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I was trying to install R-base but I'm facing unmet dependencies. I have tried all possible ways to uninstall and install, re-run mongodb services... but nothing worked. The installation shows an error. Uninstallation doesn't work. This is the error: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: mongodb-org-server : Depends: libcurl3 (>= 7.16.2) but it is not going to be installed E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages. I have tried many solutions from Stack Overflow, but nothing works. | I am not sure what caused this error, but here is what the whole error says, and also this is sitting as a notification, and preventing me from updating any software using Update Manager - Please provide some assistance or tell me how to figure out what to do to fix it. Could not calculate the upgrade An unresolvable problem occurred while calculating the upgrade. Please report this bug against the 'update-manager' package and include the following error message: 'E:Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.' |
Is it possible to add on to the text of a label without changing existing text? I'm new to mac development in Xcode so any help is appreciated. | Are there any shortcuts to (stringByAppendingString:) string concatenation in Objective-C, or shortcuts for working with NSString in general? For example, I'd like to make: NSString *myString = @"This"; NSString *test = [myString stringByAppendingString:@" is just a test"]; something more like: string myString = "This"; string test = myString + " is just a test"; |
Is there an official resource from where high resolution logos for the various Stack Exchange network websites can be obtained? I am talking about logos of network sites that are launched and have a custom logo available and not looking for generic logo that sites have which is currently in beta. I am aware of the page, but it contains icons only for a handful of main sites, such as Stack Exchange, Stack Overflow, Server Fault and Super User. Also, they do not contain the solid colored logos as seen on the landing screen of the Stack Exchange mobile apps. It would be nice if both solid and full color variants are available. An example of what I am looking for: The logos would be used for non-commercial purposes. While it would be possible to scrape off the resources from corresponding webpages, I am interested in knowing if they are available through more formal means. | On , there are download options for only certain logos/icons. Shouldn't this include all the graduated sites logos/icons? I think it should. |
What is the easiest and fastest way? I'm definitely slower than the zerg player. I usually lose because I cheese(troll), and get discovered, but I usually don't lose. What is the best build order to defend roach rush, because I'm used to cheesing and not good at making a good base? | I recently saw an that's even faster than the popular 5 roach rush build. This build gets to 7 roaches in about 4:40. How would I counter this build? I'm mostly Toss, but please suggest counters for any of the races. Update: Apparently the original creators of the build optimization program are working on Protoss and Terran versions - |
Suppose $f(x+y)=f(x) + f(y)$ for all $x,y \in \mathbb R$ and $f$ is continuous at a point $a \in \mathbb R$. Prove that $f$ is continuous at every $b \in \mathbb R$. I know that in order to prove continuity we can use the definition that states that $\lim_{x\to b}f(x+y)=f(b)$ then the function is continuous however I do not know how to show that the limit will be $f(b)$ for the function. Thanks in Advance. | Suppose that $f$ is continuous at $x_0$ and $f$ satisfies $f(x)+f(y)=f(x+y)$. Then how can we prove that $f$ is continuous at $x$ for all $x$? I seems to have problem doing anything with it. Thanks in advance. |
The square and circle below are tangent at one point and meet at four other points, as shown. If the side of the square is 8 units long, what's the radius of the circle? | An exam for high school students had the following problem: Let the point $E$ be the midpoint of the line segment $AD$ on the square $ABCD$. Then let a circle be determined by the points $E$, $B$ and $C$ as shown on the diagram. Which of the geometric figures has the greater perimeter, the square or the circle? Of course, there are some ways to solve this problem. One method is as follows: assume the side lengths of the square is $1$, put everything somewhere on a Cartesian coordinate system, find the midpoint of the circle using the coordinates of $E$, $B$ and $C$, then find the radius of the circle, and finally use the radius to calculate the circle's circumference and compare it to the perimeter of the square. The problem with that method is that ostensibly this problem is supposed to be very simple; it shouldn't require the student to know the formula for the midpoint of a circle given three coordinates. Therefore the question here is: does there exist a simple way to solve the problem without knowing any complicated geometric formulas? |
Just noticed this on superuser. Refreshed the page, still buggy. Using newest Firefox :-) | It appears that on Server Fault and Super User, the navigation bar and question title have suddenly become misplaced. The same does not occur on SO and mSO, nor on any of the other SE sites I spot-checked. This is being seen in both Chrome and Firefox and just began occurring within the last few minutes. What it should look like: While this was fixed for a few hours, it has returned as of 22:05. |
Show that a ring $R$ is a division ring if and only if, for each nonzero $a\in R$, there is a unique element $b\in R$ such that $aba = a$. $\Rightarrow$ Assume $R$ is a division ring. Let $a\in R$. So there exists $a^{-1}$ such that $aa^{-1}=1=a^{-1}a$. So $aa^{-1}=a^{-1}a$. Now I am not sure to find a $b$ such that $aba=a$? $\Leftarrow$ Assume $aba=a$ for nonzero $a\in R$. Let $r\in R$ such that $ra=1$. Then $a=aba=a(ra)=(ar)a$ so $ar=1$. Therefore $r$ is the inverse of $a$ and so $a$ is a unit and $R$ is a division ring. This hinges on the fact that $ra=1$, is that something I can say? | Let $\left(A,+, \cdot\right)$ be a ring with $1$ that satisfies the following condition: For any nonzero $a\in A$, there exists a unique $b\in A$ such that $aba = a$. Show that $b$ also satisfies $bab = b$, and that all nonzero elements of $A$ are invertible. |
Prove that it is impossible to find any positive integers a, b, c such that $(2a+b)(2b+a) = 2^c$. This problem has been driving me crazy. Thanks for helping. | I have been boggled by this question for a while as well. Prove that $$(2a+b)(2b+a)=2^c$$ Is impossible. I know that if a and b do exist then they must be even. I am trying to use this fact to contradict the statement. I haven also tried rewriting a and b as products of powers of twos and a odd factor |
I want to create my first guy in Java and I am using the GridLayout by IntelliJ. I also have to use the CardLayout to change the panels and have different screens. I have set up everything like it is in provided by IntellJ. However, I get a java.lang.NullPointerException. The error message is following: Exception in thread "main" java.lang.NullPointerException at com.intellij.uiDesigner.core.GridLayoutManager.addLayoutComponent(GridLayoutManager.java:134) at java.awt.Container.addImpl(Container.java:1130) at java.awt.Container.add(Container.java:419) at UserInferface.<init>(UserInferface.java:29) I have six other screens set up which return the root panel, so I am not gonna copy and paste the code here. They just have a panel and a get method to return the panel. Like in the demo. Here is my main window code called UserInterface. Can you guys tell me, where my error is and why I get a java.lang.NullPointerException? import screens.*; import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class UserInferface extends JDialog { private JPanel rootPane; private JPanel navigationPane; private JButton sellInterfaceButton; private JButton restockInterfaceButton; private JButton changeCapacityInterfaceButton; private JButton changeStockInterfaceButton; private JButton orderListInterfaceButton; private JButton showStockInterfaceButton; private JPanel cardPanel; final static String CHANGE_CAPACITY_INTERFACE = "Change capacity"; final static String CHANGE_STOCK_INTERFACE = "Change stock"; final static String ORDER_LIST_INTERFACE = "Order list"; final static String RESTOCK_INTERFACE = "Restock"; final static String SELL_INTERFACE = "Sell"; final static String SHOW_STOCK_INTERFACE = "Show stock"; public UserInferface(){ setContentPane(rootPane); setModal(true); cardPanel.add(new ChangeCapacityInterface().getRootPanel()); cardPanel.add(new ChangeStockInterface().getRootPanel()); cardPanel.add(new OrderListInterface().getRootPanel()); cardPanel.add(new RestockInterface().getRootPanel()); cardPanel.add(new SellInterface().getRootPanel()); cardPanel.add(new ShowStockInterface().getRootPanel()); final CardLayout cl = (CardLayout) cardPanel.getLayout(); cl.show(cardPanel, SELL_INTERFACE); sellInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, SELL_INTERFACE); } }); restockInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, RESTOCK_INTERFACE); } }); changeCapacityInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, CHANGE_CAPACITY_INTERFACE); } }); changeStockInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, CHANGE_STOCK_INTERFACE); } }); orderListInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, ORDER_LIST_INTERFACE); } }); showStockInterfaceButton.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { cl.show(cardPanel, SHOW_STOCK_INTERFACE); } }); } public static void main(String[] args) { UserInferface userInferface = new UserInferface(); userInferface.pack(); userInferface.setVisible(true); System.exit(0); } } Kind regards and Thank You! | What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely? |
Or: how do statements follow from other statements? Consider: All turtles have shells (s1), Ricardo is a turtle (s2), therefore Ricardo has a shell (s3). Why does s3 follow? | I am having trouble understanding what defines Entailment operator. On Mathoverflow I posted this question on what I perceive to be . Consider: : P therefore Q P Therefore, Q My question is could we have arbitrarily defined it such as: P therefore Q P Therefore, P However, if an advanced civilization receives information in the form of following nested structures/containers or packets, how will they interpret Modus Ponens if in an alien land Modus Ponens is not defined? Therefore, it raises the validity of MP. How do we define the implication or entailment operator? Because if we use an argument that relies on implication or entailment operator ipso facto, then it is trivial that logic is circular. Is there a flaw in my rationale? |
I'm having issues with a question in Artin, more specifically 11.3.3.e. The question asks: Find generators for the kernel of the following map: $\mathbb{C}[x,y,z] \to \mathbb{C}[t]$ given by $x \mapsto t$, $y \mapsto t^2$, $z \mapsto t^3$ Clearly we have $z-x^3$, $y-x^2$, and $z^2-y^3$ as elements of the kernel. I'm not sure how to proceed. The book uses the division algorithm in the relevant examples, but it only does that for the two-variable case. I can't see how to apply it here and I also have a hard time understanding why it works. The other four parts were straightforward maps substituting variables for numbers, this is the first that deals with parametrization. | Suppose $R=k[x,y,z]$ and $S=k[t]$. Consider the map $f:R\to S$ s.t. $f(x)=t$, $f(y)=t^2$ and $f(z)=t^3$. I suspect the kernel of this map is the ideal $(y-x^2,z-x^3)R$. It's clearly contained in the kernel, but I am not sure how to prove the reverse inclusion. |
The number of ways to put $N$ balls in $M$ boxes without any other restrictions is given by $\dbinom{N+M-1}{M-1}$. However, I couldn't find any simple explanation as to why it is true, is there any intuitive way to understand it? Thanks in advance. | I am trying to prove a formula (for ways of distributing $n$ identical balls among $r$ persons when each person may get any number of balls) ${n+r-1}\choose{r-1}$. But I am not able to prove it. I may be doing something wrong but I am not able to figure out what exactly? This is what I am doing. I put $n$ identical balls in a line. Now there are $(n+1)$ spaces/gaps between these $n$ identical things including (left to the leftmost ball and the next to the rightmost ball). So now basically I just need to select any $(r-1)$ gaps from these $(n+1)$ gaps and I will be able to create $r$ groups. So, my answer is ${n+1}\choose{r-1}$. But the actual answer to this is ${n+r-1}\choose{r-1}$ as per I want to know what am I doing wrong? Thanks! |
