URL parameter Issue while having '+' sign in the url

Not sure if anyone encountered this issue. Basically, I am doing an encoding of user details and then via email, I am sending the encoded value (which I got form crypto.encryptWithManagedIV) to the user in the email body   Below is the code:  AESKey is the encrypted value which I got using apex crypto class.     String TargetUrl = 'https://mysandbox.cs88.force.com/redirectpage';             String hyperlink  = 'Link to Join';             mail.setHtmlBody(htmlbdy);   When the user clicks this link I use get parameter on my redirect VF page  String KeyValue= ApexPages.currentPage().getParameters().get('uniqueId'); System.debug('RequestKey:-'+KeyValue);   On the browser the URL looks like :    But after doing getParameters().get('uniqueId'), I get  E f7X10FDW3ExD1+jgfcRdHD1Helxk vk=   Similarly, if the URL has & then it ignores completely the rest   In this case, I get only E by doing get parameters The plus sign is getting replaced by space, which then makes my entire decoding login fails.  Can we get the exact parameters what we have in the URL without any modifications in salesforce ??


I am using Ubuntu 13.10 and successfully installed the latest version of Eclipse, but when I  run it, I can't open menus like file, Edit, Run, etc.   Why is this and what I should do to solve this problem?


Which is the NodeJS default version for Ubuntu 20.04

Can't find any nodejs package in Ubuntu 20.04 Manifest . I'm actually running nodejs on Ubuntu 16.04, and planning to Upgrade to Ubuntu 20. Which version should I upgrade to? Thanks in advande.


Localized (or foreign language only) Area51 site

Hi all,  I understand the StackOverflow team is not fond of localized content.  However, what about localized area51 sites ?  As an example, I'm thinkg about requesting a french only DIY house building site, as we have numerous candidates to such projects in our country (yep, even french can come take a look at what happens over the ocean ;-)).  I understand site text may not yet be localized (things like the "questions", "tags", "how to format", "notify" and all other contents that are site globals).  But is it envisionned ?  And if so, will sites like the one I would like to promote be elligible as valid area51 projects ? (besides, the chosen name for the galaxy of stackoverflow-like sites is totally awesome).


Very stubborn wp_register_script / add_action vs remove

I am trying to get rid of a plugin's .js file in the  but it's not working.  It's being called here {partial code):  class awqsf{    const post_type = 'awqsf';    function __construct(){            // style for front end     add_action( 'wp_enqueue_scripts', array($this,'awsqf_front_styles'), false, '1.0', 'all',1 );              }    function awsqf_front_styles(){     wp_register_script( 'awqsf-frontjs', plugins_url( 'js/awqsf-front.js', __FILE__ ), array('jquery'), '1.0' );     wp_enqueue_script('awqsf-frontjs');   }  } //end class   I have tried a lot of different versions, wp_deregister_script and remove_action, but can't seem to get rid of it:  //deregister awqsf function my_deregister_scripts() {   //wp_register_script( 'awqsf-frontjs', plugins_url( 'js/awqsf-front.js', __FILE__ ), array('jquery'), '1.0' ); // the original wp_register_script   wp_deregister_script( 'awqsf-frontjs', 'http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js', array('jquery'), '1.0' );   wp_deregister_script("wp_enqueue_scripts", 'http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js', array("awqsf","awsqf_front_styles"), false, '1.0', 'all',1 );       wp_deregister_script( 'awqsf-frontjs', array('http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js', 'jquery'), false, '1.0', 'all',1 );   wp_deregister_script('awqsf','awqsf-front.js');   wp_deregister_script('awqsf');   //function awsqf_front_styles(){} // the function   //add_action( 'wp_enqueue_scripts', array($this,'awsqf_front_styles'), false, '1.0', 'all',1 );   // the original add_action   remove_action( 'wp_enqueue_scripts', array('http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js','awsqf_front_styles'), false, '1.0', 'all',1 );   remove_action( 'awqsf', array('http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js','awsqf_front_styles'), false, '1.0', 'all',1 );   remove_action( 'awqsf', array('http://www.spijkerbroek.me/wp-content/plugins/advance-wp-query-search-filter/js/awqsf-front.js','wp_enqueue_scripts'), false, '1.0', 'all',1 ); } add_action( 'wp_awqsf_scripts', 'my_deregister_scripts', 1 );   Can somebody get me into the right direction?


2 hundred sixty thousand VS 2 hundred sixty thousands

In the past three weeks alone, the number of people displaced inside Ukraine itself has doubled to at least 260,000, according to the UN's Vincent Cochetel in Geneva.   Is this "two hundred sixty thousand" or "two hundred sixty thousands"?


How to grep/sed/awk regex and color in man pages?

If I do man bash | grep read -c the output is 218. But I want to search only for colored regex in man. I still haven't find an approach. Any hint is welcome.


When the IFrame loads this code attaches 'click' event to 'a' tag.              function AddEventListenerToFrame(iframe)              {                 var frame = $(iframe).get(0).contentDocument;                 $('a', frame).click(function (event) {                     $(this).attr("target", "_blank");                 });             }   This works fine. But when the user clicks on the rendered menu and new partial is rendered, the clicks does not work anymore.  So, the issue is : event does not work on the new elements.  How to attach the same event for new rendered content ??


I need to buy an Ubuntu phone, where can I buy it? It is unavailable everywhere.


I have the following version of locate: $ locate --version mlocate 0.26 Copyright (C) 2007 Red Hat, Inc. All rights reserved. This software is distributed under the GPL v.2.  This program is provided with NO WARRANTY, to the extent permitted by law.  I am trying to find all files (not directories) that have some specific basename, e.g. python, so I've tried the following: $ xargs -a <(locate -b '\python') -I{} file {} | sed -E '/directory|symbolic/d;s/:.*$//g'  This prints exactly the expected output. However, I wonder if there is an efficient way to achieve that instead?


I completed the online application form for a UK visa. After I hit submit, I realized that the amount of money I wrote on my application is incorrect. Is there anything I can do to make a correction?


Close vote options will never load if I've already cast a close vote on the question

In the Android App, if I open the close dialog for a question that I've , the close options will simply be stuck loading forever.  This initially came up in version 1.0.26 on Android 4.4.2, and it's still present in version 1.0.49 on Android 4.4.3, both on a HTC One.  If I've already voted to close, I will never be presented with the close options, nor will I even be informed I've already cast a close vote previously, I'll just see the loading spinner indefinitely. When this happens, I have to wait for a while wondering if my 'net is being slow, or if I've already voted to close this question.  Here they are, loading:    And here they are, still loading, a few minutes later:


How to get Smooth Scrolling with Magic Mouse?

Smooth Scrolling with the laptop's touchpad works in almost every app (nautilus, software center, gedit..) but not with Apple's Magic Mouse. This mouse has touch surface and is just like a touchpad, but it acts like a scroll wheel when scrollign.  Also, notice that in firefox, with smooth scrolling enabled, magic mouse works exactly like the laptop's touchpad. Its the same, I dont notice any difference.  Is it possible to make it work also in all the other apps like in firefox?


