I ran this command sudo apt-get install tor-browser and I got this output. Should I apply autoremove as mentioned?      sudo apt-get install tor-browser     Reading package lists... Done     Building dependency tree            Reading state information... Done     The following packages were automatically installed and are no longer required:       linux-headers-4.4.0-21 linux-headers-4.4.0-21-generic linux-headers-4.4.0-22       linux-headers-4.4.0-22-generic linux-image-4.4.0-21-generic       linux-image-4.4.0-22-generic linux-image-extra-4.4.0-21-generic       linux-image-extra-4.4.0-22-generic linux-signed-image-4.4.0-21-generic       linux-signed-image-4.4.0-22-generic     Use 'sudo apt autoremove' to remove them.     The following NEW packages will be installed:       tor-browser     0 upgraded, 1 newly installed, 0 to remove and 44 not upgraded.     Need to get 69.5 MB of archives.     After this operation, 69.5 MB of additional disk space will be used.     Get:1 http://ppa.launchpad.net/webupd8team/tor-browser/ubuntu xenial/main amd64 tor-browser amd64 6.0.2-1~webupd8~0 [69.5 MB]

Today I ran apt-get autoremove to remove un-needed packages and it wants to remove linux-headers-3.2.0-37 and linux-headers-3.2.0-37-generic  Reading package lists... Done Building dependency tree        Reading state information... Done The following packages will be REMOVED: libglademm-2.4-1c2a linux-headers-3.2.0-37 linux-headers-3.2.0-37-generic ttf-umefont    ttf-unfonts-core 0 upgraded, 0 newly installed, 5 to remove and 0 not upgraded. After this operation, 67.6 MB disk space will be freed. Do you want to continue [Y/n]?    Is it safe to remove these? My installed kernel is a newer version than the headers that autoremove lists.  uname -r 3.2.0-38-generic


I am thinking of purchasing the Nikon D3200 its a 24.2MP camera but the pixel size is 14.8 µm² compared to the D3100 which is 14MP and a pixel size of 25.1 µm².  Is this something that i should worry about, or is it somewhat irrelevant, as the eye cannot see such fine detail?  I am worried about the digital noise. I understand that at higher ISO's like 800, I will see more noise. But at 50/100 ISO, will I notice the difference between the pixel sizes, and ultimately does this constitute to better or worse image quality?  D3100 - £269  D3200 - £329   Last question: is it worth the extra money?

This is going off of today's iPhone 5S announcement, when Phil Schiller said that "bigger pixels" is the key to a better picture.      What does this mean? Is it true or just a marketing ploy?


Let $(\Omega,\mathcal A,\mu)$ be a measure space, $p,q\ge1$ with $p^{-1}+q^{-1}=1$ and $f:\Omega\to\mathbb R$ be $\mathcal A$-measurable with $$\int|fg|\:{\rm d}\mu<\infty\;\;\;\text{for all }g\in L^q(\mu)\tag1.$$ By $(1)$, $$L^q(\mu)\ni g\mapsto fg\tag2$$ is a bounded linear fuctional and hence there is a unique $\tilde f\in L^p(\mu)$ with $$(f-\tilde f)g=0\;\;\;\text{for all }g\in L^q(\mu)\tag3.$$     Can we conclude that $f=\tilde f$?   EDIT: As we can see from , we need to impose further assumptions; but which do we really need?

Let $f$ be a measurable function on a measure space $X$ and suppose that $fg \in L^1$ for all $g\in L^q$. Must $f$ be in $L^p$, for $p$ the conjugate of $q$? If we assume that $\|fg\|_1 \leq C\|g\|_q$ for some constant $C$, this follows from the Riesz Representation theorem. But what if we aren't given that such a $C$ exists?


The series is: $\displaystyle\sum_{n=1}^\infty \dfrac1{n (\ln n)^p}$  I don't know what to do from here since $p$ is on $\ln$.   Would $p$ still have to be $> 1$ since $\ln$ is changing in terms of $n$?

Study the convergence of the following series: $$\sum_{n=2}^\infty \frac{1}{n^\alpha \cdot\ln^\beta(n)} \text{ where }\alpha,\beta \geq 0 $$   Applying d'Alembert criterion I have that $$ \lim_{n\to\infty} \frac{n^\alpha  \ln^\beta(n)}{(n+1)^\alpha  \ln^\beta (n+1)} = \lim_{n\to\infty} \left(\frac{n}{n+1}\right)^\alpha\left(\frac{\ln(n)}{\ln (n+1)}\right)^\beta = 1$$ so the nature of the series is inconclusive.  If $\alpha = \beta = 0$, then the series diverges, since $\sum_{n=2}^\infty 1 = \infty$.  Should I study the rest of the cases (i.e. if $\alpha = 0, \beta > 0$ the root test and the ratio test are also inconclusive). What is the best form to study the series?.  Thanks in advance


I need to insert a footnote for the third author, and I am using \footnotetext for it.  \author{Bleh \and Bleh Bleh \and Bleh Bleh Bleh\footnotemark} \footnotetext{Right. Works.}   This gives me the following error.  ! Incomplete \iffalse; all text was ignored after line 84. <inserted text>                  \fi    I have checked that it is introduced by footnotemark because if I remove it, it compiles.   Is there any other way to do this?

I want to attach a footnote to each author of a paper and write that their research was supported by different grants. How do I do that? Simply \footnote after each author does not work.


Tags should be suggested based on related questions When you start typing a title, you get a bunch of related questions:  When you click in the tag space however, you don't get any suggestions (save on meta):  Now if you are working within a programming framework, this works great. You say, "My question is about !" and you're off to the races. But what if you're on a site which doesn't fit in to default frameworks quite so nicely?  What the heck am I supposed to tag my question with?  What I'm currently doing (trying to get hired! errrr, ) My job title/source of my problem () My industry ()  (the suggestions for SO are a much more helpful , , ) Can't we give the user a bit better context? We already have the related questions being displayed, and those questions have tags, right?  Wouldn't it be absolutely awesome if you clicked in the tag box, and based on the related questions it gives you some suggestions even before typing based on the related questions to what you're asking? You know, something like this:  This would make it easier for many of the not-so-easily-classified sites in the SE network to save time on tag cleanup and make it easier for users to find related questions, and to tag appropriately. It is such a simple and obvious improvement, it doesn't even need freehand red circles on it! For reasons unknown, something similar to this is already implemented for Meta. For instance this is what it shows me for this post:  I have no idea how these are decided, but they aren't appearing on SE or on TW for me, only Meta SO. TL;DR Suggest tags. I don't care if you ignore the methods or design suggested above. At the end of the day, suggest tags to new users and make SE just a wee bit more civilized.

In the same way possible answers (Related Questions) are suggested when you leave the Title, possible tags should be offered when you give the Tags textbox focus.


It is a simple program to find out if an integer is a power of 4, but I couldn't understand this section when we take integer  255 & 256:   $x = $n;               while ($x % 4 == 0) {               $x /= 4;              }              if($x == 1)   Can someone explain it to me?  <?php     function is_Power_of_four($n)     {           $x = $n;           while ($x % 4 == 0) {           $x /= 4;          }          if($x == 1)         {             return "$n is power of 4";         }         else         {             return "$n is not power of 4";         }      }     print_r(is_Power_of_four(4)."\n");     print_r(is_Power_of_four(255)."\n");     print_r(is_Power_of_four(256)."\n");   ?>

I'm someone who writes code just for fun and haven't really delved into it in either an academic or professional setting, so stuff like these bitwise operators really escapes me.  I was reading an article about JavaScript, which apparently supports bitwise operations. I keep seeing this operation mentioned in places, and I've tried reading about to figure out what exactly it is, but I just don't seem to get it at all. So what are they? Clear examples would be great! :D  Just a few more questions - what are some practical applications of bitwise operations? When might you use them?


What is the difference between these sentences?     Tell me, doctor, shall I lose weight?      Tell me, doctor, will I lose weight?

"Nearly there!" Harry panted as they reached the corridor beneath   the tallest tower. Then a sudden movement ahead of them made them almost drop the crate. Forgetting that they were already invisible, they shrank into the shadows, staring at the dark outlines of two people grappling with each other ten feet away. A lamp flared. Professor McGonagall, in a tartan bathrobe and a hair net, had Malfoy by the ear.   "Detention!" she shouted. "And twenty points from Slytherin! Wandering around in the middle of the night, how dare you ––"   "You don't understand, Professor. Harry Potter's coming –– he's got a dragon!" "What utter rubbish! How dare you tell such lies! Come on –– I shall see Professor Snape about you, Malfoy!"   (Harry Potter and the Sorcerer's Stone)   Shall is  and will is . Then which is the stronger expression, "I shall see Professor Snape about you" or "I will see Professor Snape about you"?


I've a problem during the citation bibliographic source. %In the bibliography file: @article{MER,     Title = {Mars Exploration Rover Engineering Cameras},     Author = {J. N. Maki,J. F. Bell III, K. E. Herkenhoff, S. W. Squyres, A. Kiely, M. Klimesh, M. Schwochert, T. Litwin, R. Willson, A. Johnson, M. Maimone, E. Baumgartner, A. Collins, M. Wadsworth, S. T. Elliot, A. Dingizian, D. Brown, E. C. Hagerott, L. Scherr, R. Deen, D. Alexander, J. Lorre},     Journal = {Journal of Geophysical Research},     Year = 2003,     Volume = 108 }  %In the .tex file Cameras selected for this work have been taken from NASA’s MER (Mars Exploration Rover) mission \cite{MER}  After compiling I've the following warning: CItation "MER" on page 15 undefined on input line 594.

The code for reference is this  @article{matcontcl,  title= {MATCONT and CL MATCONT},  author = {A. Dhooge, W. Govaerts, Yu.A. Kuznetsov, W. Mestrom, A.M. Riet and  B.Sautois},  year = {2006},  journal = {Continuation toolboxes in matlab}, }   This is the error that follows  This is BibTeX, Version 0.99d (TeX Live 2015/W32TeX) The top-level auxiliary file: PropuestaInvestigacion.aux The style file: abbrv.bst Database file #1: biblio.bib Too many commas in name 1 of "A. Dhooge, W. Govaerts, Yu.A. Kuznetsov, W. Mestrom, A.M. Riet and B.Sautois" for entry matcontcl while executing---line 1049 of file abbrv.bst Too many commas in name 1 of "A. Dhooge, W. Govaerts, Yu.A. Kuznetsov, W. Mestrom, A.M. Riet and B.Sautois" for entry matcontcl while executing---line 1049 of file abbrv.bst Too many commas in name 1 of "A. Dhooge, W. Govaerts, Yu.A. Kuznetsov, W. Mestrom, A.M. Riet and B.Sautois" for entry matcontcl while executing---line 1090 of file abbrv.bst Too many commas in name 1 of "A. Dhooge, W. Govaerts, Yu.A. Kuznetsov, W. Mestrom, A.M. Riet and B.Sautois" for entry matcontcl while executing---line 1090 of file abbrv.bst (There were 4 error messages)   How could I fix it?


