What can be the possible rank of adjoint of matrix of order n?
Is adjoint of singular matrix singular? What would be its rank?
How do I get a file extension in PHP? This is a question you can read everywhere on the web with various answers:  $ext = end(explode('.', $filename)); $ext = substr(strrchr($filename, '.'), 1); $ext = substr($filename, strrpos($filename, '.') + 1); $ext = preg_replace('/^.*\.([^.]+)$/D', '$1', $filename);  $exts = split("[/\\.]", $filename); $n    = count($exts)-1; $ext  = $exts[$n];   etc.  However, there is always "the best way" and it should be on Stack Overflow. Could a website force the browser to go into fullscreen mode? I uploaded a pre-print of an article on arXiv 1 year ago. The article was accepted in SCI journal and currently available online. However, I found a typo mistake in one equation and want to add more discussion related one figure (On researchgate I am receiving a lot of queries regarding that figure). Should i upload a new version of pre-print on arXiv? (How citations will work in this case? as arxiv version is more advanced compare to Journal version) OrI may upload a short document on arXiv as an errata/correction with extra discussion?Or I may address errata and discussion in online page of journal? Actually this journal allows the registered users to comment and start discussion related to published article. If no exact time (such as 15:00 or 21:00) is specified about the deadline and only the date itself is given, does that mean that the Deadline date is inclusive or exclusive?  For example, if the deadline for my Research Project is 10th October (no other exact times are specified) does that mean that I can turn it in on 10th October before it turns into 11th October? Or should I submit it on 9th October before it turns into 10th? What is the "Templates" folder in the home directory for? For as long as I can remember, every time I install Ubuntu there is a folder in the home directory called "Templates." I've always just deleted it, but I'm curious: what's it supposed to be used for, and why is it in the default install? I am trying to implement the following K-map with a table    AB C     00 01 11 10       ______________     0| 1  0  1  0     1| 0  1  1  0   I implemented it like this:   \begin{table}[htdp] \begin{center} \begin{tabular}{c|c|c|c|c|}  &amp;00 &amp; 01&amp; 11&amp; 10 \\ \hline 0&amp;1&amp;1&amp;1&amp;1\\ 1&amp;0&amp;0&amp;0&amp;0\\ \end{tabular} \end{center} \label{default} \end{table}   However on the top row I have vertical lines that I'd like to not see. I went with this approach because if i was to use a one row with the information so that I wouldn't have to worry about aligning the headings. So is there a way I can get the vertical lines not to appear in the heading row? Detecting unused packages in LaTeX document I have quite a bad habit of copy-and-pasting my packages from one LaTeX document to another. Is there any way we can detect unused packages (i.e. \usepackage commands) so that they can be removed from the LaTeX document? How was Loki not crushed by Mjolnir? Is  (i.e. repulsive gravity) possible in string theory?  I have read some articles about scientists making assumptions about the existence of anti-gravity, but is it possible in string theory? How do I develop black and white negatives at home? Did spacetime start with the Big bang? Is there any substantial disadvantage to booking two one-way tickets, versus a round trip ticket?  Booking vacation travel with family of four for winter, from Northeast US to Mexico.  Round trip is pricy and no preferred travel times.  Two one ways is slightly cheaper with much preferred timing.      Different airlines there and back, both reputable national US carriers. Show that if $a$ and $b$ are positive integers, then $$\left(a +\frac12\right)^n + \left(b+\frac{1}{2}\right)^n$$is an integer for only finitely many positive integers $n$.   I tried hard but nothing seems to work. :( I'm creating a game where I have an Entity class that contains basic entity info (pos, health,..) and some functions. Enemies and Player later on inherit from this class.   Public class Entity {  public Vector2 position; public float health; ,...   Lets say that I have a function like this inside the Entity class:  public GameObject movingIntoEnemy(Vector2 movingToPoint) {     foreach (GameObject go in GameObject.Find("GameMap").GetComponent&lt;GameMap&gt;().enemyList)     {         if (go.GetComponent&lt;EnemyScript&gt;().enemy.position == movingToPoint)         {             return go;         }     }     return null; }   This function looks for a GameObject called "GameMap" and then cycles through enemies in it's list. If an enemy is found, it returns it's GameObject. Using GameObject.Find() is pretty ineffective, so what would be a better approach to this? I mean, I can't just easily use  public GameObject GameMap;   since the code is in a class, and this class needs to be instantiated first in my player/enemy scripts.  My question is - how do I attach gameObjects to this class before it is even created? What is the appropriate approach to this? I guess that I might pass these GameObjects to the class through it's constructor, but it would make things much more complicated.   Thanks in advance ;) Finite $G$ with involutory automorphism $\alpha$ with no nontrivial fixed points. Proving properties of $\alpha$. The question at hand is:     Let G be a finite group and $\alpha$ an involutory automorphism of G, which doesn't fixate any element aside from the trivial one.    1) Prove that $ g \mapsto g^{-1}g^{\alpha} $ is an injection    2) Prove that $\alpha$ maps every element to its inverse    3) Prove that G is abelian    I think I've found 1).  I assume $ g_1^{-1}g_1^{\alpha} = g_2^{-1}g_2^{\alpha} $ and from this I get $ (g_2g_1^{-1})^\alpha = g_2g_1^{-1} $, so $g_2 = g_1$ (is this correct?)   For 2) I'm sort of stumped though, not sure how to start proving that, so any help please? We completed development on our dev environment and I copied the files over from the dev server to the production server through FTP.   Then through back up and migrade module, I made a back up of the SQL database. I created a new database through Plesk with the same name, username and password. I then imported the SQL database into the new server through phpmyadmin. I go to the URL and get the Site Maintenance message (which is correct, I placed the site in maintenance mode before copying the files over) but cannot navigate to any sub pages. Generally I can add /user or /admin to the end of the url and get the login screen. However all I get are 404 errors. Are there any disadvantages to using your companions for transporting Power Armor After I read that companions don't drain the fusion core of a Power Armor when wearing it, I decided to try giving my armor to Nick so I'll always have it close by if I need it.  But I was wondering if there are any other drawbacks to that. For example, does the Armor get damaged or destroyed when the companion is under fire? get current user info using jquery ,REST and csom My goal is to get the login name and picture for the current user. I am using SharePoint 2013 Foundation. I tried three method and non of then worked correctly:   This is with jQuery SPServices:   function getCurrentUserInfo() {     var thisUsersValues = $().SPServices.SPGetCurrentUser({         fieldNames: ["ID", "Name", "Picture"],         debug: false     });      var name = thisUsersValues["Name"];      var ID = thisUsersValues["ID"];      var SIPAddress = thisUsersValues["Picture"];  }    But I am getting this error:     SCRIPT438: Object doesn't support property or method 'replace'      File: jquery.SPServices-2014.01.js, Line: 2414, Column: 17    REST API method:   function getinfo(loginName) {     var theData = {         "propertiesForUser": {             "__metadata": { "type": "SP.UserProfiles.UserProfilePropertiesForUser" },             "accountName": loginName,             "propertyNames": ["PreferredName", "PictureURL"]         }     };      var requestHeaders = {         "Accept": "application/json;odata=verbose",         "X-RequestDigest": jQuery("#__REQUESTDIGEST").val()     };      jQuery.ajax({         url: _spPageContextInfo.webAbsoluteUrl + "/_api/SP.UserProfiles.PeopleManager/GetUserProfilePropertiesFor",         type: "POST",         data: JSON.stringify(theData),         contentType: "application/json;odata=verbose",         headers: requestHeaders,         success: function (data) {             document.getElementById("profilelink").href = userProfileProperties[1];;             document.getElementById("username").innerHTML = userProfileProperties[0];             if (userProfileProperties[1] !== null) {                 document.getElementById("Userprofileimage").src = userProfileProperties[1];             }         },         error: function (jqxr, errorCode, errorThrown) {             console.log(jqxr.responseText);         }     }); }    Error:     "{\"error\":{\"code\":\"-1,        Microsoft.SharePoint.Client.InvalidClientQueryException\",\"message\":{\"lang\":\"en-US\",\"value\":\"The method         GetUserProfilePropertiesFor cannot be invoked as its parameter propertiesForUser is not supported.\"},\"innererror\":        {\"message\":\"The method GetUserProfilePropertiesFor cannot be invoked as its parameter propertiesForUser is not supported.\"        ,\"type\":\"Microsoft.SharePoint.Client.InvalidClientQueryException\",\"stacktrace\":\"     With CSOM:  //SP.SOD.executeOrDelayUntilScriptLoaded(getUserProperties, 'SP.UserProfiles.js'); function getUserProperties(targetUser) {      // get the target users domain name and account name.     var tUser = targetUser.substring(7);     // Get the current client context.     var clientContext = new SP.ClientContext.get_current();     //Get PeopleManager Instance     var peopleManager = new SP.UserProfiles.PeopleManager(clientContext);     // Get the properties to retrieve     var profilePropertyNames = ["PreferredName", "PictureURL"];     var userProfilePropertiesForUser = new SP.UserProfiles.UserProfilePropertiesForUser(         clientContext,         tUser,         profilePropertyNames);     // Get user profile properties for the target user     userProfileProperties = peopleManager.getUserProfilePropertiesFor(userProfilePropertiesForUser);     // Load the UserProfilePropertiesForUser object.     clientContext.load(userProfilePropertiesForUser);     //Execute the Query     clientContext.executeQueryAsync(onRequestSuccess, onRequestFail); }    I really don't understand where the issue is. Does anyone have an idea? How can I repeat a command every interval of time , so that it will allow  me to run commands for checking  or monitoring  directories ?   There is no need for a script, i need just a simple command to be executed in terminal. I have a new laptop which I am setting up as dual boot Windows/Linux.    I would like to access files from both Ubuntu and Windows 7.  Should I create a separate NTFS partition?