Showing that $\sqrt[3]{2}\notin\Bbb Q(\alpha_1,...,\alpha_k)$ where $\alpha_i^2\in\Bbb Q\ \forall i$

Let $F$ be the field $\Bbb Q(\alpha_1,...,\alpha_k)$ where  $\alpha_i^2\in\Bbb Q\ \forall i$  I want to show that $\sqrt[3]{2}\notin F$  I thought if $\sqrt[3]{2}\in F$ then $\sqrt[3]{2}\in\Bbb Q\cup(\alpha_1,...,\alpha_k)$ but this is not a disjoint union so I'm not sure what to do... taking the square of $\beta:=\sqrt[3]{2}$ gives $2^{2/3}=\sqrt[3]{4}\notin\Bbb Q$ but that doesn't really advance things  So I'm looking for a hint


Searching for values within a string, while loop java

what is the problem with the while loop that i've set up?      String animal;     animal = user_input.next();     animal = animal.toLowerCase();      while ((animal != "c") && (animal != "d")) {         System.out.println("Invalid input, please enter c for a cat or d for a dog");         animal = user_input.next();         animal = animal.toLowerCase();     }     if (animal == "c") {         System.out.println("you have a cat");     } else {         System.out.println("you have a dog");     }


Class singleton instance, clear function on one Hashmap clears a different one

I have a singleton class that has 2 Hashmaps, both private with their own individual(tested and working) getters and setters private static Property property = new Property();  public static Property getInstance(){     return property; }  private HashMap<String, Object> roomReturnedObj = new HashMap<>(); private HashMap<String, Object> roomTasks = new HashMap<>();  public void setRoomObjectFromResult(HashMap<String, Object> roomHashMap) {     roomReturnedObj.putAll(roomHashMap); }  public HashMap<String, Object>getRoomObjectFromResult(){     return roomReturnedObj; }   public HashMap<String, Object>getRoomTasks(){     return roomTasks; }  public void setRoomTasks(HashMap<String, Object> tasksHashMap){     roomTasks.putAll(tasksHashMap); }  The lifecycle of the app gathers tasks in the roomTasks HashMap, once gathered a parent name is assigned to this HashMap, the parent name becomes a new roomObject HashMap key with the roomTasks HashMap becoming it's object. It all behaves strangely though when I try to begin a new run through of room tasks gathering, before I begin I clear with: Property.getInstance().getRoomTasks().clear();  That function above clears the roomReturnedObj HashMap? Setting class saveBtn.setOnClickListener(View ->{             Bundle resultFinal = new Bundle();             String roomName = Property.getInstance().getRoomCount()+ ": " + Property.getInstance().getRoomName();              HashMap<String, Object> room = new HashMap<>();             room.put(roomName, Property.getInstance().getRoomTasks());              Property.getInstance().setRoomObjectFromResult(room);              Property.getInstance().setRoomCount(Property.getInstance().getRoomCount());              Log.d("Test", Property.getInstance().getRoomObjectFromResult()+ " : " + Property.getInstance().getRoomTasks());              Intent returnedResultIntent = new Intent(getBaseContext(), NewJobStart.class);             returnedResultIntent.putExtra("addRoomResult", "Success");             startActivity(returnedResultIntent, resultFinal);         });  Class that clears if (bundle != null) {             tradeTitles = bundle.getStringArrayList("TradeTitleArray");             Log.d("Test", "NewJobStart, tradeTitles received from bundle" + tradeTitles + ", Room count: " + Property.getInstance().getRoomCount());              if(Property.getInstance().getRoomCount() > 0) {                 String test = bundle.getString("addRoomResult");                 Log.d("Test", "NewJobStart, result from jobRoomDetails received from bundle" + test);                  if (test.equals("Success")) {                     Log.d("Test", "NewJobStart - return, before clear: " + Property.getInstance().getRoomObjectFromResult());                     Property.getInstance().getRoomTasks().clear();                     putToList();                 }             }         }


What is the best armor/weapons to use on The Twins

I have tried Palladium armor and Orichalicum armor and a few high damage weapons. I am having trouble with the cursed fire guy(Spazmatism) i have no trouble with the other guy.  I need to deafeat him to advance


Infinite energy with water and air balls


Is there a way to access the help FAQ from mobile app?

While using the mobile app I was wanting to see the /help page but could not find a way to get to it.  Is there a way?  If not, is it possible for new users to create an account from the app and not be able to access the site rules?


How to change style of a button in javascript?

I have a button whose original style is display: none, and after activating a function i want to change his style to an appear using style of defined class style.  I have the pause button as follows:   <li><button className="pause_button"   onClick={() =>{this.props.pause_resume();}}> </button> </li>   and the styles   .sortButton {     background-color: ivory;     color: black;     padding: 10px 25px;     border-radius: 3px;     margin: 5px;     font-size: 16px;     opacity: 1; }  .sortButton:hover {     background-color: dodgerblue;     color: white;     opacity: 1;  }  .pause_button {     display: none; }   I am trying to change the style of pause_button to be the style of sortButton  Here is what i tried, but unfortunately no change appears.    const pause_button =  document.getElementsByClassName("pause_button");     pause_button.style = "sortButton";   In a different part of my code I'm using the same way and it does make changes to the button.  const buttons = Array.from(document.getElementsByClassName("sortButton")); buttons.forEach(button => {             button.style = "sortButton"; })   The last bit of code happens after I have changed the buttons style in this way.  const buttons = Array.from(document.getElementsByClassName("sortButton"));         buttons.forEach(button => {             if(button.innerText !== text){                 button.style.backgroundColor = 'grey';                  button.style.opacity= 0.2;             }         })   All the changes except from the pause button appearing works,


Logging multiple error message in the TRY...CATCH when doing BACKUP DATABASE

When I try below:  backup database not_existing_db to disk = 'E:\Backup\not_existing_db.bak'   SSMS shows two error messages:  Msg 911, Level 16, State 11, Line 22 Database 'not_existing_db' does not exist. Make sure that the name is entered correctly.  Msg 3013, Level 16, State 1, Line 22 BACKUP DATABASE is terminating abnormally.   When I try to encapsulate it into TRY...CATCH block like below:  begin try     backup database not_existing_db to disk = 'E:\Backup\not_existing_db.bak' end try begin catch     select ERROR_MESSAGE() end catch   error_message() only shows second error which is not informative at all  I want to find a way to log both messages, so most informative error message (first) could be send by email to DBA   Please help to find out how to do that


I installed ubuntu 13.04 on my new notebook (that came with windows 8 installed) and now when I try to load windows 8 appear the error:  impossible to find command 'drivemap'. (this is in portuguese, I'm not sure if I translated it right invalid EFI file path.  ubuntu is working OK. someone knows what can I do to solve this and have both SO running? I have searched on the internet but couldn't find anything I could understand. can someone help me?