I have been playing Risk with my four best friends and i have very rarely won.  I have been wondering what is the best strategy to win at Risk?

In general what do you recommend at the beginning of the game?


Every point mass is attracted to each other with a force $F= \frac{GMm}{r^2}$. I know nothing about theories behind expanding universes but, why wouldn't the universe eventually shrink down to a minuscule space?

We live in an expanding universe - so I'm told. But how can that be possible? Everything imaginable is attracted by a bigger thing. So, why can't gravitation stop the expansion of the universe? I know the "Big Bang" theory, but is it possible that the expansion of the universe is caused by the attraction of a bigger object?


I don't have reputations enough so for that,  the most understandable answer is that they are not logia fruit users, i suspect that their are other types of devil fruit in which the body can produce as much amount of the matter(i unable to say the exact word) as they want. For example- admirals (more plasma, ice, or light), trebol( Donquixote Doflamingo family more sticky material), Blackbeard(more darkness), ace (more fire) etc. In such case the haki attack was only hits the matter covering their body and only able to scratch a little and therefore in this type of devil fruit power the body can be regained back to normal by just producing more matter. Please upvote if You find this helpful.

Why are Haki attacks not effective on Marine admirals?  In the Marineford war, we see countless instances where Haki-imbued attacks don't affect Marine admirals. When Marco and Vista attack Sakazuki, he even acknowledges that they are Haki-imbued, but nothing apparently happens:    Another case is when Whitebeard attacks Aokiji:     What's with the admirals? Their Logia powers don't seem to be easily affected by Haki attacks. I mean we have many instances where Haki has touched their body, but still there are many instances where attacks on their body don't result in damage. What's the deal with Marine admirals?


I want my Java program to round numbers off to two decimals. I've been looking at my class materials and I can't find a solution. Here's the code  import java.io.*;  import java.util.*;  public class prog58i  { public static void main (String[] args)  { //input System.out.print("the amount I wish to borrow is? "); Scanner a = new Scanner(System.in); double borrow = a.nextDouble(); //Shows amount of money someone wants to borrow  System.out.print("The loan rate I can get is? "); Scanner b = new Scanner(System.in); double rate = b.nextDouble(); //Shows loan interest rate  System.out.print("The number of months it will take me to pay of this loan is? "); Scanner c = new Scanner(System.in); double months = c.nextDouble(); //Shows months loan will be taken out   //The Math Part double MP = borrow * (rate/1200) * (Math.pow((1+rate/1200), months)) /     (Math.pow((1+rate/1200), months)- 1); double intrest = (MP * months) - borrow; double repaid = (MP*months);  //Output System.out.print( "My monthly payments will be $" +MP +"\n"); System.out.print( "Total Interest Paid is $" +intrest +"\n"); System.out.print( "Total Amount Paid is $" +repaid +"\n"); } }   I'm more looking for a tutorial or just some advice on how to do it myself.

What I would like is a method to convert a double to a string which rounds using the half-up method - i.e. if the decimal to be rounded is 5, it always rounds up to the next number. This is the standard method of rounding most people expect in most situations.  I also would like only significant digits to be displayed - i.e. there should not be any trailing zeroes.  I know one method of doing this is to use the String.format method:  String.format("%.5g%n", 0.912385);   returns:  0.91239   which is great, however it always displays numbers with 5 decimal places even if they are not significant:   String.format("%.5g%n", 0.912300);   returns:  0.91230   Another method is to use the DecimalFormatter:  DecimalFormat df = new DecimalFormat("#.#####"); df.format(0.912385);   returns:  0.91238   However as you can see this uses half-even rounding. That is it will round down if the previous digit is even. What I'd like is this:  0.912385 -> 0.91239 0.912300 -> 0.9123   What is the best way to achieve this in Java?


are there any assumptions on cross-validation? For instance, is it necessary, that a) the test and training data are independent of each other? b) the distribution of the trainig data and test data is identical? If yes, I would be particularly interessted in literature about this topic. Thanks!

According to  (also  and ), we cannot deduce just from the data alone (without any domain knowledge) which classifier is better. Of course, we use cross-validation to do precisely that.  So what are the assumptions that we implicitly make that make cross-validation a meaningful procedure?


Ten minutes have passed. Let's wait five more.   Is using have here correct?

I want to express simply that some time had elapsed. Is the following correct?     It was passed 10 minutes.   Are there any alternatives?


I've got a specific command which I want to run at startup, I am running Ubuntu GNOME 15.10 with GNOME 3.18 with systemd. But after searching I can only seem to find . So how do you run a command at startup using systemd?

How can I run scripts automatically when Ubuntu starts up so I don't have to run them manually after startup?


Hello I have the following code which allows a user to select an image.

Insert Image

           <input id="thumbage2" name="Image1"class="ModalArea2" type="file" style="display:none">            Choose Image                         <button class="ModalButton2" onclick="iImage();">Submit</button>             <button class="ModalButton2" onclick="cancel2();">Cancel</button>

   It is NOT in a form, i'm not sure if that matters.   function iImage(){ var imgsrc = document.getElementById('thumbage2'); if(imgsrc !=null){     $(document).ready(function (e) {         $('#form2').on('submit',(function(e) {             e.preventDefault();             var formData = new FormData(this);             console.log("done");             $.ajax({                 type:'POST',                 url: $(this).attr('action'),                 data:formData,                 cache:false,                 contentType: false,                 processData: false,                 success:function(data){                     console.log("success");                     console.log(data);                 },                 error: function(data){                     console.log("error");                     console.log(data);                 }             });         }));          $("#ImageBrowse").on("change", function() {             $("#form2").submit();         });     });       richTextField.document.execCommand('insertParagraph',false,"");     richTextField.document.execCommand('insertHTML',false,"[Image][Remove=Remove Image]");     richTextField.document.execCommand('insertParagraph',false,"");     document.getElementById('modal2').style.display = "none";     document.getElementById('thumbage2').value =  ""; }   }  Here is my javscript code. Basically what I want is to be able to get the file in the input field and Post it to a php file(saveImage.php) without leaving the page. How do I do this? By the way if you are wondering the purpose is to upload images and store them in Blobs in a MYSQL database. And in case it matters here is my php code:  $imageName = mysql_real_escape_string($_FILES["Image1"]["name"]);     $imageData = '';     $imageData2 = '';     $imageext = '';     if($imageName != null){         $imageData = mysql_real_escape_string(file_get_contents($_FILES["Image1"]["tmp_name"]));         $imageType = mysql_real_escape_string($_FILES["Image1"]["type"]);         $imageSize = getimagesize($_FILES["Image1"]["tmp_name"]);         $imageType = mysql_real_escape_string($_FILES["Image1"]["type"]);         $FileSize = FileSize($_FILES["Image1"]["tmp_name"]);         $imageext = $imageSize['mime'];     }      echo $imageext;   EDIT: OK i changed my JS to what everyone is saying in the comment. But this is not what i want, I want to submit the files data using ajax when a regular button is pressed not an input with type of submit. Can anyone actually help me?

I would like to upload a file asynchronously with jQuery.     $(document).ready(function () {     $("#uploadbutton").click(function () {         var filename = $("#file").val();          $.ajax({             type: "POST",             url: "addFile.do",             enctype: 'multipart/form-data',             data: {                 file: filename             },             success: function () {                 alert("Data Uploaded: ");             }         });     }); });  File <input type="file" id="file" name="file" size="10"/> <input id="uploadbutton" type="button" value="Upload"/>     Instead of the file being uploaded, I am only getting the filename. What can I do to fix this problem?


I know I don't have much rep on Super User, but I have on Ask Ubuntu.  I found a post, . And I have some potential solutions for it. Can I get permission or some other way to contact the asker? I had and have a similar issue with drivers, and I can maybe help him. Or is there a way to "make rep fast"? My issue:

From "6 Simple Tips to Get Stackoverflow Reputation Fast" at codexon.com:   Be the First to Answer. Even at the cost of quality. Use Downvotes and Comments Strategically Use obnoxious in-your-face formatting and lists. Be Aware of the 200 rep/day Limit Edit, But Don’t Edit Too Much Associate your other accounts   Courtesy of . Agree? Disagree? Walnuts? Cantaloupe?


I flagged a  yesterday as a duplicated question and now its status is set to eventinvalidated. I can see this in my Flagging History section.  I'm not sure I understand what it means since the post is still there and has not been deleted. It's the first time I have seen this status.  Could someone enlighten me about that?

A few days ago, someone posted a question about updating dataset. After some questions/comments to his question, it didn't receive answers (and no up/down vote).  1 or 2 days later, the user posted the  (he just reformulated the question, posted less code and with bad formatting, the code doesn't compile due to missing ' for comments), so it would be harder to get answer for this question . The question received a +1.   I flagged this question as a duplicate of the previous and asked user to edit the previous instead of creating a new one, but he deleted the previous.  I do not blame the asker, I understand he wanted to keep it's 5 points rep  :) And it seems he solved his problem later.  But now the flag is marked with eventinvalidated because it is impossible now to accept or reject it?   Since my flag is no longer appropriate, I am just curious about what could happen to this flag?


I have found questions similar to mine, but none of the solutions given solves my problem.  Because my algorithm is too long to fit on one page, I want it to be split on two pages. Solutions I've found involve splitting the algoritm into two algorithmic environments, and add in the second something like:  \Continuedfloat   However, I use  \begin{algorithm} \begin{algorithmic}   and I need to keep the float environment, because I want to use a caption and other things. Perhaps there is a way of defining a caption in the algorithmic environment... is there? I haven't found one.  Another problem associated with splitting the algorithm in two is that I would need to define my for loop, which spans the whole algorithm, twice; I would like to avoid this.

I am writing a few rather large pseudocode functions using algorithm and algorithmic, i.e. my code looks something like:  \begin{algorithm}                      \caption{Coolest Algorithm ever}           \label{findme}                           \begin{algorithmic} [1]                   % enter the algorithmic environment \REQUIRE    Here are a few variables \\             variable 2 \\             variable 3  \ENSURE     this is the output \\             output 2  \STATE $some cool code here$ \STATE $some cool code here$ \STATE $some cool code here$ \STATE $some cool code here$ \end{algorithmic} \end{algorithm}   Unfortunately this code does not fit on one page and I am definitely not able to split it into some subfunctions or so (I already did that as far as possible).  So now I need to split up the algorithm into two pages, but I have no idea how.  The easiest way I can imagine is just to start a new algorithm on the new page, but this time letting the line counter start at line 35 or so instead of 1. But how can I do that?  Please not that there is already a similar question here on this site, but it deals with the package algorithmicx.


