Hello after the update and upgrade on my Ubuntu, the firefox is not loading specific websites like stackoverflow, askubuntu and such sites. It loads other sites like lichess.org and also able to play youtube videos. But on these sites the error is server not found. The same error that comes when you are not connected to the internet. Now that's that I also have another problem which I don't know if related to this. When I do apt-get upgrade then it says http.kali.org not found. And on upgrade it says not secure to download. It seems like the dns is messed up from the errors that it can't connect to any such websites. I don't have any proxy or any VPN or anything of that sort. Please help me. Sorry for just this plain html but I have to write this via my phone as my Ubuntu says nope.


Unexpected output while splitting and parsing a string into int (Java)

public static void main (String args[]) {    Scanner io = new Scanner(System.in);   int a = io.nextInt();   io.nextLine();   for(int i = 0; i < a; i++ ) {        String input = io.nextLine();      String[] splitArr = input.split("\\s+");      int p[] = new int[input.length()];      int q = 0;      for (String par : splitArr) {        System.out.println(par);        p[q++] = Integer.parseInt(par);        System.out.println(p);      }      Sort(p);      } }      The input: 2 121213      Output: 121213 [I@1f96302   The last line shows the array stored in p[]. That is incorrect. Help someone!


Flights sharing the same flight numbers can be confusing. Why do flights sometimes share the same flight numbers? This means that one can find two flights that have the same flight number. Eg some airline might have one flight from x to y, another flight from a to b, and use the same flight number for both flights on the same date.


I tried to start up my computer and got a flashing file with a question mark.  So I held down the ⌥-key on boot and brought it into recovery-mode.  After going through the different options I went to the disk utility and all I see is the grayed out SuperDrive and below there is disk0 and Mac OS X Base system.   Leaving disk utility I went to reinstall Mac OS X. After the verification and agreeing the terms, it doesn't show my harddrive.   Did I unmount the harddrive or what could the reason it's not showing up?


I have downloaded Privoxy few weeks ago and for the fun I was curious to know how a simple version of it can be done. I understand that I need to configure the browser (client) to send request to the proxy. The proxy send the request to the web (let say it's a http proxy). The proxy will receive the answer... but how can the proxy send back the request to the browser (client)? I have search on the web for C# and http proxy but haven't found something that let me understand how it works behind the scene correctly. (I believe I do not want a reverse proxy but I am not sure). Does any of you have some explication or some information that will let me continue this small project? Update This is what I understand (see graphic below). Step 1 I configure the client (browser) for all request to be send to 127.0.0.1 at the port the Proxy listen. This way, request will be not sent to the Internet directly but will be processed by the proxy. Step2 The proxy see a new connection, read the HTTP header and see the request he must executes. He executes the request. Step3 The proxy receive an answer from the request. Now he must send the answer from the web to the client but how???  Useful link  : I have found this project that is a proxy (but more that I would like). I might check the source but I really wanted something basic to understand more the concept.  : I might be able to get some information over here too.  : This is a simple example. Here is a .


Minimum eigenvalue lower bound for recursively defined matrices

I have a sequence of recursively defined $R \times R$ real positive definite matrices: $$ \mathbf{B_{R}} = \begin{bmatrix}    R & R-1             & \cdots & 1           \\   R-1            &  & &            \\   \vdots            &  & \mathbf{B_{R-1}}  &             \\   1            &              & & \end{bmatrix} $$ and $$ \mathbf{B_{1}} = [1] $$ And I know the following numerically: $\frac{1}{4} \leq \lambda_{\min} (\mathbf{B_{R}})$ for $R \geq 2$. How to prove it? Furthermore, I know this is an asymptotically tight bound, because $\lambda_{\min} (\mathbf{B_{R}})$ is decreasing in $R$ (immediate from Cauchy interlacing) and $\lim_{R \to \infty} \lambda_{\min}(\mathbf{B_{R}}) = \frac{1}{4}$. It would be swell to prove this too. Addendum: initial examples from this sequence: $\mathbf{B_{2}} = \begin{bmatrix}  2 & 1                        \\   1            & 1            \\ \end{bmatrix}$, $\mathbf{B_{3}} = \begin{bmatrix}  3 & 2 & 1                        \\  2 &  2            & 1            \\ 1 & 1 & 1 \end{bmatrix}$, $\mathbf{B_{4}} = \begin{bmatrix}  4 & 3 & 2 & 1                        \\ 3 & 3 &  2            & 1            \\ 2 & 2  & 2 & 1 \\ 1 & 1 & 1 & 1 \end{bmatrix}$


What is the right way to create this type of piecewise function on LaTeX?

I've seen other solutions but they look rather bold, and messy, and very big. I want something like this, so I can use the code as a template.


I want to add two follow path constraints to a single object.  That means I want my object to follow path A, then do something else and then the object should follow path B, which begins at the end of path A.  Any Ideas?


Can't reference Format() SOQL field in VF page

I am using the format function in SOQL to format a date to DD/MM/YYYY when retrieved.  I can see the formattedCreatedDate in the debug logs and it is displaying correctly but cant reference it in a VF page. Not sure why?  My SOQL is:  consultancyOpps = [Select Id, Name, CreatedDate,FORMAT(CreatedDate) formattedCreatedDate from Opportunity where RecordType.Name = 'Consultancy ORDER BY CreatedDate DESC];   My VF page is trying to fetch {!consultancyOpps.formattedCreatedDate} but I get an error. I can display the other fields fine (Id, Name).  Not sure what I need to do to be able to display the formattedCreatedDate


Do you know any exact information about "marriage" terms?

What is the difference between:     they were married   they got married   they married?   Would you, considering what you say about these terms, tell me how to use these terms?


How do I reply to comments of users whose name contains characters not normally found in English?  For example:   Upside down letters Symbols not present in keyboard Maybe name in a different language etc...   I mean I have to type their name to reply, how do I do it?  Edit:  Is there a way other than copy and paste to do this?


Do you ever center AND standardize variables in multiple regression? It seems as if standardization would automatically center variables...is this true?


Computing the Fourier series of $f(\theta)=(\pi-\theta)^2/4$ for $0\leq\theta\leq{2\pi}$

According to p. 36 of Stein and Shakarchi's Fourier Analysis, the Fourier series is $\frac{\pi^2}{12} + \sum_{n=1}^{\infty} \frac {\cos{n\theta}}{n^2}$.   But to calculate the Fourier coefficients, I computed $\int_{-\pi}^{\pi}\frac{(\pi-\theta)^2}{4}e^{-in\theta}d\theta = \frac {1} {4} \Bigg[\frac{4\pi^2e^{in\pi}}{in}-\frac{2}{in}\int_{-\pi}^{\pi}e^{-in\theta}(\pi-\theta)d\theta\Bigg]=\frac {1} {4}\Bigg[\frac{4\pi^2e^{in\pi}}{in}-\frac{4\pi{e^{in\pi}}+2e^{-in\pi}-2e^{in\pi}}{n^2}\Bigg]=\frac{\pi^2ne^{in\pi}+\sin{n\pi}}{in^2}$  This means the Fourier series is $\sum_{n=-\infty}^{\infty}\frac{\pi^2ne^{in\pi}+\sin{n\pi}}{in^2}e^{in\theta}=\sum_{n=-\infty}^{\infty}\frac{\pi^2e^{in(\pi+\theta)}}{in}+\frac{e^{in(\theta-\pi)}}{2n^2}$, but I can't seem to  get this to equal that simple thing from the book.  Can anyone help?


Suppose we have the following logistic regression model:  $$\text{logit}(p) = \beta_0+\beta_{1}x_{1} + \beta_{2}x_{2}$$  Is $\beta_0$ the odds of the event when $x_1 = 0$ and $x_2=0$? In other words, it is the odds of the event when $x_1$ and $x_2$ are at the lowest levels (even if this is not 0)? For example, if $x_1$ and $x_2$ take only the values $2$ and $3$ then we cannot set them to 0.


I try to create a multiple lines label for this this polygon:     I red       and tried to use the "wordwrap" function with this expression:  wordwrap('high sensivtity area - red',10  )   and in the output preview (down the Expression string builder) it look fine and this is the result i'm seeking - but when i choose OK - nothing change in the map.  I don't want to use the option to put a space in the 'Wrap on character' section, because i don't want each word i separate line


How to add a custom icon or symbol to a flag link?

I'm working on a 'sample request' implementation for a commerce site using , , sessions and a little custom code.  I'd like to add an icon or a symbol to let people know that an item they are viewing has been flagged.  I'm not sure exactly how to approach this, I can imagine perhaps adding a conditional field that displays an image or check box that is then changed by  or ajax, or perhaps something more complicated in JavaScript?  It could really be as simple as adding a checkbox that is checked or unchecked as the flag link is clicked or maybe even changing the css/html on click to be identified as marked.   Anyway, grateful for any advice here.


Find Kali Security tester tools after installation

I'm a 'beginner' with Ubuntu. I tried it already a few times. I also tried Kali, etc already. I think Ubuntu is very useful, and has many possiblities. But I missed one thing from Kali. The Security tester tools (Also known als Hacking tools). I installed them like discripted , but I can't find the place they're located. It doesn't stand between my 'Toepassingen', it's called in Dutch.. I don't know the name in English, I think APPS. So my question is where i can find them on my Ubuntu PC. That is the missing link in the link below. Thanks!


I am wondering if theres some way to make it so that if there is a bunch of content in an iFrame it will just zoom out on the document essentially so it fits. Making all the content inside the iFrame smaller.  Any ideas how I would do this?  Script:  <script type="text/javascript"> function autoResize(id){     var newheight;     var newwidth;      if(document.getElementById){         newheight=document.getElementById(id).contentWindow.document .body.scrollHeight;         newwidth=document.getElementById(id).contentWindow.document .body.scrollWidth;     }      document.getElementById(id).height= (newheight) + "px";     document.getElementById(id).width= (newwidth) + "px"; } </script>   iFrame:  <iframe id="iframehtml" style="width:100%;height:100%;" onLoad="autoResize('iframe1');"></iframe>   By the way the reason there is no src set for the iFrame is because I have it in JavaScript so when you clicka a button it will edit the html of the iFrame.


I have been assigned with the task of getting part numbers out of a string in our database. I know that the part will be between the first and second comma in the string but I have no idea how to go about doing this. Any one have any suggestions? This is an example of the string I will be working with LEL,SPEC2078,14 CUT LEADS,#18 1/32


Why is $V^{\vee}\otimes W^{\vee}\longrightarrow (V\otimes W)^{\vee}$ always injective?

Let $R$ be a commutative ring with $1$. For all $R$-modules $V,W$ we have a canonical $R$-linear map $V^{\vee}\otimes W^{\vee}\longrightarrow (V\otimes W)^{\vee}$ from tensor product of dual modules into the dual of tensor product. My question is, why is this map always injective?


How to avoid the horizontal separator while using multirow?