I am unsure how to add spin and orbital angular momenta for particles different from spin 0.5. Is this the correct way (if not, can you provide a general formula for addition of these two momenta) Suppose $s = \frac{3}{2}$. Then are the possible values of $J$ then $l + \frac{3}{2}$ and $l - \frac{3}{2}$, or are there other values? Is the general formula $j = l \pm s$? | Looking back at my quantum mechanics notes, the angular momentum addition theorem is listed as: $j=j_1+j_2,j_1+j_2-1, ..., |j_1-j_2| $ (Using conventional notation) , but I'm a little unsure how to interpret the introduction of the modulus operation ($|...|$) and couldn't easily find any examples. I'm assuming you apply the modulus to any expression which would otherwise yield a negative value for $j$? I'd appreciate a nod from someone in the know :-). |
I'm working my way through a probability textbook, and i have encountered the Gamma function through the Gamma distribution. I understand that the Gamma function is an interpolating function that can give pretty accurate values of factorials across the entire Reals, in between the Natural numbers that factorials typically work for, but HOW was this function even conceived? I want to see the thought process behind this function. How did Euler decide that the Gamma function described factorial 'curve' one can draw between the discrete factorial function? He didn't just pull this function outta nowhere, there has to be a reasoning behind it, i take it? | In is a proof of Stirling's formula. I really like most of it, but at a crucial step he uses the integral identity $$n! = \int_{0}^{\infty} t^n e^{-t} dt$$ , coming from the Gamma function. I have a mathematical confession to make: I have never "grokked" this identity. Why should I expect the integral on the right to give me the number of elements in the symmetric group on $n$ letters? (It's not that I don't know how to prove it. It's quite fun to prove; my favorite proof observes that it is equivalent to the integral identity $\int_{0}^{\infty} e^{(x-1)t} dt = \frac{1}{1 - x}$. But if someone were to ask me, "Yes, but why, really?" I would have no idea what to say.) So what are more intuitive ways of thinking about this identity? Is there a probabilistic interpretation? What kind of random variable has probability density function $\frac{t^n}{n!} e^{-t}$? (What does this all have to do with Tate's thesis?) As a rough measure of what I'm looking for, your answer should make it obvious that $t^n e^{-t}$ attains its maximum at $t = n$. Edit: The kind of explanation I'm looking for, as I described in the comments, is similar to of the beta integral. |
I have no idea what graphics card hardware do I have, and have no driver installed. How can I detect what graphics card do I have to install the right driver? | I know of many ways to get a rough idea of my graphics card model. Here are two examples (instructions for Windows 7): Method 1 1) Click start 2) Type dxdiag and press enter 3) Go to the Display tab and check the Name property. Method 2 1) Click start 2) Right click on Computer and select Properties 3) Click on Device Manager 4) Expand the Display adapters to get a list of video cards Problems Unfortunately both these methods suffer from problems: 1) This is a very inaccurate measure. For example, if I have an ATI Radeon 4830, both methods will show that I have an ATI Radeon 4800 series i.e. there is no way to distinguish between different models within the 4800 series or any other series for that matter. 2) This is dependent on having the correct driver installed. If I have an incorrect driver installed, there is no way for me to find out what the correct driver should be. Question Is there any way for me to be able to determine the exact model of a graphics card without relying on having the correct driver installed. I realise there are ways to do this such as checking the documentation that comes with the computer or perhaps opening it up but I am interested in seeing if there is way of doing this with software. Edit: Please note the requirements carefully. If the method relies on reading from the driver then it is ineligible. If there is no program that can do this, is there a manual method? Some kind of website database etc? Thanks! |
i was trying to install wireless-tools in ubuntu sudo apt-get install wireless-tools when i hit enter it shows like this Reading package lists... Done Building dependency tree Reading state information... Done Package wireless-tools is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'wireless-tools' has no installation candidate help me to solve this problem | What does the above Error mean? What is an installation candidate? I was trying to do sudo apt-get install munin-memcached and I get this message: Reading package lists... Done Building dependency tree Reading state information... Done Package munin-memcached is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package munin-memcached has no installation candidate I googled for the problem and someone said to do a apt-get upgrade but it still did not solve my problem. |
I am new to Linux and just started using ubuntu 14.04. I'm trying to run imwheel process on startup by editing rc.local file. Perhaps I'm doing something wrong and I need to type a path to a program apart just the name like in terminal? when i try to do a check by running: sudo service rc.local start I get below message:INFO: imwheel started (pid=4906) Could not open display, check shell DISPLAY variable, and export or setenv it! rc.local file: #!/bin/sh -e # # rc.local # # This script is executed at the end of each multiuser runlevel. # Make sure that the script will "exit 0" on success or any other # value on error. # # In order to enable or disable this script just change the execution # bits. # # By default this script does nothing. imwheel exit 0 | How can I make an application automatically start when I have logged in? |
I transferred some IRA (both Traditional and Roth) accounts and incurred a total of $300 in fees by my originating firm that was subtracted before those transfers took place. The target firm reimbursed me for those fees but did it by adding $300 to a brokerage (non-IRA) account. Are there any tax implications in this? | I switched the brokerage for a taxable investment account last year. The new brokerage reimbursed the transfer out fee of $50 from my old brokerage. I don't have my 1099s yet but I noticed in the online tax information at my new brokerage, it has that $50 as taxable income. Is this correct? Since it's a reimbursement it doesn't seem like it should be. Unless perhaps my old brokerage would put -$50 on my 1099 from them? That seems unlikely though. |
$$\int \frac{x^2}{(x\cos{x}-\sin{x})^2} dx$$ I tried to turn it to $\tan$ and $\sec$ but it didn't work out very well. How can I evaluate this indefinite integral using regular methods? | How to find the antiderivative of $\dfrac{(\sin x)^2}{(x\cdot\cos x-\sin x)^2}$? I know that series theory can solve the problem. But I wish to solve the problem by the antiderivative way. The numerator and denominator divide the $x^2$ at the same time, don't they? |
I am really in a big trouble i have lost my 352GBs of data during Ubuntu installation. I mistakenly made a partition which caused to format My data which was already placed in that partition. The data i lost during Ubuntu installation how can i recover it. | I have a Toshiba satellite A-200 laptop with a Vista OS on it with 4 NTFS partitions (C:) Vista (D:) Entertainment (E:) Work (F:) Sources and I wanted to start using Ubuntu instead. So I tried it first from the live CD and everything was OK and all the partitions were shown and working and so I decided to install Ubuntu to replace Vista on the (C:) drive. After I did that I can no longer find my folders and files on the (D:), (E:), (F:) partitions and the only file system that is shown is one 198 GB although my HDD is 320 GB. I can't access the lost data on the remaining 120 GB which I hope is still there and not totally lost I am now working from the live CD but I am unable to install testdisk. Can I recover the Vista partitions by the product recovery CD to get my laptop back to the factory settings? Can I recover the NTFS partitions using a recovery program for Windows or will that make the problem worse? I need these data badly as I don't have a backup for them. |
I was wondering if there was another way to derive the inequality shown in the title of this question apart from calculus. Doing it with calculus is pretty straightforward: Let $f:(0,1)\to\mathbb R$ be a function defined by $f(p)=p(1-p)$. Taking the first derivative $f'(p) = 1-2p=0\Rightarrow p=1/2$ is a critical point. Then the maximum is $1/4$ and it is reached when $p=1/2$. Hence $p(1-p)\leq 1/4,$ $\forall p\in(0,1)$. | In a book on statistics, I've seen the upper bound of $p(1-p) $ to be $$ p(1-p) \le \frac{1}{4} $$ for $0 \le p \le 1$ which seemed correct. I tried to duplicate this with a simple derivation, $$p(1-p) = C$$ $$p-p^2 = C$$ Taking derivatives of both sides, gives $$1-2p=0$$ $$p=\frac{1}{2}$$ which is the value of $p$ at the maximum, and $1/2*1/2 = 1/4$. I obtained this without using the constraint $0 \le p \le 1$ though. How would I include this constraint? Through Lagrange? Is that overkill? |
How do I convert a byte[] to a string? Every time I attempt it, I get System.Byte[] instead of the value. Also, how do I get the value in Hex instead of a decimal? | How can you convert a byte array to a hexadecimal string, and vice versa? |
I bought a new Toshiba with Windows 10 installed. I downloaded “Ubuntu-14.04-desktop-i386” on a different Ubuntu computer and put it on a disk. The disk did install on the new computer. After the install finished it said remove disk and restart. After restart all it said was >>Start PXE over IPv6. Press [ESC] to exit. I have installed Ubuntu several times in the past on different computers, never saw this before. What am I doing wrong? | I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS. Should I do it with Wubi, or through the Live USB/DVD? What steps do I need to take to correctly install Ubuntu? |
I recently saw a question I wanted to answer, so I typed out an answer in the answer box. After I finished writing it, I realized I couldn't post it because I hadn't created an account on that stack yet. I clicked the button to create an account on that stack and got no warning about navigating away from the page. When I returned to the question I found about 2/3 of my answer text was deleted from the text box. Usually, I get a warning when navigating away from a page with an unposted answer, so I assumed here when I got no such warning that my answer would be saved for me. So it seems like something is not working right in this instance. Either I should have gotten a warning when clicking to create an account, or else my answer should have been properly saved as a draft before I left the page. I'm running Chrome (version 79.0.3945.130) on Windows 10. | When writing an answer on a site where you don't have an account or are not logged in, below the answer entry textbox are options to create an account or continue as guest by providing a nickname and email. I had written an answer of several paragraphs on a network site, clicked "Sign up with Google" (resulting in association to my existing network-wide profile) but after doing so instead of showing my answer to be posted, only the first five or six words were retained. I know that I had no account on this site previously because I just received the association bonus... I cannot tell whether the bug also affects totally new users or those with accounts but who are not logged in. This is a very unwelcoming user experience. Please fix it. If the intended workflow is to click "Post Answer" first and associate the account afterwards, then the sign up options should not be shown until the answer is posted, and certainly not above the Post Answer button. This problem also occurs if you already have an account on the site, and click 'sign up with google' (which allows you to successfully log in). |
I have many procedures that I use the option WITH ENCRYPTION when I create them. You can see this on the picture below, as an example: the problem with this is that when I want to save my previous version of my stored procedure, I cannot get the expected result, as you can see on the picture below. the way I am backing up the code of the stored procedures is on the link below: select 'Proc' = SCHEMA_NAME(p.schema_id)+'.'+p.name , 'Type' = per.state_desc, 'Permission' = per.permission_name , 'Login' = pri.name, 'Type' = pri.type_desc , * From sys.procedures as p left join sys.database_permissions as per on p.object_id = per.major_id left join sys.database_principals as pri on per.grantee_principal_id = pri.principal_id where ... is there a way to remove the WITH ENCRYPTION from the code of a stored procedure, before I save it? Provided I have ownership of the procedure. There is a nearly duplicated question on the link below however, on this question, I own the database. I am sysdba. I can use any resources, but I would like a solution via T-SQL. | I am working on a third party database. When I try to view the definition of a view by right clicking, CREATE TO and then to NEW QUERY EDIT WINDOW, I am getting an error: This property may not exist for this object or may not be retrievable due to insufficient access rights. The text is encrypted. |