I am a new user on Ubuntu. Currently, i am running Ubuntu 14.04 32-bit on my PC. Lately, I've been facing problem in installing any software or package using terminal. I've also tried the following codes to fix this but it failed...    sudo apt-get autoclean   sudo apt-get clean   So this is how it looks like....  sajal@sajal-945GCMX-S2:~$ sudo apt-get install aircrack-ng Reading package lists... Done Building dependency tree        Reading state information... Done You might want to run 'apt-get -f install' to correct these: The following packages have unmet dependencies:  aircrack-ng : Depends: libc6 (>= 2.15) but it is not going to be installed                Depends: libgcrypt11 (>= 1.4.5) but it is not going to be installed                Depends: libsqlite3-0 (>= 3.5.9) but it is not going to be installed                Depends: zlib1g (>= 1:1.1.4) but it is not going to be installed                Depends: wireless-tools but it is not going to be installed                Depends: iw but it is not going to be installed                Recommends: wget but it is not going to be installed  minitube : Depends: libc6 (>= 2.3.6-6~) but it is not going to be installed             Depends: libgcc1 (>= 1:4.1.1) but it is not going to be installed             Depends: libphonon4 (>= 4:4.2.0) but it is not going to be installed             Depends: libqt4-dbus (>= 4:4.5.3) but it is not going to be installed             Depends: libqt4-network (>= 4:4.5.3) but it is not going to be installed             Depends: libqt4-script (>= 4:4.5.3) but it is not going to be installed             Depends: libqt4-sql (>= 4:4.5.3) but it is not going to be installed             Depends: libqtcore4 (>= 4:4.8.0) but it is not going to be installed             Depends: libqtgui4 (>= 4:4.8.0) but it is not going to be installed             Depends: libstdc++6 (>= 4.2.1) but it is not going to be installed             Depends: phonon but it is not going to be installed             Depends: phonon-backend-gstreamer but it is not going to be installed or                      phonon-backend             Depends: dbus-x11 but it is not going to be installed E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution)   Please help me with this........

Whenever I attempt to install aircrack-ng in terminal I get the following error:  Package aircrack-ng is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source However the following packages replace it:   iw  E: Package 'aircrack-ng' has no installation candidate"   I'm new to Ubuntu and so have no idea what to do.


I have two Strings:  String string1 = "Abcdef" String string2 = "Axyz"   I usually code in python, so I'm really new to java. How do I compare these to strings and find out which one would come first in a dictionary(I mean the book not the datastructure)?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


Suppose $f$ is $C^\infty$ on an open set $U$, and $x \in U$. Does $Tf$, the Taylor series centered at $x$, converge in a neighborhood of $x$ to some function(not necessarily the original function $f$)? To be more precise, if $B$ is an open ball centered at $x$ contained in $U$, do we have $Tf$ converges in $B$? I’m not asking about Taylor series not equal to the original function. It’s a totally different question.

The Wikipedia page () proves that $$f(x) = \begin{cases}  \exp(-1/x),  & \mbox{if }x>0 \\ 0, & \mbox{if }x\le0 \end{cases}$$ is a non-analytic smooth function. But I don't understand why the fact that "the Taylor series of $f$ at the origin converges everywhere [where does "everywhere" mean here?] to $0$" implies the Taylor series converges to $0$ when $x>0$? Can someone explain this in greater detail? I guess there should be a gap in my understanding of power series.


So, I was on Sci-Fi.se and noticed I got a badge from MV.SE, but for some hilarious reason, it rendered as the logo for the rebel alliance. I checked other sites, and sure enough badges in your history render the badge image for whichever site they are on. I'm not sure if this could be considered a bug, but I'll raise it anyway so it's documented.

It's so cool that the notification reminds you of the colour of badge you've earned. But I am a little puzzled by the symbols:      Is it feasible to use the symbol from the earned site? At the moment it uses the symbol from the site I happen to be on (as you can see by looking to the left of the dropdown in each case.)


While thinking about primes I just noticed a nice structural relationship between prime-factorization and infinite-dimensional integer vectors and I'm wondering what's known about this. Here is the setup: Let $\mathbb Z_{>0}$ be the set of positive integers and $\mathcal P = \{2, 3, 5, \dots\}$ the set of primes. Any positive integer $n$ can uniquely be written as $$n = 2^{k_{n,2}}3^{k_{n,3}}\dots = \prod_{p \in \mathcal P}p^{k_{n,p}},$$ where only finitely many of the coefficients $k_{n,p}\in\mathbb Z_{\ge 0}$ are nonzero. Actually, if we allow the coefficients to take on negative values then we can write each positive rational number $q \in \mathbb Q_{>0}$ in a similar way: $$q = 2^{k_{q,2}}3^{k_{q,3}}\dots = \prod_{p \in \mathcal P}p^{k_{q,p}},$$ for some $k_{q,p} \in \mathbb Z$ (if we assume that the fraction $q$ is fully simplified, the coefficients are uniquely determined). So we can associate each positive rational number $q$ uniquely with some infinite dimensional vector $$(k_{q,2}, k_{q,3}, \dots).$$ Let's call such a vector a ``prime factorization vector". Note that adding two such vectors corresponds to multiplying their associated positive rational numbers and subtracting them corresponds to dividing their associated positive rational numbers. Of course, vectors can not only be added and subtracted but one can perform all kinds of geometric operations with them. Question: What is known about the relationship between the geometry of the ``prime factorization vectors" introduced above and their associated positive rational numbers? (or about the relationship of prime factorization vectors and their associated positive integers?)

Since every natural number can be represented as $a=2^{n_1}3^{n_2}5^{n_3}7^{n_4}\cdots p_k^{n_k}\cdots$ it makes sense to represent natural numbers by vectors, using the properties of logarithms:  $$\log a=n_1 \log 2+n_2 \log3+n_3 \log5+\cdots$$  This space appears to be similar to the usual Euclidean space if we extend it to an infinite number of dimensions.   If we allow negative coordinates, we can also put all rational numbers in this space. For example, here is part of the plane $(\log 2, \log 3)$:       Does this space have any application in number theory? If it is studied, then how is it usually defined? Are the usual Cartesian vector dot product and the usual Euclidean norm used? Or does it make sense to use a different norm (for example, taxicab norm)?


I want to use my old iPhone 4S as a "software token machine", so I installed and configured all the needed apps in there (and just those ones). It is running iOS v9.3.6.  One app, at its latest version, is refusing to install (SafeNet MobilePass) because my phone doesn't run iOS v10.  Before ditching definitely my plan, is there a way to install an older app version without jailbreaking?  P.S. I only have Linux PCs as it  a PC could be needed.

I want to install the  on my iPhone. On the phone I have iOS 7. When I try to install the App, it tells me it needs at least version 8 of iOS.  I do not want to upgrade my iOS version, especially for the sole purpose of installing an App. However, I do want to use it, it's kind of important.  I searched for a while about how to do this, but I could only find solutions that would work if you installed the App before and it shows up on the "Purchases" page in iTunes or something like that. And this doesn't apply to this case.    How can I install an older version of the App (one that requires "only" iOS 7) without having to upgrade the operating system on my iPhone ?


I've tested many different operating systems on the same machine. Windows 7, 8, 8.1, OS X, Ubuntu, Linux Mint,  Android x86, and Remix OS.   All the Unix-like/based operating systems had in common a near zero shutdown time,  maybe like 3 seconds.   All the Windows versions took considerably longer to shut down,  I am talking about 30 seconds to one minute.   Is there a general reason for this?

I have installed Windows 7 64 bit and Ubuntu 10.10 32 bit on my machine. The partition sizes are 400 GB and 100 GB receptively. I've always wondered how Ubuntu shuts down so fast? It takes only 5 seconds or less whereas Windows 7 takes a lot longer.   Although, I have more programs installed on Windows 7, but still its shut down time was much more than that of Ubuntu during first month of install. It was 10-15 sec approx. I'm not counting the time used for installing updates sometimes, when shutdown is clicked in Windows 7.  What makes Ubuntu shutdown and boot(faster than Windows 7 but not by wide margin) so fast. Is it the file system? will it be other way around if I had swapped partitions spaces(Can't try this now)? Sorry I don't have Computer Science background, so don't know detailed structure and architecture of OS. Any pointers to this will help me cure my curiosity.


By the inverse function theorem, we know that $G'(x)=1/F'(G(x))$, where $G=F^{-1}$. I want to obtain $G''(x)$, but I don't know how to get the derivative of $F'(G(x))$. Any hints?

I know that the derivative of the inverse function of $f(x)$ is $g'(y) = \frac{1}{f'(x)}$ But how to derive the formula for the second derivative of g(y) knowing that $\left[\frac{1}{f(x)}\right]' = -\frac{f'(x)}{(f(x))^2}$ ?  I just started studying this chapter, so please try to be as simple as possible ;-) Thank you.


After reading  and , I'm still afraid of accidentally buying shoddy non stick coating or pan , damaging it, and wasting money. What are some tips or advice to choose the most reliable, durable non stick coating or pan? Are there any keywords or chemicals to look for or avoid? I'm using this pan just on , not inside the oven.

I already have cast iron skillet but I can't find a decent "normal" pan, for eggs and stuff, sometimes steaks, more or less general purpose.   Here are some more features: high quality, durable, non stick, oven safe, dish washer safe, extremely flat surface - not to be higher in the middle, this is very important.  Of course pricier usually means better quality, but is it worth it based on the criteria I'm after? Is it likely to be worth going from pans below $60, to pans from $60 to $130, or to pans over $130?


I'd like to check /etc/passwd      $ cat -n /etc/passwd          1  ##          2  # User Database          3  #           4  # Note that this file is consulted directly only when the system is running          5  # in single-user mode.  At other times this information is provided by          6  # Open Directory.          7  #          8  # See the opendirectoryd(8) man page for additional information about          9  # Open Directory.         10  ##         11  nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false   As we see, the firt 10 lines are commented, the result I desire some command like      $ cat -n [11:] /etc/passwd      nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false           root:*:0:0:System Administrator:/var/root:/bin/sh      daemon:*:1:1:System Services:/var/root:/usr/bin/false      _uucp:*:4:4:Unix to Unix Copy Protocol:/var/spool/uucp:/usr/sbin/uucico   How to accomplish it?

I'd like to know if there is a way that I could cat file like php.ini and remove all lines starting with ;  For example, if the file contained this:  ;   - Show all errors, except for notices ; ;error_reporting = E_ALL & ~E_NOTICE ; ;   - Show only errors ; ;error_reporting = E_COMPILE_ERROR|E_ERROR|E_CORE_ERROR ; ;   - Show all errors except for notices ; error_reporting  =  E_ALL & ~E_NOTICE   and I ran the correct command cat | {remove comments command}, then I would end up with:  error_reporting  =  E_ALL & ~E_NOTICE   Note - I assumed that cat would be the best way to do this but I'm actually fine with the answer using another utility like awk, sed, egrep, etc.