Getting error while excuting the below code = Exception in thread "main" java.lang.NullPointerException

/* 1538254052650   Marionette  DEBUG   [6442450945] Received DOM event pageshow for  Exception in thread "main" java.lang.NullPointerException*/  public static void setUp() throws Exception {  System.setProperty("webdriver.gecko.driver","D:\\\\Selenium\\\\New\\\\Driver('s)\\\\geckodriver.exe");  File pathBinary = new File("C:\\Program Files\\Mozilla Firefox\\firefox.exe");  FirefoxBinary firefoxBinary = new FirefoxBinary(pathBinary);    DesiredCapabilities desired = DesiredCapabilities.firefox();  FirefoxOptions options = new FirefoxOptions();  desired.setCapability(FirefoxOptions.FIREFOX_OPTIONS, options.setBinary(firefoxBinary));  WebDriver driver = new FirefoxDriver(options);  driver.navigate().to("http://www.demo.guru99.com/v4/index.php");  driver.manage().window().maximize();  driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);  }  public static void main(String args[]) throws Exception {      setUp();      driver.findElement(By.name("uid")).sendKeys("mngr152686");      driver.findElement(By.name("password")).sendKeys("YgabAzy");      driver.findElement(By.name("btnLogin")).click();      Thread.sleep(3000);     System.out.println("Login Succsful");   }


How does the windows run dialog locate executables?

When I enter "firefox" in the windows run dialog (i.e. the dialog that appears when you hit windows+R), firefox will launch.  However, "firefox.exe" is not in my %path% because when I type "firefox" in cmd.exe, I get     'firefox' is not recognized as an   internal or external command, operable   program or batch file.   So apparently an executable doesn't need to be found in the windows %path% in order to be discoverable by the run dialog. How does this work?


I am not able to connect to my wifi as my wifi adapter is not getting detected. I have tried a lot of solutions online, but nothing seems to be working.  ifconfig wlan0  wlan0: error fetching interface information: Device not found  When I do ifconfig, it showed a docker0 interface which previously wasnt there. So I uninstalled docker, but the wlan0 still isnt getting detected. Is there any solution for this?


I'm currently using ViewPager to slide through different Layouts.  I have two so far and these two Layouts have Buttons.  I have a main Layout and two layouts which are loaded in the main layout.  <Button         android:layout_width="120dp"         android:layout_height="120dp"         android:text="@string/when"         android:id="@+id/when_button"         style="@style/ShadowText"         android:background="@drawable/button_background_states"         android:gravity="center"         android:padding="10dp"         android:adjustViewBounds="true"         android:textColor="@color/text"         android:textSize="20sp"         android:textStyle="bold"         android:layout_marginBottom="20dp"         android:layout_alignParentBottom="true"         android:layout_centerHorizontal="true" />   This is one of my buttons. But I want every button on every layout to be clicked. And when the buttons clicked to be played a sound:  final Button button = (Button) findViewById(R.id.when_button); button.setOnClickListener(new View.OnClickListener() {     public void onClick(View v) {         MediaPlayer mp = MediaPlayer.create(getBaseContext(),                 R.raw.when);         mp.start();     } });   This used to be in my onCreate, but now it makes my app crash. I'm a ultra newbie, I just cannot think of a way to set different events on those different buttons.  Process: com.phakeapps.mladmerindzhey.app, PID: 18970     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.phakeapps.mladmerindzhey.app/com.phakeapps.mladmerindzhey.app.MainActivity}: java.lang.NullPointerException             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)             at android.app.ActivityThread.access$800(ActivityThread.java:135)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:136)             at android.app.ActivityThread.main(ActivityThread.java:5001)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:515)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)             at dalvik.system.NativeStart.main(Native Method)      Caused by: java.lang.NullPointerException             at com.phakeapps.mladmerindzhey.app.MainActivity.onCreate(MainActivity.java:24)             at android.app.Activity.performCreate(Activity.java:5231)             at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)             at android.app.ActivityThread.access$800(ActivityThread.java:135)             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)             at android.os.Handler.dispatchMessage(Handler.java:102)             at android.os.Looper.loop(Looper.java:136)             at android.app.ActivityThread.main(ActivityThread.java:5001)             at java.lang.reflect.Method.invokeNative(Native Method)             at java.lang.reflect.Method.invoke(Method.java:515)             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)             at dalvik.system.NativeStart.main(Native Method)   I'm following   I do believe the problem is that the buttons are in different files, but I'm not sure how to find them when a layout is changed.


How to hide/remove Print Page header from jquery data table print?

<script>      $(document).ready(function() {      $('#example').DataTable({      dom: 'Bfrtip',                buttons: [         {             extend: 'print',         }     ]                 });   });   </script>   This is  the script I have got from jquery data table documentation which is printing properly my jquery data table. Just I want to remove the header whixh is getting printed alongwith this data. How can I remove it ?


Find $a$ such that $(x+a)(x+1991)+1=(x+b)(x+c)$ with $a,b,c\in\Bbb Z$

Find all integer values of $a$ such that the quadratic expression $(x+a)(x+1991)+1$ can be factored as a product $(x+b)(x+c)$ where b and c are integers.   I tried to do it by comparing the two expressions but I can't proceed.


Find the smallest value of $a\in\mathbb{N}$ such that $7^{21}\cdot 2^{50}+a$ divisible by $9$. The only thing I know is that an integer is divisible by $9$ is the sum of its digits is divisible by $9$.


I am a new user and I am having trouble working around this issue. When I sudo-apt update, I get the error:
Hit:1 http://us.archive.ubuntu.com/ubuntu groovy InRelease                      Ign:2 http://ddebs.ubuntu.com groovy-updates InRelease                          Hit:3 http://ppa.launchpad.net/system76/pop/ubuntu groovy InRelease             Hit:4 http://us.archive.ubuntu.com/ubuntu groovy-security InRelease             Ign:5 http://ddebs.ubuntu.com groovy-security InRelease                         Hit:6 http://apt.pop-os.org/proprietary groovy InRelease             Hit:7 http://us.archive.ubuntu.com/ubuntu groovy-updates InRelease   Ign:8 http://ddebs.ubuntu.com groovy-proposed InRelease              Hit:9 https://repo.nordvpn.com//deb/nordvpn/debian stable InRelease  Hit:10 http://ddebs.ubuntu.com groovy-updates Release                Hit:11 http://us.archive.ubuntu.com/ubuntu groovy-backports InRelease Err:12 http://ddebs.ubuntu.com groovy-security Release   404  Not Found [IP: 91.189.94.8 80] Hit:13 http://ddebs.ubuntu.com groovy-proposed Release Err:14 http://ddebs.ubuntu.com groovy-updates Release.gpg   The following signatures couldn&apos;t be verified because the public key is not available: NO_PUBKEY C8CAB6595FDFF622 Err:15 http://ddebs.ubuntu.com groovy-proposed Release.gpg   The following signatures couldn&apos;t be verified because the public key is not available: NO_PUBKEY C8CAB6595FDFF622 Reading package lists... Done E: The repository &apos;http://ddebs.ubuntu.com groovy-security Release&apos; does not have a Release file. N: Updating from such a repository can&apos;t be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ddebs.ubuntu.com groovy-updates Release: The following signatures couldn&apos;t be verified because the public key is not available: NO_PUBKEY C8CAB6595FDFF622 W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://ddebs.ubuntu.com groovy-proposed Release: The following signatures couldn&apos;t be verified because the public key is not available: NO_PUBKEY C8CAB6595FDFF622
  What can I do to fix this? Thank you.