I just started using blender and I'm trying to make an animation. It's got it's armatures linked to the body via armature deform but whenever I try to move them in pose mode I get and error saying "cannot select linked when sync selection is enabled". When I don't and I actually manage to move the armatures, the body doesn't move with them even though they're linked and every video I watched says that's all I need to do. Can anyone explain how to solve my problems here please? | So, I'm currently developing a game with unity for which I created a bird, rigged it, and created several actions for it. I then unwrapped and textured it. But now all the actions aren't working anymore! And whenever I try to rotate/move a bone all i get is the error message: "Cannot select linked when sync selection is enabled". I think it might be related to the UV editor, but i have no clue what I should do there. I hope anyone can help! |
Health.SE apparently has 1 view/day, according to Area51 (given that multipler users were active just minutes ago, this seems rather unlikely), Pets and Latin Language are even down to nil. (Pictures are just proofs in case this can’t be replicated) eosio.SE has 328 visits/day, seems legit Bioinformatics, IoT, SiteCore, have 1 visit/day Monero has 3 visits/day all other sites have 0 visits/day So far, I went until Latin Language in the Area51 tab, then I got rate limited [This IP address has performed an unusual high number of requests and has been temporarily rate limited.] | In the , can monitor some things like the total traffic on the site. However, it seems to be broken at the moment, all figures are almost zero. This is how it looks for Meta Stack Exchange (other sites show similar pictures): |
Find remainder when $777^{777}$ is divided by $16$. $777=48\times 16+9$. Then $777\equiv 9 \pmod{16}$. Also by Fermat's theorem, $777^{16-1}\equiv 1 \pmod{16}$ i.e $777^{15}\equiv 1 \pmod{16}$. Also $777=51\times 15+4$. Therefore, $777^{777}=777^{51\times 15+4}={(777^{15})}^{51}\cdot777^4\equiv 1^{15}\cdot 9^4 \pmod{16}$ leading to $ 81\cdot81 \pmod{16} \equiv 1 \pmod{16}$. But answer given for this question is $9$. Please suggest. | How do I efficiently compute $a^b\bmod c$: When $b$ is huge, for instance $5^{844325}\bmod 21$? When $b$ is less than $c$ but it would still be a lot of work to multiply $a$ by itself $b$ times, for instance $5^{69}\bmod 101$? When $(a,c)\ne1$, for instance $6^{103}\bmod 14$? Are there any other tricks for evaluating exponents in modular arithmetic? This is being asked in an effort to cut down on duplicates, see and . |
Is $[0,1]\cap\mathbb{Q}$ a compact subset of $\mathbb{Q}$. No it is not. Since $\mathbb{Q}$ is dense in $\mathbb{R}$ for any open set in [0,1] there is a rational that belongs to that set. Since there are infinite open sets in [0,1] by the standard topology there is not a sub covering that would be finite, since it be composed of infinite number of rationals. Question: Is this proof right? Thanks in advance! | Consider the topological subspace $\mathbb{Q} \cap [0,1]$ endowed with the usual topology of $[0,1]$, since $[0,1]$ is Hausdorff and that $\mathbb{Q} \cap [0,1]$ is not closed, we conclude that $\mathbb{Q} \cap [0,1]$ is not compact, i.e., there exist an open covering $\{O_i\}_{i \in I}$ of $\mathbb{Q} \cap [0,1]$ such that for any finite index set $J \subseteq I$, $\displaystyle \bigcup_{j \in J} O_j \subset \mathbb{Q} \cap [0,1]$, where the inclusion is strict. My question is if there is an explicite example of such open covering? |
I have performed a few installs of Xubuntu (because its lighter than ubuntu) but am always annoyed by the fact Xubuntu installing loads of unwanted stuff (and thus taking a long time onto a usb) when I only select that I want the Xubuntu graphical deskop (in the checkbox list while installing). How do I prevent Xubuntu from installing: office applications cd burning apps music and media players etc. When all I want is the core system, plus a web browser and the dev tools? Also is there any way to make a customized install so it sets up things like user name, domain etc, and other settings such as swappable upon install? | I'm fairly new to linux but I want to install it on my chromebook with crouton. Is there a way to install something like lubuntu or xubuntu without any of the software normally bundled? For example, I don't need a music manager, libre office, an internet browser (I will install chrome). I would rather just choose these kinds of programs myself and install what I need rather than have them included. Is this possible? |
Starting from the FRW metric (for simplicity flat space, radial direction only): $$ds^2=-c^2dt^2+a(t)^2dr^2$$ If we take $dt=0$ then the proper distance $ds(t)$ between two spatially separated points at cosmological time $t$ is given by: $$ds(t)=a(t)dr$$ Now at the present time $t_0$ we can define $a(t_0)=1$ so that we also have: $$ds(t_0)=dr$$ Therefore by eliminating $dr$ in the above equations we find: $$ds(t)=a(t)\ ds(t_0)$$ If we define $ds(t)=1$ so that a hydrogen atom has a unit proper diameter, at any time $t$, then the equivalent diameter at the present time $t_0$ is given by: $$ds(t_0)=\frac{1}{a(t)}$$ According to quantum mechanics the mass/energy of a quantum system is inversely proportional to its size. Therefore if the mass/energy of the hydrogen atom at time $t$ is one unit then the mass/energy of an equivalent atomic system at the present time $t_0$ is $a(t)$ units. Thus can one infer that hydrogen atoms at time $t$ in the future have an energy that is a factor $a(t)$ higher relative to the energy of hydrogen atoms today? | I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for. So here is my question: One often hears talk of space expanding when we talk about the speed of galaxies relative to ours. Why, if space is expanding, does matter not also expand? If a circle is drawn on balloon (2d plane), and the balloon expands, then the circle also expands. If matter is an object with 3 spatial dimensions, then when those 3 dimensions expand, so should the object. If that was the case, we wouldn't see the universe as expanding at all, because we would be expanding (spatially) with it. I have a few potential answers for this, which raise their own problems: Fundamental particles are 'point sized' objects. They cannot expand because they do not have spatial dimension to begin with. The problem with this is that while the particles would not expand, the space between them would, leading to a point where the 3 non-gravity forces would no longer hold matter together due to distance Fundamental particles are curled up in additional dimensions a la string theory. These dimensions are not expanding. Same problems as 1, with the added problem of being a bit unsatisfying. The answer seems to be (from Marek in the previous question) that the gravitational force is so much weaker than the other forces that large (macro) objects move apart, but small (micro) objects stay together. However, this simple explanation seems to imply that expansion of space is a 'force' that can be overcome by a greater one. That doesn't sound right to me. |
The title says it all, really. In the world cups for different sports, the player lead children on the field. Why? | I have seen many soccer matches. I often see that players enter the field with children. Why do they enter with the children? |
I have a character with the Guild Artisan background. His guild was an Alchemists' Guild so he is proficient with the alchemist's tool kit. I mentioned to the DM that I could theoretically chop up monster corpses for use as alchemical raw materials and he said it was a good idea but provided no guidance. Is there any published material that explains how to do this in 5th edition? Because the last time I saw guidelines, they were in the AD&D Dungeon Master's Guide. | I haven't played D&D for a while though recently I have started playing it with my kids. The group is made out of five. So far they have acted with wisdom and they have been lucky which allowed them to slay the Green Dragon in Thundertree. Are there any rules for disassembling the dragon for the sake of doing things such as selling its meat and making armor from its scales? |
According to Einstein's theory of relativity, the more speed something has the slower that time passes for it; and presumably when traveling at the speed of light, time stops entirely. So this means that when a photon is created, the rest of existence virtually pauses until the photon ceases to exist, and then the rest of existence begins again. If time is stopped while the photon exists, then what are we measuring when we measure light? In order to measure the actual photon, we would need to take the measurement while time was standing still. Speed requires time, so why do we say that light travels at a speed? | I read with interest about Einstein's Theory of Relativity and his proposition about the speed of light being the universal speed limit. So, if I were to travel in a spacecraft at (practically) the speed of light, would I freeze and stop moving? Would the universe around me freeze and stop moving? Who would the time stop for? |
I want to write a C program to read a png's pixel values without any external libraries (excluding zlib for decompression). I have studied the for png's and have seen some which do the same. Currently, I am trying to read the bytes of the png into an array. Currently, I am using which has some black dots that I would use to verify the pixel coordinates in the final array. However, when printing the retrieved array I only get the first four bytes of the png: ëPNG I verified that it was not in fact printing the bytes that is the problem when I asked for the sizeof() the array and it returned 4. I don't understand what is wrong with this code: #include <stdio.h> #include <stdlib.h> int main(int argc, char* argv[]) { FILE *fp = fopen(argv[1], "rb"); unsigned char* file_data; fseek(fp, 0, SEEK_END); long int length = ftell(fp); rewind(fp); file_data = (char *)malloc((length+1)*sizeof(char)); fread(file_data, length, 1, fp); printf("%s\n", file_data); printf("%d\n", sizeof(file_data)/sizeof(file_data[0])); fclose(fp); return 0; } | First off, here is some code: int main() { int days[] = {1,2,3,4,5}; int *ptr = days; printf("%u\n", sizeof(days)); printf("%u\n", sizeof(ptr)); return 0; } Is there a way to find out the size of the array that ptr is pointing to (instead of just giving its size, which is four bytes on a 32-bit system)? |
I've found a huge collection of old family photos that are the negative strips (roughly 6 pictures a strip). I had a scanner that would allow me to digitally save the photos from the negatives one at a time; however, this seems like it will take me a century to do them all. What's my options in either hardware or taking them somewhere to get done that will go faster than my current method? is a similar scanner to the one I'm using now. | I have thousands of old pictures which were sitting in a photo album. Unfortunately, instead of the photo album protecting the pictures, the plastic coverings yellowed, and the pictures themselves had to be carefully extracted from the books. There is also quite a bit of powdered paper (the backings on the books pretty much fell apart while we extracted the pictures), and the fronts of the images are still a bit sticky. These pictures are 30+ years old, are often extremely faded, and were originally taken on (what I think is) "110 film" -- they are approximately 2.5" squares. Anyway, I need to scan all these images in to preserve them from further decay. Unfortunately, it's taking forever -- going through less than 100 images took an entire day, even if one discounts any time spent in Photoshop trying to remove some of the photo album's artifacts on the images. What I really need is some method of scanning the images in faster. Most automated solutions aren't going to work because they accept 4x6s as their smallest image size, and even if that was not the case, the adhesives still stuck to the prints would probably ruin any such device in 5 seconds flat. Is there a better way of doing this (i.e. fast scanner?) that wouldn't take so much time? |
I am reading "Radio Theory Handbook" and am confused with the statement that says that electrons are moving through the wire at snails pace.But it goes on to say the "electrical effect" is instantaneous. I assume he means the speed of light. Then what is this mysterious electrical signal in the wire that moves at the speed of light? Is it the EMF? By definition electricity is the flow of electrons. But yet the electrons are said to travel slow? There cannot be a contradiction. I am asking for help in clarifying this. Thank you. There is another question " Is voltage the speed of the electrons? This is not the same question. I am not asking about voltage. I am asking about the apparent contradiction given the fact that electricity which is the flow of electrons has an almost instantaneous effect while the electrons themselves more very slowly. Although it is not the same question there was enough useful information there and along with all the excellent responses that my question has been well explained. | Current is the amount of electrons passing through a wire. Can we say that voltage is the speed of those electrons? |