Is it possible to install AdBlock Plus, uBlock or something equivalent via terminal?   I am using Ubuntu 18.10 and want to install adblocking extension for Firefox 64. I could easily do that by launching Firefox and a few mouse clicks, but I need to repeat this operation on quite many computers and am seeking a way to automate it.

I want to improve my unattended script adding some Firefox addon, however I cant find the way,  Can someone help to find out how to?   Example: (Want to install adblockPlus plugin and set a new default webpage)  wget https://addons.mozilla.org/firefox/downloads/latest/1865/addon-1865-latest.xpi firefox -silent -install-global-extension addon-1865-latest.xpi -setDefaultBrowser www.google.es   Thanks in advance.


I am getting an undefined control sequence when using \col in a \foreach loop.  ! Undefined control sequence. \pgfkeyscurrentkey ->\col     \documentclass[tikz, dvipsnames]{standalone} \usepackage{mathtools} \usepackage{pgfplots} \pgfplotsset{compat = 1.8} \begin{document} \begin{tikzpicture}   \begin{axis}[     samples = 500,     no marks,     xlabel = $\scriptstyle x$,     ylabel = $\scriptstyle y$     ]     \foreach \u/\col in {1/red, 2/blue, 3/OliveGreen}{       \addplot+[\col, domain = -4:4, variable = \v]       ({(exp(\u) + exp(-\u)) / 2 * cos(deg(v))},       {(exp(\u) - exp(-\u)) / 2 * sin(deg(v))});     }   \end{axis} \end{tikzpicture} \end{document}   And also, how can I use \addlegendentry for the plot with a loop?

I like TikZ's capability to traverse multiple variables separated by a slash in the foreach (as in the example below). I am looking for something equivalent in PGFplots? I saw in the documentation that say you can't nest the foreach in PGFplots as you can in TikZ, but that only make this kind of feature more important.    Two other small issues:    I like the \x notation so that is why I am using \pgfplotsforeachungrouped. Is there a reason why I should be using pgfplotsinvokeforeach instead?  Also, what is the correct syntax to be able to use a variable to define the list instead of having the actual list in the code. In the following I'd like to be able to reference \ListWithLabels in the foreach.    \documentclass{minimal} \usepackage{pgfplots}  \newcommand*{\ListWithLabels}{-2/a, -1/b, 1/c, 2/d} \newcommand*{\ListWithoutLabels}{-2, -1, 1, 2}  \begin{document} \begin{tikzpicture} \draw [->][gray, thin](-3,0) -- (3,0) node[blue, right] {$x$};  \draw [->][gray, thin](0,-3) -- (0,3) node[blue, above] {$y$};  %\foreach \x/\l in \ListWithLabels {  % works \foreach \x/\l in {-2/a, -1/b, 1/c, 2/d} {     \draw [thick, red]         (\x,-2pt) -- (\x,2pt)         node [red, above] {\l}; } \end{tikzpicture}  \begin{tikzpicture} \begin{axis}[     minor tick num=0, axis y line=center, axis x line=middle,      xmin=-3, xmax=3, ymin=-3, ymax=3, xlabel=$x$, ylabel=$y$,     xtick={0},  xticklabels={}     ]  %\pgfplotsinvokeforeach{-2, -1, 1, 2}{             % works %   \addplot [mark=none,color=red, thin, samples=2] %       coordinates{(#1,-0.05) (#1,0.05) }; %}  %\pgfplotsforeachungrouped \x in {\ListWithoutLabels}{  % does not work \pgfplotsforeachungrouped \x in {-2, -1, 1, 2}{    % works     \addplot [mark=none,color=red, thick, samples=2]%         coordinates{ (\x,-0.08) (\x,0.08) }; }   %\pgfplotsforeachungrouped \x/\l in {-2/a, -1/b, 1/c, 2/d}{ % does not work %   \addplot [mark=none,color=red, thin, samples=2]% %       coordinates{ (\x,-0.05) (\x,0.05) } %        node [red, below] {\l}; %}  \end{axis} \end{tikzpicture} \end{document}   Update: I saw  post which explains that the macro in TikZ needs to be not be sourrouned by {}. But that does not work for the PGF commands.  Here is another related post on


I am working on this demo. How can I get the value of $(this) or even checked element when dynamically adding some checkboxes to a hidden content like bootstrap modal?    $('#exampleModal').on('show.bs.modal', function(e) {    for (var i = 0; i < 3; i++) {     $('.modal-body').append('<input type="radio" name="addOD" value="item' + i + '" />');   } })  $('input:radio[name=addOD]').on('click', function() {   console.log($(this).val());   var val = $('input:radio[name=lenseopttype]:checked').val();   console.log(val); }); <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">      <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">   Launch demo modal </button>

Modal title
         <button type="button" class="close" data-dismiss="modal" aria-label="Close">           &times;         </button>

         <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>         <button type="button" class="btn btn-primary">Save changes</button>

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


How do I prove that the sets $x = \{y\}, y = \{z\} \text{ and } z =\{x\}$ can’t exist with the axiom of regulation/foundation in ZFC?  I’m having the damnest time trying to prove this since the sets are not assumed to be transitive sets.    I’ve tried using powersets and union operations but these have brought me no luck thus far. I’m beginning to wonder whether or not this is possible to prove.

No other axioms. There are $3$ sets such that:  $x\in y$; $y\in z$; $z\in x$;  These sets violate foundation.    I don't get it... For $x$, $z\in x$, so z must be the $\epsilon$-minimal member but the only member of $z$ is $y$.  $z \cap x = \{y\}\cap\{z\} = \emptyset$. None of the members of $z$ (only $y$) are members of $x$ so doesn't that satisfy definition of Foundation?  Please help this noob, thanks


How can I make this work on macOS terminal?  sed -i 's/config.action_mailer.default_url_options =.*$/config.action_mailer.default_url_options = {:host => "localhost:3000"}/g' config/environments/development.rb sed: 1: "config/environments/dev ...": command c expects \ followed by text

I'm writing shell scripts for my server, which is a shared hosting running FreeBSD. I also want to be able to test them locally, on my PC running Linux. Hence, I'm trying to write them in a portable way, but with sed I see no way to do that.  Part of my website uses generated static HTML files, and this sed line inserts correct DOCTYPE after each regeneration:  sed -i '1s/^/<!DOCTYPE html> \n/' ${file_name.html}   It works with GNU sed on Linux, but FreeBSD sed expects the first argument after -i option to be extension for backup copy. This is how it would look like:  sed -i '' '1s/^/<!DOCTYPE html> \n/' ${file_name.html}   However, GNU sed in turn expects the expression to follow immediately after -i. (It also requires fixes with newline handling, but that's already answered in )  Of course I can include this change in my server copy of the script, but that would mess i.e. my use of VCS for versioning. Is there a way to achieve this with sed in a fully portable way?


My friend brought me a Xtreamer Q mobile phone with broken screen, clockworkmode is working, but USB debugging mode is disabled, I found some posts about how to enable it from adb i tried them and none of them worked. here :   and from this tutorial i learnt how to edit build.prop file.   the commands i have used are: adb pull, adb remount, adb push. While i was under clockworkmode i mounted system and i pulled build.prop then i added this line to it persist.service.adb.enable=1, used remount then pushed the file after that reboot, but i couldn't find the device in adb when it have booted normaly. Next i tried to set adb_enabled to 1 in /data/data/com.android.providers.settings/databases/settings.db by following some steps from here  ttp://forum.xda-developers.com/showthread.php?t=774507 and it also didn't worked "The device was not listed". Also i have tried this zip file from clockworkmode it didn't work too...    My phone do not support USB org cable  my files after editing:

The screen of my phone is physically broken, so it doesn't display anything, but the touch aspect does seem to be working, as I can unlock my phone, and get haptic feedback.  Before I go to get it replaced, I'd like to back up some personal data from the built-in memory to the SD card. I'm fairly certain that if I can get adb to recognize the device, then I can use  to see where I am touching the screen and do what I need to do. Problem is, when I plug it in, it's not recognized, while my emulator is.  I suspect that I might not have USB debugging enabled, which I think is necessary for adb to work. If this is the case, can someone give me screenshots of their Droid X (running 2.3.X) going from the home screen, through all the menus, to activating debug mode? Hopefully I can do it by dead reckoning and adb from there.  Edit: I haven't changed anything about the ROM or launcher; it's all stock.


I want to execute a for loop, create new variables with values that vary with the loop iteration, and refer to the new variables within the loop or later in the shell script. Can't figure out how to refer to the new variables because of the way they are being evaluated. A simple example of what I need but does not work -  for i in {1..4}  do  my${i}var="./path_to/my${i}file"  echo $my${i}var  done

Is there a way to create bash variables and assign them values via a loop?  Something along the lines of:  #!/bin/bash  c=0 for file in $( ls ); do     var"$c"="$file";     let c=$c+1; done   EDIT: Thank you to @Costas and @mdpc for pointing out this would be a poor alternative to a list; the question is theoretical only.


I can include pdf documents as they are in the common pdf document, but I cannot do it with common page numbering in the top right corner.  The following fancyhdr does not have any effect on have page numbering on the top of pdf documents.  It would be great if the page numbering would be on top of pdf documents because they are just articles where plenty of space there.  Code proposed based on the thread  about base document  \documentclass{article} \usepackage{pdfpages}  % https://tex.stackexchange.com/q/56316/13173 \usepackage{fancyhdr} \pagestyle{fancy} \fancyhf{} \fancyhead[R]{\thepage}  \renewcommand{\headrulewidth}{0pt} % Werner, remove top margin border  \begin{document} \includepdf[pagecommand=\thispagestyle{plain}]{sforzo.pdf} \includepdf[pagecommand=\thispagestyle{plain}]{testData.pdf} \includepdf[pagecommand=\thispagestyle{plain}]{sforzo.pdf} \end{document}   Fig. 1 Output with pagestyle{plain} where you see that the approach decreases the size of the page,  Fig. 2 Output with pagestyle{fancy} and renewcommand     The fancy pagestyle looks better, but I would still like to maintain  the page size.  The following Werner's proposal stays in loop and never ends, so I cannot get any output with it  \let\oldincludepdf\includepdf \renewcommand{\includepdf}[2][]{\oldincludepdf[pagecommand=\thispagestyle{fancy},#1]{#2}}   Werner's correct answer  \usepackage{letltxmacro} \LetLtxMacro\oldincludepdf\includepdf \renewcommand{\includepdf}[2][]{\oldincludepdf[pagecommand={\thispagestyle{fancy}},#1]{#2}}   Output without decreasing the page size    TeXLive 2016 OS: Debian 8.5

I'm writing a report, in LaTeX. And I need to include, as appendices, other latex documents I have written. I am currently doing this using pdfpages and it works. However, the inserted PDF has no page numbers and it overlays my base documents page numbering, resulting in no page numbers on the PDF pages. My questions:   How to solve the above problem. Is there a better way to do this.


