.04 on a partition of the SATA. I have no issues with the windows partition. Whenever I boot into ubuntu, though, my laptop screen stays black. Its not a black light, it just as though the laptop screen just doesn't turn on. Ubuntu functions normal though. I've tried connecting an external monitor from the HDMI port and that monitor works fine. Using that I can also see that my laptop monitor is detected and I can even use it. It just stays black. Has anyone some idea why this might be happening? I've tried updating my graphics card drivers but that didn't help. I'm not very experienced with Ubuntu and so am not sure what else to do. | I am trying to boot Ubuntu on my computer. When I boot Ubuntu, it boots to a black screen. How can I fix this? Table of Contents: |
If I control a and a few other creatures of power 2 or less and my opponent uses , can I get back creatures that are dying to the wrath or do they have to have been in the graveyard before the wrath was cast? I'm unsure how the stack should work here | has the following ability: Whenever a creature you control with a +1/+1 counter on it dies, return that card to the battlefield under your control at the beginning of the next end step. I had a number of creatures on the battlefield, including Marchesa herself, with one or more +1/+1 counters on them when was played, destroying each creature on the board. When Marchesa and several other creatures would be killed simultaneously, Does Marchesa's ability trigger for herself? Does Marchesa's ability trigger for the other creatures under my control with +1/+1 counters? In attempting to resolve the issue, we tried to look things up, leading to , which cites Rule 603.6d as proving that Marchesa's ability should trigger both for herself and for each other creature with +1/+1 counters. Unfortunately, none of us could actually understand Rule 603.6d, aside from this example: Two creatures are on the battlefield along with an artifact that has the ability Whenever a creature dies, you gain 1 life. Someone plays a spell that destroys all artifacts, creatures, and enchantments. The artifacts ability triggers twice, even though the artifact goes to its owners graveyard at the same time as the creatures. The example certainly seems analogous to me, but without understanding the actual rule, rather than just the example, we weren't too sure. A complete answer has to not only answer the question, but back up that answer with citation and explanation of the official rules on the matter. |
Let's have the following address of the network: 192.168.176.0/23. What are the first and last IP addresses of this network? Following this answer I assume that: /23 means 23 bits for the subnet. At 8 bits per byte we get 16 bits for the first two bytes, and then seven (7) for the third => 1111 1111. 1111 1111. 1111 1110. 0000 0000, right? It means our last two bytes will be of the form (nnnn nnnH. HHHH HHHH), where n is a subnet bit and H a host bit. Thus the network address is (nnnn nnn|0 0000 0000) -> .0, the broadcast is (nnnn nnn|1 1111 1111) -> 2^9 is broadcast? Impossible. Here I miss something, something simple. So what would be the first and last IP? This is what I don't get following the answer mentioned in the link above (by b0fh). First 192.168.176.1, last 192.168.177.254? | This is a about IPv4 Subnets. Related: How does Subnetting Work, and How do you do it by hand or in your head? Can someone explain both conceptually and with several examples? Server Fault gets lots of subnetting homework questions, so we could use an answer to point them to on Server Fault itself. If I have a network, how do I figure out how to split it up? If I am given a netmask, how do I know what the network Range is for it? Sometimes there is a slash followed by a number, what is that number? Sometimes there is a subnet mask, but also a wildcard mask, they seem like the same thing but they are different? Someone mentioned something about knowing binary for this? |
I have a list of lists and I want to assign to the first element of each list a value in order from 0 to 3. I wrote the following code: var = [[-1] * 5] * 4 for i in range(4): var[i][0] = i+1 print(var) The output is [[4,-1,-1,-1,-1], [4,-1,-1,-1,-1], [4,-1,-1,-1,-1], [4,-1,-1,-1,-1]] But it should be: [[1,-1,-1,-1,-1], [2,-1,-1,-1,-1], [3,-1,-1,-1,-1], [4,-1,-1,-1,-1]] How do I do it? | I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3 The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]] Then I changed one of the innermost values: my_list[0][0] = 5 Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]] which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it? |
I moved to the U.S. on 8th Oct. I will be having total income of around $11,500 in these 3 months. Currently the tax is being deducted from my income which includes state tax/federal tax/SSN tax/Medicare tax. Will all the tax be refunded to me? And as I have also stayed more than 181 days in India during the year, do I need to pay tax on this income in India? Any help will be greatly appreciated. | I left India on 8th October 2014 and started working in USA from 13th Oct 2014. For my income in India, my employer deducted tax at source (Rs 30,000). In US too, my employer deducted tax at source but I filed for extension for income tax. Now that I have fulfilled substantial presence test in US, I am filing the return as Resident Alien for 2014 (I have never been to US before and I am on H1B). So the questions: Should I declare India's income while filing tax return for US for Calendar year 2014? In India, if I declare that I didn't work after October, I'll get 100% tax refund as my income will be below tax bracket (after deductions like 80C etc). So I think that is not correct. How to know the amount of tax I have to pay in India? Do I have to declare my US income there? I don't have any other income from any sources in India. |