Creating a table in IEEE transaction format. The last cell of the table has to combine two rows. I can put the same text using the multirow package, but the horizontal separator cuts right through the text. Here is my code for the table.   \begin{table*} \centering \begin{tabular}[l]{|l|l|l|l|} \hline \textbf{Description} & \textbf{Constraints} & \textbf{Objective} &\textbf{Remarks}\\ \hline Sum rate maximisation with given sum power&$\sum_{i=1}^Kp_i$&$\sum_{i=1}^Kr_i$&Solved~\cite{Barman2014a}\\      \hline Sum power minimisation with given sum rate&$\sum_{i=1}^Kr_i$&$\sum_{i=1}^Kp_i$&Proposed here\\ \hline Weighted rate maximisation with individual power constraints&$p_i\leq p'_i\quad\forall i$&$\sum_{i=1}^Kw_ir_i$&Solved~\cite{Tse1998}\\ \hline Sum power minimisation with individual rate constraints&$r_i\leq r'_i\quad\forall i$&$\sum_{i=1}^Kp_i$&Sub-optimal solution proposed~\cite{Yu2006}\\ \hline Weighted sum power minimisation with individual rate constraints&$r_i\leq r'_i\quad\forall i$&$\sum_{i=1}^K\lambda_ip_i$&Not solved\\ \hline Weighted sum power minimisation with weighted rate constraint&$\sum_{i=1}^Kw_ir_i$&$\sum_{i=1}^K\lambda_ip_i$&\multirow{2}{*}{Standard convex problem}\\ \hline Weighted sum rate maxisation with target weighted power constraint&$\sum_{i=1}^K\lambda_ip_i$&$\sum_{i=1}^Kw_ir_i$&\\ \hline \end{tabular} \end{table*}   And here is my output table.  As you can see the problem is with the "Standard convex problem". How to make the line stop at the previous column. Also please tell me how to post a large block of code here with proper tabulation. I cannot format it correctly. Sorry for the trouble.


polling a file in java, get the latest written file content to a string

I would like to create a java program which would poll a log file infinitely. Whenever there is some entry into that logfile, i would like to read the latest contents into the file just written.   can anyone please let me know the efficient method to do this? as this should run 24/7 getting cpu spikes is not desirable.   i did my basic research and found the following but didnt help much:


The Stack Exchange Network Profile/Accounts links should be made optional

I recently noticed a new feature, the network profile link, just under the flag weight in my user profile page. It probably seemed like a good idea but I really don't like it. Here's why:  I am very committed to StackOverflow, use my real name for the account, take a professional approach to it and hope to use it as something of a portfolio-light at some point in the future.   Every now and then I venture onto other Stack Exchange sites but I do so with mostly different names for different SE sites. I have posted some questions and answers that I would rather not have connected back to my Stack Overflow account. They've been silly or controversial and have nothing to do with software engineering. I would rather a potential employer not see these posts or even see links to other sites I may be a member of. There are sites where mere membership can be offensive to people. For example: Atheism, Christianity, Skepticism, etc. I really do not want these sites and accounts to be linked back to something that I do take seriously such as SO.   It is also a matter of privacy. I see the network profile and accounts links as something akin to using a particular browser and finding out that the browser is publishing your history for all the world to see. Some might be OK with that but not me. There are SE sites I find interesting and want to participate in from time to time but only anonymously. Had I known that all of my SE accounts would at some point be tied and published together I would have never signed up for many of them.  I would very much like to see a check box when editing my profiles that specifies whether or not my SE accounts should be displayed.  Thank you for your consideration.


Proving that the given set has at most $2^{n-1}$ elements

Let $n$ be a natural number and $X$ = {$1,2,...,n$}. For subsets $A$ and $B$ of $X$ we deﬁne $A\Delta B$ to be the set of all those elements of $X$ which belong to exactly one of $A$ and $B$. Let $F$ be a collection of subsets of $X$ such that for any two distinct elements $A$ and $B$ in $F$ the set $A∆B$ has at least two elements. Show that $F$ has at most $2^{n-1}$ elements. Find all such collections $F$ with $2^{n−1}$ elements.  I have no clue on how and where to start. Please help.


Two columns with different background color and height of whole page

I want to create page with two columns with different background color and height of whole page. What I was able to do is two columns with different background color but I can't set proper height and there is small gap between two columns and another gap between top of the page and top of the columns. I want to remove these gaps. Also I want to create vertical line between two columns. Right now I have minipages packed inside \colorbox which allows me to create all four borders but I only want one.   Final effect should look like this:    This is what I figured out for now:  \documentclass{article} \usepackage{blindtext} \usepackage{xcolor} \usepackage{geometry} \geometry{margin=0in}  \begin{document} \noindent \fcolorbox{black}{red}{ \begin{minipage}{.3\textwidth}   test \end{minipage} } \fcolorbox{yellow}{yellow}{ \begin{minipage}{.7\textwidth}   test \end{minipage} } \end{document}


Can I post the same question to multiple community, i.e. stackoverflow and serverfault?

When asking question about collectd I was confused, as to where do I ask this question, stackoverflow or serverfault, because both communities are discussing this topic.  Is there any ways for sharing some questions to multiple communities and get inputs/answers?


Picking up wild cards from the discard pile

Can you pick up a wild card from the discard pile with two wildcards from your hand to start a Canasta of wildcards?


java library for reading RSS and ATOM feeds

I am looking for libraries which can read RSS / ATOM feeds in my J2EE application (based on JBoss Seam).   Is  the only application there for reading feeds?  I am assuming the Seam RSS  is only for generating RSS feeds and not for reading feeds.


Is it possible to transfer your Pokemon Go account to Trainer Club?

I am  with the Google login for Pokemon Go. Is there any way, be it contacting support or through Trainer Club, to either link my Google account to a new Trainer Club account or transfer my account to a Trainer Club account?  It seems like a better idea to have a Trainer Club account, so if there are Google login problems it won't matter.  Does anyone know if something like this is possible?


When I write something like this:     I am a man that is doing these things.   Is it correct to shorten it like this?     I am a man doing these things.   And does it require commas?


Can I use OLS to estimate an ARX(1) model?

Is a statistically correct to find the parameters of the model $$ Y_t = \beta_1 Y_{t-1} + \beta_2 X + \epsilon $$ by just using OLS? For example, there won't be any problems with bias of the coefficients?


General Linear Model vs. Generalized Linear Model (with an identity link function?)

My question relates mostly around the practical differences between General Linear Modeling (GLM) and Generalized Linear Modelling (GZLM). In my case it would be a few continuous variables as covariates and a few factors in an ANCOVA, versus GZLM. I want to examine the main effects of each variable, as well as one three-way interaction that I will outline in the model.  I can see this hypothesis being tested in an ANCOVA, or using GZLM. To some extent I understand the math processes and reasoning behind running a General Linear Model like an ANCOVA, and I somewhat understand that GZLMs allow for a link function connecting the linear model and the dependent variable (ok, I lied, maybe I don't really understand the math). What I really don't understand are the practical differences or reasons for running one analysis and not the other when the probability distribution used in the GZLM is normal (i.e., identity link function?). I get very different results when I run one over the other. Could I run either? My data is somewhat non-normal, but works to some extent both in the ANCOVA and the GZLM. In both cases my hypothesis is supported, but in the GZLM the p value is "better". My thought was that an ANCOVA is a linear model with a normally distributed dependent variable using an identity link function, which is exactly what I can input in a GZLM, but these are still different. Please shed some light on these questions for me, if you can!  Based on the first answer I have the additional question: If they are identical except for the significance test that it utilized (i.e., F test vs. Wald Chi Square), which would be most appropriate to use? ANCOVA is the "go-to method", but I am unsure why the F test would be preferable. Can someone shed some light on this question for me?


How to prevent people to ask for registration in Drupal 7?

There is no login block in my website but everyday I see lot's of strange emails are sent they ask for registration. How do I can modify Drupal to reject every registration request?


Instant approval of revisions for users with edit privileges

It's not consistent to leave an edit pending for approval (thus not making available for everyone else and locking its state) after a user who has those privileges have given his endorsement.   You could say why don't I improve the edit, but that makes no sense for something that is correct and it would not follow the "keep it simple" policy.  Update:  This is the current time line:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. I see the question and the pending revision and then cast my approval. It doesn't take effect yet, still not legible. Even for me if I didn't take care of copying the question source because it disappears from my own revision page!   I might agree that one's approval is indicative of both revision's quality and editor's competence. But we should retain that the main objective is to ask and answer questions. So, I propose this model:   Someone who doesn't know about formatting makes a question. It's not legible A user without edit privileges amends the formatting. The correction is not visible, still not legible. A user with edit privileges cast his approval. Revision takes effect. Although it keeps the pending approval (the Edit (1) button). If a second user with edit privileges cast a rejection, it also takes effect as a rollback.


Confusion on how the Tessaract got to Earth

How did the Red Skull on Earth get the Tessaract if Odin took it and locked it away in the weapons vault on Asgard after taking it from the frost giants in the first war? [avengers]


Macbook 16" won't extend desktop with Display Port Chaining

I have a new Macbook 16" running 10.15.3 OSx with an AMD Radeon Pro 5500M 4 GB for the graphics card and I'm unable to get the desktop to extend using just Display Port chaining.   The monitors I'm trying to chain together are a  and a .  The 27" is a new monitor that I received with the laptop however the 24" I've had for several years and was using in a chained model with my Lenovo laptop that I'm moving away from.  I have tried the following configurations without any success and the best that I've been able to achieve is that the 24" mirrors the 27" but will never extend to it's own desktop.  Chained  MBP USB-C -> 27" USB-C (MST Enabled) -> DP -> 24" DP (DP 1.2 Enabled) = "Mirror"  MBP USB-C -> 27" DP (MST Enabled) -> DP -> 24" DP (DP 1.2 Enabled) = "Mirror"  MBP USB-C -> 27" DP (MST Enabled) -> DP -> 24" DP (DP 1.2 Disabled) = "Mirror"  MBP USB-C -> 24" DP (DP 1.2 Enabled) -> DP -> 27" DP (MST Enabled)  = "Out of Sync Error on 27"  MBP USB-C -> 24" DP (DP 1.2 Enabled) -> DP -> 27" DP (MST Disabled)  = "Out of Sync Error"  UnChained (Using two cables to drive them at the same time)  MBP USB-C -> 27" USB-C (MST Enabled) = "Extended"  MBP USB-C -> 24" DP (DP 1.2 Enabled) = "Extended"  What is causing the chaining to only allow mirroring?  ** UPDATE ** (3/22 @ 13:27 PST)  I've attempted to go back to a know good configuration using the original two monitors that I used with my Lenovo setup to try chaining those two monitors together removing the 27" from the equation and even with that configuration the two external monitors will only mirror each other.  It seems like the USB-C ports on the new MacBooks are not true Display Port 1.2+ compatible and requires individual connections to each external monitor that you want to extend your desktop to.  What gives apple?


I have ubuntu 14.04 lts and it's always freezes.When I wrote this message they froze 5 times.I have notebook with intel core i3,8gb ram and nvidia 740m.How to prevent it?


How do I swith Firefox channel from beta to stable?