Just upgraded from 7.18 to 7.23 and selected to upgrade all modules and all I got is neverending 'Preparing to update your site' on Installing updates page on /authorize.php?batch=1&op=start&id=40  So what if I refresh page or something will the site crash or something?  UPDATE: It just crashed after like 20 minutes of nothing and I got this error:  An AJAX HTTP error occurred. HTTP Result Code: 500 Debugging information follows. Path: /authorize.php?batch=1&id=40&op=do StatusText: Service unavailable (with message) ResponseText: PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: DELETE FROM {queue} WHERE (item_id = :db_condition_placeholder_0) ; Array ( [:db_condition_placeholder_0] => 8656 ) in SystemQueue->deleteItem() (line 273 of /modules/system/system.queue.inc).Uncaught exception thrown in shutdown function.PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: UPDATE {batch} SET batch=:db_update_placeholder_0 WHERE (bid = :db_condition_placeholder_0) ; Array ( [:db_update_placeholder_0] =&gt; a:12:{s:4:&quot;sets&quot;;a:1:{i:0;a:15:{s:7:&quot;sandbox&quot;;a:0:{}s:7:&quot;results&quot;;a:2:{s:3:&quot;log&quot;;a:1:{s:5:&quot;views&quot;;a:1:{i:0;a:2:{s:7:&quot;message&quot;;s:57:&quot;Installed &lt;em class=&quot;placeholder&quot;&gt;views&lt;/em&gt; successfully&quot;;s:7:&quot;success&quot;;b:1;}}}s:5:&quot;tasks&quot;;a:0:{}}s:7:&quot;success&quot;;b:0;s:5:&quot;start&quot;;d:1377856599.71076107025146484375;s:7:&quot;elapsed&quot;;i:0;s:5:&quot;title&quot;;s:18:&quot;Installing updates&quot;;s:12:&quot;init_message&quot;;s:40:&quot;Preparing to update your site&lt;br/&gt;&amp;nbsp;&quot;;s:8:&quot;finished&quot;;s:38:&quot;update_authorize_update_batch_finished&quot;;s:4:&quot;file&quot;;s:35:&quot;modules/update/update.authorize.inc&quot;;s:16:&quot;progress_message&quot;;s:29:&quot;Completed @current of @total.&quot;;s:13:&quot;error_message&quot;;s:22:&quot;An error has occurred.&quot;;s:3:&quot;css&quot;;a:0:{}s:5:&quot;total&quot;;i:12;s:5:&quot;count&quot;;i:12;s:5:&quot;queue&quot;;a:2:{s:4:&quot;name&quot;;s:17:&quot;drupal_batch:40:0&quot;;s:5:&quot;class&quot;;s:10:&quot;BatchQueue&quot;;}}}s:16:&quot;has_form_submits&quot;;b:0;s:11:&quot;current_set&quot;;i:0;s:11:&quot;progressive&quot;;b:1;s:3:&quot;url&quot;;s:36:&quot;/authorize.php?batch=1&quot;;s:11:&quot;url_options&quot;;a:0:{}s:10:&quot;source_url&quot;;s:0:&quot;&quot;;s:8:&quot;redirect&quot;;s:28:&quot;/authorize.php&quot;;s:5:&quot;theme&quot;;s:5:&quot;seven&quot;;s:17:&quot;redirect_callback&quot;;s:11:&quot;drupal_goto&quot;;s:2:&quot;id&quot;;s:2:&quot;40&quot;;s:13:&quot;error_message&quot;;s:110:&quot;Please continue to &lt;a href=&quot;/authorize.php?batch=1&amp;amp;id=40&amp;amp;op=finished&quot;&gt;the error page&lt;/a&gt;&quot;;} [:db_condition_placeholder_0] =&gt; 40 ) in _batch_shutdown() (line 537 of /includes/batch.inc).

Recently I started getting an error every time I try and add a content no matter what type.  This is the error that shows up in the browser:     Additional uncaught exception thrown while handling exception.        Original   PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT COUNT(cid) FROM {comment} WHERE status = :status; Array ( [:status] => 0 ) in comment_count_unpublished() (line 313 of /Applications/MAMP/htdocs/modules/comment/comment.module).        Additional      PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: INSERT INTO {watchdog} (uid, type, message, variables, severity, link, location, referer, hostname, timestamp) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4, :db_insert_placeholder_5, :db_insert_placeholder_6, :db_insert_placeholder_7, :db_insert_placeholder_8, :db_insert_placeholder_9); Array ( [:db_insert_placeholder_0] => 1 [:db_insert_placeholder_1] => php [:db_insert_placeholder_2] => %type: !message in %function (line %line of %file). [:db_insert_placeholder_3] => a:6:{s:5:"%type";s:12:"PDOException";s:8:"!message";s:154:"SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: SELECT COUNT(cid) FROM {comment} WHERE status = :status; Array ( [:status] =&gt; 0 ) ";s:9:"%function";s:27:"comment_count_unpublished()";s:5:"%file";s:56:"/Applications/MAMP/htdocs/modules/comment/comment.module";s:5:"%line";i:313;s:14:"severity_level";i:3;} [:db_insert_placeholder_4] => 3 [:db_insert_placeholder_5] => [:db_insert_placeholder_6] => ; [:db_insert_placeholder_7] =>  [:db_insert_placeholder_8] => 127.0.0.1 [:db_insert_placeholder_9] => 1338336955 ) in dblog_watchdog() (line 154 of /Applications/MAMP/htdocs/modules/dblog/dblog.module).   I also get the following error in my php error file:     PHP Fatal error:  Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2006 MySQL server has gone away' in /Applications/MAMP/htdocs/includes/database/database.inc:2136        Stack trace:   0 /Applications/MAMP/htdocs/includes/database/database.inc(2136): PDOStatement->execute(Array)   1 /Applications/MAMP/htdocs/includes/database/database.inc(664): DatabaseStatementBase->execute(Array, Array)   2 /Applications/MAMP/htdocs/includes/database/database.inc(2315): DatabaseConnection->query('SELECT expire, ...', Array, Array)   3 /Applications/MAMP/htdocs/includes/lock.inc(167): db_query('SELECT expire, ...', Array)   4 /Applications/MAMP/htdocs/includes/lock.inc(146): lock_may_be_available('theme_registry:...')   5 /Applications/MAMP/htdocs/includes/theme.inc(447): lock_acquire('theme_registry:...')   6 /Applications/MAMP/htdocs/includes/bootstrap.inc(427): ThemeRegistry->set(Array)   7 [internal function]: DrupalCacheArray->__destruct()   8 {main}         thrown in /Applications/MAMP/htdocs/includes/database/database.inc on line 2136   I am having a little trouble deciphering these error messages. Could anyone help me understand what's going on here?


First of all, my apologies if it looks like a duple of , but since this question dates from more than 2 years, I thought it could be worth mentioning here.  I have this number "1" since last week:    And when I click on it, I go to this page:    First I thought it will disapear by itself, but since it still there, I thought it is probably a bug that I might report.    EDIT: The answer of the  question says:     This indicator is shown only to moderators and users who've gained access to the moderator tools.   As I didn't reach the requested 2k rep points, I did not have access to the moderator tools.  You can see I have not access to moderator tools:

Since a , I see more than I should:    I see no reason to see 134 posts are awaiting review, when there is literally nothing I can do about them. I think it is a bug, because notification is meant as something that will make me act. When I know I usually can't, obviously I will start to ignore it.  If it's not a bug, please remove bug tag and explain how it is supposed to be useful, or how can I switch to only seeing notifications about things I can act on.  Note that apaprently there are no flags for me, neither. I see only stats, migrated, close, delete, there, as if there was no flags waiting:    If you expect us to click on it every few minutes  just to see personalized numbers next to queues, why don't you simply query for personalized numbers every few minutes and cache them for us? It should cost you similar, in database usage, and will save us a lot of clicking and frustration.  If all this number means is "there might be reviews, or not" or "for sure there are none"  it would be simpler just to hide "review" link in the second case. We don't need two links with the same function next to each other, thank you, one is enough, and meaningless numbers are only irritating.


What is the difference between primary and secondary coverage on a travel policy for someone who does not have primary health care? Is there any difference whatsoever (in terms of claims and/or payment to the health facility, or anything else)?

What is the difference between primary coverage and secondary coverage on a travel insurance policy? Which is recommended for short-term travelers?


Could we say that the set $\{1,x,x^2,x^3,x^4,\cdots\}$ is a basis of the vector space of polynomials ? Note that, for example the set $\{e_1,e_2,e_3,\cdots\}$ such that $e_n=(\delta_{n,k})_{k \in \mathbb{N^*}} $ is not a basis for the vector space $\mathbb{R}^\infty$, even though the set $\{e_1,e_2,e_3,\cdots,e_n\}$ is a basis of $\mathbb{R}^n$ for any $n \in \mathbb{N}^*$.

I don't understand how to find a basis for a polynomial vector space. Can someone help me with an example?


I use Windows 10 File Explorer and I want to search in indexed locations include compressed archives (zip). In File Explorer folder settings there is only "when searching non-indexed locations" > "include compressed archives"... Please, can you help me how to do it? Thanks, Jiri

In File Explorer, I can enter search terms in the upper-right search box to search the current folder and all subfolders. I can also navigate the folder tree of zip archives like any other folders. However, if I want my searches to include files in a zip archive I have to navigate to the specific folder in the zip archive where the file is located. My searches never include files in zip archives if I'm not in the archive, and when I am in the archive my searches don't include files within the archive's subfolders.  Is there a way for my searches to include zip archive subfolders?


I've seen servers do this, why can't I, and how?

I've seen multiple servers where you can connect from any (recent) major version. (Example, 1.9, 1.8 OR 1.7) And they all seem to be able to do it. Alas, a simple google search did not fix the problem. Any ideas? Thanks guys.  (PS: The Minecraft server is running on the latest Spigot for 1.10 as of 6/27/16)


How do I show the left hand side bottom menu which is present right after Shift-A added object Torus once I've closed it? It should be labelled Add Torus in this case.

When you first add a cylinder, you have the option to change the number of vertices, etc, but once you do anything else in blender, it seems you no longer can edit those parameters.   Is there a setting anywhere or an add-on that allows these parameters to be edited later on? If not, how easy would such an addon/feature be to create for anyone reading this?


Thanks in advance for help.  You can better understand problem by observing following code:  Save

link 1

  $('.save-btn').click(function() {     $('ul').append('
link 2
')     return false; })  $('.newLink').click(function() {     $(this).addClass('active') // ".newLink" is not adding "active class"    return false; });   I want to simply add active class to link having class name "myLink" by click event.  I know the problem is "click event", appended anchor tag on window.load is adding active class perfectly.    Image Description: Link "Abc Xyz" should add "active class" on click (active link will have blue background according to my image)

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I have been searching for a definitive answer for the max load for a LAMP server. I have 4 dual core processors, so does this mean that the max load is 4.0, or is it based on cores - 8.0?  The server has 4 CPUs, Intel(R) Xeon(R) CPU 5160 @ 3.00GHz. The distro is CLOUDLINUX 6.5 (built on CentOS).

