How can I make a keyboard shortcut to turn off and turn on the screen? I changed my laptop from a Lenovo U310 to a Dell Inspiron 7537. The Lenovo had a special key for turning off and on the screen, but the Dell doesn't have it. I want to know if there is a command for turning off and on the screen by using the same keyboard shortcut (something like CTRL+A, or similar).
Is there any way to make a hotkey turn the screen off? How can I make a script (or make some changes) to allow me to turn the screen off in Ubuntu (12.04) whenever I want, the way thevscreen can be turned off in Cellphones?  And how can I make a combination of keys (a shortcut) to execute that script?  I want to conserve power.  I've seen this question    but there is no hotkey for it.  Moreover, in the answer, it is said that there are many ways to accomplish this so I'd like to know more.
One time pad: why is it useless in practice? The symmetric cryptosystem one-time pad (OTP) seems to be very beautiful since it is perfectly secret according to Shannon. Many books, however, point out the main drawback: one must create a secret key the same length as the plaintext. For this reason, the concept of perfect secrecy has these days been abandoned, and we prefer other cryptosystems.   Now, for example, suppose I want to encode my text message with the ASCII scheme, and moreover suppose that this plaintext is 10 gigabytes long, therefore (using an OTP) the key must be the same length, 10 gigabytes. I think, however, this is a ''sustainable price'' because I'm sure that the ciphertext can't be attacked.  Practically, I don't understand why having such long keys with an OTP is a big disadvantage if we reach "the dream"-- namely, perfect secrecy. Nowadays the storage of information is very easy, so what is the real problem? I can, for example, share the "long key" in person. Zoom in/out on click in OpenLayers 3? I have a huge amount of 2D-coordinates, associated with a value, e.g.:    x   |   y   | value 27.50   52.15   12.51 61.83   13.32   57.56 36.23   21.83   41.73 40.46   85.67   25.20 ...   The data is not tabular and I Want the points between two data-points to be interpolated in some way (which way is not really clear, yet)  I want to preset the data as heatmap like this:   Is there any ready-to-use package for PSTricks or TikZ to do it? Looking at the picture below, it's easy to see why the perimeter of a polygon inscribed in a circle is an underestimation of the circle's perimeter. This follows from the triangle inequality: Any side (say $AB$) of the polygon is shorter than the circular arc with the same endpoints ($\stackrel{\frown}{AB}$). Summing all these inequalities shows the perimeter of the inscribed polygon is indeed smaller than that of the circle.  I'm wondering if there is proof that the perimeter of a circumscribed polygon always overestimates the perimeter of the circle, which is as simple as that of the inscribed polygon case. Thanks! [Probability]need help to understand the following expression Why and how does C# allow accessing private variables outside the class itself when it's within the same containing class? Run a program from python, and have it continue to run after the script is killed What is the problem with nested environments using \BODY (environ package)? This question led to a new package:      I want to define some environments, which place their content into multiple different other environments. To access the contents I used the environ package, which introduces the \BODY command. However at some point pdflatex seemed to be stuck in an infinite loop.  I reduced it to a minimal example:  \documentclass{article} \usepackage{environ}  \NewEnviron{assertion}{Assertion: \BODY} \NewEnviron{outerassertion}{\begin{assertion}\BODY\end{assertion}}  \begin{document}  \begin{assertion} test \end{assertion}  \begin{outerassertion} test2 \end{outerassertion} \end{document}   Any ideas how to work around this problem? I guess, the problem is with the \BODY command since everything works fine as long as I use it in only one of the new environments. I need to graph a rectangle on the Cartesian coordinate system. Is there an equation for a rectangle? I can't find it anywhere. Is there any way of doing something like,  &lt;script runat=server&gt;     Platform.Load("core","1");     //initialize DE     var _Sent = DataExtension.Init("_Sent");     //retrieve data     var _Sent_data = _Sent.Rows.Retrieve();     Write("Length: " + _Sent_data.length); //returns 0 &lt;/script&gt;   What would the external key for a system dataview be? Script for display wrapper class Account list of records? Hi i am trying to write script for display list of records from wrapper class.   @remoteaction     public static wrappercls getaccounts(){         string account = 'select id,name,accountnumber from account';         listacc = database.query(account);         count = listacc.size();         system.debug('#####'+count);         wrappercls wra = new wrappercls(count,listacc);         return wra;     }      public class wrappercls{         public integer count11;         public list&lt;account&gt; account;          public wrappercls(integer count11,list&lt;account&gt; account){             this.count11 = count11;             this.account = account;         }     }    This class returns list of account records and record count parameter.Need to display these records in page.Is it possible if possible Please help me on this..  Script  &lt;script&gt;   function getallaccounts(){     exremote.getaccounts(         function(result,event){             if(event.status){              }             else {              }        },{escape:true}     ); } &lt;/script&gt;   Thanks in Advance... The reminder email says:     We noticed you have not accepted our invitation to join Stack Overflow Careers. Only 3 days remain before it expires [...]      But please act soon: this invitation expires in 14 days [...]   Is it 3 days or 14 days now? I want to search for what += means, but Google won't return any documents.  Also when I come across some PHP code I don't understand I can't search for the keywords as written.  How can I search for these special characters or include these special characters in a search. Why is Steam only showing me "Buy" instead of "Play" option for a game shared via Family Sharing? I thought the whole point of Family Sharing was so that multiple copies of the game didn't have to be bought. I have no problem downloading the game, but instead of "Play", my only option once it's downloaded is "Buy". Am I missing something? Here is a quesion that has been bugging me. You know how you can set up a program to run on start up right?  Well, how can i tell it to start minimized, like you would do in windows?   TeamViewer starts open, but I need it minimized, and Tray-it just doesn't seem as elegant of a way to do it. How to get battery status? How do I get the battery status on an iPhone? Disable Repeated System Alerts in iOS 7 On iOS 7, there is a feature under Cellular in Settings called: Use Cellular Data For:. This lists all of the apps I have on my iPhone 4 with individual On/Off Switches to disable or enable cellular data. So, I disable it on several of my apps, one of which being Music. When I open my Music app, it tells me…     Cellular Data is Turned Off for "Music"   You can turn on cellular data for this app in Settings.   This alert does not occur once, but every time I clear the Music app from my multitasking and re-open it. Is there a way to dismiss this alert once and forever?  The alert looks something like this, but for Music: Visiting Greece with back-to-back Schengen visas (One from Germany, other from Italy) Why is the wild card character * so different between the zip and rm commands? I put together a script to do some file operations for me. I am using the wild card operator * to apply functions to all files of a type, but there is one thing I don't get. I can unzip all files in a folder like this  unzip "*".zip   However, to remove all zip files afterward, I need to do   rm *.zip   That is, it does not want the quotation marks. The unzip, on the other hand, does not work if I just give it the * (gives me a warning that "files were not matched").   Why is this different? To me, this seems like the exact same operation. Or am I using the wild card incorrectly?   in Unix do not really go into this, and I could not locate anything in the rm or zip docs.  I am using the terminal on a Mac (Yosemite). So the complex number z is given as   $z=1-cos(2\theta)-isin(2\theta)$  And the question is to find the argument of z in terms of $\theta$.   So, I used the formula for calculating the argument of a complex number:  $arg(z)=arctan (\frac{sin(2\theta)}{1-cos(2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{1-(1-2sin^2\theta)})$  $=arctan (\frac{2sin\theta cos\theta}{2sin^2\theta})$  $=arctan (\frac{cos\theta}{sin\theta})$  $=arctan (cot\theta)$  $=arctan (tan(\frac{\pi}{2}-\theta))$  $=\frac{\pi}{2}-\theta$  But apparently the answer is $\theta-\frac{\pi}{2}$.  Where might have I gone wrong?  Edit: the domain given in the question for $\theta$ was $0≤\theta≤\pi$