I need help to evaluate the integral with the residue theorem: $$\int_{-\infty}^{\infty}\frac{\ln{(x^2+a^2)}}{x^2+b^2}\,dx$$ where a,b>0 real numbers. I think I could consider the contour integral where C is the half circle in the first two quadrant. But I'm not sure how to continue. Could someone help me? | How to evaluate the following improper integral:$$\int_{0}^\infty {\ln(a^2+x^2)\over{b^2+x^2}}dx,$$ where $a,b>0$. I tried to suppose $$f(a)=\int_0^\infty {\ln(a^2+x^2)\over{b^2+x^2}}dx,$$ based on the convergence theorem, and then I tried $${df(a)\over da}=\int_0^\infty {2a\over {(a^2+x^2)(b^2+x^2)}}dx = {\pi\over b(b+a)},$$and then $$f(a)={\pi\over b}\ln(b+a)+C,$$where $C$ is a constant, but I don't know how to find the constant $C$. Could anyone tell me that, and explain why? Or could anyone find other methods to evaluate the integral? If you could, please explain. Thanks. |
My question is we are the normal user. We can't access the file which we didn't have the permission. We are executing the passwd command then how that command is able to access that file. We are executing the passwd command as a normal user. Can anyone explain to me?. | How does Linux know that it has to give euid 0 (uid of root) to only certain process like passwd, setuid, etc. If a process can gain root permissions, will it not lead to potential security breaches in the Linux platform? For example, if I write a program that can can gain root user permissions like passwd, I may corrupt important system files like /etc/passwd, /etc/groups. How does Linux manage to still be secure? |
For example , in page What does the (2) mean in bpf(2) ? | For example: man(1), find(3), updatedb(2)? What do the numbers in parentheses (Brit. "brackets") mean? |
I have strings that need to be placed into lists; for instance I require that C C .0033 .0016 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' C becomes ['C', 'C', '.0033', '.0016', 'International Tables Vol C Tables 4.2.6.8 and 6.1.1.4', 'C'] So everything in quotes becomes a single list element; otherwise, everything separated by whitespace becomes a single list element. My first idea was a simple split, place the items that don't contain ' into a new array, and then place the ones that are in a quoted-section back together: >>> s.split() ['C', 'C', '.0033', '.0016', "'International", 'Tables', 'Vol', 'C', 'Tables', '4.2.6.8', 'and', "6.1.1.4'", 'C'] >>> arr = [] >>> i = 0 >>> while i < len(s): v = '' if s[i].startswith("'"): while not s[i].endswith("'"): v = v.append(s[i]+ " ") i += 1 v.append(s[i]) arr.append(v) else: arr.append(s[i]) But this strategy is pretty ugly, and in addition I have to assume that the string was split on a single space. s.partition("'") seemed very promising: >>> s.partition("'") ('C C .0033 .0016 ', "'", "International Tables Vol C Tables 4.2.6.8 and 6.1.1.4' C") but it's awkward because I have to partition again as I iterate through, and it's context-sensitive as to which one was in quotes. Is there a simple Python3 way to split this string as described above? | I have a string which is like this: this is "a test" I'm trying to write something in Python to split it up by space while ignoring spaces within quotes. The result I'm looking for is: ['this','is','a test'] PS. I know you are going to ask "what happens if there are quotes within the quotes, well, in my application, that will never happen. |
Suppose you have a die. On average, how many rolls does it take for all the faces (1 through 6) to have appeared? Also, what kind of distribution is this? (I thought of this question when watching rain fall on my driveway; I wondered how long it takes for rain to completely cover the whole driveway.) | What is the average number of times it would it take to roll a fair 6-sided die and get all numbers on the die? The order in which the numbers appear does not matter. I had this questions explained to me by a professor (not math professor), but it was not clear in the explanation. We were given the answer $(1-(\frac56)^n)^6 = .5$ or $n = 12.152$ Can someone please explain this to me, possibly with a link to a general topic? |
In reviewing, most of post properties are hidden (e.g. votes score) for reviewer will can't use it for his decision. But sometimes I see different tips (direct and indirect) that are indicates post correctness For example, answer accepted icon: This screenshot was created after reviewing, but accepted icon was appeared before, when post was loaded for reviewing Also sometimes I notice: That post creator's account is deleted Post comments indicating post correctness I think that these items are unnecessary tips and using them is cheating | I think many of us already aware, still I wanted to let you know that First Post and Late Answers review posts are generated on specific time interval. When time comes for post generation I follow some tricks Click and till a Post appears for review Then right-click and select Open in new tab 5-8 time. Then in every page follow the below steps Open the Question of post appeared in review in New tab If Page/Question not exists then simply downvote since post was deleted because of -ve response. Else if page exists then Check the review post's Net Reputation If reputation is -ve then simply downvote the post came in review Else one may select No Action needed. This way if in any case a post comes for "Are you paying attention" can be handled easily. I think if a post comes in review should not allow to view post. |
I have a form that can be cloned via jquery. I can submit all the inputs if I use: <form method="POST" action="insert_mydata.php" id="myForm"> But if I try to use: $(function() { $("#myForm").submit(function() { $.ajax({ type: "POST", url: "insrt_mydata.php", data: $('#myForm').serialize(), success: function(data) { alert(data); alert("Successful"); } }); return false; }); }); Please help me find out what I am missing. Thank you. The script I am using to clone the form: $('.add').click(function(e){ e.preventDefault(); var lastRepeatingGroup = $('.repeatingSection').last(); var cloned = lastRepeatingGroup.clone(true); cloned.insertAfter(lastRepeatingGroup).find(":text").val(""); resetAttributeNames(cloned); }); How does the two method differ from each other as the latter is working (Data are being inserted the way I want it to be), while the jquery method is not. Thank you. | I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off. This happens on page ready and works just fine. The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound. I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option. |
I've been using csvtools to read data from CSV files. Is there any way to read data directly from a ODS file, to put the data into a LaTeX document? | This question led to a new package: Suppose you have an localc spreadsheet myspread.ods and you want to insert the content of the range H4:I40 as a table into your latex document. I know that I can export the table or just do some copy and paste. However is it possible to write something like: \includespread{file=myspread.ods,range=H4:I40} Then the table in my LaTeX-document changes when the corresponding spreadsheet changes. Would be nice to have also the possibility to modify global appearence properties of the table as optional arguments of \includespread. |
Creation of Singleton class in Java has been discussed and debated in various communities multiple times. Even after all the discussions, the debaters aren't satisfied with array of provided solutions. My question is simply to find out the best & most effective way to create any class Singleton in Java & C++. | What is an efficient way to implement a singleton pattern in Java? |
I want to switch J1's position with the card under it after the deck array is shuffled. Is there a way to reference J1 without knowing its position in the array? Thank you. import random deck = ['AC', '2C', '3C', '4C', '5C', '6C', '7C', '8C', '9C', 'TC', 'JC', 'QC', 'KC', 'AS', '2S', '3S', '4S', '5S', '6S', '7S', '8S', '9S', 'TS', 'JS', 'QS', 'KS', 'AH', '2H', '3H', '4H', '5H', '6H', '7H', '8H', '9H', 'TH', 'JH', 'QH', 'KH', 'AD', '2D', '3D', '4D', '5D', '6D', '7D', '8D', '9D', 'TD', 'JD', 'QD', 'KD', 'J1', 'J2'] # shuffle deck random.shuffle(deck) #switch Joker1 with card under it | Given a list ["foo", "bar", "baz"] and an item in the list "bar", how do I get its index (1) in Python? |
Imagine this simple script below (just a simple example) where I call a javascript file using Naked execute_js. I can run this from my system command line because I installed Naked using pip. from Naked.toolshed.shell import execute_js, muterun_js output= execute_js('D:\\myFolder\\myJavaScript.js) Now, to use it from inside blender, I downloaded the package so I have all the file in: D:\myFolder\modules\Naked In blender, I have this script where I add the path to the Naked files: import sys sys.path.insert(0, 'D:\\BLENDER_EARTH_PROJECT\\modules\\Naked') output= execute_js('D:\\myFolder\\myJavaScript.js) But I still can't access execute_js. What am I missing here? Is this not the correct way to do this? | I'm currently developing a script for Blender to handle Mesh Frequency Decomposition. The script is nearly complete, but i need one more thing: The SciPy library to compute eigenvalues and eigenvectors. Following the installation instructions on , I'm able to install it as well as Numpy. Numpy works fine, but I can't even import SciPy: Traceback (most recent call last): File "/CAF_FD.py", line 4, in <module> ImportError: No module named 'scipy' Error: Python script fail, look in the console for now... By the way, I'm working on Linux 64 bit and I've installed SciPy and Numpy with my package manager. Edit: When I try to use SciPy with a terminal prompt, it works. |
Hi I am trying to render a model of Sintel. While using the render view port shading in the 3d view the eyes looks perfectly fine: But when I actually render it, these grey splotches show up under her eyes: Does anyone know what may be causing this? For reference, I downloaded this model from here: . | Since the Denoise feature was added to Blender I only use the default setting with it and it really does the work. But sometimes the denoise is noticable on some of my renders. How can I overcome the blurred effect? Denoising for me is a big help because my system is quite aged. |
I am not a physicist, I am just an engineer. But I dared to ask whether the temperature changes the perception of time. Let's consider a particle that "stops" at absolute zero. I was thinking as a hypothesis, that our perception of time changes and the particle actually does not stop at all. | Time has many definitions per se, but the basic idea being it's "the measurement of change" so as we know, all matter looses it's ability of changing with the loss of kinetic energy. and the where it becomes zero is the absolute zero (−273.15°C). so my question would be, will time stop/freeze at Absolute zero? and does time get slow while reaching there? |
I am developing a chat application. Using this app users can send friend requests. once two users become friends they can message each other and visit friends profiles. When two users become friends(imagine X and Y), in a situation where X visits Y's profile and at the same time Y visits X's profile, the app get crashed. | What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely? |
In the Harry Potter books, women in the magical cover very important roles, and are equal to men from this point of view. This emancipation is similar to what has been quite recently achieved in our times (in UK, at least) What is remarkable is that, when describing ancient magical society, JK Rowling seems to remark that this equality was real also in those times. Even when speaking about a century ago or before, women with powerful roles are cited. I am also thinking about quidditch, which is the main magical sport and is played by both men and women on equal basis (at Hogwarts, at least). I tend to believe this is a JK Rowling's specific choice. Are there any sources where she talks about this? | There are racial struggles and examples of racism, (Muggle-borns, centaurs, hous-elves, goblins, etc.) but are there any examples in the Wizarding World of sexism? Have witches and wizards always had equal rights? |
While I was dual booting with the USB I got structed with screen containing only "-" blinking on the screen. I have nearly waited for 30 min. It did not work. I turned on the PC again my Windows 10 was degraded to Windows XP, how it's possible? But the Windows XP does not contain anything, totally blank but the data is present. I can't access the Windows XP also as it is only blank again. I tried to boot the system with pendrive it has worked and I gone through the process after the process i.e. the booting is completed and I successfully installed Ubuntu but after restarting this line is displaying To reboot the device press any key or insert a boot device to boot The main thing while I am booting Ubuntu is the other space in my disk is filled with Windows 10 and XP while partitioning but while reacting I can't get both of them. I can't get the OS to run. Can you help me in this regard and what are the steps to take and to get the Windows 10 again? | I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install. What can I do to fix this? |
