I use gedit to modify/create files in my system, and sometimes I see that after editing, a duplicate file is created by the name of samename~  Just that ~ is extra. Why does this happen? Is there any significance of this file or is it okay if I delete it (I usually do)?
When ever I save a gedit file in a directory, two copies of it get saved with identical content. Ex: If the gedit file is named as file_name and saved in Home directory then when u ls the Home directory you get file_name and file_name~ in the list. When the file command is run against them I get ASCII text, with very long lines for both of them when I view their contents using the less command they seem to largely contain identical content. The ~ file is a copy of the file when it was saved for the penultimate time. Can someone please help me in understanding as to why such a file (the file with a trailing ~ mark in its name ) is created?
probability of $k$ boxes contain exactly $1$ ball How to preserve custom number formatting after closing a workbook? I have created a custom format ##,##0.0,,, CTRL+J %% in Excel 2010 to display  10000 as 0.1 100000 as 1.0 1000000 as 10.0 10000000 as 100.0 100000000 as 1,000.0 and so forth.  The problem I am facing is that once I apply this format, save and close the workbook, the next time I open it the format gets changed by multiplying by 10 (100000 is displayed as 10.0).  I don't understand how it is getting changed automatically the next time I open it. However, when I apply other formats they remain unchanged. I created a bitmap with transparent background but in the Windows Picture Viewer I see the white background and even if I reopen it in Photoshop CS3. how do I make sure the white colour in bitmap is really transparent or see if contain any transparent colour? Windows update doesn't progress beyond 0 KB 0% Can someone explain the layer system? I am really confused with the different uses of the terms "Layers" and "Passes" in Blender. Can someone please explain how they work in Blender. I know about Render Passes like AO, Diffuse and so on, but there seems to be a confusion with layers. Also, how do the layer buttons work in the properties panel like in the image shown? I get it that you can assign objects onto certain layers, but whats the difference between "Scene" and "Layer" buttons in the image? How do they refer to rendering? How can you see what layer a certain object is on? Prove that $x^{2} \equiv -1 \pmod p$ has no solutions if prime $p \equiv 3 \pmod 4$. This is problem 3.18 from Patrick Morandi's Field and Galois Theory.     Give an example of fields $k \subseteq K \subseteq L$ and $l \subseteq L$ for which $l/k$ and $L/K$ are algebraic, $k$ is algebraically closed in $K$, and $lK = L$, but $l$ is not algebraically closed in $L$.   This question has been asked twice, namely  and , though neither had any answers, and only some inconclusive comments. Normally I wouldn't ask the question again, but after struggling with it for weeks at this point, I emailed Morandi, and he gave me some hints.  He told me that he remembers finding an example, but that he isn't sure. He told me that it would need to be over characteristic $p$ and that the extensions (at least some of them I suppose) could not be separable. Moreover, he told me that $K = k(x)(a)$, where $a$ is a root of an irreducible polynomial $f(x,y) \in k(x,y)$ (I'm not 100% what the root of a two variable polynomial is). Finally, he said that $l$ is an algebraic extension of $k$, where $f$ becomes reducible over $l$. Still however, I can't come up with anything. I was hoping that with these extra hints, someone would be able to figure it out.  He did point out that there is a chance that there is an error in the question, but I haven't managed to prove that such an example cannot exist. Is it possible to somehow mark a System.Array as immutable.  When put behind a public-get/private-set they can't be added to, since it requires re-allocation and re-assignment, but a consumer can still set any subscript they wish:  public class Immy {     public string[] { get; private set; } }   I thought the readonly keyword might do the trick, but no such luck. "Any" followed by singular or plural countable nouns? This question has troubled me for ages despite my several attempts of looking it up in dictionaries or usage books. Do we say, "Do you have any ideas" or "Do you have any idea"? I do see an example where "any" means "it doesn't matter who/which/what", therefore "You can borrow any book you like." Also, does it matter between using it in questions and negatives? Let $G$ be a finite abelian group s.t. it contains a subgroup $H_{0} \neq (e)$ which lies in every subgroup $H \neq (e) $. Prove that $G$ must be cyclic.   Also what can be said about $o(G)$ ?    I'm clueless about this problem from Herstein. I tried to think $G$ might be a solvable group and its subgroups are all normal (as $G$ is abelian) . But I'm unable to get further. Boot stuck at logo screen after upgrading to 14.10 Android backup/restore: how to backup an internal database? sorry fresh user. I installed about 9 days ago and had issues with Unity disappearing which took 5 days of headaches to fix. It never did fix, I reinstalled.   I set up Plex (media server) and while the server is running and can be accessed by external network devices, I can't add files. Plex says this is because of permissions. I have gone up and down the forums here and at Plex to get an answer. It seems everyone says   chmod -R 755 /media/My\ Book/Videos   will change permissions to allow the folder "Videos" on my external USB 2.0 NTFS 3TB Western Digital drive (which is mounted and accessible through the file manager) as well as every sub-directory and file contained therein to be accessible to user "Plex".  