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


I put 5 pounds of cold chicken in my crock pot at about 2 am. I had put lemon pepper and salt in with it. I got up this morning about 9:30 or 10 and discovered that it seems my slow cooker broke right after I put it on last night.  It smells fine and it is cold. I drained the water and washed it. Then put it in regular oven at 350. Is it safe to eat, if it smells and tastes ok?

If I left food out of the refrigerator for some period of time, is it still safe? If I left it out too long, can I salvage it by cooking it more?


I associated plain text files with vim with right click - properties -   open with, and it works fine within nautilus, however when I click or   right click - open a text file at the desktop, vim is not called and there is either not a error message, and no other editors (like gedit)  is opened. However, right click - open with other application - choose vim works fine. Logs from journalctl /usr/bin/gnome-shell: gnome-shell[1267]: Could not create transient scope for PID 8605:        GDBus.Error:org.freedesktop.DBus.Error.UnixProcessIdUnknown: Process     with ID 8605 does not exist.                                                                                gnome-shell[1267]: ../clutter/clutter/clutter-actor.c:10558: The         clutter_actor_set_allocation() function can only be called from within   the implementation of the ClutterActor::allocate() virtual function.      The vim version is 8.1. (runs at the terminal and vim-gtk not installed) It works normal before changing the default open-with settings. However, I just tried to set the associate program back to gedit, but surprisingly files on the desktop still not able to open with left click and right click - open, even I set back to gedit.

I created a shortcut to a text file called "imp" on right-clicking it from the default file manager everything works well. But on clicking it on the desktop I get this  Any Idea why?


If you want to proof $\binom{n}{k}$ + $\binom{n}{k+1}$ = $\binom{n+1}{k+1}$, you have to differentiate between 5 cases. Why 5 cases and where do they come from ? It should have something to do with  $\binom{N}{k}$ = $\frac{n!}{k!(n-k)!}$ .

I'm trying to prove that ${n \choose r}$ is equal to ${{n-1} \choose {r-1}}+{{n-1} \choose r}$ when $1\leq r\leq n$.  I suppose I could use the counting rules in probability, perhaps combination= ${{n} \choose {r}}=\frac{n!}{r!(n-r!)}$.  I want to see an actual proof behind this equation.  Does anyone have any ideas?


In C++, I have some troubles understanding the difference between these 3 ways where const is used :  int get() const {return x;}         const int& get() {return x;}       const int& get() const {return x;}    I'd like to have a clear explanation with examples to help me understand the differences.

What is the difference between const and readonly in C#?   When would you use one over the other?


From practical point of view we know the width of photons is proportional to wavelengths (experiments for light going through tiny holes: it starts with a specific size of the holes, etc). And nobody talks in high-math language for this, though yes, like rings of smoke we understand that when hole size is small enough "effects" depend of materials, objects, etc, because of field density, probability, etc.  What about the photon length, what is it from the similar experiments (were there such experiments)? You are the only person I saw who mentioned that length of photon might be constant.  Any Ideas on what it is? Thank you! P.S. As to comments in quant-equations, packets, etc. - I see it as lack of our math, not as an explanation.

When light is emitted (or received) one photon at a time, what is the duration of each pulse? Is it related to the wavelength? Is it possible to create a laser pulse (or a radio wave) shorter than the wavelength (period of oscillations)?


What are the polygon count standards for game assets? I'm thinking about games that are lower poly but aim for the best graphics possible, I'm thinking like L4D / L4D2 or Insurgency level of detail.

Recently, I am trying to create 3D models for my own game project. However, when I do some researches on game models, I come up with the term - game-ready models and I could not find any clear definition online. Could anyone tell me about what exactly is game-ready models and how to know if my 3D models (created by Blender mainly) is suitable for games.  From what I know by far, quad topology is preferred in Blender. However, for most of the game engine, triangle topology is preferred (Please correct me if I am wrong). Does it mean I have to manually change the models in Blender from quad topology to triangle topology before importing to the game engine?  Thanks for any helps.


Sophos has detected the following: C2/Generic-B detected in C:\Windows\System32\svchost.exe How do I get rid of this? Many thanks in advance!

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


Perhaps it's not technically a privilege, but one would expect the  (awarded at 200 rep) to be listed along with all the other awards mentioned on the .

Currently, the first time a user on the Stack Exchange network reaches 200 reputation, they get an extra 100 rep on that account and all their  accounts. I believe this should be documented as a privilege at 200 rep (along with the lessening of adverts).


However, I have not met with any issues yet, but sometimes it might happen when we are using two completely independent frameworks, which might have two classes of common name. So, to resolve compiler ambiguity, how to specify that this class refers to this framework and this belongs to that framework. Like in Java, we can specify fully qualified class name like java.pkg.Class. I know that all the classes are preceded by some characters those might identify the framework (like NS, SK, MK, etc.), but it still can happen. Is there any mechanism that I am missing? I have never heard of fully qualified class name in Objective C.

Objective-C has no namespaces; it's much like C, everything is within one global namespace. Common practice is to prefix classes with initials, e.g. if you are working at IBM, you could prefix them with "IBM"; if you work for Microsoft, you could use "MS"; and so on. Sometimes the initials refer to the project, e.g. Adium prefixes classes with "AI" (as there is no company behind it of that you could take the initials). Apple prefixes classes with NS and says this prefix is reserved for Apple only. So far so well. But appending 2 to 4 letters to a class name in front is a very, very limited namespace. E.g. MS or AI could have an entirely different meanings (AI could be Artificial Intelligence for example) and some other developer might decide to use them and create an equally named class. Bang, namespace collision. Okay, if this is a collision between one of your own classes and one of an external framework you are using, you can easily change the naming of your class, no big deal. But what if you use two external frameworks, both frameworks that you don't have the source to and that you can't change? Your application links with both of them and you get name conflicts. How would you go about solving these? What is the best way to work around them in such a way that you can still use both classes? In C you can work around these by not linking directly to the library, instead you load the library at runtime, using dlopen(), then find the symbol you are looking for using dlsym() and assign it to a global symbol (that you can name any way you like) and then access it through this global symbol. E.g. if you have a conflict because some C library has a function named open(), you could define a variable named myOpen and have it point to the open() function of the library, thus when you want to use the system open(), you just use open() and when you want to use the other one, you access it via the myOpen identifier. Is something similar possible in Objective-C and if not, is there any other clever, tricky solution you can use resolve namespace conflicts? Any ideas?  Update: Just to clarify this: answers that suggest how to avoid namespace collisions in advance or how to create a better namespace are certainly welcome; however, I will not accept them as the answer since they don't solve my problem. I have two libraries and their class names collide. I can't change them; I don't have the source of either one. The collision is already there and tips on how it could have been avoided in advance won't help anymore. I can forward them to the developers of these frameworks and hope they choose a better namespace in the future, but for the time being I'm searching a solution to work with the frameworks right now within a single application. Any solutions to make this possible?


select * from customer select * from TableName Why can't we use the '*' symbol in soql as in SQL

I got the answer "Salesforce is a multitenent environment and performing such query including wildcard can affect other tenants" but I do not understand how other tenants will be affected by this Query.Most of the limitations in salesforce like limit in soql queries and No. of Dml in one context is limited and the reason is shared Environment(Multitenant).I actually want to know how one tenant can affect other tenant ?


Exercise Let $A, B \in M_{m\times m}(\mathbb{C})$ complex matrix such that $AB = BA$. Show that $e^{A+B} = e^{A}  e^{B} = e^{B}e^{A}$. Proof: As we know, $e^{A+B} = \sum_{n=0}^{\infty} \frac{(A+B)^{n}}{n!}$ an the goal is show that this expression is equal to $\sum_{n=0}^{\infty} \sum_{m=0}^{\infty} \frac{A^{n}B^{m}}{n!\cdot m!}$ so I proceed as follows: $$\begin{align}   e^{A+B} &= \sum_{n=0}^{\infty} \frac{(A+B)^{n}}{n!} \\ &= \sum_{n=0}^{\infty} \frac{\sum_{i=0}^{n} {n\choose i}A^{n-i}B^{i}}{n!} \\ &= \sum_{n=0}^{\infty} \frac{\sum_{i=0}^{n} \frac{n!}{i!(n-1)!}A^{n-i}B^{i}}{n!} \\ &= \sum_{n=0}^{\infty} \sum_{i=0}^{n} \frac{A^{n-i}}{(n-i)!}\cdot \frac{B^{i}}{i!}   \end{align}$$ And I got stuck at this point of the demonstration. As you can see, I really feel closer to the result, but I don't know how to manipulate the last equation. I appreciate any ideas :)

If $A$ and $B$ are $n\times n$ matrices such that $AB = BA$ (that is, $A$ and $B$ commute), show that      $$ e^{A+B}=e^A e^B$$    Note that $A$ and $B$ do NOT have to be diagonalizable.


While reading about pair production, I came across the concept of negative energy. What is negative energy exactly? And can there be negative mass corresponding to this energy?

When Dirac found his equation for the electron $(-i\gamma^\mu\partial_\mu+m)\psi=0$ he famously discovered that it had negative energy solutions. In order to solve the problem of the stability of the ground state of the electron he invoked Pauli's exclusion principle and postulated that negative energy states well already filled by a "sea" of electrons. This allowed him to predict the positron, viewed as a hole in the sea.  This interpretation was ultimately discarded owing to its inapplicability to bosons and difficulties with explaining the invisibility of the infinite charge of the sea.  According to my understanding, the modern argument goes something like this. There is a discrete symmetry of the lagrangian called charge conjugation $\psi \rightarrow \psi^c$ which allows the negative energy solutions to be interpreted as positive energy solutions for a second mode of excitation of the electron field with opposite charge, called positrons. The decay of electrons to positrons is then suppressed by the $U(1)$ gauge symmetry of the lagrangian forcing conservation of electrical charge.  According to this interpretation What Dirac would have missed was the lagrangian formalism. Is this historically and physically correct?


I import an .obj model fine (a church) and a .png texture created in Mesh lab. However when I apply the image as a texture, nothing happens. I switch to 'material' mode, but still nothing. I am wondering if I have to use a UV map, but I thought that the texture .png would be applied automatically given that it was exported with the Mesh from Mesh lab.