I did the mistake to try Firefox beta a while back. Now it's nagging me all the time about updates. I've tried the solution given , but to no help.  How do I get off the beta channel when on a Mac?  I'm on FF 36.


I want a open source(community edition) document management system on Ubuntu which has a web interface

I have installed Ubuntu 12.04LTS on a PC and have been trying to make it a server for hosting the source code and storing documents of our small company. We have a need to run a document management system for our binary machine drawings and other documents.   I liked the Gitlab model for source code control that lets me use Ubuntu as server and provides a web interface for Windows users to work on their projects using clients like Source tree etc.  I tried all the links that I get when I searched on the web - OpenKM, DocMGR, Epiware but none works. Is there none that exists and that actually works on Ubuntu (or Linux)?


What is the point of redundant samples in bootstrapping?

While studying machine learning I read about different sampling methods. Simple holdout, N-fold cross validation are straightforward. However, I somehow miss the point of bootstrapping. Its definition says that it's just a way to inflate the sample set simply by duplicating some random samples and I cannot figure what is the point in this -- seemingly no additional information in a learning process just by seeing the same instances again and again (on the contrary: others say that omitting redundant points from the training set is recommended for computational efficiency and for some other statistical reason as well). So what is the explanation here?


Would an anti-magic zone affect a dragon's breath weapon?

One of my players has a special crystal that emits an anti-magic zone 5-feet around them.  It was just picked up so they're trying to figure out what to do with the crystal.  Suddenly they are ambushed by a Green Dragon who opens with its Acid Breath.  So the question is, would the crystal's anti-magic zone negate the dragon's breath?


Sci-fi dystopian book about a boy who rides a motorcycle

I have vague memories of reading this book in the mid 1990's. It centers about a boy selected to work with a super computer overlord kinda thing. I think there are aircraft that monitor thought. And I think the boy escapes at night on a futuristic motorbike? Any ideas? Thanks


Principle Component Analysis on categorical predictors

I tried running prcomp() on my training set, which contains some categorical/factor predictors (as well as a binary response), and was given an error saying my data needs to be numeric. Can PCA not be performed at all with categorical features? Or is there a way to work around the function...  Thank you!


How do I run the SSH command to set StrictHostKeyChecking=no?

I'm trying to run the command ssh -o StrictHostKeyChecking=no but I'm a bit lost as to how to run it. I've tried running it from a shell script, but the output was the man page or settings that lists out all the parameters.   I then tried running that command from the shell (Cygwin) itself, but got the same man output. How do I run the command? Do I need to provide credentials or anything?


Can I enter Romania and stay for four weeks with a Schengen visa?

I am Indonesian. This month I will go to Iasi, Romania for student exchange. But I will go there after staying one night in France, then take a plane to Iasi, Romania. Do I need to apply for a Romanian visa to enter and stay there for approximately 4 weeks if I already have a Schengen visa issued by France's embassy?


If I flagged a question will I ever be able to vote to close it?

I've recently gained the close voting privilege. I was looking over my flag history for questions I'd flagged which both didn't get closed and didn't get fixed, and I've found a few. The flags were both marked as helpful and unhelpful.  But when I go to those questions I can't vote to close them as it says "You have already flagged this question for closure". Does this mean I will never be able to vote to close on these questions again? If so why?  If this is the case it seems quite problematic to me because it means a mod can unilaterally take away my voting rights on those questions with no explanation. I have no problem with mods insta-closing or reopening, as those actions can be reverted later on. I also have no expectation that my intuitions as to what is too broad or opinion-based line up with the community's consensus either - that's what makes the voting system good because it does take agreement to close these questions when each person can only get 20% there. But if I'm prevented from voting because I flagged in the past then I can't put my 20% opinion out there (even if sometimes it's going to be the only vote) - it will forever be 0%.


write out figures, tables and their captions to additional file

Some places hosting academic documents want to have all figures, tables and their captions provided in separate files. Of course, I can copy everything from my ready-made PDF by hand, but I'd love to have a way to do this in a more programmatic fashion. Also, there are some inherent problems, like references and citations not working correctly, as even though packages like xr or xcite are probably useful, with a sufficiently complicated setup (biblatex+biber+backref) they don't really work. Here's what I'm thinking: I could try to patch the table and figure environments to, in addition to displaying their contents, write them to one (or more) external files, using \documentclass{standalone}. These patched environments could then provide a patched \caption command that would again write it's content to a text file. For this, I would need to pay attention to fully expand the contents of the figure and table environments as well as the captions, to make sure that all the references and citations map to the correct numbers, labels, etc, and of course, the result will never be perfect, but editing the files by hand will probably still be less work than doing everything from the beginning. I'm unsure if this is a reasonable project to attempt, and if there are any obvious pitfalls I'm overlooking, or if there might be a package that already does what I'm hoping for.


What does it mean if a function is onto?

I've heard the term "onto" several times but still not sure what it means or implies.  It's often said along with the function is "one-to-one".


WoeUSB Error Code 256 with NTFS formatted USB

I tried to create a Windows 10 USB boot medium with WoeUSB. I formatted a USB drive with an NTFS partition, but WoeUSB complains with:  Installation failed! Exit code: 256 Log: WoeUSB v@@WOEUSB_VERSION@@ ============================== Mounting source filesystem... Error: File "/media/woeusb_source_1543626298_6098/sources/install.wim" in source image has exceed the FAT32 Filesystem 4GiB Single File Size Limitation and cannot be installed.  You must specify a different --target-filesystem. Refer: https://github.com/slacka/WoeUSB/wiki/Limitations#fat32-filesystem-4gib-single-file-size-limitation for more info. Unmounting and removing "/media/woeusb_source_1543626298_6098"... You may now safely detach the target device   I've also tried to start WoeUSB via command line, did not work.  sudo woeusb --partition Win10_1809Oct_English_x64.iso /dev/sdb   My iso is located in:     home/sawyer/Downloads/Win10_1809Oct_English_x64.iso  Thanks in advance! I've been trying to get windows installed for three nights now, so any help towards that goal is greatly appreciated.


How to calculate the difference between two times accurately across midnight?

I've seen  which is an excellent simple solution to calculating the difference between two times. However I've run into an issue when trying to calculate the difference between midnight and times which are either after midnight or before midnight. I'm sure the fix is obvious, but I'd love to get some advice. Below is what I'm trying to do: work out the difference between a target sleep time and actual sleep time.     The fifth column is the result I want - showing either a positive or negative time duration. I can't work out how to achieve this though.  Below is Morgoth's solution in the linked question, which successfully shows the difference between two times when the first time is before midnight and the second time is before or after midnight.     As I've shown above, this solution doesn't work for my scenario - subtracting 23:30 from 00:00, for example, gets 23:30:00, whereas I want it to return -0:30:00 (or 0:30:00. The polarity doesn't matter, so long as it's consistent which is positive and negative.)  Is there a simple fix to do this?  EDIT: Here's


How many ways to iterate a map in java? why iterat a mai if we have already for loop?

One can iterate through a SortedMap by using the iterator from myMap.entrySet().iterator(). But does this iterator preserve the ordering of the sorted map object ?  The SortedMap interface does not have its own methods to iterate through the entries. What is the standard way to iterate ordered through the entries?


How did the Death Eaters take the Ministry of Magic?

Yesterday I watched Harry Potter and the Deathly Hallows: Part 1, and I was wondering how exactly the Death Eaters took the Ministry? In the movies we never saw that. Later I checked on Wikipedia's book article and it just said that they kill the Minister. Was it a Coup d'état or a conspiracy? Why didn't any of the authorities help the Ministry?


Over the weekend I was working on my git repository to exclude some files.  This morning it dawned on me that I need to add those patterns to the gitignore file, but... I don't remember all the files I excluded.  Is there a way to get git to show me all the files it is excluding?


How both inertial frames of reference are valid when it comes to time dilation?

Suppose a spaceship is moving at uniform speed of 0.5c relative to another inertial frame of reference such as earth, Frame E. From the frame of reference of spaceship, Frame S, the clock of Frame E is running slow. For someone in Frame E, the clock of Frame S is running slow. In terms of the special relativity both are correct and equally valid.   Frame S decelerates and starts co-moving with the Frame E; I think we can say that after the deceleration both frames become a single inertial frame. If a person who was aboard the spaceship compared his clock with that of earth, he would find that spaceship's clock was running slow assuming the clocks were synchronized before the spaceship started its journey. I'm ignoring the effects of gravity.  Before the deceleration, according to Frame S, the clock of Frame E was running slow. Likewise, according to Frame E, the clock of Frame S was running slow. After the deceleration, it became 'physically' clear that which clock was really running slow and which frame was actually valid. Was it the deceleration which affected the time, or was it really that Frame S's clock was running slow? Does the special theory of relativity assume that the 'rule' of validity is only applicable as long as both inertial frames of reference are moving relative to each other? Could you please help me with it?


My phone have been stolen and I have many pictures on it, and secret things! How can I trash every thing on it through a Whatsapp message? I have not tired anything yet.


WAMP server: Cannot get localhost to work

When i click on the local host tab of my WAMP server it opens up the webpage but gives a blank page with the following error:  HTTP Error 404. The requested resource is not found.   I have researched online about the problem and uninstalled Skype and turned off my firewall as suggested. However it did not solve it.  What else can be done to solve the issue?   When I "test port 80" within the apache tab I get the following message:  Your Port 80 is actually used by:  Server: Microsoft-HTTPAPI/2.0   note: The WAMP server is online, yet the icon is still red. I am using a windows 64 bit laptop.


How can I make it so materials are linked to objects instead of data, with Python?

How to add material to selected objects via python? Material must be linked to Object (not Data).


What is the right operator in vb.net for test if a String is not equal?

I tried something like this  Do Until !test.equals("1234") Or !test.equals("xyxyxyx")   ...  Loop   How can I write that in vb.net?


PLease, dear native English speakers, help me to understand the meaning of the expression "a year on" within the context "The reality is that, a year on, a true 4K standard is still very much a work in progress..." Thank you a lot!


Electric field line density : Theory vs Reality

I've already went through . Yet, I still can't understand the meaning of "density" of electric field lines whose number is, in reality, infinite.  One of the answers , for instance, states that the ratio of two densities is independent of the number of field lines, so even when their number is infinite, they would always end up canceling each other when computing the ratio of two densities ( for the field lines generated by a point charge), the mathematical  proof of this statement makes sense. However, in reality, the number of field lines is infinite, and field lines don't cancel each other, so even if we get further from our point charge, the number of field lines per unit area would still be infinite, no matter how far or near we're from the source.   Am I missing something?


Unable to create field for PostGIS layer. PYQGIS

I'm having some troubles to create a new field in a postgis layer.This is the code I'm trying to use, but nothing happens, no field is created:  from PyQt4.QtCore import *  dbnam = "pruebapython" uri = QgsDataSourceURI() uri.setConnection("localhost", "5432", dbnam, "postgres", "xxxxxxx")     uri.setDataSource("", "masa", "geom","","gid")  layer = QgsVectorLayer(uri.uri(),"masa","postgres") #layer = QgsVectorLayer('/xxx/xxx/xxxxx/xxx/xxx/DatosTest/MASA.SHP', 'MASA', "ogr") layer.startEditing()  layer.dataProvider().addAttributes([QgsField("mytext", QVariant.LongLong )]) layer.updateFields() layer.commitChanges() idx = layer.fieldNameIndex( 'mytext' ) if idx == -1:     print "No field" else:     QgsMapLayerRegistry.instance().addMapLayer(layer) print 'Done!'   If I uncomment the layer which is a shapefile and I comment the posgres one, the field is created perfectly. What am I missing? Could anyone help me?  The QGIS log shows this:  Consulta errónea: ALTER TABLE "masa" ADD COLUMN "mytext"  devolvió 7 [ERROR:  syntax error at end of input             LINE 1: ALTER TABLE "masa" ADD COLUMN "mytext"]   How can I solve this?


Creating 700 m x 700m grid in ArcGIS for Desktop?

I'd like to know how to create 700m x 700m grid array in ArcGIS.   I am a beginner at GIS.   I'd like to develop the insect distribution map.


how to run a original database on my local server

I am totally a noob in server side development.I have been given the task of using  a original database of a company and make a copy on my local server for testing the server.I have the link and username and password too. What I don't know how to access the database given, I know the username and password.I know mysql is used but I don't know which commands to use and how to use mysql. I tried googling it but couldn't find any solution.  I have sql workbench , how can I use it?


How to force all CPU cores to run at maximum turbo boost frequency?

My goal is to force all CPU cores to run at maximum turbo frequency (4 x 3.9 GHz) using CentOS 7. Here is the output of cpupower frequency-info:  analyzing CPU 0:   driver: acpi-cpufreq   CPUs which run at the same hardware frequency: 0   CPUs which need to have their frequency coordinated by software: 0   maximum transition latency: 10.0 us   hardware limits: 1.60 GHz - 3.50 GHz   available frequency steps:  3.50 GHz, 3.50 GHz, 3.30 GHz, 3.10 GHz, 2.90 GHz, 2.70 GHz, 2.50 GHz, 2.30 GHz, 2.10 GHz, 1.90 GHz, 1.70 GHz, 1.60 GHz   available cpufreq governors: conservative userspace powersave ondemand performance   current policy: frequency should be within 1.60 GHz and 3.50 GHz.                   The governor "performance" may decide which speed to use                   within this range.   current CPU frequency: 3.50 GHz (asserted by call to hardware)   boost state support:     Supported: yes     Active: yes     3600 MHz max turbo 4 active cores     3700 MHz max turbo 3 active cores     3800 MHz max turbo 2 active cores     3900 MHz max turbo 1 active cores   Turbo boost is working as expected - all 4 cores fully loaded are reaching 3.6 GHz. But it would be nice to have 3900 MHz max turbo 4 active cores or less (at least 4 x 3.7 GHz). How to control it?  Is it possible?


Xubuntu 16 Conky breaks notifications and menus

I am running into an interesting problem that I haven't seen before. Without Conky running, my notification bar works fine. But as soon as I start Conky and click on any icons like sound, or dropbox, the menu doesn't appear. I thought it was a problem with my XFCE settings. I am running 4 monitors in a 2x2 pattern, main monitor is bottom left, I have my task bar on the bottom of that screen, and conky on the right side of that monitor.  Additionally, it also breaks the menus on programs like Notepadqq, the file menus at the top of the window don't show up right, but right click menus work fine. Any ideas?


Why no exception when finally has return clause

The code snap is like below:    public static void main(String[] args) {     System.out.println(echo("jjj")); }  public static String echo(String str) {     try {         int a = 1/0;     } catch (Exception e) {         throw e;     } finally {         return str;     } }   Why can I get the output and no exception occurs? And if I put the return clause out of finally, then exception occurs. How could return(in finally) stop exception?


I have a program that takes the day, minute and day that i enter and restarts my PC when the conditions are met. However i want to make it so it does that every time my PC start. So far i only have the restart and the Startup solved but i dont know how to make my program store the variables. I had an idea to write them to a txt file and read them for there, but i dont know how to do that or is there a better way to do what i want. MY code is down dellow: private void button1_Click(object sender, EventArgs e)         {             Hide();              while (true)             {                 DateTime datetime1 = DateTime.Now;                  label4.Text = datetime1.ToString("dddd");                  if (textBox1.Text == datetime1.Hour.ToString() && textBox2.Text == datetime1.Minute.ToString() && comboBox1.Text == label4.Text)                 {                     System.Diagnostics.Process.Start("shutdown.exe", "-r -f -t 0");                      Close();                 }                  Thread.Sleep(60000);             }              string createText = "" + Environment.NewLine;             File.WriteAllText(path, createText);         }          private void SetStartup()         {             RegistryKey rk = Registry.CurrentUser.OpenSubKey                 ("SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Run", true);                 rk.SetValue("Restart.exe", Application


How to slice a huge image into smaller ones with 'Save for Web'

I have a huge image (1024*256000) which I want to slice horizontally into 100 images of 1024*256.   I'm using Adobe Photoshop CS6. I created the horizontal slices with the Slice tool and the  Divide option.  Save for web allows me to save the images, but only at a 32.03% scale. If I try to change the Percent field to 100%, it gives me the following error:  A value between 0.01 and 32.03 is required. Closest value inserted.   Is there any way around this?


Why does this mobile phone battery have 4 terminals?

Why do some mobile phone batteries have 4 terminals? I want to use a mobile phone battery for my project.


What is the difference between a calculus and an algebra?

You can have a lambda calculus, the calculus of the real numbers or a logical calculus but on the other hand you could also have an algebra of sets, a Lie algebra, or a linear algebra.  Is there any convention which dictates whether something is an algebra or a calculus?  From my understanding, a calculus seems to give you information about objects you might encounter within a space, while an algebra gives you information about the interactions and structure within the space as a whole. Is this correct?


The chain rule for derivatives - actual meaning

Consider the derivative of y with respect to t: dy/dt, according to the chain rule:      $\frac{dy}{dt} = (\frac{dy}{dx})(\frac{dx}{dt}) $   This means that the derivative of $y$ with respect to a variable $t$ is the coordinate of $y$ with respect to $x$(i.e. the slope at $x$) times the coordinate of $x$ with respect to $t$.    How would it make sense more intuitively?   Intuitively in the sense, that it would make more sense physically or well, intuitively rather than just analytically, i.e. just using algebraic laws, it would be rather meaningful, if it made sense in a sort of a logical argument.  And how do we take this further to the second order deriative of parametric equations: d2y/dx2 = (dy'/dt)/(dx/dt)


$n^a$ integral for all integer $n$ implies $a$ integral

Let $a>0$ be a real number, such that for all integers $n\geq 1$: $n^a \in \mathbb N$ Show that $a$ must be an integer.    It's not difficult to show this when $a$ is a rational number: $2^\frac{p}{q}$ is irrational when the fraction is in lowest terms and $q \neq 1$.  When $a$ is irrational, then for all $n\geq 1$, there exists $m_n\in \mathbb N^*$, such that: $$a = \frac{\log m_n}{\log n}; \quad \text{$m_n$ is not a power of $n$}$$  I think considering $n=2,3$ is enough to show a contradiction, but I can't seem to find it. This is what I get: $$a = \frac{\log p}{\log 2} = \frac{\log q}{\log 3}$$ $$p = 2^{\log q/\log 3} $$  I think the RHS is irrational when $q$ is not a power of $3$, but I can't prove it. The closest thing I have to a solution is . But it uses an unproven conjecture, and I was hoping for a more elementary proof.


How to report a no-more-valid-answer to a locked question?

(last answer on the first page) is linked to a question which exists no more. I wanted to flag it to get it removed but the question is locked and there is no flag option. How can I report it?


Avoiding numerical cancellation question for $\sin x -\sin y$ for $x \approx y$

When trying to avoid cancellation, one tries to reformulate the equation in order to avoid subtraction between almost equal terms.   In $\sin (x) - \sin (y), x \approx y$ the suggested solution is to reformulate it to $$2\cos\left(\frac{x+y}{2}\right)\sin\left(\frac{x-y}{2}\right)$$  But I don't understand how it is any better? The subtraction between $x, y$ remains. Is it because $\lvert\,\sin(x)-\sin(y)\,\rvert\leq \lvert\,x-y\,\rvert$, so cancellation is less likely to happen between $x,y$ than the sines?


How to save as much money as possible from my salary?

I have 10 months of work, which's my first work experience, and during this period I haven't saved anything in my bank account. I spend all of my salary on rent, which represents 32% of it and the rest in the daily expenses. I want a way to keep as much money as possible because I really need it to do many things.


Please help to prove this to show that $S$ is abelian

Let $S$ be a semi-group. Recall that a semi-group is a non-empty set with a binary composition in which associativity holds. Please help me to prove that:  If in a semi-group $S$, $x^{k+1}=x$ and $xy^{k} x=yx^{k} y\,\,\,\,\forall x,y\in S$ and for some $k\geq 1$  then show that $S$ is abelian.  Any help would be appreciated.


Unable to run ConTeXt (pdfTeX) after upgrading to Mac OS X 10.9 Mavericks

I recently upgraded to Mac OS X 10.9 (Mavericks) and tried to run a old ConTeXt document using  TeXWorks. I got the following error:  /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/universal-darwin13/rbconfig.rb:212: warning: Insecure world writable dir /usr/local in PATH, mode 040777 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require': /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/base/switch.rb:501: invalid multibyte escape: /\xFF/ (SyntaxError)     from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'     from /usr/local/texlive/2013/texmf-dist/scripts/context/ruby/texexec.rb:11:in `<main>'   I had earlier loaded MacTeX 2012. I got the same error as above. So I thought may be it has to do with my TeX installation. I removed MacTeX 2012 and installed MacTeX 2013. But ended up with the same problem (error message as above).  I am kind of lost. I am new to Mac and was enjoying the TeX/LaTeX/ConTeXt experience.  Would appreciate help.


PWM complementary square output waveforms

PWM channels in certain microcontrollers such as the SAM3X8E have two complementary square output waveforms, PWMH and PWML, per channel. What is the purpose of having two waves that are the inverses of each other?


note that this was part of a mega question split as requested  I'm a film student working on a script on a Star Wars film as a personal project, I know there is little to no chance that I would ever get to work on a star wars film but we can dream. Anyway I would like some questions answered to help clarify how things work in the Star Wars universe. Any help would be appreciated.  First Question: What is a Balance of the Force?  Something I always found interesting was one of Spoony's old written reviews of Star Wars Episode III in which he makes a good point, how does wiping out the Sith bring balance to the force, surely all you’re doing by killing them is making the force more imbalanced as one side is vastly stronger than the other. Surely to get true balance, one must except both the Light and the Dark and be able to use them in harmony like how Luke did in episode 6. He was able to use deceit & truthfulness, Fear & Joy and most importantly, Anger and Compassion. This can be best seen in the final battle in the Death Star as he was able to use anger as a strength and then did not get consumed and used compassion, effectually using both sides of the force in balance.