I have used file manager and as soon as you click to change permissions it changes right back. When I chmod with -c it tells me every file is changed (usually 600) to 755 as I commanded it to do. I did   ls -l   to verify and there is no change. (I also used ls -l to make sure I knew who the owner was and it is me (mvl1014). ls -al gives me the same info.)  I swear to god I tried to sudo it and after smashing my head against this keyboard for basically the entirety of my day, I tried it as root. I was scared shi-less but couldn't come up with anything else. sudo su to root and then chmod -R -c /media/My\ Book/Videos  Same result. -c told me every single file was changed and a check in Unity or in terminal confirmed not a darn thing changed.  Now it seems to me that even if that isn't the thing stopping Plex from working there is still a problem with this command not going through.  12.04LTS -- on gen 1 i7 (2.7 GHz I believe) with 6 GB ram   I've attempted to attach a screenshot but I'm told I need 10 reps to do so, which means I'm copy/pasting too.  Please excuse my obfuscation, but Lorem Ipsum seemed unnecessary. And I tried multiple ways to format this but it looks perfect every way and messed up each time in the preview below. (Ugh, I'm a mess.)  $ chmod -R -c 755 /media/My\ Book/Videos  .....  .....  .....  mode of `/media/My Book/Videos/xxxx/xxxx/xxxx.mkv' changed from 0600 (rw-------) to 0755 (rwxr-xr-x)    ls -al shows:  mvl1014@FX6800:/media/My Book/Videos$ ls -al   total 88  drwx------ 1 mvl1014 mvl1014     0 Aug 28 15:17 .   drwx------ 1 mvl1014 mvl1014 20480 Sep  3 14:29 ..  drwx------ 1 mvl1014 mvl1014  8192 Aug 28 15:18 xxxx drwx------ 1 mvl1014 mvl1014 49152 Aug 16 14:02 xxxx drwx------ 1 mvl1014 mvl1014  8192 Aug 27 21:36 xxxx drwx------ 1 mvl1014 mvl1014  4096 Jul 23 19:09 xxxx   I apologize if this has been asked. I looked through this place plus at all the suggested "Similar Questions". The closet thing I got to an answer , but running the provided code with my own UID didn't work either. No room for a new \dimen How to exceed left margin with longtable I'm trying to make a longtable that is wider than the textwidth at a certain moment. I've tried different things always ending up with a different problem:  First possibility: If I use the adjustwidth environment the longtabu does not align correctly. The left margin stays fixed and the right margin gets out of the page. This in contrast, if I do the exact same thing to make a tabu (instead of longtabu), it works perfectly. I think using the adjustwidth is the best way to go, but I can't manage to get it working.  Second possibility: I've found a solution using the fullwidth package. That package does the trick on small longtables, but freezes when I'm trying to do it on my big longtable. The command \setlength\LTleft{-2cm} didn't work as well.  The final option I tried was to use geometry. But that changes the margin of the whole page thus making a page break which I'm not interested in. The code I used for this was  \newgeometry{left=1.2cm} \begin{longtable} long table stuff \end{longtable} \restoregeometry   Here's an example of what I want contra what I get  \documentclass[a4paper]{article} \usepackage{longtable} \usepackage{chngpage} \usepackage{lipsum} \usepackage{tabu}  \begin{document} \section{This is the original textwidth.} \lipsum[1]  \section{This is the width I need for my longtabu} \begin{adjustwidth}{-1in}{-1in} \begin{tabu} to \linewidth {*{13}{|X[l]} |} 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ \end{tabu} \end{adjustwidth}  \section{This is what happens} \begin{adjustwidth}{-1in}{-1in} \begin{longtabu} to \linewidth {*{13}{|X[l]} |} 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ 01 &amp; 02 &amp; 03 &amp; 04 &amp; 05 &amp; 06 &amp; 07 &amp; 08 &amp; 09 &amp; 10 &amp; 11 &amp; 12 &amp; 13 \\ \end{longtabu} \end{adjustwidth}  \end{document} Does RSA work for any message M? SVM for unbalanced data I want to attempt to use Support Vector Machines (SVMs) on my dataset. Before I attempt the problem though, I was warned that SVMs dont perform well on extremely unbalanced data. In my case, I can have as much as 95-98% 0's and 2-5% 1's.   I tried to find resources which talked about using SVMs on sparse/unbalanced data, but all I could find was 'sparseSVMs' (which use a small amount of support vectors).  I was hoping someone could briefly explain:   How well SVM would be expected to do with such a dataset   Which, if any, modifications must be done to the SVM algorithm What resources/papers discuss this Number of permutations of $n$ elements where no number $i$ is in position $i$ I am trying to figure out how many permutations exist in a set where none of the numbers equal their own position in the set; for example, $3,1,5,2,4$ is an acceptable permutation where $3,1,2,4,5$ is not because 5 is in position 5.  I know that the number of total permutations is $n!$. Is there a formula for how many are acceptable given the case that no position holds its own number? If I run history, I can see my latest executed commands.  But if I do tail -f $HISTFILE or tail -f ~/.bash_history, they do not get listed.  Does the file get locked, is there a temporary location or something similar? Does C1 code coverage analysis exist for Ruby? I'm currently using  to get C0 code coverage analysis for a rails project that I'm working on.  However, those results are practically meaningless- I have 100% coverage according to rcov (as it only covers C0 analysis) and I've barely written half the test cases for the functionality that exists thus far.  I'm used to the useful results from the code coverage in Visual Studio 2008 Team, which has C1 coverage.  Are there any tools that provide similar coverage for ruby?