Prove that $$gcd(2^{2^m}+1, 2^{2^n}+1)=1$$ if $m, n$ are positive integers such that $m \neq n$.  A Hints to solve the problem is also given in the book as follows:  Let $m>n$. Then $2^m=2^{n}2^{m-n}=2^n.2k$ for some integer $k$, (since $m>n$). Let $2^{2^n}=x$. Then $2^{2^m}-1=x^{2k}-1$ and it is divisible by $x+1$.  I am still unable to solve. Please help.


Why does a capacitor block DC and not AC?

If someone can explain why a capacitor blocks DC, but not AC, with some math, I will understand all of that much better. I know that there are picture animations illustrating this, but I really want to know this a little bit more detailed.


Let Y(1), Y(2), Y(3), Y(4), Y(5) denote the order statistics of a random sample of size 5 from a distribution having p.d.f.

Help me to solve this problem please..  Let $Y_{(1)}, Y_{(2)}, Y_{(3)}, Y_{(4)}, Y_{(5)}$ denote the order statistics of a random sample of size 5 from a distribution having p.d.f. $f(y) = e^{(-y)}, 0 < y < \infty$, zero elsewhere. Show that $Z_1 = Y_{(2)}$ and $Z_2 = Y_{(4)} − Y_{(2)}$  are independent. Hint: First find the joint p.d.f. of $Y_{(2)}$  and  $Y_{(4)}$.


I cannot sync contacts from my iPhone to my Gmail account. I have a standard Google account setup in my Mail, Contacts, Calendars settings (Exchange is not available to me). Also, my Gmail is set as my default account.   Note, my contacts are synced from Gmail to my iPhone, but not in reverse; meaning, any contact I add on my phone never makes in into my Gmail contacts. I'd like to not have to do this manually or through iTunes.


If a directory is a file, can I see the contents of that file?

If a directory is a special file in unix with filenames and corresponding inodes, is there any way to print the entire contents of this file?


On the position of multiple sub and superindices

In tensorial analysis, the position of covariant and contravariant indices may be relevant. The following image shows the output of {A_i}^j and {\tilde{A}_i}^j:    But I expect the second expression (with the tilde) to have the index j at the right of the index i. Why do they behave different? How can I obtain something like the first expression?  Also, I am trying to write an expression like {{{A_i}^j}_k}^m (see following figure), but I get the error Double subscript. How can I write something like this?


Is it true that you can unlock Mater Balls at the Poké Marts and how if possible? If not, where can I find more Master Balls?


how to add elements to an Arraylist of an object in Java?

So, I have a class with some vectors and I'm trying to add elements to those vectors. But, when I try to push elements with add method, it throws NullPointerException. I'm using eclipse as editor. package com.vogella.eclipse.ide.first;  import java.util.Vector;  public class Qr {       // The class   int x,y;   Vector<String> at = new Vector<String>(); }   public class cls {   public static void main(String[] args) {     Qr[] var = new Qr[5];     String q = new String("ggg");      var[1].at.add(q);     System.out.print("gg");   } }  It throws an error  Exception in thread "main" java.lang.NullPointerException  at sf.eclipse.ide.first.nfd.main(nfd.java:89)  Is this correct or am I doing something wrong?


How to prevent HashMap to store duplicate Object type value and returns the existing value reference?

I have below program snippet.  public class MapKeyAsAnObject {      public static void main(String[] args) {          Employee e1 = new Employee(1, "abc"); // P         Employee e2 = new Employee(2, "xyz");         Map<Employee, String> map = new HashMap<Employee, String>();         map.put(e1, "Object1");         map.put(e2, "Object2");          System.out.println(map.get(e1)); // A         System.out.println(map.get(new Employee(1, "abc"))); //B     } }  // My pojo class class Employee {      private int id;     private String name;      public Employee(int id, String arg) {         this.id = id;         this.name = arg;     }             }      In Above program, statement 'A' returns "Value1" which is fine because   i pass the same reference to get the value but in statement 'B' which   returns null but i want to get "Value1" Because both Employee class in statement 'P' and 'B' having same employee data which i want to prevent to store as well as want to return the reference of e1 in statement 'B' .what should be done to achieve the goal.


Consider the scenario where you measure the time it takes for light to travel to the left 10 meters and to the right 10 meters. Both measurements will take the same time, even though we are moving through space at crazy speeds. This must mean that light is not moving relative to "space" as a whole. What does it move relative to? The light emitter? If so, try shooting two beams of light 10 meters from the wall. The first time the emitter is stationary; the second time it is moving at 100 m/s. Am I mistaken in thinking that it would hit the wall slightly faster? Wouldn't this light be moving faster than the light emitted from the stationary source?


How many ways are there to distribute 6 distinct books to 3 people so that each person gets at least one book?

I used stars and bars for this, and my reasoning states that using 2 bars and 6 stars would work. There are 5 spaces to put the bars, so it is 5 choose 2, which is 10, but the answer is much larger at 540. Can I solve this using stars and bars, and how can I do this with PIE?


Install Lubuntu 18.10 on a 4GB Virtual Machine

I read that is possible to install Lubuntu on a 4 GB pendrive, so I would like to do the same on a 4GB virtual machine (on VirtualBox 5.2). The problem is that when I execute it, it says that there is no enough space and that 8GB are required. How can I install it?  EDIT: I'm asking a different question. How can I simulate the installation of Lubuntu on a 4GB pendrive on a virtual machine?


I have the following function: $$f(a)=\text{argmin}_{t\in\mathbb{R}} \left\{\sum_{i=1}^n\frac{1}{2}(1-a)(b_i-t)^2+a| b_i-t |\right\}\quad ,a\in[0,1]$$  Is there a way to show that the function is monotone in $a$?  Edit: for $a=0$ we have the mean of $\beta_i$s and for $a=1$ we have the median. I'm interested in the cases when $a\in(0,1)$, in particular that the function is bounded by the mean and median.


I am just very confsed about how to do these sort of questions where they give you a point in the middle of two charges. The farthest I've gotten in questions relating to coulomb's law, is using the formula \$F = {kq_1q_2 \over d^2}\$ to work out one of the unknowns when given two variables. Can someone please explain how you would do a question like this:  Two point charges of charge -2 µC and -3 µC respectively are separated by a distance of 15 cm. Point X is positioned at an equal distance away from each of the charges.      a. Determine the net electric field at X.     b. Find the point of equilibrium between the charges.


Why are angles dimensionless and quantities such as length not?

So my friend asked me why angles are dimensionless, to which I replied that it's because they can be expressed as the ratio of two quantities -- lengths.   Ok so far, so good.  Then came the question: "In that sense even length is a ratio. Of length of given thing by length of 1 metre. So are lengths dimensionless?".   This confused me a bit, I didn't really have a good answer to give to that. His argument certainly seems to be valid, although I'm pretty sure I'm missing something crucial here.


What are the advantages of ReLU over sigmoid function in deep neural networks?