I want to use one domain name on 2 servers at a time.If one server is not working then my visitors can see my website without any problem from other server.Can i use one domain name on two different hosting services? | I'm planning on releasing an iOS app that downloads video from my server. If hundreds of people on the launch day try to do this, then my website and the services that my server provides will clearly go down. How do you host a website on multiple servers? When someone tries to access my site, how is their request passed to an available server? How do Apple and Google do it? Thanks for your help. |
I have a stack overflow account and just now(not more than hour ago) each and every question I had ever asked or an answer I had written got down voted. I would have understood if few of my Q and A being marked down.. but as almost all my activity is marked down I am suspecting something fishy. I would like an explanation and/or some justification for the act? Can anyone help? Or can I at least know who I Ticked off to get a reaction like this? | While browsing Stack Overflow, I noticed that I lost a lot of reputation: Is this serial downvoting? Will it be corrected by a rep-recalculation? How often are those done? Here's a second instance: |
Let $N$ be a normal subgroup of $G$. Is the group $G$ always isomorphic to the group $G/N \times N$? I don't think this is true but I can't think of a counter-example. What's an easy counter-example (or way to prove the contrary)? | Respected all Please help me on this problem. Suppose that $G$ is given group and $N$ be a normal subgroup of $G$ and $N$ is isomorphic to $G_1$ as groups. If $G/N$ is isomorphic to the group $G_2$, can we establish that $G$ is isomorphic to the group $G_1\times G_2$ ? |
I have 3 fields. Category, sub-category and products. Sub-category is the dependent picklist of category and Products is the dependent picklist of Sub-category. But, not all Categories have Sub-categories so Products should also be a dependent picklist of Category. Is it possible for Products to have 2 controlling picklists? I did my research and it stated that this can be achieved only through VF page. Is there no possible way I can do this using customisation? Also, can someone please tell me how to do this using a VF page? I did read the other post on this topic but it was mentioned that this can be done using VF page. But the question is pretty old so is there any provision to do it now with the recent releases? Thanks! | I have 3 picklist in an object Test1, Test2, Test3 1. Test2 is dependent on Test1 2. Test3 is dependent on both.. Test1 and Test2 I want to have Test3 picklist showing values accordindly. i.e if U selected Test1 = First and Test2 = SA . I should be able to see "IST,ABC and PQR" in Test 3. Is this possible??? |
Let $L$ be a languague. How can I show that there is no model ($L$-structure) $M$ for a contradiction? M $\models \phi \land \lnot \phi$ It seems very intuitive to me but how do I prove it? | Looking at Tarki's semantics wrt First Order Logic, I have some problems in pinning down the true reason why, given an $L$-structure $M$, and any $L$-sentece $\sigma$ (atomic for simplicity), we have $$M \not\models \sigma \wedge \neg\sigma$$ In this context, structures are sets with given functions and relations that interpret their symbolic counterparts. Given the actual definition of "$\models$", everything boils down to the fact that the sets we are working with are well-behaved, in the sense that we cannot have $$a \in P \wedge a \not\in P$$ But then I ask myself why the reason behind this. Is it a "consistency" assumption we are making on these sets? And if these sets are described by ZF, are we assuming the consistency of ZF? Thanks |
So far I have been told what the problem was but have been provided with no way of fixing it. My computer is able to install updates, but when I hit check under the update menu it tells me to check my internet connection and gives me this error, W:Failed to fetch http://ppa.launchpad.net/ubun-tor/ppa/ubuntu/dists/precise/main/source/Sources 404 Not Found W:Failed to fetch http://ppa.launchpad.net/ubun-tor/ppa/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found E:Some index files failed to download. They have been ignored, or old ones used instead. Anybody know a fix for this? Is no one going to answer my comment down below? | PPA seems to be constantly offline. Whenever I use sudo apt-get update, this error is shown: W: Failed to fetch http://ppa.launchpad.net/ 404 Not Found How do I fix these errors? |
When my girlfriend processes her code in WinEdt on Windows 7, she gets awkward looking "special" letters. (Precisly, these are Serbian letters -- from our home country.) She used: \usepackage[T1, T2A]{fontenc} \usepackage[utf8]{inputenc} \usepackage[serbian]{babel} % This isn't relevant here, but I put it for perspective She also put document properties to utf8, so when she types, all the letters should be encoded in utf8, right? But when she processes her file with pdflatex, she gets . Notice how normal alphabet letters are fine, but the serbian letters (2nd line, word određeno) are different from the others. But, when I process the same .tex file on my Mac (with TexShop), I get a . You can see that it looks regular, although I used the exact same code as her. Why does this happen? She uses utf8 encoding on her WinEdt, and also in the document. Shouldn't it work fine? EDIT: The solution is to include CM-Super font family into MikTex, and it works perfectly. So I guess whenever people have problems regarding European languages and special character formatting, you should check for CM-Super fonts :) | My friend and I are working on the same subject and I asked her to see her work. I noticed that her pdf rendering (if it's really that) is a lot different than mine even though we use the same "template". We both use TexMaker with MikTeX, hers is on Mac, mine is on Windows. Left is mine, right is hers. If anyone knows what cause the difference here and could help me getting the same thing that would be great. Thank you. |
I have a site at hostgator, using their "Business account". It's cheap, and comes with a private SSL cert. HOWEVER, their MySQL settings are such that any db connection goes stale fairly quickly, and then the hostgator staff try to convince you to use a VPS or dedicated server at multiple times the expense. I'm creating and deploying WebAPIs, which can have a 'conversation' which exceeds 60 seconds. When this occurs, the db connection handle is stale, causing any db operations after my timeout to fail. I'm in the process of implementing the following solution, but am curious if anyone else has solved this issue (where they can not modify their my.ini or my.cnf to give MySQL more resources) in a similar or completely different manner. last part of a hook_update: $ret = db_query( "UPDATE {my_table} set field1 = '%s', field2 = %d ... WHERE vid - %d", $node->field1, $node->field2, ... $node->vid ); if (!$ret) { // get private storage directory for this node: $cexStorage = _cex_front_getCexStore(); $nodeFilesPath = DRUPALROOT.'/'.$cexStorage.'/'.$node->storeDir; $fname = $nodeFilesPath.'/recover.node'; $readyToWrite = serialize( $node ); file_put_contents( $fname, $readyToWrite ); if (file_exists( $fname )) { _dbgReport( 'seems to have worked!' ); } } Then this is called in my hook_form, right after I determine that node->nid is valid: function _cex_front_recover_node( &$node ) { if (!isset($node->storeDir)) { _dbgReport( '**************************** _cex_front_recover_node: no storeDir!!!' ); return; } // get private storage directory for this node: $cexStorage = _cex_front_getCexStore(); $nodeFilesPath = DRUPALROOT.'/'.$cexStorage.'/'.$node->storeDir; $fname = $nodeFilesPath.'/recover.node'; if (file_exists( $fname )) { $recovered = file_get_contents( $fname ); if ($recovered) { // no longer needed: unlink( $fname ); $recoveredNode = unserialize( $recovered ); // restore the key values I need to proceed with this node: $node->stage = $recoveredNode->stage; $node->rnid = $recoveredNode->rnid; $node->iris = $recoveredNode->iris; cex_front_update( $node ); } else { _dbgReport( '********* failed to read "'.$fname.'"' ); } } } I'll be pairing the logic down to only store the key fields I need, but this works! Sure beats upgrading my server at 3x the expense. Anyone else doing something like this? | Recently I started getting an error every time I try and add a content no matter what type. This is the error that shows up in the browser: Additional uncaught exception thrown while handling exception. Original PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT COUNT(cid) FROM {comment} WHERE status = :status; Array ( [:status] => 0 ) in comment_count_unpublished() (line 313 of /Applications/MAMP/htdocs/modules/comment/comment.module). Additional PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: INSERT INTO {watchdog} (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array ( [:db_insert_placeholder_0] => 1 [:db_insert_placeholder_1] => php [:db_insert_placeholder_2] => %type: !message in %function (line %line of %file). [:db_insert_placeholder_3] => a:6:{s:5:"%type";s:12:"PDOException";s:8:"!message";s:154:"SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT COUNT(cid) FROM {comment} WHERE status = :status; Array ( [:status] =&gt; 0 ) ";s:9:"%function";s:27:"comment_count_unpublished()";s:5:"%file";s:56:"/Applications/MAMP/htdocs/modules/comment/comment.module";s:5:"%line";i:313;s:14:"severity_level";i:3;} [:db_insert_placeholder_4] => 3 [:db_insert_placeholder_5] => [:db_insert_placeholder_6] => ; [:db_insert_placeholder_7] => [:db_insert_placeholder_8] => 127.0.0.1 [:db_insert_placeholder_9] => 1338336955 ) in dblog_watchdog() (line 154 of /Applications/MAMP/htdocs/modules/dblog/dblog.module). I also get the following error in my php error file: PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2006 MySQL server has gone away' in /Applications/MAMP/htdocs/includes/database/database.inc:2136 Stack trace: 0 /Applications/MAMP/htdocs/includes/database/database.inc(2136): PDOStatement->execute(Array) 1 /Applications/MAMP/htdocs/includes/database/database.inc(664): DatabaseStatementBase->execute(Array, Array) 2 /Applications/MAMP/htdocs/includes/database/database.inc(2315): DatabaseConnection->query('SELECT expire, ...', Array, Array) 3 /Applications/MAMP/htdocs/includes/lock.inc(167): db_query('SELECT expire, ...', Array) 4 /Applications/MAMP/htdocs/includes/lock.inc(146): lock_may_be_available('theme_registry:...') 5 /Applications/MAMP/htdocs/includes/theme.inc(447): lock_acquire('theme_registry:...') 6 /Applications/MAMP/htdocs/includes/bootstrap.inc(427): ThemeRegistry->set(Array) 7 [internal function]: DrupalCacheArray->__destruct() 8 {main} thrown in /Applications/MAMP/htdocs/includes/database/database.inc on line 2136 I am having a little trouble deciphering these error messages. Could anyone help me understand what's going on here? |
How can one show that there is a bijection from $\mathbb N$ to $\mathbb Q \times \mathbb Q $? | How can I prove that the Cartesian product of two countable sets is also countable? |
let $f : X \to X $ be an isometry $d((f(x)),f(y)) = d(x,y)$ for all $x,y \in X$. It could easily be shown that $f$ is continuous and injective. Now if we let $X$ to be compact, need to show that it is surjective in this case. The proof proceeds as following: Suppose $f(X) \neq X$. Then there exists a $a \in X$ such that $a \not \in f(X)$. The function $f$ is continuous, and since $X$ is compact so is $f(X)$. Notice that $f(X)$ is compact in $X$, being hausdorff $f(X)$ is closed, making $X - f(X)$ open. Then for this $a$, I can find a $\epsilon$ neighbourhood such that $B(a,\epsilon) \subset X - f(X)$. This is ofc, not the whole proof. However I understood the other part easily, only problem I have is here that why $X$ is hausdorff so that $f(X)$ is closed in $X$. I'm not given that it is Hausdorff or anything. Thanks! | A prelim problem asked to prove that if $X$ is a compact metric space, and $f:X \to X$ is an isometry (distance-preserving map) then $f$ is surjective. The official proof given used sequences/convergent subsequences and didn't appeal to my intuition. When I saw the problem, my immediate instinct was that an isometry should be "volume-preserving" as well, so the volume of $f(X)$ should be equal to the volume of $X$, which should mean surjectivity if $X$ is compact. The notion of "volume" I came up with was the minimum number of $\epsilon$-balls needed to cover $X$ for given $\epsilon > 0$. If $f$ were not surjective, then because $f$ is continuous this means there must be a point $y \in X$ and $\delta > 0$ so that the ball $B_\delta(y)$ is disjoint from $f(X)$. I wanted to choose $\epsilon$ in terms of $\delta$ and use the fact that an isometry carries $\epsilon$-balls to $\epsilon$-balls, and show that given a minimum-size cover of $X$ with $\epsilon$ balls, that a cover of $X$ with $\epsilon$-balls could be found with one fewer ball if $f(X) \cap B_\delta(y) = \emptyset$, giving a contradiction. Can someone see a way to make this intuition work? |