In "The Best of Both Worlds, Part 2", when it seems all is lost, as a last resort, Riker decides he is going to ram the Borg at maximum warp in a bid to stop them reaching Earth, which would of course destroy the Enterprise. We never find out if it would have worked, and yes it was an act of despair, but the question remains: why did Starfleet not just use unmanned ships as weapons, or even just strap a huge ship-sized missile to a warp drive? | During the Wolf-359 incident, 39 starships were destroyed, and 11,000 people were killed or assimilated. Why didn’t one of the smaller ships warp into that one Borg cube? Doesn’t warping into it destroy anything? Even if it just warps through without touching, one could program the navicom to self destruct while the ship is in the middle of Borg cube. |
I'm using a callback to create an object, which I'd like to parse. I'm able to parse the object when the name/value pair I've specified exists, but unable to identify when the name/value pair in my object is undefined. JSON Object with name/value pair populated: parseMe([{"item1" : "", "item2" : "", "item3" : [], "item4" : "content goes here"}]); JSON Object with name/value parsed undefined: parseMe([{"error" : "Not available"}]); Parsing logic EX: var renderR=""; function parseMe(data){ renderR=""; if(data[0].item4!="collapse") renderR=data[0].item4; //if name/value pair isn't equal to "collapse" render it. else if(data[0].item4==='undefined'){ document.getElementById('div1').style.display='none'; //if name/value pair is undefined in object hide the div. } } | What's the best way of checking if an object property in JavaScript is undefined? |
The zero point energy of a vacuum is different depending on speed and gravity. The zero point energy of the curved geometry of spacetime near a blackhole is higher compared to a distant observer, so to a distant observer it looks like there’s positive energy radiation where there should be zero energy. That energy difference is a result of the curved spacetime around the black hole which is related to its mass, so therefore the energy comes from the black hole’s mass, and the loss of this positive energy can be crudely thought of as the addition of negative energy. | Could someone please provide an explanation for the origin of ? (Ideally someone who I have been speaking with on the h-bar) Any advanced maths beyond basic calculus will most probably leave me at a loss, though I do not mind a challenge! Please assume little prior knowledge, as over the past few days I have discovered that much of my understanding surrounding the process as virtual particle pairs is completely wrong. |
I'm trying to split lines in this file by new line symbol "\n" and it's simply not working... I've tried: String[] words = strLine.split("\n"); System.out.println(Arrays.toString(words)); [abbot abbot [ˈæbət] <N>\n opat] String[] words = strLine.split("\\n"); System.out.println(Arrays.toString(words)); [abbot abbot [ˈæbət] <N>\n opat] String[] words = strLine.split("\\r|\r"); System.out.println(Arrays.toString(words)); [abbot abbot [ˈæbət] <N>\n opat] Even this: String[] words = strLine.split(System.getProperty("line.separator")); System.out.println(Arrays.toString(words)); [abbot abbot [ˈæbət] <N>\n opat] I'm reading the file using BufferedReader and readLine method. | I'm trying to split text in a JTextArea using a regex to split the String by \n However, this does not work and I also tried by \r\n|\r|n and many other combination of regexes. Code: public void insertUpdate(DocumentEvent e) { String split[], docStr = null; Document textAreaDoc = (Document)e.getDocument(); try { docStr = textAreaDoc.getText(textAreaDoc.getStartPosition().getOffset(), textAreaDoc.getEndPosition().getOffset()); } catch (BadLocationException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } split = docStr.split("\\n"); } |
I have a string stored in table "13/12/1985 12:00:00 a.m." when i tried to convert this to Datetime, i am getting an exception saying "String is not a valid DateTime Format". It is because the first part of the string(13) is month. Is there any way to convert the above string to (mm/dd/yyyy hh:mm:ss am/pm) format?. Actually the string saved in table is in the format of "dd/mm/yyyy". I want to convert to "mm/dd/yyyy" in Datetime | I'm reading text from a flat file in c# and need to test whether certain values are dates. They could be in either YYYYMMDD format or MM/DD/YY format. What is the simplest way to do this in .Net? |
I've inherited a TinyDNS configuration that have following entries for SPF: @domain.com:x.x.x.3:a::86400 @domain.com:x.x.x.103:c:10:86400 =domain.com:x.x.x.3:86400 =mail.domain.com:x.x.x.3:86400 =mail.domain.com:x.x.x.103:86400 'domain.com:v=spf1 ip4\072x.x.x.3 ip4\07231.130.96.103 ptr\072mail.domain.com +mx a -all:3600 'mail.domain.com:v=spf1 ip4\072x.x.x.3 ip4\072x.x.x.103 ptr\072mail.domain.com +mx a -all:3600 'a.mx.domain.com:v=spf1 ip4\072x.x.x.3 ip4\072x.x.x.103 ptr\072mail.domain.com +mx a -all:3600 This is the result from SPF record lookup and validation for: domain.com SPF records are primarily published in DNS as TXT records. The TXT records found for your domain are: v=spf1 ip4:x.x.x.3 ip4:x.x.x.103 ptr:mail.domain.com +mx a -all SPF records should also be published in DNS as type SPF records. No type SPF records found. Checking to see if there is a valid SPF record. Found v=spf1 record for domain.com: v=spf1 ip4:x.x.x.3 ip4:x.x.x.103 ptr:mail.domain.com +mx a -all evaluating... SPF record passed validation test with pySPF (Python SPF library)! I'm struggling with this from yesterday and cant figure it why this validator returns No type SPF records found. I see in BIND we cand define SPF type record with example.com. IN SPF "v=spf1 a -all", but in TinyDNS we only have TXT records that we set for SPF, maybe this is a problem? | This is a about setting up . I have an office with many computers that share a single external ip (I'm unsure if the address is static or dynamic). Each computer connects to our mail server via IMAP using outlook. Email is sent and received by those computers, and some users send and receive email on their mobile phones as well. I am using to generate an SPF record and I'm unsure about some of the fields in the wizard, specifically: Enter any other domains who may send or relay mail for this domain Enter any IP addresses in CIDR format for netblocks that originate or relay mail for this domain Enter any other hosts which can send or relay mail for this domain How stringent should SPF-aware MTA's treat this? the first few questions i'm fairly certain about... hope i have given enough info. |
I'm just starting to learn Blender so I don't know whether I'm being stupid here, but it seems to me that the Solidify modifier is counting the wall thickness twice. A wall thickness of .5m in a 1m object means no hole surely? (Blender 2.9 on a MacBook Catalina) | I'm Having trouble with setting the thickness applied by solidify. The selected block is 15 by 28 cm (single mesh sides) and the thickness of solidify is set to 3mm (pointing inwards). Checking off even thickness makes it even worse. I was using the function in a different object earlier today and it worked just fine. Is there something I'm missing or is this just a bug? Feel free to treat me like an idiot, I've literally started using blender yesterday :) |
I have a Nikon D5000 I was wondering what is a good lens for taking baby and children portraits | I have a Nikon D5100 and want to see whats the best lens for shooting pictures of a baby and kids running around inside and outside? I would like to stay under $1,000. Thanks for the help. |
On my Macbook Air running Sierra 10.12.5, there is no longer a Dictionaries directory under /Library, so the below suggested fix no longer seems to apply: Is there still a way to do this? | It's possible to change the font and the font-size for 3-finger lookup popup. You just need to edit css file for dictionaries you use, e.g.: sudo vim /Library/Dictionaries/New\ Oxford\ American\ Dictionary.dictionary/Contents/Resources/DefaultStyle.css find html.apple_client-panel body { and edit properties Now I actually want to go further and make the entire popup area bigger - little wider and little taller. How can I do that? |
I think this is not a duplicate of the question John mentions. That question asks specifically why the balloon makes a spiraling movement, which in general is not the case (the answers pay only attention to two variables: the nozzle and air resistance, for which there isn't a fixed centre of drag) while I ask the broader question which variables make the movement chaotic (which it is for sure while its velocity responds in a non-linear way to these variables). The non-spiraling movement can be seen as a sequence of (infinite) little pieces of circular trajectories because there are other variables influencing the motion of the balloon too (like the chaotic air movement around the moving balloon, which causes a non-fixed center of drag). When a balloon goes flat it makes a chaotic movement through the air. Is it the interaction with the air, the behavior of the part through which the air escapes (in which case the balloon will also trace out a chaotic trajectory on the moon), or what? | When an air-filled balloon is released without its opening tied up, it moves in a circular path rather than a straight line. Why is that? |
I want to meet some persons in Manhattan but I'm not sure how to message them about it. I'll meet you on Manhattan. (OR) I'll meet you in Manhattan. | I'm sure virtually everyone agrees that people live on the Isle of Wight, but in Ireland. Apparently the usage depends somewhat on physical size, but that can't be the whole story. How exactly do we decide which form to use? And are there any really glaring 'outliers' that don't fit the normal pattern? LATER - I must just add that the most uncertain case I've found so far is The Falklands. Most people go for in there, but a substantial minority (about 1 in 3) opt for on. |
I'm trying to install TeamViewer on my computer, but I got the following message when I tried to launch the application : Could anyone be able to tell me what do I have to do to fix this problem? | After installing TeamViewer 11 on Ubuntu Desktop 64-bit 16.04, I get the error: Verification of your teamviewer version failed, Teamviewer will quit for security reason. Please reinstall teamviewer I have uninstalled and purged several times, and I always get the same error on install. TeamViewer 10 works 100% fine. I need version 11 as clients have upgraded. |
Why do we use standard deviation instead of variance? sample variance (S2) = standard deviation (S) = | I was wondering what the difference between the variance and the standard deviation is. If you calculate the two values, it is clear that you get the standard deviation out of the variance, but what does that mean in terms of the distribution you are observing? Furthermore, why do you really need a standard deviation? |
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