The state of the art of non-linearity is to use rectified linear units (ReLU) instead of sigmoid function in deep neural network. What are the advantages?  I know that training a network when ReLU is used would be faster, and it is more biological inspired, what are the other advantages? (That is, any disadvantages of using sigmoid)?


limit of the sum $\frac{1}{n+1}+\frac{1}{n+2}+\cdots+\frac{1}{2n} $

Prove that : $\displaystyle \lim_{n\to \infty} \frac{1}{n+1}+\frac{1}{n+2}+\frac{1}{n+3}+\cdots+\frac{1}{2n}=\ln 2$    the only thing I could think of is that it can be written like this :  $$ \lim_{n\to \infty} \sum_{k=1}^n \frac{1}{k+n} =\lim_{n\to \infty} \frac{1}{n} \sum_{k=1}^n \frac{1}{\frac{k}{n}+1}=\int_0^1 \frac{1}{x+1} \ \mathrm{d}x=\ln 2$$  is my answer right ? and are there any other method ?(I'm sure there are)


What episode is the image that chat.SE uses for the not found from?

When you try to head to a page that doesn't exist on chat.SE, it gives you a 404 page, with something like:     We couldn't find the page you requested. We did, however, find some guys with an even more serious problem.      Try searching for a particular message   Browse the available rooms   Occasionally, messages or rooms may be removed for reasons of moderation: spam, off topic, abuse, etcetera.      If you feel something is missing that should be here, contact us.   And this image:    I can recognize Riker, Picard, and Worf in the image, wearing... snow hats?  What TNG episode is this from?


import time  for i in range(100):      time.sleep(0.1)      print("sleeping is happening")   I think it will print the string every 0.1 seconds, but actually it prints the string 100 times on the output client after the code is done.  The answer is a little different (python version 3.5):  following is not useful   import sys sys.stdout.flush()    and   print("sleeping is happening", flush = True)   is corret.


How do I access the index in a for loop like the following?  ints = [8, 23, 45, 12, 78] for i in ints:     print('item #{} = {}'.format(???, i))   I want to get this output:  item #1 = 8 item #2 = 23 item #3 = 45 item #4 = 12 item #5 = 78   When I loop through it using a for loop, how do I access the loop index, from 1 to 5 in this case?


Deleting small gaps (slivers) between polygons?

I try to delete the slivers that appeared when I have merged some polygons.   I have two different cases:  For the CASE 1, no problem I fill the gap with:  CREATE OR REPLACE FUNCTION sliver_killer(geometry,float) RETURNS geometry AS $$ SELECT ST_BuildArea(ST_Collect(a.geom)) as final_geom FROM ST_DumpRings($1) AS a WHERE a.path[1] = 0 OR (a.path[1] > 0 AND ST_Area(a.geom) > $2) $$ LANGUAGE 'sql' IMMUTABLE;  UPDATE merged SET geom = sliver_killer(geom,50::float);   A function that fill all the gaps smaller than x square meter.  BUT for the CASE 2, when the small gaps are "open" I can't manage to fill those gaps.   I have try something like: buffer(1) followed by buffer(-1)  but of course I obtain some rounded corners. Did someone have a true solution ?


How can I copy a big file from one Windows machine to another limiting speed transfer?

Because of traffic reasons I am not able to transfer big files inside my network, unfortunatelly, I need to do such thing everyday.   I usually transfer these files by coping and pasting from my computer to another network drive(\targetIP\targetpath), just like this:    TIs there any tool, Windows configuration or some technique to limit file speed transfer to 10Mb/s?  PS: I don't want to use FTP or another protocol.


Ubuntu 17.04 introduces a swap file to replace swap partitions.  However, I would prefer not to have any disk-based swap space at all, so I would like to know how to turn the swap file off.  Clarification: I need a way to turn the swap file off permanently.  AFAIK, the swapoff command only disables it temporarily.  Clarification 2: I do not want swapping disabled completely, as I am using zram as my swap.  I only want the swap file disabled.  My question specifically deals with the swap file, while the answers to the other questions deal with either turning off the swap partition, or they deal with turning off all swap.  I do not want either, I just want the swap file turned off.


Link to Stack Exchange in Site Stats doesn't work properly

Similar to  and ; but right now it's different; it seems to lead to the right page, the site list/grid on stackexchange.com, but the wrong part of the page.  Example: :    The formatting is broken due to the , but the link, , is broken as well. Depending on whether I'm logged in or not, it either leads to :    or to :    but in neither of the cases, the Sports site is scrolled to or selected.


How do I share my desktop PC internet with tablet/mobile?  I have a desktop PC with an internet connection. The connection is via Ruckus MM2211 (I think it's a gateway). I have a TPLINK TL-WN721N USB wifi adapter. Is it possible to share my desktop connection with my tablet?


How to code oscillator driven by Gaussian white noise? Edit: How to convert ODE to a system of SDE's?

I have written some python code which was designed to try to solve the following differential equation: $$\ddot{x}+\omega_0^2x=\eta(t),$$ where $\eta(t)$ is the gaussian white noise, with mean 0 and variance 1. The initial conditions are: $$x(0)=\dot{x}(0)=0.$$ The code is given here:  import numpy as np import matplotlib.pyplot as plt from scipy.stats import norm  class HarmonicOdeSolver:     def __init__(self, dt, x0, xd0, omega_squared):         "Inits the solver."         self.dt = dt         self.dt_squared = dt ** 2         self.t = dt         self.omega_squared = omega_squared         self.x0 = x0         self.xd0 = xd0         self.x = [xd0 * dt + x0, x0]      def step(self):         "Steps the solver."         xt, xtm1 = self.x         xtp1 = (2 - self.omega_squared * self.dt_squared) * xt - xtm1 \              + self.dt_squared * norm.rvs()         self.x = (xtp1, xt)         self.t += self.dt      def step_until(self, tmax, snapshot_dt):         "Steps the solver until a given time, returns snapshots."         ts = [self.t]         vals = [self.x[0]]         niter = max(1, int(snapshot_dt // self.dt))         while self.t < tmax:             for _ in range(niter):                 self.step()             vals.append(self.x[0])             ts.append(self.t)         return np.array(ts), np.array(vals)  solver = HarmonicOdeSolver(1e-2, 0, 0, 1) snapshot_dt = 1.0 ts, vals = solver.step_until(1000, snapshot_dt) plt.plot(ts, np.sqrt(vals ** 2)) plt.plot(ts, np.sqrt(ts / 2))   The code was taken from and explained . I naively hoped that I could simply add the following line of code:  self.dt_squared * norm.rvs()   to simulate Gaussian white noise. One problem I have noticed is that the results appear to be highly dependent on the time step used. In a similar  we found that the variance of the oscillator should grow as: $$\sqrt{\langle x(t)^2\rangle}\sim\sqrt{\frac{t}{2}}.$$ I would like to reproduce this result, does anyone know of a simple way to simulate a harmonic oscillator driven by white noise?  EDIT: Thanks for the help WoofDoggy, however, I am still confused. When you turned the ODE into a system of stochasic differential equations should you have not done this: $$dX_t=\dot{X}_tdt,$$ $$d\dot{X}_t=-\omega_0^2X_tdt+dW_t,$$ but instead you have done this: $$dX_t=\dot{X}_tdt+dW_t,$$ $$d\dot{X}_t=-\omega_0^2X_tdt?$$


why there are just 4 options for rendering animation?