I am using the moment npm module. I am comparing two dates and want to see if there in the same day. Is there a clean way of doing that using the moment package or using straight javascript or typescript? | Can someone suggest a way to compare the values of two dates greater than, less than, and not in the past using JavaScript? The values will be coming from text boxes. |
I have a collection of files and directories with strange names, they contain spaces and the special characters \, *, ), ( and ?. All of them cause problems when I try to use them in the command line or scripts, e.g.: $ cd space dir bash: cd: space: No such file or directory $ cat space file cat: space: No such file or directory cat: file: No such file or directory $ cat ( bash: syntax error near unexpected token `newline' $ echo content >\ > ^C $ ls ? ( ) * ? \ How do I enter file or directory names that contain special characters in the terminal? | I want to enter the following folder in the terminal: Milano, Torino (Jan)-Compressed How should I write the command cd to enter this directory? Spaces and several other special characters like \, *, ), ( and ? cause problems when I try to use them in the command line or scripts, e.g.: $ cd space dir bash: cd: space: No such file or directory $ cat space file cat: space: No such file or directory cat: file: No such file or directory $ cat ( bash: syntax error near unexpected token `newline' $ echo content >\ > ^C $ ls ? ( ) * ? \ How do I enter file or directory names that contain special characters in the terminal in general? |
I try to use a relative path for the algorithm "Set style for vector layer" in the processing modeler, but it works only with absolute path. A similar request is , but the answer doesn't suit me. It is proposed to copy the files to the root of the hard drive. I need to share the model and the qlm files with external users who may not have access to the root of the disk or whose disk is not named c: / and aren't on the same network. Would someone have a other solution? | Using QGIS 3.0, we are working on creating a tool that will allow people to check that their snapping is correct with several linear features stacked on each other. A co-worker of mine figured out how to do it. However, when you first set it up, you have to open the graphical modeler and set the style manually. What she currently has is a path to her own desktop to the folder that has all the possible styles. I am trying to find a way to make it universally, find the CURRENT users profile, THEN search for the file path. Currently the path is set to something like this: C:/Users/jwagner/Desktop/Staging Folder/Layer Styles/CableVertex_Incorrect.qml I tried editing it to use something like this: Environ("USERPROFILE") & "\Desktop\V1.2\Layer Styles\CableVertex_Incorrect.qml" We have also tried using "%," and "~" to no avail. The end goal is to have this path already set when we give people the model file. That way we aren't having to personally show every single person on our project how to set styles. I know from personal experience that it will lead to problems later on down the line when trusting everyone else to remember how to properly do it on their own. |
It would be nice if for each question only relevant reputation points appear, for both the question and the answers. Based on the question tags. If a question is about Linux, we don't care about Windows reputation points. If a question is about networks, we don't care about database reputation points... | I posted this as an answer to another question, but after some thought, I think it qualifies as a feature request in its own right. I would like to see a per-tag breakdown (based on a question's tag list) of each answerer's reputation in addition to their lump sum reputation. Something like this: Question is tagged with: C# winforms combobox An answer would look like this: Blah blah blah Eric 200 C#170 winforms50 combobox10 This would give more insight into how credible a person's answer is. I think it will also be more rewarding for people that are more active in less popular tags. I'm not sure how difficult it would be to implement though. |
I want to remove an object in a list while doing foreach loops Here's the code List<Book> listBooks = response.body().products; for (Book book: listBooks) { if(!book.category.equals("scifi")){ listBooks.remove(book); } } listBooks.remove(book) doesn't work. | We all know you can't do the following because of ConcurrentModificationException: for (Object i : l) { if (condition(i)) { l.remove(i); } } But this apparently works sometimes, but not always. Here's some specific code: public static void main(String[] args) { Collection<Integer> l = new ArrayList<>(); for (int i = 0; i < 10; ++i) { l.add(4); l.add(5); l.add(6); } for (int i : l) { if (i == 5) { l.remove(i); } } System.out.println(l); } This, of course, results in: Exception in thread "main" java.util.ConcurrentModificationException Even though multiple threads aren't doing it. Anyway. What's the best solution to this problem? How can I remove an item from the collection in a loop without throwing this exception? I'm also using an arbitrary Collection here, not necessarily an ArrayList, so you can't rely on get. |
I have a problem with checking variables in the "if". I get a userPhoneNumber variable from SharedPreferences and phoneNumber of SmsMessage. I will displaying Toast with both variables and they are the same, but the if didn't work. Where is the problem? My BroadcastReceiver class: public class IncomingSms extends BroadcastReceiver { String userPhoneNumber = ""; String senderNum= ""; String message= ""; final String TAG="LocationService"; GPSTracker gps; double latitude = 0.0; double longitude = 0.0; // Get the object of SmsManager final SmsManager sms = SmsManager.getDefault(); public void onReceive(Context context, Intent intent) { SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(context); userPhoneNumber = settings.getString("userPhoneNumber", ""); Log.e(TAG, "userPhoneNumber:"+userPhoneNumber); int duration = Toast.LENGTH_LONG; // Retrieves a map of extended data from the intent. final Bundle bundle = intent.getExtras(); try { if (bundle != null) { final Object[] pdusObj = (Object[]) bundle.get("pdus"); for (int i = 0; i < pdusObj.length; i++) { SmsMessage currentMessage = SmsMessage.createFromPdu((byte[]) pdusObj[i]); String phoneNumber = currentMessage.getDisplayOriginatingAddress().toString(); senderNum = phoneNumber; message = currentMessage.getDisplayMessageBody(); turnOn(context); } // end for loop } // bundle is null } catch (Exception e) { Log.e("SmsReceiver", "Exception smsReceiver" +e); } Log.i("SmsReceiver", "senderNum: " + senderNum + "userPhoneNumber: "+ userPhoneNumber + "; message: " + message); } public void turnOn (Context context){ Intent i = new Intent(context, MyService.class); gps = new GPSTracker(context); Toast.makeText(context,"Method turnOn!\nsenderNum: "+senderNum + "\n userPhoneNumber: " + userPhoneNumber, Toast.LENGTH_LONG).show(); if (senderNum == userPhoneNumber) { Toast.makeText(context,"works in IF", Toast.LENGTH_LONG).show(); if(gps.canGetLocation()){ latitude = gps.getLatitude(); longitude = gps.getLongitude(); i.putExtra("Latitude", latitude); i.putExtra("Longitude", longitude); context.startService(i); }else { gps.showSettingsAlert(); } } gps.stopUsingGPS(); } | I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug. Is == bad? When should it and should it not be used? What's the difference? |
as written , I should put this lines: deb mirror://mirrors.ubuntu.com/mirrors.txt precise main restricted universe multiverse deb mirror://mirrors.ubuntu.com/mirrors.txt precise-updates main restricted universe multiverse deb mirror://mirrors.ubuntu.com/mirrors.txt precise-backports main restricted universe multiverse deb mirror://mirrors.ubuntu.com/mirrors.txt precise-security main restricted universe multiverse on the top in my /etc/apt/sources.list file, and this should be all that is needed to make it automatically pick a mirror for me based on my geographical location. because the file sources.list is read-only, what should I do? tried $ sudo mount -o rw,remount /etc/apt/sources.list but it wasn't found.. | I can't seem to edit and save config files in the root system (eg: /etc/dhcp/dhcpd.config); it just says "permission denied" or the save option is blocked in the text editor. I'm pretty sure I'm a root user, but how do I make sure? If I am a root user, how do I fix this? |
I know how to show that Y is complete and sufficient for part A using the exponential family form, but how do I get the UMVUE for part B? I know we probably use Y and go for an unbiased function of Y, but I simply do not know how to get this. | Suppose that $X_1, \ldots, X_n$ follows Bernoulli distribution $B(1,p)$, then what is the UMVUE of $p^s$ and $p^s + (1-p)^{n-s}$? I suppose I should use the Lehmann–Scheffé theorem. Now $\overline{X}$ is a sufficient and complete statistic, I need to find a function of $\overline{X}$ whose expectation is $p^s$ and $p^s + (1-p)^{n-1}$. But I don't know how to find such a function. Any hint would be welcome! |
I have a 250 MB backup SQL file but the limit on the new hosting is only 100 MB... Is there a program that let's you split an SQL file into multiple SQL files? | I need to move entire tables from one MySQL database to another. I don't have full access to the second one, only phpMyAdmin access. I can only upload (compressed) sql files smaller than 2MB. But the compressed output from a mysqldump of the first database's tables is larger than 10MB. Is there a way to split the output from mysqldump into smaller files? I cannot use split(1) since I cannot cat(1) the files back on the remote server. Or is there another solution I have missed? Edit The --extended-insert=FALSE option to mysqldump suggested by the first poster yields a .sql file that can then be split into importable files, provided that split(1) is called with a suitable --lines option. By trial and error I found that bzip2 compresses the .sql files by a factor of 20, so I needed to figure out how many lines of sql code correspond roughly to 40MB. |
It is quite easy given a single article to find all the articles citing it. However, having two or more articles, how do I find all the articles simultaneously citing these? | For given papers A and B, I would like to search for all papers that cite both A and B. I guess one can generalize to papers {A,B,C,...} and find all papers that cite all of them. A quick Google Scholar and Web of Science search revealed nothing. Google Scholar has a "cite=..." thing in the URL, which I messed with a bit to no avail. |
Can you help me to prove "Show that for any square-free integer $n > 1, \sqrt{n}$ is an irrational number."? I'm asked to show that any square-free number $n, n^{\frac{1}{2}}$ is irrational. I applied proof by contradiction here and assumed $n^{\frac{1}{2}}$ is a rational number. Therefore $n^{\frac{1}{2}}$ is equal to, lets say, $\frac{a}{b}$ where a and b are natural numbers. Since $b^{2} \times n = a^{2}$, I know that $n$ must contain a square number but I cannot prove it yet. I hope you can help me. | It is well known that $\sqrt{2}$ is irrational, and by modifying the proof (replacing 'even' with 'divisible by $3$'), one can prove that $\sqrt{3}$ is irrational, as well. On the other hand, clearly $\sqrt{n^2} = n$ for any positive integer $n$. It seems that any positive integer has a square root that is either an integer or irrational number. How do we prove that if $a \in \mathbb N$, then $\sqrt a$ is an integer or an irrational number? I also notice that I can modify the proof that $\sqrt{2}$ is irrational to prove that $\sqrt[3]{2}, \sqrt[4]{2}, \cdots$ are all irrational. This suggests we can extend the previous result to other radicals. Can we extend 1? That is, can we show that for any $a, b \in \mathbb{N}$, $a^{1/b}$ is either an integer or irrational? |
Is there a way to vote a question "belongs on" a StackExchange site, that is not one of the sites provided in the close > off topic menu? | I posted a question which was closed as off-topic and it seems like it could fit on another site in the network. How can I go about moving it there? What is migration? When can a question be migrated, and who can migrate it? When should I consider migration, and when is it inappropriate? What causes a migration to be blocked and what happens after? What causes a migration to be rejected and what happens after? Anything else I should know about migration? |