Let $F\in\operatorname{End}_R(M)$, where $M$ is a Noetherian $R$-module. If $\operatorname{Coker}F$ is of finite length, is Coker and Ker of all powers of $F$ of finite length? Is the condition of being noetherian necessary?


p-values for all lags in a cross-correlation calculation

I am testing the lead-lag relationship among two variables with cross-correlation function (CCF) by SPSS. however, SPSS computes CCF coeficient for all defined lags, but it does not determine the p-value for them, how I can obtain the p-value of various lags?  For some variables that are not normally distributed, I used their ranked form in CCF, to simulate a kind of CCF with Spearman's method, in this case, how would it be possible to obtain p-value for each lag?


Let $f(x)$ be differentiable over $\left[0,1\right]$ with $f(0) = f(1) = 0$. Prove that $f'(x) - 2f(x)$ has a zero in $(0,1)$

for a final exam review for Real Analysis, the following problem is asked:  Let $f(x)$ be a differentiable function over $[0,1]$. Suppose that $f(0) = f(1) = 0$. Prove that $f'(x) - 2f(x)$ must have a zero inside of $(0,1)$.  My initial idea was to use Rolle's Theorem, since both endpoints are equal to 0 in order to show that $f'(x)$ must have a zero, but I'm not sure how to go from there. I've also tried to use the Cauchy Mean-Value Theorem by letting $g(x)$ be a function with $g'(x) = f'(x) - 2f(x)$, but I wasn't quite sure how to use that to prove the statement.  We can't use any integration as the last chapter we've done is on differentiation. If anyone could point me in the right direction I'd appreciate it.


Prevent frame view with GoDaddy forward (301 with mask)

I have a domain name at GoDaddy and have forwarded it to an external domain, using the settings 301 with mask.  However, when I go to my GoDaddy domain and press view source code then I only get that the page is embedded in a frame. Like this:  <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"    "http://www.w3.org/TR/html4/strict.dtd"> <html>  <head>   <title>TITLE HERE</title>   <META name="description" content="DESCRIPTION HERE"><META name="keywords" content="KEYWORDS HERE"> </head> <frameset rows="100%,*" border="0">   <frame src="MYGODADDYDOMAIN.COM" frameborder="0" />   <frame frameborder="0" noresize /> </frameset>  <!-- pageok --> <!-- 04 --> <!-- --> </html>   How can I prevent this and get a normal redirect?


how can I wait for a java sound clip to finish playing back?

I am using the following code to play a sound file using the java sound API.      Clip clip = AudioSystem.getClip();     AudioInputStream inputStream = AudioSystem.getAudioInputStream(stream);     clip.open(inputStream);     clip.start();   The method call to the Clip.start() method returns immediately, and the system playbacks the sound file in a background thread. I want my method to pause until the playback has completed.  Is there any nice way to do it?  EDIT: For everyone interested in my final solution, based on the answer from Uri, I used the code below:  private final BlockingQueue<URL> queue = new ArrayBlockingQueue<URL>(1);  public void playSoundStream(InputStream stream) {     Clip clip = AudioSystem.getClip();     AudioInputStream inputStream = AudioSystem.getAudioInputStream(stream);     clip.open(inputStream);     clip.start();     LineListener listener = new LineListener() {         public void update(LineEvent event) {                 if (event.getType() != Type.STOP) {                     return;                 }                  try {                     queue.take();                 } catch (InterruptedException e) {                     //ignore this                 }         }     }; clip.addLineListener(listener ); }


I've some problem with my usb 3.0 and an external HD. Both works fine because if I plug my external HD to the usb 2.0 all works ok, and If I plug a memory stick to the usb 3.0 all works ok.  USB 3.0 + HD = BAD USB 2.0 + HD = OK USB 3.0 + MEMORY STICK = OK USB 2.0 + MEMORY STICK = OK  ...do you have some ideas?


Incorrect Title on Google Search Results

We have just created a new website and have submitted a sitemap via google search console. When we run site://example.co.uk the search results have appeared but for some unknown reason they have "Kyle insurance brokers" tagged on the end of the title but there is no reference to that within our site. Why does this happen?


Why do we have String class, if StringBuilder or StringBuffer can do what a String does?

I've always wondered why does JAVA and C# has String (immutable & threadsafe) class, if they have StringBuilder (mutable & not threadsafe) or StringBuffer (mutable & threadsafe) class. Isn't StringBuilder/StringBuffer superset of String class? I mean, why should I use String class, if I've option of using StringBuilder/StringBuffer?  For example, Instead of using following,  String str;   Why can't I always use following?  StringBuilder strb; //or StringBuffer strbu;   In short, my question is, How will my code get effected if I replace String with StringBuffer class? Also, StringBuffer has added advantage of mutability.


Concatenating fields in field calculator of QGIS?

Is there a way to concatenate fields in field calculator of QGIS? (e.g. hectares + ' ha')


If $x,y$ are nilpotent and commute, $x+y $ is nilpotent.

Let $A$ a ring. Supose that $x,y \in A$ are nilpotents elements and that $xy=yx$. Prove that $x+y$ is nilpotent.


Group of order $108$ not simple using Sylow theorems on Sylow-$2$-subgroups

Show that any group of order $108$ is not simple.   I can show this using Sylow theorems on Sylow-$3$ subgroups. I was not able to completely justify for Sylow-$2$ subgroups though.  In case of Sylow-$2$ subgroups we have the following :   $n_2|27$ and $n_2\equiv1 \mod2\implies n_2=1,3,9,27$, where $n_2$ is the number of distinct Sylow-$2$ subgroups. For the case $n_2=1$ or $n_2=27$, its quite straightforward and the case $n_2=3$ can be shown using extended Cayley theorem.  For $n_2=9$, using extended Cayley theorem $\exists\; \theta:G\to S_9$ a group homomorphism. But I am not able to show that $\ker\theta\neq\{1\}$. Also if I assume $ H$ and $K$ are two Sylow-$2$ subgroups of order $4$, then $H\cap K\trianglelefteq G$ but I cannot show $|H\cap K|\neq1$ necessarily.   Can anyone suggest how to proceed for this case $n_2=9$?


I want to summon an arrow that is fired in the same direction as the player that it is summoned closest to, is this possible with just commands and as minimal command blocks as possible? (not one command block for like ever 30°)  Currently I have tried summoning it without gravity and right after it spawns teleporting it using /execute as @e[type=arrow,name="guardarrow",scores={lifetime=1..1}] at @s rotated as @p run tp @s ~ ~ ~ ~ ~ (lifetime scoreboard is just +1 per tick) which for about 0.5s rotates the arrow and then it rotates back, making this method useless. Using the Motion:[x.x,x.x,x.x] nbt doesn't work since it has to be able to go in all directions. So is there any way to make this work properly?  Also: When teleporting the arrows to move them they apparently don't hit things, they go straight through mobs


Bud sells $n$ different brands of ales. When you place an order, Bud sends you one bottle of  ale, chosen uniformly at random from the $n$ different brands,  independently of previous orders.   Jim wants to try all different brands of ale. He repeatedly  places orders at Bud (one bottle per order) until he has received  at least one bottle of each brand.   Define the random variable $X$ to be the total number of orders that  Jim places. Determine the expected value $E(X)$. Use Linearity of Expectation. If Jim has received exactly  $i$ different brands of ale, how many orders does he expect to place  until he receives a new brand?    I'm unsure of how to use Linearity of Expectation to solve this problem. I have the following so far.  $x$ = the total number of orders that Jim places.  Since we know with every new brand of ale Jim receives, then his chance to get a new ale is less.  $E(x) = \sum_{i=0}^n (1-\frac{i}{n})$  First ale he receives, probability of a new type is and as follows: $1, 1-\frac{1}{n}, 1-\frac{2}{n},...,1-\frac{n-1}{n},1-\frac{n}{n}$ until he gets n different ales then there is no chance for him to receives new brands.   Could someone assist me with this proof?


linear algebra - Compute matrix associated to quadratic form.

We have a form: $Q: R^3\to R$, $Q(x) = 3x_1^2 + 3x_2^2 - 2x_1x_2 + 4x_1x_3 + 4 x_2x_3$, where $x = (x_1, x_2, x_3)$ is an arbitrary vector from $R^3$.  The problem is to compute canonical form using Jacobi's Method.  The only problem I've faced is in figuring out how to compute matrix associated to quadratic form $Q$.  Thank you for any advice.  I also know that the base for this form is: $B = \{e_1= (1, 0, 0), e_2 = (0, 1, 0), e_3 = (0, 0, 1) \}$. And that this matrix has the form: $\begin{bmatrix}a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33}\end{bmatrix}$.  Where $a_{ij} = Q(e_i, e_j)$.


Splitting field over $\mathbb{Q}$ (polynomial)

Let $n \in \mathbb{N}$.   How to compute the splitting field of $x^n-2$ over $\mathbb{Q}$?  I did it like this:  $x^n-2=0  \Leftrightarrow x=\sqrt[n]{2}$  Then $x=\sqrt[n]{2}$ is the root of $x^n-2$.  So the splitting field is $\mathbb{Q}(\sqrt[n]{2})$.  I'm not sure if this is complete. Or can another root be found here?


Why shouldn't I use "Hungarian Notation"?

I know what Hungarian refers to - giving information about a variable, parameter, or type as a prefix to its name. Everyone seems to be rabidly against it, even though in some cases it seems to be a good idea. If I feel that useful information is being imparted, why shouldn't I put it right there where it's available?  See also:


Prove: A is a positive definite symmetric matrix and   $\forall x \in \mathbb{R^n}$ define $||x||_A$ by $||x||_A=\sqrt{x^TAx}$  Show $||x||_A$ is a vector norm.  My solution: For $||x||_A$ to be a vector norm, $||x||_A=\sqrt{x_1^2+x_2^2+...+x_n^2}=\sqrt{x^Tx}$ must be satisfied. since $A$ is symmetric, $A=A^T$, thus $||x||_A=\sqrt{x^TAx}=\sqrt{x^TA^Tx}=\sqrt{(Ax)^Tx}$. Since $A$ is positive definite it must have full range. Thus the set of all vectors $b$ for which $Ax=b$ must have a solution. Thus, we can choose $Ax=x$.  Thus, $\sqrt{(Ax)^Tx}=\sqrt{x^Tx}$. Thus, $||x||_A=\sqrt{x^Tx}$ and $||x||_A$ is a vector norm.   I'm not sure if we can choose $Ax=x$. Any comments are welcome.


how to drop_caches in OpenVZ centos6 container

I have tried   sudo sh -c 'echo 3 > /proc/sys/vm/drop_caches'  sudo echo 3 > /proc/sys/vm/drop_caches  echo 3 > /proc/sys/vm/drop_caches  echo 3 | sudo tee /proc/sys/vm/drop_caches   and a bunch of other variations but with every try I get   bash: /proc/sys/vm/drop_caches: Permission denied   How do I clear the ram used for buffers/cache in my centos6 openvz container?  It seems like the only way to do what I need is to reboot the container.