I am creating a model of a glass and I would like to put a drawing on it (a png picture).  I know how to do it using Blender Render, but not with Cycles Render. Help :)


So I'm trying to create a generic deck of cards that I can populate with any type of card, here's is the code for the Deck class and the Card class:  Deck.h:  #pragma once #include "Card.h" class Deck { private:     Card* m_current_card;     Card* m_first_card; public:     Deck();     template<class T>        void populate(T*);     void next(); };   Deck.cpp:  #include "Deck.h" #include <iostream> Deck::Deck() {     m_first_card = nullptr;     m_current_card = m_first_card; } template<class T> void Deck::populate(T* card) {     int counter = 0;     for (int i = 0; i < 4; i++) {         for (int j = 0; j < 13; j++) {             card = new T(i,j);             if (counter > 0) {                 m_current_card->next_card(card);                 next();             }             else {                 m_first_card = card;                 m_current_card = m_first_card;             }             counter++;         }     } } void Deck::next(){     m_current_card = m_current_card->get_next(); }   Card.h:  #pragma once class Card{ private:     int m_suit;     int m_face;     Card* m_next_card; public:     Card(int,int);     void next_card(Card*);     Card* get_next(); };   Card.cpp:  #include "Card.h" #include <iostream> Card::Card(int suit,int face){     m_suit = suit;     m_face = face;     m_next_card = nullptr; } void Card::next_card(Card* card){     m_next_card = card; } Card* Card::get_next(){     return m_next_card; }   when I try to execute my code in main for example like the following:  #include "Deck.h"  int main() { Card* card = nullptr; Deck thedeck; thedeck.populate(card); }   it gives me this error :  >main.obj : error LNK2019: unresolved external symbol "public: void __thiscall Deck::populate<class Card>(class Card *)" (??$populate@VCard@@@Deck@@QAEXPAVCard@@@Z) referenced in function _main   What am I doing wrong here, am I using templates incorrectly?

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


I try to use this command in command block in 1.7.9 version but it isn't working, why?  /give @p yellow_flower 1 0 {display:{Name:"Mleczyk",Lore:[Mlecz za AlphaTesty, -Sid Leniwiec]}},{ench:[{id:34,lvl:1]}

Often, when making a command block contraption, you need to set an entity's data tag. These tags can sometimes be very long, with many layers of nested curly and square brackets. For example, this is the command to summon a villager with a single custom trade:  /summon Villager ~ ~ ~ {Profession:3,Career:2,Offers:{Recipes:[{buy:{id:minecraft:diamond,Count:6b}},sell:{id:minecraft:diamond_hoe,tag:{ench:[{id:16s,lvl:10s}]}]}}   The single-line command block interface of Minecraft makes it incredibly difficult to find and fix errors, especially when it comes to mismatched brackets. In fact, for illustration purposes, I put an error in the above command.  What techniques can I use to find and fix unbalanced square or curly brackets when writing long and complicated data tags?


By calculation, I guess this limit is 0, but I don't know how to prove it. Please give me some hints, thank you.  (Uniform convergence is useless here since the integrand is not uniform convergent on $[0,\pi]$, is it?)

I'm stumped at the last part of this problem. Could anyone advise, please? Thank you.  Here is  my  proof.   Define  $f: \mathbb{R} \to \mathbb{R}$ by $$ f(x) = \left\{\begin{aligned} &\frac{\sin nx}{nx}&&, x \neq0 \\ &1 &&, x=0 \end{aligned} \right.$$   Hence, $$f(x) = \sum^{\infty}_{k=0}(-1)^k\frac{(nx)^{2k}}{(2k+1)!} , \forall x \in \mathbb{R} \mbox{ and } f \in {\mathscr R[0,b]}.$$  $$\int^{b}_{0} \frac{\sin nx}{nx}dx = \int^{b}_{0}f(x)dx=\sum^{\infty}_{k=0}\int^{b}_{0}(-1)^k\frac{(nx)^{2k}}{(2k+1)!}dx= \sum^{\infty}_{n=0}(-1)^k\frac{(n)^{2k}b^{2k+1}}{(2k+1)(2k+1)!}$$  $$\lim_{n \to \infty} \sum^{\infty}_{k=0}(-1)^k\frac{(n)^{2k}b^{2k+1}}{(2k+1)(2k+1)!}=  ?$$


I want to install windows 10 in my Old Laptop, Processor is Core 2 Due (T6500 @ 2.10 GHz, 2M Cache, 800 MHz FSB), RAM 4 GB, Storage 300 GB. is it possible? how much speed or slow?

I am looking to upgrade my system to Windows 10 RTM, but I'm afraid of losing performance.  I researched on the site but found details (maybe I have not sought duty) on the hardware minimum.  What are the minimum and recommended requirements for running Windows 10 RTM?


This might seem like a stupid question, but my instructor could not give a straightforward answer.  If a body is kept in contact with a completely vertical surface i.e. right angle to the ground, and only force on the body is the force of gravity straight downwards.Then normal force on the body would be zero. We know that frictional force on the body is proportional to the normal force, hence it is also zero. Does that mean there is no friction whatsoever, despite the surface rubbing?

Let's say that there is a book sliding down a vertical wall such that the only fundamental force acting on it is gravity. I want to say that there is a frictional force slowing the book down; however, I can't find a normal force acting on it, so I can't calculate the kinetic friction force.  Is there any frictional force?  For reference, the book has a mass of $3.5kg$ and a coefficient of kinetic friction of $0.13$.


This is a problem I had for long time. I use software to generate Latex (SW). It adds lots of empty lines.  Which ends up using extra white space between a text and the displayed equation that follows.  I've always fixed this by manually removing these empty lines once I am done editing the document. But this is time consuming to do each time.   Is there some command one can add to the preamble only to tell Latex to automatically ignore empty lines, or treat them as if they had % as first character?  I will first show a MWE that shows the problem and then show what I tried after that.  Compare the output of this file  \documentclass[11pt]{article} \usepackage{amsmath} \usepackage[grid]{eso-pic} \setlength\parindent{0pt} \begin{document} line 1  \begin{align*} x &= y \end{align*}  line 2 \end{document}   With this file  \documentclass[11pt]{article} \usepackage{amsmath} \usepackage[grid]{eso-pic} \setlength\parindent{0pt} \begin{document} line 1 %     \begin{align*} x &= y \end{align*} % line 2 \end{document}   Here it is side by side    The left image is for the first file above. You can see it has extra space before the \begin{align} and after \end{align} which I do not like.  I'd like to obtain same output as the right side image (less space), but without having to manually edit the latex file each time by either adding % or to delete the blank lines.   This is what I tried. I saw this question  but this requires one to manually edit the Latex file and add commands after preamble.  I saw this  and I tried the solution there which says     Redefine \par, for example \let\par\relax   But that broke many things in my main build and I was getting many latex errors. The second solution there which says      Redefine \endlinechar to be 32   This is what I tried.   \documentclass[11pt]{article} \usepackage{amsmath} \usepackage[grid]{eso-pic} \usepackage[subtle]{savetrees} \setlength\parindent{0pt} \endlinechar=32 \begin{document} line 1  \begin{align*} x &= y \end{align*}  line 2 \end{document}   update: I need to try the above again on my main build. I had written it wrong before. Will update soon to see if it worked.  I also tried the package \usepackage[moderate]{savetrees} and this is the result  \documentclass[11pt]{article} \usepackage{amsmath} \usepackage[grid]{eso-pic} \usepackage[moderate]{savetrees} \setlength\parindent{0pt} \begin{document} line 1  \begin{align*} x &= y \end{align*}  line 2 \end{document}   Here is side by side    So \usepackage[moderate]{savetrees} did what I want for this example. But when I tried it on large document, I found it compresses things too much in many other places and made line too close to each others. So I did not like the effect. When I tried \usepackage[subtle]{savetrees}, the space was not removed any more.    So I am not sure what to try next.  I asking if there is some other solution to try. Again, I want all empty lines to be treated as %. But by modifying the preamble only. Not the internals of the document, as the document itself is auto-generated.   Using texlive 2017. I use lualatex to compile latex file.

With the goal of making the latex source easier to parse, I was wondering if one could (locally or globally) disable the latex default behaviour of creating a new paragraph when it encounters an empty line.  Obviously, I can always just put a % on empty lines when I don't want a paragraph. Nevertheless, I was wondering if there is a different solution.  Finally, I would also like to know if such an alternative solution would be considered good form or not.


I know that I have to get to a point where an summation is multiplied by $133$ but I don't know how to get there. I tried formating the equation like $11^2\times11^n + 12 \times 12^ {2n}$ but I got stuck there and I don't really know how to prove it with induction. I really need to solve this. Thank you for your help and sorry if I misspelled anything. Also sorry that you have to edit it, I don't really know how to make superscripts.

Prove $133\mid \left(11^{n+2}+12^{2n+1}\right)$, where $n$ is a non-negative integer.  So, I went about proving this using Fermat's theorem.  So I had $11^{n}\cdot 11^2+(12^2)^n= 0\ (\mod 133)$ then $11^n\cdot 11^2+1728^n=0\ (\mod133)$  and finally $1^n+132^n=0\ (\mod 133)$.  Then I said $133^n=0\ (\mod133)$ because $133$ raised to any power will have a remainder of $0$. Did I apply Fermat's theorem correctly?


My friend Thomas asked me to come in his home with my brother Solomon. So me and my brother were on the way to his house. Thomas called me (on the phone) while I was on my way over and asked me "where did you reach?"   Then I replied, "I'm climbing down the road". As soon as I said that sentence, my brother started laughing and pointed me out that it is not a correct sentence.   Actually at that moment I was very tired and that road was also very steep (hard slope). And I was having difficulty walking down that road. So I was trying to express my tiredness to my friend. My question is whether it is correct to use 'climbing down' instead of 'walking down' in a sentence?

My friends and I were walking down from the road. The road was too steep, so I said:     I am climbing down the road.   As I used to climb down with the word road, we had argument, and my friends said that climbing down the road is not correct usage. Were they correct?


I accidentally created a file when I meant to pass an option.  Now I have a file named: -myfile that I can not delete with rm -myfile  $ touch hi > -myfile $ rm -myfile  rm: invalid option -- 'm' Try 'rm ./-myfile' to remove the file ‘-myfile’. Try 'rm --help' for more information.

How do you remove a file whose filename begins with a dash (hyphen or minus) -?  I'm ssh'd into a remote OSX server and I have this file in my directory:  tohru:~ $ ls -l total 8 -rw-r--r--    1 me  staff  1352 Aug 18 14:33 --help ...   How in the world can I delete --help from a CLI?  This issue is something that I come across in different forms on occasion, these files are easy to create, but hard to get rid of.  I have tried using backslash  rm \-\-help   I have tried quotes  rm "--help"   How do I prevent the minus (dash or hyphen) character to be interpreted as an option?


Let $f \colon \mathbb{R} \to \mathbb{R}$ be an increasing function. Prove or disprove: $f$ is Lebesgue measurable.  Thank you all for the great comments I'll receive! :D

Could you guide me how to prove that any monotone function from $R\rightarrow R$ is Borel measurable? Since monotone functions are continuous away from countably many points, would that be helpful in proving the measurability?