I need to render animation and there are only 4 options to render.  I select png. at the output and then are only AVI raw, AVI jpeg, frame server and FFmpeg video options. I want QuickTime or another format.  what shall I do? I have the latest version installed. it runs on an iMac with graphics Radeon Pro 580 8192 MB and


I see generated Orbs of light being lying on floor, but I can't seem to pick them up when I pass over them, nor is there anything relevant in Destiny keyboard controls. Any ideas how to do this ?  Also, will I be seeing my generated Orbs, esp. when playing single player ?  Thanks!  EDIT: I've seen the "duplicate question", but because none of answers there mentioned that Orbs can only be picked when super-ability meter is low (as mentioned in the only reply to this post), which is what was puzzling me in the first place.


Theoretically, how could a wormhole be made?

Concentrating a lot of matter in one place will make a black hole, not a wormhole. A wormhole would change the topology of spacetime. Does General Relativity allow this? I know there are wormhole solutions to GR field equations, but they are static solutions. Is there a time evolving solution to the GR equations in which a flat region of spacetime transforms into a wormhole geometry/topology due to an appropriate inflow of matter and energy and negative energy? What determines where the other mouth of the wormhole forms?


How to join paths into forming a shape to later fill with color

Hi there, I'm very new to Illustrator and it's been some days (if not weeks) that I'm trying to find a solution for this problem. I basically had an image in the background and used the pen tool on top to reproduce the different lines. So at the moment it's all paths. But as you can see, the outer line is all together. What I want to do is to join the top lip path into one shape, lower lip other shape, tongue another, and so on. The idea is to paint each of those shapes in different colours but I can't find a way to join them or even separate the outer line (I tried scissor, eraser, cut in the anchor, but no luck). Any help would be much appreciated (or suggestion on the right way of doing something like this).


help with lme() for nested random effects factors

this is a fairly basic question, but I have spent all day trying to figure it out (including reading other questions on this page), and I could really use some help.  I am trying to run a simple mixed model with one random effect nested under a one fixed effect. In short, I have two study sites with multiple activity measurements (i.e., repeated measures) for individuals at each site. So "activity" is my response, "site" is a fixed effect factor, and "individual" is a random effects factor that is nested under site (i.e., each individual is present at only one site, but I have multiple data points for each individual). I have tried to use the following line of code, but I am not convinced that I am doing it correctly.  result <- lme(activity~site+individual,data=table1,random=~1|individual/site)  Specifically, my questions are as follows:  First, do I need to specify individual both in the second term of the model and in the final term? If I am understanding correctly, the second term specifies the fixed effects, and the final term specifies the random effects, so listing "individual" in both places seems incorrect, but if I don't do that, then I do not get any output for individual.  Second, for nesting terms, my initial impression was that you always started with the higher order terms (e.g., "site/individual" would nest individual within site), but if I do that with these data, I get error messages and NaN values. So, do I list individual/site or site/individual?  Third, since the nesting term is listed as the random term, will that make the model run with both individual and site as random effects? I need to make sure that the model retains site as a fixed effect, while including individual as a random effect.  Thank you for the help   Edit: it was pointed out to me that my question may be a duplicate of a previous question (); however, that question ended up not using a nested design, thus the nesting issues that I am asking about were never resolved. Thanks again.


Construction loan for new house replacing existing mortgaged house?

Let's say I buy a home with an ordinary thirty-year mortgage, intending to renovate the house slowly and live there a long time (ten years at least).  Five years into the mortgage, however, I decide I want to build a new house, but I would like to stay at the same address.  In other words, I want to have the old house demolished, and build a new house on the now-empty lot (while I live in a rental), then move back in to the new house and live there indefinitely.  The new house will be bigger and better than the old, so once it's done, the real estate as a whole (land plus improvements) will be worth much more than the original loan amount.  Is there a loan product that covers this kind of process?  Can I take out a construction loan to finance the new building, and then roll it into a conventional mortgage, the way that people do who are building houses on raw undeveloped lots?  What happens to my old mortgage when I do this?  I suspect that the lienholder may not want me to destroy the old house since that reduces the value of the property (at least temporarily) to the value of the raw land, but what other option is there?  What do people do who want to buy an old house for the location, but intend from the start to tear it down and build a new house?  Can this only be done with a large cash outlay upfront?


Locked posts - displaying up/downvote buttons

Why some locked questions and answers display up/downvote button        and some not?         Tap the image to see what questions I am writing about.  As Richard Tingle pointed, on mobile site both questions have their vote arrows shown.


Creating .bib file containing only the cited references of a bigger .bib file in Windows

Mine is closely related to this one:   I ask the same question but with a solution for Windows. The mentioned solutions bibexport, and bibextract don't seem to be available. I think it's possible to run these programs through something like MinGW, but I'd like to be able to have something that works on the command line so that I can build it into my usual build command.  Any help is very much appreciated.


In Problems in Mathematical Analysis, Volume 2 by Kaczor and Nowak, Problem 2.3.34 is stated as follow.   Find this limit using L`Hôpital rule  $$\lim\limits_{x\to\infty}x((1+\frac{1}{x})^x-e).$$  I have tried by using L'Hospital rule five times but have no result.  I can compute this limit by using Taylor expansion.


Does $A$ a UFD imply that  $A[T]$ is also a UFD?

I'm trying to prove that $A$ a UFD implies that $A[T]$ is a UFD.   The only thing I am sure I could try to use is Gauss's lemma.  Also, how can we deduce that the polynomial rings $\mathbb{Z}[x_1,\ldots,x_n]$ and $k[x_1,\ldots,x_n]$ are UFDs?


Simple Python IDE that supports multiple tabs and a Python shell?

I have been trying to pick a good IDE for Python and stick to it.  I looked at this question as well  which lists lots of IDEs, but doesn't tell whether they have the features I am after or not.   I tried Sublime Text and Atom. I was able to get a Python shell on Sublime Text, but that doesn't work sometimes. In Atom, I tried to hack it by adding a package called REPL Term, but that throws an error. PyCharm on the other hand looks heavy and expensive.  So, I was really looking for an IDE with three features:   Being able to display multiple files at once as tabs. Having a Python shell where you can load a script Possibly displaying a file tree.


Would it be better to use a 35mm prime instead of a 50mm prime on a cropped sensor body?

It's said that 50mm is close to what the human eye sees and is a very versatile focal length in general, especially good for street photography which is what I'm most interested in. That being the case, if I have a cropped sensor (1.6) would I better off with a 35mm prime since it would give me a field of view similar to a 50mm lens (35 X 1.6 = 56) as opposed to a 50mm prime which would give me a field of view similar to an 80mm  lens (50 X 1.6 = 80)?


Example of an incomplete inner product space?