Why did Princess Leia knowingly lead the Deathstar to the Rebel base?

After Han and Luke rescue Princess Leia from the Deathstar, one of the first things Leia says to Han-after they fight off a very meager squad of Tie Fighters-is that their escape was too easy, and that the only explanation for the ease of their escape was that they were being tracked.                                                       HAN                      Not a bad bit of rescuing, huh? You                       know, sometimes I even amaze myself.                                   LEIA                      That doesn't sound too hard. Besides,                       they let us go. It's the only                       explanation for the ease of our                       escape.                                   HAN                      Easy... you call that easy?                                   LEIA                      **They're tracking us!**                                   HAN                      Not this ship, sister.       [...]                                   WILLARD                      When we heard about Alderaan, we                       were afraid that you were... lost                       along with your father.                                   LEIA                      We don't have time for our sorrows,                       Commander. **The battle station has                       surely tracked us here.**                           (looking pointedly to                            Han)                      It's the only explanation for the                       ease of our escape. You must use the                       information in this R2 unit to plan                       the attack. It is our only hope.             EXT. SPACE             The surface of the Death Star ominously approaches the red             planet Yavin.    Leia personally witnessed the awesome power of the Deathstar destroy her home planet, and admitted that it was only a hope that a weakness could be found in the stolen data R2 was carrying.                                    LEIA                      At least the information in Artoo is                       still intact.                                   HAN                      What's so important? What's he                       carrying?                                   LEIA                      The technical readouts of that battle                       station. I only hope that when the                       data is analyzed, a weakness can be                       found. It's not over yet!    Why was Leia so willing to knowingly lead the Deathstar to the Rebel base?   When faced with the destruction of her home world she was clever enough to send them to an abandoned base, why didn't Leia use the Millennium Falcon to lead them away from the Rebel stronghold? Why didn't she get Han to drop them off somewhere they could meet up with some sympathizers and catch a new ride to the Rebel base or just ship R2 there? Why didn't she insist that R2 figure out how they were being tracked and disable the beacon? Or even better yet, why didn't she use this knowledge to her advantage and lead the Deathstar to a strategically advantageous location to engage or ambush it, like a meteor or asteroid rigger to explode? As clever as she was the only solution shouldn't have been, "They're following us. We had better lead them exactly where they want us to and hope that we can come up with a plan before they catch up to us!"  I'm not the only one to wonder about this:


Attempting to assign value to a 2D list at index ij causes value to be assigned on each row at j

I'm stunned by this behavior, and can't seem to pinpoint what's causing the issue. I'd consider myself fluent in Python, but I'm completely at loss here. >>> board = [[0]*3]*3  >>> board [[0, 0, 0], [0, 0, 0], [0, 0, 0]]  >>> board[1] [0, 0, 0]  >>> board[1][1] 0  # Expected behavior: [[0, 0, 0], [0, 1, 0], [0, 0, 0]] >>> board[1][1] = 1  # Actual behavior: >>> board [[0, 1, 0], [0, 1, 0], [0, 1, 0]]  Running Python 3.9.5 on arm64 macOS 11.4 % python3 --version Python 3.9.5


How do I compile a C# script at runtime and attach it as a component to a game object

The idea here is to let users program the behaviour of an agent in a way that reminds of the "Screeps" game, where you get to develop code which later runs and dictates the behaviour of your units.  My idea is to let users develop the behaviour or their units with C# code, compile that code at runtime and attach it as a MonoBehavior to an existing game object.  How can I achieve this?


How to impose a class to only accept certain data types

I am wondering how to apply a specific filter to a class declaration in order to only accept certain data types.   Say I want the following two classes:    // Here, T can only be an array type. ie. int[], uint[], byte[], etc. public class myClassArray<T> where T is Array {  }  // Here, T can only be an integral numeric type. ie. int, uint, byte, etc. public class myClassNotArray<T> where T is NotAnArray {  }   In both cases I still want to be able to do basic arithmetic.  I have tried a bunch of things, but everything failed pretty badly. I think it is because I do not really understand what characterises a specific data type and how to find out what does.    For instance and Array seems to implement:   "ICloneable, System.Collections.IList, System.Collections.IStructuralComparable, System.Collections.IStructuralEquatable"   but somehow, doing something of the sort still does not allow me to do arithmetic:    public class myClassArray<T> where T : ICloneable, System.Collections.IList, System.Collections.IStructuralComparable, System.Collections.IStructuralEquatable {    public voidDoSomeStuff(T value1, T value2)    {         // I would like this to work:         for (int idx = 0; idx < value1.Count(); idx++)         {             var result = value1[idx] - value2[idx];             .....                         }     } }


Indirect speech - which statement is correct?

I read this statement in an English book and I wonder if this statement is correct:  She told me that she still remembers how scared everyone was.  I have learned that in indirect speech statements the present-tense verbs must be converted to past-tense verbs. Rendering the statement thus:  She told me that she still remembered how scared everyone was.  Is either incorrect?


Can I declare a duplicate page via javascript for google?

Most sources of documentation state that one can declare a webpage a duplicate of another by applying this tag on the duplicate page:  <link rel="canonical" href="(absolute URL to original page)">   I could generate the above tag via the script below:  <script> var l=document.createElement('Link'); l.rel='canonical';l.href='(absolute URL to original page)'; document.getElementsByTagName('head')[0].appendChild(l); </script>   My question is, would google be able to process this javascript and believe I'm declaring the page as a duplicate page? or would I be forced to use the link tag in the header?  I ask because I'm trying to reduce the unnecessary bytes required to be processed before the actual user readable content begins.


Fix for the message 'We are no longer accepting answers from this account'

Trying to answer a question, I'm getting the message 'We are no longer accepting answers from this account. See the Help Center to learn more.'  It happens that I had a SINGLE post, and it was deleted because somebody considered it not being very informative, so I EDITED it, but it remains deleted, and it's like this post is causing me not to be able to answer questions...  This happens to me on different ips, and I'm not able to find the reason.  How can I completely delete that answer of mine? I cannot even upvote anything.  I think that this system is so bad 'banning' people this way, without making it clear why you have been banned. Lots of people are 'duplicating' my question, and I do it again being as frustrated as I am. Believe me, I've been participating in lots of tech forums and this is the first time I'm being banned. And what a way to do it!  Right now I cannot completely delete it, and the editing remains unuseful too, as I cannot undelete it, either.  How can I fix this?


How do I set LibreOffice to spellcheck in British English? When I set it to BE now, it doesn't spellcheck anything. I'm using the latest LibreOffice in Ubuntu 17.04.


It says I need 10 rep to answer this question because of a spam lock, but I have 37 and cannot add my answer.    Furthermore, I made a rather larger bounty on another question and now I can't add comments to any questions. This seems like a rather unusual restriction, as I should never just "lose" that privilege that I earned a long time ago, there should be a cap on wagering away so much rep that I can't function anymore or contribute meaningfully, despite having a relatively trusted account.


When creating a WordPress page, a "-2" suffix is added to new pages' permalinks

I have noticed after deleting an original page in WordPress with lets say a permalink of your_domain.com/contact/ and then trying to recreate the same page with the same name/slug, my WP is generating a "-2" at the end of the link, like: your_domain.com/contact-2/.  I don't understand why, since the original page was deleted. Why is WordPress treating new pages as if the original still exists? How to I clean WP caches, if such a thing even exists?Thank you ahead of time for clearing this up for me.


I have a SQL Server 2012 database. I noticed value of Reason for early termination of statement optimization for some queries and all gave Good Enough Plan Found. Now my questions are:   What are all the possible types of  “Reason for early termination of statement optimization”. I did searching for this in msdn but didn’t get a complete list of values. Is there a DMV or extended event to list all queries for which optimization was terminated due to reasons other than Good Enough Plan Found? I referred following two articles which does not list the complete list of possibilities. [Also, they give me different result in my database].


Having trouble in a statement made in sakurai modern qm

I am facing trouble with a statement made after eq 5.2.4 in sakurai modern qm and the statement is $P_1(E-H_0-\lambda P_1VP_1)$ is singular in $P_1$ subspace. How one can we show the validity of the statement.


I have installed Scilab with sudo apt-get install scilab, and all went good until I tried to open the software, it just does not open, what I tried to do was install a new version of Java, and it make it kind of work, when I start it from the console like this:   cd /usr/bin ./scilab    but it still having some kind of trouble, I want it to start with the icon, but it looks to be impossible, please help me.   Warning: Could not find Java package '/usr/share/java/jlatexmath-fop-1.0.6.jar'. Some problems during the loading of the Java libraries occurred. This could lead to inconsistent behaviours. Please check SCI/etc/classpath.xml. Gtk-Message: 00:21:02.501: Failed to load module "canberra-gtk-module"   also I tried to install the 6.0.1 version of Scilab from the page, but at the moment of opening Scilab from the bin folder, a error comes up, saying that Scilab can not make the main class of Scilab :/ heelp


Are there reasons to revoke my degree if I shared old notes with a current student who was caught plagiarizing my work?

I graduated university (UK University) a couple of years ago with a first. My friend is currently enrolled at the same university and was struggling with an assignment I had completed and still had a copy of. I let him have a look at it to help him but he ended up copying some of it and it was flagged by turnitin. The head of governance at the uni has emailed him and heavily implied that he knew that I gave him a copy of my assignment. I spend the whole morning googling potential repercussions for a graduated student "colluding" and am now terrified that my degree might get revoked or my file will be tagged for misconduct. Does anyone know what the repercussions could be??


Free plugin to create/display Photoshop measurement annotations

I found this plugin SpecKing that looks like it's just about exactly what I'm looking for, I haven't tried it out yet though because I was hoping to find a free, maybe even open source alternative..  Does anyone know of any open-source and/or free Photoshop plugins similar to this one?  I'm looking to extend the functionality of the measure tool so as to actually display annotated measurements of the measured distances for convenient reference.. like a blueprint basically.


LAStools in QGIS 2.8.5: "missing dependency. lastools folder is not configured"

I am using QGIS 2.8.5 Wien and I am trying to install LAStools toolbox. I followed the instructions in  to install it.  I did everything said on the link, but when I tried to run it, it said:     missing dependency. this algorithm cannot be run :-( lastools folder is not configured. please configure it before running lastools algorithms.


Why field tables are not getting removed when I remove the field?

I have a content type with 20 different fields.   Now the project requirement changed and I dont need 15 fields of them. So I removed all those unwanted 15fields from content type.   But the database is still holding all the 15 tables and also the revision table, Why? What happens if I remove it?  I feel like having these many unused tables in database might impact the performance. Will it really have impact on the performance?


C++ / Polymorphism / Virtual Functions / Why is my child class's function not being called?