How do we create a new document starting on different pages? (Such as the first page of the document starts on 3 instead of 1.)

I have a seven page long paper which will be assembled with other papers. I know that the first page of my paper will be page 68 in the assembled work. What can i do to tell LaTeX to start counting from 68?


So, I need to download a package and all its dependencies for armhf Debian. The thing is that I am stuck on an Ubuntu machine. How can I download all of this stuff?

What is the easiest way to update/upgrade an offline Ubuntu machine with the help of a Windows machine that has internet access?  This question also applies to installing new packages offline and not only updates/upgrades.  The Linux system shall remain completely cut off from the Windows machine, meaning there should be no ethernet connection or the likes between the two computers.  Update:  Please have patience, since I haven't updated this since two weeks. There are some complications getting apt-offline to work properly on Lubuntu and all other methods seem to be too old and deprecated:  AptOff - last update 2006 AptMedium - last update 2007 Keryx - last update 2011, looks like this project was discontinued  I hope I will be able to somehow update the offline machine, finally.  While I was still not able to update/upgrade the offline system due to authentication errors, I accepted an answer, because it's taking too long.


I have a copy of David Bohm's  and also a copy of T.M. Helliwell's . I was wondering if anyone has used these texts and if they're sufficient in providing an in depth inquiry into special relativity.

I am looking for a textbook that treats the subject of Special Relativity from a geometric point of view, i.e. a textbook that introduces the theory right from the start in terms of 4-vectors and Minkowski tensors, instead of the more traditional "beginners" approach. Would anyone have a recommendation for such a textbook ?  I already have decent knowledge of the physics and maths of both SR and GR ( including vector and tensor calculus ), but would like to take a step back and expand and broaden my intuition of the geometry underlying SR, as described by 4-vectors and tensors. What I do not need is another "and here is the formula for time dilation..." type of text, of which there are thousands out there, but something much more geometric and in-depth.  Thanks in advance.


I am facing below error:  java.io.IOException: Cannot run program "C:\abc\man\b\manu.bat C:\Users\12x\test\testFiles\abc.properties" (in directory "C:\Users\12x\test\testFiles\abc.properties"): CreateProcess error=2, The system cannot find the file specified     at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048).   Please find the code i am using:  public class TestProcess {   public TestProcess(Path workPath, Path exe, Path logbackConfig,                       Path propertyfile) throws IOException {      String exeSuffix = "";     if (OS.indexOf("win") >= 0) {       exeSuffix = ".bat";     }     builder = new ProcessBuilder()             .directory(workPath.toFile())              .command(workPath.resolve(exe).toAbsolutePath().toString() + exeSuffix+ " " + propertyfile)             .redirectOutput(Redirect.INHERIT)             .redirectError(Redirect.INHERIT);   My aim is to run a bat file(which is present in C:\abc\man\b folder) followed by abc.properties(which is in another folder C:\Users\12x\test\testFiles).  In code above, workPath has the value  C:\abc\man\b   and propertyfile has  C:\Users\12x\test\testFiles

In my Java application, I want to run a batch file that calls "scons -Q implicit-deps-changed build\file_load_type export\file_load_type"  It seems that I can't even get my batch file to execute. I'm out of ideas.   This is what I have in Java:  Runtime.    getRuntime().    exec("build.bat", null, new File("."));   Previously, I had a Python Sconscript file that I wanted to run but since that didn't work I decided I would call the script via a batch file but that method has not been successful as of yet.


Does a Sri Lankan national who holds a valid US visa need an airport transit visa to transit through an airport in Italy?

I found many related questions on this site but I am still not sure about the rules. How can I decide if I need a visa to transit? Schengen members as of May 2021 are as follows:  Austria Belgium Czech Republic Denmark (excluding Greenland and the Faroe Islands - but an open border with the Schengen Area is maintained) Estonia Finland France (excluding overseas departments and collectivities) Germany Greece Hungary Iceland Italy Latvia Liechtenstein Lithuania Luxembourg Malta Netherlands (excluding Aruba, Curaçao, Sint Maarten and the Caribbean Netherlands) Norway (excluding Svalbard) Poland Portugal Slovakia Slovenia Spain (except Ceuta and Melilla) Sweden Switzerland


I am an experienced programmer, but have very little experience of parsing/validating XML documents. I am trying to learn it. Can someone please tell me what the difference is between an "XML schema" and an "XML namespace"?  According to my limited knowledge, I guess both of them define the tags that an XML document can have and define the data type/validation rules for them. But I am confused whether or not both of them do the same things? And if not, what is the difference?

This is something that I always find a bit hard to explain to others:  Why do XML namespaces exist?  When should we use them and when should we not? What are the common pitfalls when working with namespaces in XML?   Also, how do they relate to XML schemas? Should XSD schemas always be associated with a namespace?


$V$ is a vector space and for any positive integer $n$, there exists a linearly independent subset $S_n \subseteq V$ of size $n$.  Is $V$ infinite-dimensional and how do I go about proving this?

Let $S$ be a vector space. Suppose that for any positive integer $n$, there exists a linearly independent subset $S_n ⊆ V$ of size $n$.   How do you show that $S$ is not finite dimensional but infinite-dimensional.  I understand that to be finite dimensional then it must have a finite then  there exists a finite set that such at $\operatorname{Span}(T)=S$. So would it be right to prove by contradiction that there is not a finite spanning set that satisfies $\operatorname{Span}(T)=S$, and hence I could argue that the vector space $S$ is infinite dimensional.  How would I show that $S$ does not have a spanning set $T$, such that $\operatorname{Span}(T)=S$?


I have an external hard-drive formatted as NTFS which I use to back-up and store files from both Linux and Windows (as I am dual-booting). I recently bought a new computer and installed Linux Mint 20 on it, and I would like to copy some of the files from my back-up to my computer's internal HD. I noticed that every single file in every single subfolder I copied from the hard-drive has had the option Allow executing file as program enabled in its permissions. How can I safely recursively run through a directory and set all files in all subdirectories as non-executable (including hidden ones and in hidden folders starting with .)? Also, is there a way of preventing this to happen in a NTFS hard-drive or would I be better off creating two partitions on it, an EXT4 for Linux and a NTFS for Windows?

I made a backup to an NTFS drive, and well, this backup really proved necessary. However, the NTFS drive messed up permissions. I'd like to restore them to normal w/o manually fixing each and every file.  One problem is that suddenly all my text files gained execute permissions, which is wrong ofc. So I tried:  sudo chmod -R a-x folder\ with\ restored\ backup/   But it is wrong as it removes the x permission from directories as well which makes them unreadable.  What is the correct command in this case?


how do I get a function from another script and insert it into a button, I did this is giving this error  "Object reference not set to an instance of an object"  public Button Mybutton;      void Indice(){         if (index <= 0)     {         index = 0;     }      if (index >= 2)     {         index = 2;     }          if (index == 0)     {         Mybutton.GetComponent<Button>().GetComponent<MyScript>().MyFunction();     }     else if (index == 1)     {         Mybutton.GetComponent<Button>().GetComponent<MyScript>().MyFunction2();     }     else if (index == 2)     {         Mybutton.GetComponent<Button>().GetComponent<MyScript>().MyFunction3();     }

Since many users are facing the NullReferenceException: Object reference not set to an instance of an object error in Unity, I thought that it would be a good idea to gather from multiple source some explanation and ways to fix this error.  Symptoms I am getting the error below appearing in my console, what does it mean and how do I fix it?  NullReferenceException: Object reference not set to an instance of an object


What this question is about:  It occurred to me that even experienced users occasionally forget that they either:    received viable answers to existing questions or  need to edit existing questions to get more appropriate answers.   What this question is not about:   I'm not suggesting that we badger "or otherwise nudge" users into accepting answers to their questions, as per this discussion:  I'm not duplicating the discussions about reminding/educating new users to accept answers to their questions, as discussed here:  and elsewhere.   My personal rationale:  I suspect that OPs occasionally hesitate to accept an answer in hope that someone will later post a better answer even though there may already be acceptable answers provided. I know that I have done this in the past and then forgotten about my question, only to remember months or years later that I hadn't yet accepted a viable answer to my question.  For busy people, it's inconvenient to go through your activity history and find the question with the upvoted answer that still was never accepted. The inconvenience factor is enough of a deterrent that busy people don't always do it.   My proposal:  For a question with unaccepted answers for over a year, could we please alert the OP with a link (this is the key feature) to their question with a suggestion to perhaps review their question to edit it if no acceptable answers have been provided (or something like that)?  Perhaps there could be other criteria to prevent obnoxious reminders, such as the question needing to have at least 3 suggested answers or that the suggested answers must have been upvoted at least 3 times or that the question has been upvoted at least once or something like that.

As well all know there are a lot of questions which never get accepted answers.  Some might be justified as no one has answered them yet, or the OP doesn't feel that the question has been answered to their satisfaction. But I’m sure there are thousands of questions out there that can become accepted, and for some reason or another they haven’t been yet.  I have an idea to try and address this.  Now for questions in your profile that have not been accepted for a certain length of time we get a message asking us to consider placing a bounty on that question to help us get the right answer, which is fine.  As accepting answers gives 2 rep points to the user, would it be worth us also showing them ‘potential rep’ so that they know how much they could gain if they where to accept answers in all of their remaining questions.  As an example, someone could have asked 20 questions and only 10 of them have been accepted. They could get a message saying:  “Your unaccepted questions equates to an additional 20 rep points…”  Of course I wouldn’t want it to make people accept just for the hell of it, more to make them remember that they get rep for the accepted answers so it’s worth revisiting old questions to see if any can be accepted.  Thoughts?  Edit    Thanks for the comments so far.  Certainly I don’t want people accepting an answer just for the sake of rep. I suppose I'm just thinking of how we can get people to go over their unaccepted questions again, just in case they've forgotten about some of them, and maybe realise that one or two of them can now become accepted.  For example, if you have someone who’s asked a hell of a lot of questions and most have no accepted answer yet, surely there’s a chance that they might have forgotten about some of those questions.


I recently bought a nexus 9 running android lollipop.  I wanted to either dual boot or install Ubuntu touch on it, and I noticed that most nexus devices were working. However the website hasn't been updated for the new nexus 6 or 9.  Is it possible to install Ubuntu touch on a nexus 9?

With the announcement of the Ubuntu Phone OS I'd like to know what phone (and tablet) models are supported at this time.  Note from foss & Oli: We are making this the master question for all future "Will this work on <insert random tablet/phone/device here>?!" questions


I don't know how new Stack Exchange sites get opened. I've found some of the new SE sites to be very useless. There are many different and important subjects that are not being addressed by any SE site. I strongly suggest creating a new SE site about unscientific psychology. I have come across many questions that are related to human problems that I would like to ask on an SE site.  How do new SE sites get opened up? Is there a place for voting up new SE sites?

I have an idea or subject that should have a Q&A, and want to propose a new site. How can I do this?  Related: