Find the value of $\cos 1^\circ + \cos 2^\circ + \cos 3^\circ +.....+\cos 180^\circ $
$\sum \cos$ when angles are in arithmetic progression
How to change LCD brightness from command line (or via script)? Why does Ubuntu only support versions for a limited time (and what does it mean)? In a bash script sometimes you need the user to wait some seconds for a background process to finish.  I usually use for example:  sleep 10   How can I add a kind of progressbar to the script, so the user knows how long to wait?  I installed the command bar but I don't understand the manual. How come $32.5 = 31.5$? (The "Missing Square" puzzle.) I'm not quite sure how this happened, but somehow a completely empty hierarchy of directories has ended up in my repository:  com/ com/companyname/ com/companyname/blah/ com/sun/ com/sun/java/ com/sun/java/jax_rpc_ri/   I think what happened was that these directories did have files in them, but then a developer realized he/she shouldn't have checked them in in the first place since these are by-products of the build process, so he/she removed the files but somehow the empty directories are left in the repository as ancient relics.  How can I remove this from CVS? The only results I seem to be able to find on google say that there shouldn't be a need to remove empty directories as CVS won't keep them around in the first place, and that the -P (prune) options to cvs update should remove them from the working directory  - which is zero help if you actually have empty directories in your repository.  A cvs remove and cvs commit doesn't seem to take care of this situation:  $ cvs remove -Rf com cvs remove: Removing com cvs remove: Removing com/companyname cvs remove: Removing com/companyname/blah cvs remove: Removing com/sun cvs remove: Removing com/sun/java cvs remove: Removing com/sun/java/jax_rpc_ri $ cvs commit com cvs commit: Examining com cvs commit: Examining com/companyname cvs commit: Examining com/companyname/blah cvs commit: Examining com/sun cvs commit: Examining com/sun/java cvs commit: Examining com/sun/java/jax_rpc_ri $ ls -l com total 24 drwxrwxr-x  2 matt matt 4096 Oct 15 14:38 CVS drwxrwxr-x  9 matt matt 4096 Oct 15 14:38 companyname drwxrwxr-x  4 matt matt 4096 Oct 15 14:38 sun   It's still there!  Does SVN have this weird behavior too? Remove automatically added keyboard inputs and prevent them from coming back (Windows 10) I have 2 languages installed on my computer, both with a single input method.  I have 2 keyboards: CES-CSQ and ENG-US.    However lately (maybe after the last Win10 update) I started to see 2 additional keyboards in my systray  - namely CES-CS and ENG-CSQ.    Is there there a way to remove those 2 input options (CES-CS, ENG-CSQ) which I do not see in the Control panel's Language options?  Solution described at  question does not apply to my problem because I do not see input options that I want remove in Control panel's Language options. Are neutrinos affected by electromagnetic forces? I know they don't interact with matter nor any electromagnetic forces, but I know they have mass, very little mass but they have. When something has mass it must be attracted by gravity and other objects (electromagnetic) right? Can't boot into Ubuntu in Windows 10 / Ubuntu dual boot I installed Ubuntu on a Dell XPS 13 laptop that had Windows 10 preinstalled on it. I installed it from a USB flash drive on a partition. When I boot my computer I can only boot into Windows 10 and Ubuntu is nowhere to be seen.  If I boot into my USB then I can see that Ubuntu is installed, but I can't get to it from the BIOS boot menu. Accepted answers don't float "on top" when self-answered? On , the accepted answer doesn't float on top. Apart from that, the display is correct (i.e. the V mark and the green border)  If I sort by "vote", I've got the following answer order:   Jezell Marc Gravell chilltemp (Accepted) Shaun Bowe   By "oldest":   Marc Gravell Jezell chilltemp (Accepted) Shaun Bowe   and by "newest":   Shaun Bowe chilltemp (Accepted) Jezell Marc Gravell     I'm using Firefox V.3.5 : Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1) Gecko/20090624 Firefox/3.5 (.NET CLR 3.5.30729)  Feel free to ask for more debug information if needed. Parse JSON using Python? Use Expect in a Bash script to provide a password to an SSH command Rational + irrational = always irrational? I had a little back and forth with my logic professor earlier today about proving a number is irrational. I proposed that 1 + an irrational number is always irrational, thus if I could prove that 1 + irrational number is irrational, then it stood to reason that was also proving that the number in question was irrational.  Eg. $\sqrt2 + 1$ can be expressed as a continuous fraction, and through looking at the fraction, it can be assumed $\sqrt2 + 1$ is irrational. I suggested that because of this, $\sqrt2$ is also irrational.  My professor said this is not always true, but I can't think of an example that suggests this.  If $x+1$ is irrational, is $x$ always irrational?   Actually, a better question is: if $x$ is irrational, is $x+n$ irrational, provided $n$ is a rational number? Very large log files, what should I do? ( deals with a similar issue, but it talks about a rotated log file.)  Today I got a system message regarding very low /var space.   As usual I executed the commands in the line of sudo apt-get clean which improved the scenario only slightly. Then I deleted the rotated log files which again provided very little improvement.  Upon examination I find that some log files in the /var/log has grown up to be very huge ones. To be specific, ls -lSh /var/log gives,   total 28G -rw-r----- 1 syslog            adm      14G Aug 23 21:56 kern.log -rw-r----- 1 syslog            adm      14G Aug 23 21:56 syslog -rw-rw-r-- 1 root              utmp    390K Aug 23 21:47 wtmp -rw-r--r-- 1 root              root    287K Aug 23 21:42 dpkg.log -rw-rw-r-- 1 root              utmp    287K Aug 23 20:43 lastlog    As we can see, the first two are the offending ones. I am mildly surprised why such large files have not been rotated.  So, what should I do? Simply delete these files and then reboot? Or go for some more prudent steps?  I am using Ubuntu 14.04.  UPDATE 1  To begin with, the system is only several months old. I had to install the system from scratch couple of months back after a hard disk crash.  Now, as advised in ,  I first checked the offending log files using tail, no surprise there. Then, for deeper inspection, I executed this script from the .  for log in /var/log/{syslog,kern.log}; do    echo "${log} :"   sed -e 's/\[[^]]\+\]//' -e 's/.*[0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\}//' ${log} \   | sort | uniq -c | sort -hr | head -10 done   The process took several hours.  The output was in the line of,   /var/log/syslog : 71209229  Rafid-Hamiz-Dell kernel:  sda3: rw=1, want=7638104968240336200, limit=1681522688 53929977  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device 17280298  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device    1639  Rafid-Hamiz-Dell kernel:  EXT4-fs warning (device sda3): ext4_end_bio:317: I/O error -5 writing to inode 6819258 (offset 0 size 4096 starting block 54763121030042024)        &lt;snipped&gt;  /var/log/kern.log.1 : 71210257  Rafid-Hamiz-Dell kernel:  attempt to access beyond end of device 71209212  Rafid-Hamiz-Dell kernel:  sda3: rw=1, want=7638104968240336200, limit=1681522688    1639  Rafid-Hamiz-Dell kernel:  EXT4-fs warning (device sda3): ext4_end_bio:317: I/O error -5 writing to inode 6819258 (offset 0 size 4096 starting block 954763121030042024)    (/dev/sda3 is  my home directory. As we can find,   lsblk /dev/sda NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT sda      8:0    0 931.5G  0 disk  ├─sda1   8:1    0 122.1G  0 part / ├─sda2   8:2    0   7.6G  0 part [SWAP] └─sda3   8:3    0 801.8G  0 part /home    Why a process will want to write beyond the limit is actually outside the scope of my comprehension. Perhaps I will want to ask a different question in this forum if this continues even after a system update.)  Then, from  (you may want to check  for a deeper understanding), I executed,   sudo su - &gt; kern.log &gt; syslog   Now, these files have zero sizes. The system is running fine before and after a reboot.   I will watch these files (along with others) in the next few days and report back should they behave out-of-line.  As a final note, both  the offending files (kern.log and syslog), are set to be rotated, as inspection of the files (grep helped) inside  /etc/logrotate.d/ shows.  UPDATE 2  The log files are actually rotated. Looks like the large sizes were attained on a single day. Nvidia driver updated - mixed versions of 304.88 and 319.32 My problem is that after trying to update my driver through the additional drivers GUI I can't boot Ubuntu with GUI anymore, since Xorg says the kernel module is of version 304.88 (The old version before I updated) but the driver components are of version 319.32 (The new version)  This is the output of dpkg -l | grep nvidia  dkpg -l | grep nvidia ii nvidia-304 : 304.88-0ubuntu0.0.3  NVIDIA binary Xord driver, kernel module and VDPAU library ii nvidia-319 : 319.32-0ubuntu0.0.1  NVIDIA binary Xord driver, kernel module and VDPAU library ii nvidia-common : 1:0.2.44.2  Find obselete NVIDIA drivers ii nvidia-current : 304.88-0ubuntu0.0.3  Transitional package for nvidia-current ii nvidia-settings : 304.88-0ubuntu.0.0.3  Transitional package for nvidia-settings ii nvidia-settings-304 : 304.88-0ubuntu.0.0.3  Tool for configuring the NVIDIA graphics driver ii nvidia-settings-319 : 319.32-0ubuntu.0.0.1  Tool for configuring the NVIDIA graphics driver   That's the output of that file.  The message startx gives me is:  NVIDIA: API mismatch: the NVIDIA kernel module has version 304.88, but this NVIDIA driver component has version 319.32. Please make sure that the kernel module and all NVIDIA driver components have the same version.     Fatal server error:    no screens found   I understand that something went wrong during the update, so I wonder how to fix this so that the remaining parts of 304 are removed and replaced with 319. I don't know hwere to start because I thought that nvidia-current was the one that would update to 319 and so reinstalling that didn't work. And I googled and found that somebody said to try to install/reinstall/uninstall this package: nvidia-current-updates-dev  But I didn't have that package installed so it did not help. Other than that, I am clueless. I hope the information I provided will be enough so I can get an answer soon.  EDIT:  lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04.3 LTS Release: 12.04 Codename: precise  uname -a Linux SQuad 3.2.0-52-generic #78-Ubuntu SMP Fri Jul 26 16:21:44 UTC 2013 x86_64 x86_64 x86_64 GNU/LINUX This is more of a panic question after reading reviews on Istanbul Atatürk Airport. They said it's messy and hard to navigate, therefore I'm asking questions here in name of my girlfriend who will need to transit through this airport.  My girlfriend (Canadian national) traveling from Toronto (YYZ) to Istanbul (IST) for a couple hours (~4 hrs, so transiting) in order to come to Pristina (PRN). I would like a quick guideline on how to pass through this airport seamlessly without facing any trouble or delay.  Her tickets are both with Turkish Airlines. She purchased it via a third party (Flighthub.ca). It's only one booking and it includes both flights in it.   Once my girlfriend departs, she's obviously required to follow the signs and go to the transit area. Once she's there, will she be required to present a ticket? Where does she get that ticket? Does she get it in YYZ or does she need to visit a counter in IST and get it? After she's got the proper ticket, what does she need to do exactly? Wait in line to have her passport checked? Will they also control her carryon?  After this step, does she simply go to the PRN flight gate and that's it?   We're simply worried about Istanbul Atatürk Airport because of the recent things that happened in Turkey (coup attempt and ISIS attack) and she doesn't wanna somehow end up locked up there. I've read that the airport is a mess lately and a lot of people will be there waiting in line. So, another question: Are 4 hours enough?  I would appreciate a step by step guideline on how she needs to navigate and what she needs to do in that airport to have a smooth experience without facing any delays. Also some misc information on Istanbul Atatürk Airport would be appreciated. Display header and footer in all PDF pages using VF My vf page     &lt;apex:page renderAs="pdf" Controller="testpdf1"&gt;     &lt;head&gt;         &lt;style type="text/css" media="print"&gt;             @page              {                 size: 8.5in 11in;/* width height */             }              @page              {                 @top-center                  {                     content: element(header);                 }                  @bottom-left                  {                     content: element(footer);                 }             }              div.header              {                 padding: 10px;                 position: running(header);             }              div.footer              {                 display: block;                 padding: 5px;                 position: running(footer);             }              .pagenumber:before              {                 content: counter(page);             }              .pagecount:before              {                 content: counter(pages);             }         &lt;/style&gt;     &lt;/head&gt;      &lt;div class="header"&gt;             &lt;div align="right"&gt;Header&lt;/div&gt;     &lt;/div&gt;      &lt;div class="footer"&gt;         &lt;div&gt;Page &lt;span class="pagenumber"/&gt; of &lt;span class="pagecount"/&gt;&lt;/div&gt;     &lt;/div&gt;      &lt;div class="content"&gt;         &lt;p&gt;             &lt;apex:repeat value="{!opp}" var="item"&gt;                 &lt;tr&gt;                     &lt;td class="tableContent"&gt;{!item.Name}&lt;/td&gt;                 &lt;/tr&gt;             &lt;/apex:repeat&gt;         &lt;/p&gt;     &lt;/div&gt; &lt;/apex:page&gt;   Controller  public class testpdf1 {     public list&lt;Account&gt; opp{get;set;}      public testpdf1()     {         opp=[SELECT Name  from Account limit 50];     } }   I am getting all records in pdf format but able to get header in first page only and i am not getting header from second pages how can i display header to all pages. What is the distance between the centers? Two unit circles overlap in such a way that exactly half the area of each circle is within the overlap. How far apart are the centers of the two circles? Finding the unique rock with its weight I have 12 rocks, all have the same weight except for one rock, but I don‘t know which rock is. How do I know which rock is different from other, and also know that rock heavier or lighter, with maximum 3 comparating steps. My only tool is just a balance that can only compare the weight between the rocks. Is it possible to have global color swatches or color styles in Photoshop? I'm looking for a way to use one color in multiple different layers, and then be able to change that color in all the layers in one single place.  Lets say that I have four layers using #ffffff. Now I want to know what my design looks like with #ffff00 instead. How can I do this without manually changing all four layers?  I can add that adjustment layer on hue/saturation is not really what I'm looking for. What I need is something like "change all #ffffff to #ffff00." Prove that there is no non-zero linear operator on $\mathbb C^{2}$ such that $(\alpha | T\alpha) = 0$