I looked around, and most questions deal with why you would use virtual, what polymorphism is and so on.  I am having a problem in my program and I want to know WHY the child function is not being called and how to actually CALL the child function in this situation.  I can emulate my problem:  #include <string> #include <iostream> #include <vector>  class BaseA {   public:   BaseA(const std::string &n)     : name(n)   {   }    virtual void print() const   {     std::string str("");     str += name;     std::cout << str << std::endl;   }    protected:   std::string name; };  class BaseB : public BaseA {   public:   BaseB(const std::string &n, const std::string &v)     : BaseA(n), value(v)   {   }    void print() const   {     std::string str("");     str += name;     str += ' ';     str += value;     std::cout << str << std::endl;   }    private:   std::string value; };  int main() {   std::vector<BaseA> vec;   vec.push_back(BaseA("cat"));   vec.push_back(BaseB("cat", "kitten"));    for(BaseA &obj : vec)     obj.print();    return 0; }    Why is the output: cat cat? How do I change the output to "cat cat kitten " using BaseB::print()?


Alter default audio output device from command-line

I have 2 audio output devices:   5.1 Speaker System attached via Toslink Gaming Headset attached via USB   Is there a simple way to change which device is the default output device, from the command-line?  I'm interested in scripting it.


Which are the non Schengen countries that allow entry for Schengen visa holders?

There are countries in the Balkan area that allow entry if you have a Schengen visa but am not able find a definite list of all those countries. Knowing that will save me getting a visa for all those countries when I do my mega Euro trip.


I'm trying to perfectly overlap two images, one complementary of the other, but apperas a white stripe in the conjunction of the path, all points are perfectly aligned how can I fix?


Drupal adding multiple directories to URLs creating duplicate content

I have a Drupal 7 site that is creating a seemingly infinite stream of sub-directories creating a vast amount of duplicate content. For example:  example.com/test/ - is a legitimate page.  example.com/test/test/ - is a duplicate of the above, and this goes on and on like so:  example.com/test/test/test/test/test/test/test/test/test/test/test/test - etc etc.  All of these pages are crawlable and returning a 200 code. I'm not very familiar with Drupal and I can't pinpoint what is causing this. Any ideas?  Many thanks.


What do the steps in ROC curve represent?

I have got the following ROC for a binary classification task using scikit-learn's Gaussian Naive Bayes classifier. The graph shown here shows the ROC curve and has various step like shape. I want to know that what do these steps represent.


what is the equivalent of CustomMasterUrl.SetInherit in CSOM

in C#   SPWeb web = SPContext.Current.Web; PublishingWeb publishingWeb = PublishingWeb.GetPublishingWeb(web); publishingWeb.CustomMasterUrl = "/_catalogs/masterpage/mycustom.master"; publishingWeb.CustomMasterUrl.SetInherit(true, true); publishingWeb.Update();   this code will change the master page and "Reset all subsites to inherit masterpage"  Is there a CSOM equivalent for CustomMasterUrl.SetInherit(true,true)?


I would like to ask a question on SO. However, a search reveals that a similar question has been asked, and I feel my question would get marked as a duplicate. The similar question has few answers - one of which is the accepted answer; and this answer is not the one I am looking for (i.e. it's a strategy change rather than a real solution to the answer).  I am very motivated to get an answer to this question - and thus would like to drive forward responses; possibly by offering a decent sized bounty.  Should I simply ask my question, or is it possible to get "ownership" of the similar question?


I have been trying to use the /give command to give a named book, but I can't seem to give it. I keep on getting the error message of:  Line 1, Column 2 Missing '}' or object member name.  What am I doing wrong?


How can I get distribution name and version number in a simple shell script?

I'm working on a simple bash script that should be able to run on Ubuntu and CentOS distributions (support for Debian and Fedora/RHEL would be a plus) and I need to know the name and version of the distribution the script is running (in order to trigger specific actions, for instance the creation of repositories). So far what I've got is this:  OS=$(awk '/DISTRIB_ID=/' /etc/*-release | sed 's/DISTRIB_ID=//' | tr '[:upper:]' '[:lower:]') ARCH=$(uname -m | sed 's/x86_//;s/i[3-6]86/32/') VERSION=$(awk '/DISTRIB_RELEASE=/' /etc/*-release | sed 's/DISTRIB_RELEASE=//' | sed 's/[.]0/./')  if [ -z "$OS" ]; then     OS=$(awk '{print $1}' /etc/*-release | tr '[:upper:]' '[:lower:]') fi  if [ -z "$VERSION" ]; then     VERSION=$(awk '{print $3}' /etc/*-release) fi  echo $OS echo $ARCH echo $VERSION   This seems to work, returning ubuntu or centos (I haven't tried others) as the release name. However, I have a feeling that there must be an easier, more reliable way of finding this out -- is that true?  It doesn't work for RedHat. /etc/redhat-release contains : Redhat Linux Entreprise release 5.5  So, the version is not the third word, you'd better use :  OS_MAJOR_VERSION=`sed -rn 's/.*([0-9])\.[0-9].*/\1/p' /etc/redhat-release` OS_MINOR_VERSION=`sed -rn 's/.*[0-9].([0-9]).*/\1/p' /etc/redhat-release` echo "RedHat/CentOS $OS_MAJOR_VERSION.$OS_MINOR_VERSION"


Need a way to extract headers of the column with results

I am using a query to output a result into CSV file. the query is   select distinct FirstName,LastName,Company,State,Email1,Email2,contact_number,Cellphone,Cellphone2 into outfile '/tmp/prudential.csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' ESCAPED BY '\\' LINES TERMINATED BY '\n' From person;   is there a way where I can get Headers of the columns as-well in the CSV file.


How do you create an ip alias using iproute utils?

While reading the O'Reilley book on Apache Web Server, they gave an example on using ifconfig to set ip aliases on an interface:  ifconfig ep0 192.168.123.2 ifconfig ep0 192.168.123.3 alias netmask 0xFFFFFFFF ifconfig ep0 192.168.124.1 alias   I became curious: how would you do the same thing using the iproute utils on Linux?


Meaning of $\hat{\beta}$ of the linear regression model

In the simple linear regression model, $\hat{\beta}$ is the sum of independent normally distributed random variables.  Is it false because in linear regression there is $\beta$ and not $\hat{\beta}$?


How to uninstall steam64 for linux/ubuntu?

I'm seeing people say things like sudo apt-get remove steam and sudo dpkg -r steam but neither are working.   I ran dpkg-query -l *steam* and I get the following:  Desired=Unknown/Install/Remove/Purge/Hold | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad) ||/ Name           Version      Architecture Description +++-==============-============-============-================================= un  steam          <none>       <none>       (no description available) rc  steam-launcher 1.0.0.47     all          Launcher for the Steam software d un  steam64        <none>       <none>       (no description available)   Not sure if this helps.  The steam FAQ doesn't seem to help either. I'm pretty sure I didn't do any apt-get install for Steam. I downloaded the steam_latest.deb from the website. Any ideas?   Update: I do have what I believe to be the folder in ~/.steam. What I'm wondering now is, if I remove this folder, what else do I need to remove?


let X,d be a metric space d(x,A) = inf{d(x,a):a of A} d(A,B) = inf{d(a,b):a of A, b of B}  (i) prove that d(x,A) = 0 iff x is an element of A bar for this I came to the conclusion that the above statement isn't true, assuming A bar is the compliment of A then if x is and element of A then d(x,x) = 0 is an element of {d(a,b):a of A, b of B} and it's infimum and is therefore d(x,A)=0 for x an element of A not A bar.  was it a trick question or am I wrong?  (ii) Give an example of closed, disjoint subsets A and B of the plane R^2 for which d(A,B) = 0.  does such an example exist?  since A and B are closed they contain there boundary points, so d(A,B) = the distance between their closest boundary points since they are disjoint those aren't the same point and therefore it isn't equal to 0.    was this a trick question, or is my logic off?


Mathematical Induction: Sum of first n odd perfect cubes

The series is $$P_k: 1^3 + 3^3 + 5^3 + ... + (2k-1)^3 = k^2(2k^2-1)$$ and I have to replace $P_k$ with $P_{k+1}$ to prove the series.  I have to show that $$k^2(2k^2-1) + (2k-1)^3 = (k+1)^2[2(k+1)^2-1]$$  I'm sorry that I'm asking but their are just so many factors the algebra just passes over my  head. Any help is appreciated.


If $A = \tan6^{\circ} \tan42^{\circ},~~B = \cot 66^{\circ} \cot78^{\circ}$ find the relation between $A$ and $B$

My trigonometric problem is:     If $A = \tan6^{\circ} \tan42^{\circ}$ B = cot$66^{\circ} \cot78^{\circ}$ find the relation between $A$ and $B$.    Working :   $$B = \cot 66^{\circ} \cot78^{\circ} = 1- \frac{\tan24^{\circ}+\tan18^{\circ}}{\tan42^{\circ}}$$  $$A= \tan6^{\circ} \tan42^{\circ} = 1- \frac{\tan6^{\circ} +\tan42^{\circ}}{\tan48^{\circ}}$$  but it seems  this is the wrong way of doing this...please suggest. Thanks!


Bash script to monitor log, match keyword then send commands

#!/bin/bash sudo tail -fn0 /home/main/time.log | grep -o --line-buffered 'garage\|garden\|porch' | head -1 |     while read line; do  sudo pkill -f porch.sh & sudo pkill -f garage.sh & done   I'm trying to write a script that monitors a log, and upon matching a keyword, it will fire off some commands.  Problem is, what I've pieced together will work only once, then exit and stop monitoring.   I have "head -1" added to grep, because I want this to execute after the first keyword only, and prevent it from executing a multitude of times should multiple keywords appear in the tail of the log. So, basically, If multiple keywords appear in the tail, I want it to execute at the first keyword, ignore the rest of the keywords, execute the scripts listed, then go back to monitoring the tail of the log.  I would prefer the script to remain active after it matches a keyword and continue monitoring the tail of the log for any new keywords that might get logged.  Any advice is much appreciated. Thank you!


Is there any disposable email service that allows receiving verification emails at a temporary address?

Is there any disposable email service that allows receiving verification emails at a temporary address that self-destructs after 24 hours so that it will be helpful in automation of 'customer registration and verification' test case?


The ideal generated by $x^m-1$ and $x^n-1$ in $\mathbb{Z}[X]$ is principal.

I can show that $(x^m-1, x^n-1) \subseteq (x^{(m,n)} - 1)$, but I am stuck with the other inclusion. i.e. showing there exist polynomials $p, q \in \mathbb{Z}[X]$ such that $p(x)(x^m-1) + q(x)(x^n-1) = x^{(m,n)}-1$. I can't use Bezout's identity because $\mathbb{Z}[X]$ is not a PID. I computed some examples but I can't see a general patttern. e.g. \begin{align} (x^5-1) - (x^3 + x)(x^2-1) &= x-1 \\ (x^2-1)(x^5-1) -(x^4+x^2+x)(x^3-1) &= x-1 \\ (x^4-1) -x^2(x^2-1) &= x^2-1 \end{align} Thanks in advance.


How often should I tin my soldering iron?  It doesn't seem to pick up the solder quickly any more; I have to hold it there for 10 seconds before it melts.


Seeking feedback on my cover letter for UK standard visitor visa application

I am scheduled to apply for a UK visitor visa on 13 July and have stated that I plan to stay for the whole six months. I've decided to include a cover letter to explain the circumstances of my request. I'd appreciate it if you could provide feedback on the below text:


Are there specific rules to build expressions with or without articles?