The definition of a Hilbert space is a complete inner product space. I am struggling to imagine what an incomplete inner product space would look like, especially since inner products by definition must be maps on vector spaces whose scalar fields are either $\mathbb R$ or $\mathbb C$. Since $\mathbb R$ and $\mathbb C$ are complete and inner products are (sesqui)linear, it seems that any inner product must be complete. Is the definition of Hilbert space redundant?  In short, what's an example of an inner product space that is not complete?  It seems one of the following must be the case:   All inner product spaces are complete, and the definition of Hilbert space is redundant. Inner products can be defined on more general fields than $\mathbb R$ and $\mathbb C$, for example $\mathbb Q$ and other subfields of $\mathbb R$. The definition of Hilbert space simply rules out these incomplete subfields from consideration. There exist genuine inner product spaces over $\mathbb R$ and/or $\mathbb C$ that are not complete, which would be the most interesting and unexpected situation.


Transiting through Incheon (Seoul), South Korea

I'm planning to fly from Ulaanbaatar to Melbourne via Seoul (and Kuala Lumpur).  However, can I actually enter South Korea using this visa waiver? I'm hoping to meet a friend there for a few hours before flying. Also, would traveling via Malaysia affect this policy?  Transit tourists bound for another country Eligible countries  Applicable to all countries (save for Macedonia, Cuba, Syria, Sudan and Iran) that are not granted visa-free entry into Korea.  Applicable to…  Those with a visa (excluding Japanses Group Visa, excluding e-visa) or a re-entry permit for U.S., Japan, Canada, Australia, or New Zealand (5 countries) and traveling to any one of those countries through Korea.  Those traveling from any one of the five countries mentioned above, whose final destination is not Korea.  However, please note that the first bullet points are not applicable to those travelling to/from Guam and Saipan, which are unincorporated territories of the United States.   Requirements  Must have a confirmed onward flight ticket for departure within 30 days after entering Korea, in addition to having no record of criminal offence in the five countries mentioned above.


How to find a projecting of a point into the intersection of semi-spaces?

I have a point $A\in\mathbb{R}^n$ and a set of $k$ constraints of the form $$a_i + \alpha a_j+ \geq \epsilon$$ for $\epsilon>0$ and $a_i$ the $i$ dimension of $A$. How can I find the projection of the point against this set? I am suspecting that if I project iteratively against each semi-space/restriction, I'll have the job done.


Examples of Non-Noetherian Valuation Rings

For valuation rings I know examples which are Noetherian.      I know there are good standard non Noetherian Valuation Rings. Can anybody please give some examples of rings of this kind?    I am very eager to know. Thanks.


Floating point arithmetic not producing exact results

I need to do some floating point arithmetic in Java as shown in the code below:  public class TestMain {     private static Map<Integer, Double> ccc = new HashMap<Integer, Double>() {       { put(1, 0.01); put(2, 0.02); put(3, 0.05); put(4, 0.1); put(6, 0.2);         put(10, 0.5); put(20, 1.0); put(30, 2.0); put(50, 5.0); put(100, 10.0);       }     };      Double increment(Double i, boolean up) {         Double inc = null;          while (inc == null) {             inc = ccc.get(i.intValue());              if (up)                 --i;             else                 ++i;         }         return inc;     }      public static void main(String[] args) {         TestMain tt = new TestMain();          for (double i = 1; i < 1000; i += tt.increment(i, true)) {             System.out.print(i + ",");         }     } }   This is to simulate the range of values given as output by the .  Floating point arithmetic in Java seems to introduce some unexpected errors. For example, I get 2.180000000000001 instead of 2.18. What use are floating point numbers is you can't trust the results of arithmetic performed on them? How can I get around this issue?


Cross Validation in an Imbalanced data set

What is the point of oversampling an imbalanced data set if the ratio of the classes needs to be preserved in Cross validation ? If I have 1000 rows in a data set where 800 rows belong to one class and 200 rows to another class, this would be considered an Imbalanced data set due to it's skewed distribution. If I over sample the smaller class by just duplicating the rows and make it 400 rows, the ratio of the major and minor class is changed. Now having done that, why would I ensure in my cross-validation folds (if I should) that the ratio of majority to minority class is still 80:20 ? What am I missing here ? Additionally, my test set might not have the same ratio of classes. How can I ensure that the skewed distribution does not impact my model ?


$\sqrt[b_1]{a_1}+\sqrt[b_2]{a_2}+\cdots+\sqrt[b_k]{a_k}$ not an integer

Is it true that all numbers of the form $\sqrt[b_1]{a_1}+\sqrt[b_2]{a_2}+\cdots+\sqrt[b_k]{a_k}$ are not integers, where $a_i,b_i$ are positive integers such that none of the $k$ terms is an integer? I think this must be a theorem somewhere, probably a fundamental theorem in number theory, but not sure what it would be called.


Why C# supports structure when we have classes and interfaces for supporting OOP concepts

When we can achieve all the OOP concepts using classes and objects then why C# still support structures.


I need to change the login URL from /user to /my-url  I found this module:  module. But I think this could be done in other way. Plus, this module has some conflicts with multilingual sites.


how to parse hex or decimal int in Python

I have a string that can be a hex number prefixed with "0x" or a decimal number without a special prefix except for possibly a minus sign. "0x123" is in base 16 and "-298" is in base 10.  How do I convert this to an int or long in Python?  I don't want to use eval() since it's unsafe and overkill.


Why is my terminal invisible after minimizing it ubuntu 12.10

I am using 12.10. I am able to get my terminal with [super] + [w] keys but not with alt + tab keys. why is it invisible after minimizing the terminal. how can i correct it ?


The command could not be located because ‘/bin:/usr/bin’ is not included in the PATH environment variable

I got this error message when restarting my ubuntu laptop. I went into a login loop, and so I pressed ctrl + alt + F3 To access terminal, which I did, but I experienced this error: Command 'lesspipe' is available in the following places  * /bin/lesspipe  * /usr/bin/lesspipe The command could not be located because '/bin:/usr/bin' is not included in the PATH environment variable. lesspipe: command not found Command 'dircolors' is available in '/usr/bin/dircolors' The command could not be located because '/usr/bin' is not included in the PATH environment variable. dircolors: command not found Command 'ls' is available in '/bin/ls' The command could not be located because '/bin' is not included in the PATH environment variable. ls: command not found  I temporarily fix this error running below command, but when I open again, this error is again coming, I again running below command. export PATH="/usr/bin:/bin:$PATH"   But when I comeback to login, it still fails with same error. Any help to resolve this? I am on ubuntu 20.04.1 LTS echo $PATH returns -bash: /home/username/.local/bin:/usr/local/bin:...: no such file or directory


Loud, low-frequency "booming" sound in car

I drive a Scion XD, and I've noticed that whenever I drive at about 40mi/hr or so with just the back windows rolled down, I get a loud "booming" effect at roughly 10Hz. What causes this? I assume it has something to do with air pressure "bouncing" back and forth in the car.  I can try to sketch the interior, if needed.


Does opacity:0 have exactly the same effect as visibility:hidden

If so, does it effectively deprecate the visibility property?  (I realize that Internet Explorer does not yet support this CSS2 property.)