Given $a_1 =1$, $a_2=2$ and $$a_{n+1}=\sqrt{a_n}+\sqrt{a_{n-1}}.$$ To find the limit, I assumed that $a_n =a_{n+1}=a_{n-1}$, as $n$ tends to $\infty$ but this can be assumed if the sequence converges. How to prove that this sequence is convergent? | Question: Consider a sequence $\{a_{n}\}$ such that $a_{1},a_{2}>0$, and for all $n \in \mathbb{N}$ we have: $$a_{n+2}=\sqrt{a_{n+1}}+\sqrt{a_{n}}$$ Prove that : $\displaystyle\lim_{n\to\infty}a_{n}$ exists and find this limit. My work: If this limit exists, let $\displaystyle\lim_{n\to\infty}a_{n}=x>0$; then we have $$x=\sqrt{x}+\sqrt{x}\Longrightarrow x=4$$ But I can't see how to prove the limit of $\{a_{n}\}$ exists. Thank you for you help! |
I am flying to Vancouver and staying in a hotel for three days before boarding a cruise ship to Alaska. The cruise ends in Anchorage and I fly home via Seattle to Heathrow the same day. Do I say yes or no to 'in transit' on the ESTA application please? | We're going on a cruise leaving from Texas in a couple of months, and I'm not sure what to respond to this question with - we're arriving and then staying in a hotel for one night before departing on the cruise and visiting 3 other countries before eventually returning and flying home. Should we say "yes" to this question and enter the hotel we're staying at in Texas for one night as the point of contact? Thanks |
I am using Python for my postgraduate studies and I am having trouble running my code when I try to use processing in Qgis using the command-line interface. I think the error is really easy to fix it but right now I do not know how to fix it. When I run my code I have this Traceback (most recent call last): File "urban_canopy_element.py", line 100, in <module> output=general.run('qgis:clip',{'INPUT': input_layer, \ NameError: name 'run' is not defined I do not know where the error is. Attach the source code import os import sys #from os import path from qgis.core import * from qgis.core import (QgsApplication, QgsDataSourceUri,QgsCategorizedSymbolRenderer, QgsClassificationRange, QgsPointXY, QgsProject,QgsExpression,QgsField,QgsFields,QgsFeature, QgsFeatureRequest,QgsFeatureRenderer,QgsGeometry,QgsGraduatedSymbolRenderer, QgsMarkerSymbol,QgsMessageLog,QgsRectangle,QgsRendererCategory, QgsRendererRange,QgsSymbol,QgsVectorDataProvider,QgsVectorLayer, QgsVectorFileWriter,QgsWkbTypes,QgsSpatialIndex) ####################################33 QgsApplication.setPrefixPath("/usr", False) #import processing sys.path.append('~/.local/share/QGIS/QGIS3/profiles/default/python/') ################################################# os.chdir("~/rsync/avaliar_umep/") input_file="~/rsync/avaliar_umep/Height-rec-wg.shp" clip_polygons_file="~rsync/avaliar_umep/grilla01.shp" output_folder="~lixo/" input_layer = QgsVectorLayer(input_file, "input file", "ogr") QgsProject.instance().addMapLayer(input_layer) tile_layer = QgsVectorLayer(clip_polygons_file, "clip_polys", "ogr") QgsProject.instance().addMapLayer(tile_layer) tile_layer_dp=input_layer.dataProvider() print(tile_layer_dp) EPSG_code=int(tile_layer_dp.crs().authid().split(":")[1]) tile_no=0 clipping_polygons = tile_layer.getFeatures() heightshapes=[] for clipping_polygon in clipping_polygons: print("Tile no: "+str(tile_no)) tile_no+=1 geom = clipping_polygon.geometry() area=geom.area() print(area) clip_layer=QgsVectorLayer("Polygon?crs=epsg:"+str(EPSG_code)+\ "&field=id:integer&index=yes","clip_polygon"+str(tile_no), "memory") clip_layer_dp = clip_layer.dataProvider() clip_layer.startEditing() clip_layer_feature = QgsFeature() clip_layer_feature.setGeometry(geom) (res, outFeats) = clip_layer_dp.addFeatures([clip_layer_feature]) clip_layer.commitChanges() #print(clip_layer.extent())# linha desnecessaria neste momento clip_file = os.path.join(output_folder,"tile_"+str(tile_no)+".shp") output=processing.run('qgis:clip',{'INPUT': input_layer, \ 'OVERLAY': clip_layer, 'OUTPUT': "memory:"}) outputlayer=output['OUTPUT'] Thanks. I am looking foward for your help. Regards | I'm writing a script which must work outside of QGIS GUI. I call some API functions from qgis.core but I'd like to use the processing plugin. I'm able to import processing with sys.path.append() but I can't run any process. Moreover, all "native" algs are missing in QgsApplication.processingRegistry().algorithms() So is it possible to run processing that way ? What am I missing ? import os, sys from qgis.core import * QgsApplication.setPrefixPath('/usr', True) qgs = QgsApplication([], False) qgs.initQgis() sys.path.append('/usr/share/qgis/python/plugins') from processing.core.Processing import Processing Processing.initialize() import processing layer1 = QgsVectorLayer('data/ROUTE_PRIMAIRE.SHP') layer2 = QgsVectorLayer('data/ROUTE_SECONDAIRE.SHP') processing.run('qgis:union', layer1, layer2, 'test.shp') # returns nothing I'm on QGIS 3.0.1 - Debian 9 |
I installed the brand-new iOS 9 public beta today, and when I open the Stack Exchange app (1.3.1), it displays the blue gradient loading screen, flashes a shot of a blank feed for a half-second, and then blacks out and exiles me to the home screen. (For what it's worth, I'm on an iPhone 6, so there's no old hardware to blame the problem on. The app was working perfectly on iOS 8.4.) UPDATE: Now most of the app is working fine. The one thing that isn't working is the left sidebar. The buttons related to my profile work fine, but whenever I try to use the sidebar to go to a different Stack Exchange site, it blacks out. The About and All Sites screens also load, but when I select a site from All Sites, that also crashes the app. | In build 1.3.1.214, the app will crash in iOS 9 betas 1 & 2 once tapping on the menu icon > sites > Stack Overflow (or any other site you're subscribed to). |
I have seen lots of examples of how to create a table in R from a data.frame, but my question is how can I create a table from a graph output in R? I am working with the package AdehabitatHR, and I have produced some graphs showing variation in area (metres) as a function of $k$. Thus can someone tell me how to create a table from a (xy) line graph. This is my script #Read the data file Ade <- read.csv("Ade.csv", header=TRUE, dec=",") data <-SpatialPointsDataFrame(Ade[,4:5],as.data.frame(Ade[,2])) #Check the data frame is correct str(data) head(data, 2) # Examines the changes in home-range size for various values of k LoCoH.k.area(data, krange=50:90, percent=95, unin = c("m"), unout = c("km2"), duplicates=c("random"), amount = NULL) | Anybody have any experience with software (preferably free, preferably open source) that will take an image of data plotted on cartesian coordinates (a standard, everyday plot) and extract the coordinates of the points plotted on the graph? Essentially, this is a data-mining problem and a reverse data-visualization problem. |
How do I find the limit of this function: $$L=\lim_{n\to\infty} \dfrac{x^n}{n!}$$ for any real $x$? I tried using the sandwich theorem but couldn't reach the proper inequality. | Why is $$\lim_{n \to \infty} \frac{2^n}{n!}=0\text{ ?}$$ Can we generalize it to any exponent $x \in \Bbb R$? This is to say, is $$\lim_{n \to \infty} \frac{x^n}{n!}=0\text{ ?}$$ This is being repurposed in an effort to cut down on duplicates, see here: Coping with duplicate questions. and here: . |
I am using abbreviations for well-known phrases: e.g., "Nash equilibrium" becomes NE and "neural networks" becomes NN. Should I use "an NN" or "a NN"? Does it matter whether a reader "unfolds" the abbreviation or not when reading? That is, I think it is often the case that NE is read "Nash equilibrium", then it seems appropriate to use "a NE". | In the following example, is it appropriate to use a or an as the indefinite article, and why? He ate __ green apple. I know that in the case of just "apple", it would be "an apple," but I've heard conflicting answers for "green apple," where the noun is separated from the article by an adjective. Also, which is more appropriate in this case: He ate __ enormous Pop-Tart. |
Is there any good application for Windows, where can I have combat map, something like figures and maybe some tracker (HP, initiative, etc.) where can I try out some combat situations in Pathfinder rules? It doesn't need to be with automated calculations. | As the younger members of our group get older, they are going off to college or {gasp} getting on with their lives. We still game but are finding it harder to get together as distances increase. Since they all have computers and are tech savvy, what software is available for virtual table top play? Being a webmaster and database administrator I have access to all the technology I could possibly need. So be sure to include system requirements. I just need to know what my options are. One thing I need to add. Some of the players will still be at the physical table and 1 or 2 will be remote. This means I need to accommodate both types in each game session. Also having the ability to do Non-D&D is a plus as our group plays many different systems. For me there is only one answer. I can try each of the systems since I'm webmaster/DBA and have that kind of a setup, but I will in the end choose one. (There Can Be Only One!) As a service to the group I will give a full 'review' of what I did to evaluate and what/why I choose a particular solution. I think that in the end the fantastic answers here will help others regardless of what I do. Isn't that the best thing? |
I'm interested in understanding compositum of general fields better. Assume we have $\Omega/K/F$ and $\Omega/L/F$ field extensions, and consider the composite $KL$. It seems to me that every $a \in KL$, exists $n_1,n_2 \in \mathbb{N}$, $ \left \lbrace k_i \right \rbrace_{i=1}^{n_1}, \left \lbrace k'_i \right \rbrace_{i=1}^{n_2} \subseteq K$ and $ \left \lbrace l_i \right \rbrace_{i=1}^{n_1}, \left \lbrace l'_i \right \rbrace_{i=1}^{n_2} \subseteq L$ such that: $$ a = \frac{\sum_{i=1}^{n_1} k_i l_i}{\sum_{j=1}^{n_2} k'_j l'_j} $$ (That is since the family of all such sums is closed under addition, multiplication, and distribution because of the abelian nature of fields, therefore all numbers of this form are subfields that contain both K and L) Is it a correct way to refer to a compositum of fields? When is it correct that the general item of an extension is $a = \sum_{i=1}^{n} k_i l_i$? | Where $F$,$K$ are two fields. What does the element in the composite field $FK$ look like? All the elements are generated by the elements of $F$ and $K$? (combination of the elements of $F$ and $K$) I think $FK$ is pretty close to the free product of $F$ and $K$; is $FK \subsetneq F*K$? Thank you! |
The size or effective distortion field of a gravitational-wave perturbation at any given location in space-time is determined by the distance separating the source and that location. This describes a gradient of gravitational-wave intensity that ranges from the minuscule to the macroscopic. So, a confluence of gravitational sources sufficiently large within the Milky Way galaxy for example or within 1000 ly of the earth will yield a much larger gravity wave, a wave that may even cause damage. So why does no one speak of this? | Assume two black holes in the most common size range, spiraling into each other until they merge. The event releases significant amounts of energy via gravitational waves, which warp the space-time. If the distortion is powerful enough, it would get noticed in daily life, or perhaps even detected by the proprioceptors in the human body. How close, as an order of magnitude estimate, would you have to be to the merger to perceive it like that, without any instrument? |
I have a Mojang account and I own Minecraft on it but cannot login to Minecraft using the Minecraft website, the Mojang website or the Minecraft launcher. On the Mojang website I get the error "unknown email or password" and on the Minecraft website I get "Oops, unknown username or password. If you are logging in with a Mojang account make sure to use your e-mail address as username." I also can't login to tekkit using it either. | I created a Mojang account and downloaded the Minecraft launcher, but when I started it up, I couldn't log in. Since the log in fields did not require a username, I tried typing in my email, and still couldn't log in. I've tried after resetting my password, but that didn't work either. What am I supposed to do to log in and play? |