In English, there are lots of expressions built using articles like:   at the station to the cinema play the piano have breakfast (no article) take a bath take a shower   Are there specific rules or tips to help determine whether or not to use an article before the noun? Or do we always need to depend on a dictionary?


How to solve $x^{17}\equiv 37$ in $\mathbb{Z}/101\mathbb{Z}$?

I need to solve the equation $x^{17}\equiv 37$ in $\mathbb{Z}/101\mathbb{Z}$.   I've looked into these topics (,  ) but couldn't derive a solution.     So summarize what I know:       101 is prime $\implies \mathbb{Z}/101\mathbb{Z}$ is cyclic group (or even a field) since $\mathbb{Z}/101\mathbb{Z}$ is cyclic it has a generator with the same order of $\mathbb{Z}/101\mathbb{Z}$. In this case the generator has order $\phi(101)=101-1=100$  due to Fermat I have $x^{100}\equiv 1$ $mod(101)$ $\phi(101)=100=2^2\cdot 5^2$ I have tried in vain to orient myself to:  I know that the (only) solution is $x=52$   Can somebody help me?


Is there a way to see how many times a question has been viewed on iOS app?

When I access Stack Exchange in my browser, there's a helpful stat on the top right of the page that states how many times a question has been viewed. This stat is helpful because it tells the asker if people are reading and considering their question.   However, I can't seem to find where this stat is located in Stack Exchange's iOS app. Is there a place I can see how many times my question has been viewed from the app?


I'm trying to implement a typed vector class that can either have arbitrary number of Int or Double coordinates  There is an abstract method add, that should add two coordinates. This is implemented in derived class for Double as def add(a: Double, b:Double) = a + b  The test I'm running is val v1 = Vect(2.5, 2.3) val v2 = Vect(1.4, 5.6)  println(v1) println(v2) val v3 = v1 + v2 println(v1) println(v2) println(v3)  prints Vect[ArrayBuffer(2.5, 2.3)] Vect[ArrayBuffer(1.4, 5.6)] Vect[ArrayBuffer(2.5, 2.3)] Vect[ArrayBuffer(1.4, 5.6)] Vect[ArrayBuffer(3.9, 7.8999999999999995)]  I wonder why 2.3 and 5.6 adds up to 7.8999999999999995.


I up-voted an answer but the red highlight around the up arrow never came as can be seen below.    To make sure, I voted again and got the error message.


is there any way I can run Linux commands in the web?

I am looking for software/application that can help me of checking some Linux commands working in a browser irrespective of OS. I mean Live CLI in the browser.  Thank you.


Movie in which kid with a leg problem falls in a sewer accident and goes to a parallel universe

I am looking for a movie in which a kid fell in a sewer accident/challenge and ends up in a different universe. I remember the kid having a problem with one of his legs some sort of iron staff was surrounding his leg from the knee down.


Java HashMap.put throwing NullPointerException with "new" keyword

I have checked everywhere for a solution to this problem and simply cannot find one despite its apparent simplicity.  I keep getting a NullPointerException when calling myFunction():  private static Map<String, Map<String, Integer>> data;  public Class() {     data = new Map<String, Map<String, Integer>(); }  public static void myFunction(String key, String val0, int val1) {     boolean createNewEntry = false;     if(null == data) {         createNewEntry = true;     }     else if(!data.containsKey(key)) {         createNewEntry = true;     }     if(createNewEntry) {         data.put(key, new HashMap<String, Integer>()); // This throws a NullPointerException.     }     data.get(key).put(val0, data.get(key).get(val0) + val1); }   The stack trace (with some project-specific data removed) is as follows:  Could not pass [Event] to [JAR file] v1.0.0 org.[parent].event.EventException     ... (irrelevant) Caused by: java.lang.NullPointerException     at net.[package name].[class].myFunction([source file].java:93)     at net.[package name].[class].otherFunction([source file].java(108)     at net.[package name].[other class].anotherFunction([other file].java(65)     at net.[package name].[main class].on[Event]([main file].java:97) ~[?:?]     at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source) ~[?:?]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:[versioning number]]     at java.lang.reflect.Method.invoke(Unknown Source) ~[?:[versioning number]]     at org.[a different package name].plugin.java.JavaPluginLoader$1.execute([a file].java:301) ~[[versioning number]:[more data]]     ... 15 more   Thank you in advance for any insight into this problem.


(Py-) CUDA under Linux from live USB stick

My question is similar to .  What I would like to have is a USB stick with a Linux installation on it such that I can boot from the stick and run PyCUDA programs on the GPU. That is, I need a live Linux stick with CUDA installation.  Is that possible? Has anybody done it? Can it be done such that the CUDA installation remains and keeps working when plugging the stick into another computer?


I have a long text and I want to create a link within the document to a particular paragraph (for example write something like "as shown here" where clicking on "here" will take the reader to that paragraph).   Is this possible to do?


I've recently downloaded and installed Ubuntu on my lenovo ideapad 100, and once in a while it seems it is connected to the wi-fi, but the browser doesn't load any page; but, after turning off and on the "Enable Wi-Fi" option, it usually reconnects. Right now, it won't connect again and won't show any available wi-fi around. Any way to get the internet back without restarting the whole system?


We have just started learning about continuity and this is basically the first assignment on this subject so I'm very unsure about how everything works. My attempt of a solution is as follows; Let $g:\left[0,\frac{1}{2}\right]\ ->\left[0,\frac{1}{2}\right]\ $such that  $ g\left(x\right)\ =\ f\left(x\right)\ -\ f\left(x+\frac{1}{2}\right)$ Note that $g$ is continuous, hence by the fixed point theorem there exists a point $C$ in $\left[0,\frac{1}{2}\right]$ such that $g\left(C\right)\ =\ C$. Therefore there exists a $C$ in $\left[0,\frac{1}{2}\right]$ such that $ g\left(C\right)\ =\ f\left(C\right)\ -\ f\left(C+\frac{1}{2}\right)$. Now am I missing something? Because it seems just too simple to me.. also I didn't even use the fact the $f(0) = f(1)$ which is suspicious. Edit: I'm seeing now that i didn't use the theorem correctly, since it just says that $g\left(C\right)\ =\ f\left(C\right)\ -\ f\left(C+\frac{1}{2}\right)= C $. and C is not necessarily $0$..


Can I ask questions about asking questions?

This is that type of question, but it's fundamental.  Information on Meta Stack Exchange states I can ask anything related to the Stack Exchange websites, its communities and some other stuff, but I have questions such as this about just asking questions which is not directly connected to Stack Exchange.  The FAQ doesn't satisfy me completely. Where were the FAQ asked? Was it here?  If this question is legitimate (Not the greatest questions you've seen... I know) in the Meta Stack Exchange community then I can be more specific. I'm new to this and just trying to get to know how and what I ask in here.


Discrepancy with lsof command when trying to get the count of open files per process

I am trying to get a list of open files per process. I ran the following one-liner from :  lsof | perl -lane '$x{"$F[0]:$F[1]"}++; END { print "$x{$_}\t$_" for sort {$x{$a}<=>$x{$b}} keys %x}'   It returns the total count of open files, and the process name and pid. The result is sorted in ascending order, and the last line is as follows:  1065702 java:15437   So when I run lsof -p 15437, I would expect it to return the same number, however I'm getting:  $ lsof -p 15437 | wc -l 403   Why the discrepancy?  Addendum  A third source of discrepancy:  $ cd /proc/15437/fd $ ls -1 | wc -l 216


How to create grid in GIMP (not sure if the filter is good)

I'm a beginner to GIMP, and I'd like to create a grid.   I searched Google and all it gave me was to use the Filter > Render > Grid plugin, but for my job all I want to do is something like this:  Let's say I have a square image that's 1530 x 1530, and I want the grid to be an 8 x 8 matrix with grid lines that are 1px wide. I don't want to calculate the right spacing on each grid cell as the grid filter gives me; I just want GIMP to calculate the right spacing and grid line width for this image.  Is there a way to do it right?


How to save a symbol or graphic style in Illustrator?

I designed a link button in Illustrator, much like the ask question button here.  Since I am new to all this, I have difficulties creating just the perfect shape every time, so I want to save that button as a symbol or graphic style so that the next time I can just click on it and change the text length.  How do I save as a symbol or graphic style?


I can't seem to choose root access when doing the recovery start and I don't get the # prompt either.  Where do I type the command? The way it is it doesn't recognize it.  Trying fsck I'm denied permission. It seems I don't have r/w access to the filesystem.


If $p+q+r=0$, find the value of the determinant

If $p+q+r=0$, prove that the value of the determinant $$ \Delta= \begin{vmatrix} pa & qb &rc \\  qc & ra &pb\\  rb& pc & qa  \\  \end{vmatrix} =-pqr \begin{vmatrix} a & b &c \\  b & c &a\\  c& a & b  \\  \end{vmatrix}$$  My Try:Since $p+q+r=0$ we have $$a(p+q+r)+b(p+q+r)+c(p+q+r)=0$$ $\implies$ $$(ap+qc+rb)+(qb+ra+pc)+(rc+pb+qa)=0 \tag{1}$$ Now applying $C_1 \to C_1+C_2+C_3$ and then applying $R_1 \to R_1+R_2+R_3$ for $\Delta$ we get $$\Delta=  \begin{vmatrix} 0 & qb &rc \\  qc+ra+pb & ra &pb\\  rb+pc+qa& pc & qa  \\  \end{vmatrix}$$ Any clue here?


I'm a new user here, and I wanted to post a question in Math.SE, but whenever I try to post a question I get a message saying I can only post 50 question in 30 day period. But, I haven't even started posting.


How to check the number of set bits in an 8-bit unsigned char?

So I have to find the set bits (on 1) of an unsigned char variable in C?  A similar question is  But it uses an algorithm that's not easily adaptable to 8-bit unsigned chars (or its not apparent).


What is the difference when I have for example,   int var1, *ptr; ptr = &var1; // the pointer ptr copies the address of var1, hence ptr points to var1?  int var1, *ptr; ptr = var1; // ptr points to var1, but does not have the address of var1, so can not change the value of address var1?   int *var1, *ptr; *ptr = *var1; // copy value of var1 into the location pointed to by ptr?   are my comments correct ?


I have downloaded an ISO file recently.  How do I burn it to a CD or DVD or mount it?


What is the difference between mathoverflow.net and math.stackexchange.com?

The title says it all: I'm confused as to the difference between mathoverflow.net and math.stackexchange.com.  Can anyone elaborate?  My its descriptions math.sx is a "Q&A for people studying math at any level and professionals in related fields" and MathOverflow is a "Q&A for professional mathematicians".  That's not a big help... :-)


Can I take a flight that departs after midnight of the day my Schengen visa expires?

I have short term german visa for three days.  I don't have a flight in my budget on the 3rd day night so I want to know if I can finish my immigration on the 3rd day night and take up the flight next day morning.   Do the airline companies and immigration allow such things.