I'm looking for a formula to calculate the chance that (n) rolls of a d(y) produces any of (x) specific numbers (k) times, where x,y,n,k > 0, k <= n, and x <= y. AnyDice is a neat thing to know about, but I'd much rather have the formula itself. I know this sounds like stat homework but I guarantee you it's for tabletop shenanigans. I recently ran a one-shot combining , the one page 90's hacker rpg created by Grant Howitt, and D&D 5e, to create a sort of... Persona'esc experience. I created this table: ...to handle contesting rolls between the system. It worked well enough for a one shot but it seemed rolls with 5e's d20 system generally had a leg up over hack the planet's d6's. I'm asking for this formula in order to assist in better balancing any other hackbrained one-shot ideas I think up in the future. | After realizing that my knowledge of how probabilities function has waned significantly, I'm wondering what the probability of rolling multiple 6's or higher (6-10) on four 10-sided dice, five 10-sided dice, etc. up to nine 10-sided dice. As well, what the probability of rolling a 7 or higher, 8 or higher, 9 or higher on the same sets of dice as mentioned above. Something like; %chance rolling 3 of 6-10 on 4d10, %chance rolling 3 of 7-10 on 4d10, %chance rolling 3 of 8-10 on 4d10, %chance rolling 3 of 9-10 on 4d10, etc. %chance rolling 3/4/5 of 6-10 on 5d10... etc. I've tried creating some functions on AnyDice, but I either can't get the function(s) to work, or I fear I may be misunderstanding my results. How do I make this work? |
I'm on the Diplomatic Immunity quest and I'm playing on an Xbox. I never received my weapons out of the chest and I've tried loading from old saves which still did not take me out of the Thalmor Embassy. | I'm currently doing the quest "Diplomatic Immunity" and I'm stuck. I wish to begin the quest over again so I can continue on with the game. |
I have two constants, defined in the same static class: public static class MyConstants { public const string ABC = "ABC"; public const string DEF = "DEF"; } I use them in a combined manner, elsewhere in my application: Console.WriteLine(MyConstants.ABC + MyConstants.DEF); I'm trying to determine if the concatenation is optimized at compile time, resulting in the assembly containing a value of ABCDEF at some address when disassembled, or if it stays separate. I followed the instructions on to view the disassembly of my code in a console application and it appears that it is not stored as ABCDEF, nor separate as ABC, DEF: was a good read, but ultimately confused me in relation to my question (likely due to my lack of C++ knowledge). I've looked at several other posts and don't really seem to be getting anywhere near the answer. Does C# optimize the concatenation of two constants in the compiled version of an application, any/everywhere that concatenation is used? NOTE: The goal is to further obfuscate the full value of ABCDEF, making it harder to find. | For instance, does the compiler know to translate string s = "test " + "this " + "function"; to string s = "test this function"; and thus avoid the performance hit with the string concatenation? |
Proof that $ \sin \sqrt{x}$ is not periodic function using contradiction method ? My approach For periodic $$f(x+T)=f(x)$$ Let $x=0$ $$\sin \sqrt{(T+0)}=\sin\sqrt{0}$$ $$\sqrt{ T} =n\pi$$ Let $x= T$ $$\sin \sqrt{2T}=\sin\sqrt{T}$$ After this I can't able to solve | $\sin\sqrt x$ is not a periodic function. How can one prove this? |
Using the --group-directories-first option I can group the ls output as follows: [a-z directories] [a-z files and symlinks] However, I would like symlinked directories to appear with the rest of the directories, like this: [a-z directories and symlinked directories] [a-z files and symlinked files] Using the -L (dereference) option gets me half way there. Symlinked directories are sorted the way I want, but they appear just as normal directories, the information that they are symlinks is lost. Is there any way to group directories and symlinked directories first, while still preserving the colour coding showing which directories are symlinks? | ls option --group-directories-first causes directories to be listed on the top, which makes the output of ls nice and clean: ls -l --group-directories-first However, it does not act on symlinks, which are actually symlinks to directories. There is a possibility to use ls -l -L --group-directories-first which will list both kind of directories on top, but will not distinguish between proper directory and symlinked directory, which is again confusing. Can ls display symlinked directories on top, while still keeping them distinct from regular directories? EDIT: I am using bash. |
Let f be the function on $[-\pi,\pi]$ given by $f(0)=9$ and $f\left( x \right) = \frac{{\sin \left( {\frac{{9x}}{2}} \right)}}{{\sin \left( {\frac{x}{2}} \right)}}$ for $x\ne 0$. Find the value of $\frac{2}{\pi }\int\limits_{ - \pi }^\pi {f\left( x \right)dx} $ My approach is as follow. The function is continuous at $x=0$. Hence it is contionuos for $[-\pi,\pi]$ $f\left( x \right) = \mathop {\lim }\limits_{x \to 0} \frac{{\sin \left( {\frac{{9x}}{2}} \right)}}{{\left( {\frac{{9x}}{2}} \right)}} \times 9 \times \frac{{\left( {\frac{x}{2}} \right)}}{{\sin \left( {\frac{x}{2}} \right)}} = 9$ $\frac{x}{2}=\theta$ $\frac{2}{\pi }\int\limits_{ - \pi }^\pi {f\left( x \right)dx} $ $\int\limits_{ - \pi }^\pi {\frac{{\sin \left( {\frac{{9x}}{2}} \right)}}{{\left( {\frac{{9x}}{2}} \right)}}dx} \Rightarrow 2\int\limits_{ - \frac{\pi }{2}}^{\frac{\pi }{2}} {\frac{{\sin \left( {9\theta } \right)}}{{\sin \left( \theta \right)}}d\theta } \Rightarrow 4\int\limits_0^{\frac{\pi }{2}} {\frac{{\sin \left( {9\theta } \right)}}{{\sin \left( \theta \right)}}d\theta } $ $ \Rightarrow 4\int\limits_0^{\frac{\pi }{2}} {\frac{{\sin \left( {8\theta + \theta } \right)}}{{\sin \left( \theta \right)}}d\theta } \Rightarrow 4\int\limits_0^{\frac{\pi }{2}} {\frac{{\sin \left( {8\theta } \right)\cos \left( \theta \right) + \cos \left( {8\theta } \right)\sin \left( \theta \right)}}{{\sin \left( \theta \right)}}d\theta } $ $ \Rightarrow 4\int\limits_0^{\frac{\pi }{2}} {\left( {\frac{{\sin \left( {8\theta } \right)\cos \left( \theta \right)}}{{\sin \left( \theta \right)}} + \cos \left( {8\theta } \right)} \right)d\theta } $ $\int\limits_0^{\frac{\pi }{2}} {\cos \left( {8\theta } \right)d\theta } = 0$ How so I proceed form here as expansion of $sin(8\theta)$ is cumbersome. Is their any formula of converting $sin(n\theta)$ in terms of $sin(\theta)$ | Solve the following integral: $$ \frac{2}{\pi}\int_{-\pi}^\pi\frac{\sin\frac{9x}{2}}{\sin\frac{x}{2}}dx $$ |
I am working on a very complex scene, including areas that have particle systems (grass, flowers, etc.), mostly created with the Botaniq and Graswald addons. Because the scene is so heavy, I have broken it down in sections and I am linking each area into the main file, instead of appending. The problem is, when these areas come into the main file, the particle systems' collections (instancing objects) are visible and on ground level, meaning they are are showing up on the render. Is there any way to hide these things or what is usually the procedure? Bonus question: For such a heavy file, is it better to work with linked files or just appending? Does anyone know what is more optimized? | To clarify i'm not in this instance trying to hide emitter. The emitter oblong shape with arrow is supposed to be there. The particles are all based on a torus shape so all the little pink coins are based on that but i want to hide from render the large torus i have elsewhere on the screen. I un-clicked camera under ray visibility but then lost both the particles and the large torus. Thanks for any tips. |
How do I share my desktop PC internet with tablet/mobile? I have a desktop PC with an internet connection. The connection is via Ruckus MM2211 (I think it's a gateway). I have a TPLINK TL-WN721N USB wifi adapter. Is it possible to share my desktop connection with my tablet? | is it possible to share my desktop pc internet to my mobile phone? im using HTC Hero and a wired internet connection on my desktop pc |
Let $A \in GL_n(\mathbb{F})$ and $\chi_A$ denote the characteristic polynomial of $A$. I want to calculate $\chi_{A^{-1}}$. I know that the characteristic polynomial of $A$ is of the form $$\chi_A(\lambda)=\lambda^n -Tr(A)\lambda^{n-1}+...+(-1)^ndet(A).$$ Using the form of $\chi_A$ how can i calculate $\chi_{A^{-1}}$? | Given the characteristic polynomial $\chi_A$ of an invertible matrix $A$, I'm to find $\chi_{A^{-1}}$. I can see that this is theoretically possible. $\chi_A$ uniquely determines the similarity class of $A$, which uniquely determines the similarity class of $A^{-1}$, which uniquely determines $\chi_{A^{-1}}$. Calculating the coefficients of $\chi_{A^{-1}}$ explicitly and then relating them to the coefficients of $\chi_A$ seems unfeasible. I thought about calculating the factors instead, which could be easier since I at least have some idea what the linear factors $\chi_{A^{-1}}$ are (since I can see how to get the eigenvalues of $A^{-1}$ from those of $A$), but that doesn't help me with potential higher-degree irreducibles or repeated linear factors. Also, we're not supposed to know the eigenvalues of $A^{-1}$, at least I don't think so, since calculating them is the next question. Any hints? |
After trying to download Dropbox I get an error message in top bar of screen: "Unknown error ''(E:Malfomed line 56 in source list/etc/apt/sources.list(distparse))' This usually means that your installed packages have unmet dependencies." It suggested running Package Manager or apt-get in the terminal but that produced nothing very helpful. As a newbie to Ubuntu I'm rather lost! | I have unistalled and reinstalled the Ubuntu Software Center as per info I found in a similar thread and I got the same response about line 91 or something like that. I just tried to upload a screen shot but since I'm new it won't allow me to. I also can not figure out how to cut and paste anything so I have to hand type what the error screen says, both when I attempt to open the software center and nothing happens, when I try to enter commands into the terminal to uninstall, reinstall, whatever I get the same following: COULD NOT INTITIALIZE THE PACKAGE INFORMATION An unresolvable problem occured while initializing the package information Please report t:his bug against the 'update-manager' package and include the following error message: 'E: Malformed line 91 in source list/etc/apt/sources.list (dist parse) E: The list of sources could not be read., E: The package list of status file could not be parsed or opened. How do I report bugs? What can be done about this. I have searched and everything everyone says to do leads me back to the same line error message. So, I don't know how to get to line 91 in the source list; to tell you what it says. Sorry, I'm really new to this. That is what I need is to find out how to get there and fix what it says. I would really like to NOT have to re partition my hard drive and start from scratch, so I'm really looking forward to getting this problem solved. I need to be able to install new software. |
Currently I am attacked by malware. I try to use Kaspersky Internet Security + manually delete suspicious folders. However, Whenever I restart my computer, some suspicious folders reappear and my google chrome and firefox are attacked. That's, I believe there are some files that Kaspersky Internet Security and my bare eyes cannot detected, which continuously install malware into my computer. Now, I want to trace back which files installed the suspicious folders. Please help me to do that. Thank you! | What should I do if my Windows computer seems to be infected with a virus or malware? What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware? This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits. |
I'm using this PHP code to get my sql query which joins 2 tables ... both table have the same "size" field, but the results is not the same in both... code: mysql_query("SELECT * FROM cart INNER JOIN tbl_product ON tbl_product.product_id = cart.product_id WHERE .......) or die(mysql_error()); The result of this query shows me Cart_id, member_id, product_id, size, .... and a second size 1 of the size comes the cart table and 1 from the product table.. then I try to retrieve my data while($data2 = mysql_fetch_array( $data)) { $size= $data2['size']; But I get the second size in my result and I need the first one.. I need the cart.size ... how can I do this ? | I have two tables in my database: NEWS table with columns: id - the news id user - the user id of the author) USERS table with columns: id - the user id I want to execute this SQL: SELECT * FROM news JOIN users ON news.user = user.id When I get the results in PHP I would like to get associative array and get column names by $row['column-name']. How do I get the news ID and the user ID, having the same column name? |
I have a hp laptop and pre installed windows 8 . I download an iso of ubuntu 14.04 lts. When i installed it using wobi, it reboot, install and again reboot and it shows two option for boot 1 windows 8 , 2- ubuntu . I click on ubuntu then ubuntu start and shows an error like this "serious error found while checking drive/. Press i for ignore ,s for skip mounting ,m for manual setup" . Please help me what can i do ? if i use bootable pendrive for install, it install on a partition of my pc's hard drive .it don't boot ? i am beginer on linux please help me | I'm absolutely new to Linux. I would like to know how to install Ubuntu alongside the pre-installed Windows 8+ OS. Should I do it with Wubi, or through the Live USB/DVD? What steps do I need to take to correctly install Ubuntu? |
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