This is what I would like to do: Tab A Column A has a mass of numbers, Tab B Column B will have numbers inputted into it. I need to have the Tab B Column B highlight showing a match to a number in Tab A or have a 'Yes' or 'No' answer appear in Tab B column A indicating a match. Any ideas how to do this?


If $G$ is non-abelian, then $Inn(G)$ is not a normal subgroup of the group of all bijective mappings $G \to G$

Let $(G,\cdot)$ be a group and  let $\mathfrak{S}(G)$ be the set of all bijective mappings from $G$ to $G$.   Show that: If $G$ is non-abelian, then $Inn(G):=\{\kappa_a  \vert a\in G\}$ is not a normal subgroup of $(\mathfrak{S}(G),\circ)$  First of all, this is not homework, but we had it in university as an exercise and didn't get a solution from our lecturer. So I am just looking for a correct proof, since we have easter holidays and it is not possible to ask him.  Thanks in advance!


In an accept-reject algorithm, we need to find c such that pj/qj≤ c for all j for which pi > 0 . And, the probability of accepting in any iteration is 1/c. Why is c guaranteed to be more than 1?


Are these two cout line both treating the array the same in C++?

I am trying to figure out the difference if any between these two lines of code. I exceeded the index limit and that in return outputted garbage as expected for both so they behave the same I presume but I am unsure and wanted to get an definite answer.    Thank you in advance.   arr[] = {1,2,3,4,5,6}; cout << arr[5] <<  endl;    cout <<  5[arr] << endl;


Command-line tool for finding out who is locking a file

I would like to know who is locking a file (win32). I know about , but I would like a command-line tool which does more or less the same thing.  I also looked at , but it seems only applicable for files opened remotely.


Windows don't boot after set Windows to Diagnostic startup in msconfig (Win7)

In opened msconfig.exe window, General tab, I set the startup selection to Diagnostic startup. After rebooting system windows didn't boot, even in safe boot. Operation system is Windows 7. How can i resolve it?


When reviewing close votes, also display the answers

When I review close votes of questions, I am curious to see the answers that some of these questions got. The reason for that is that sometimes I can get a better understanding of how to judge a question I'm reviewing when I also see an answer to that question. Can the whole question thread just be added after the question part?


Is ECB mode safe to use with RSA encryption?

Firstly, bear with me, I'm relatively new to cryptography. In a recent static analysis scan of our application, one of the findings complained that we are using ECB:     A mode of operation of a block cipher is an algorithm that describes how to repeatedly apply a cipher's single-block operation to securely transform amounts of data larger than a block. Some of the modes of operation include ECB (Electronic Codebook), CBC (Cipher Block Chaining) and CFB (Cipher Feedback).  ECB mode is inherently weak, because it results in the same ciphertext for identical blocks of plaintext. CBC mode does not have this weakness, making it the superior choice.   We are using ECB with RSA.  Our understanding is that RSA doesn't support anything other than ECB as it doesn't permit a block size bigger than the size of the key's modulus, and therefore would only ever encrypt a single block (or throw an exception if breaching block size).   Our suspicion therefore is that the static code analysis tool is searching for 'ECB' in our code base irregardless of the crypto algorithm used.  Given our choice of an RSA crypto algorithm, is there an inherent weaknesses using ECB mode?


How to draw connecting lines in plain color?

Since there is no option for flat shading in OpenGL ES2, is there a workaround to disable the color interpolation when different color is being passed to each of the vertices?  Update: I'm working with OpengGL ES 2.0 in android. I'm given with these vertices which I used to draw shapes by connecting them with lines. Now I need to change color of each of these lines individually. I tried passing a color matrix for each vertex through vertex shader to fragment shader but the color gets interpolated (which actually makes sense, since I'm giving different color to two vertices). I did some googling about that and found out glSmoothShader cannot be disabled in OpengGL ES.  Is there a way to color those lines without the colors getting interpolated?  Or is there a way to use multiple triangles to draw a line between two vertices that way i can flat color each of those triangles.


Transit visa for Korea going to Fiji island

I am a filipino citizen. I will be travelling to Fiji Island and my layover is in Korea. Do I need to get a transit visa in Korea? Thanks.


Why does the Guide Number have a distance given with it?

I am learning photography and looking to buy a flash. I learned the basics of the flash, and as far as I saw everywhere, the Guide Number had a feet unit with the ISO number; e.g. 160' at 100 ISO.  I came across this format and I don't know how to interpret it — it displays the feet, ISO and another distance. See for example   I don't understand what it means by 196.85' (60 m) ISO100 at 200 mm position or 190.29' (58 m) ISO100 at 105 mm position. Can someone please help me interpret this?


Where and how can I view skype logs (Chat and Voice history)?

Where and how can I view my skype logs (Chat and Voice history)? Does it get saved somewhere in PC by default? Can I choose a folder location myself to start saving voice and chat history?


How to get a list of applications installed in Ubuntu dash?

In Gnome, we have applications grouped up based on their type (like - games, accessories, et al). But in Unity, we need to manually type in the Unity to get the App.  Is there any keyword/utility to display the applications in GUI?  Ubuntu Version : 14.04 Hardware : Dell Inspiron 3437


I can't connect to  or  — the initial connection times out every time. I check this every week, and it worked fine last time, so it must be something pretty recent. (Further HTTPS deployment?)


Is there an equivalent svn command for `git add --patch`?

Looking for an equivalent svn command to the selective adding and committing in git:  git add --patch


Proving that the non-negative real line is complete

Heads up: I am very new to abstract algebra and proofs.  Take the non-negative real line $X = 0 \cup \mathbb{R}^+=[0, +\infty)$. We know that $X\subset \mathbb{R}$ and that $\mathbb{R}$ is complete. Define now the Euclidean metric $d(x,y) = \lvert x - y \rvert$. Then $(X,d)$ spans a metric space. I wish to show that this metric space is complete.  So for an arbitrary sequence $(x_n)$ we need $d(x_n, x) < \varepsilon$, where $x\in X$, that is the sequence has to converge to $x$ which is in the set we are working with. Then $(x_n)$ is Cauchy, and since the sequence was arbitrary $X$ is complete.  This is what I know we require, however, I am unsure if I am on the right track.  My attempt:  Consider a sequence that is Cauchy, $(x_m)$. Then for every $\varepsilon$, there is an $N=N(\varepsilon)$ such that $$d(x_m, x_r) = \lvert x_m - x_r\rvert < \varepsilon .$$ As $m\to \infty$ $x_m\to x$. How do I prove that $x\in X$ so that the arbitrary Cauchy sequence converges to a point in $X$ (thereby completing the proof)?  Any help would be appreciated.


Is R output reliable (specially IRT package ltm)

This may seem like a foolish question, but it is critical for me to have some expert advice on this.   I am doing some research on students' learning levels in India. I am using R software (ltm package) to calculate student scores (ability estimates as per IRT model).   Features of the data:  No of students: 15,000 Test papers: 3 different forms No of questions in one form: 50  My concern is whether R outputs are reliable enough to publish the results in research community or the results from R software can be questioned, specifically with respect to ltm package. Also if R can handle such large data comfortably without compromising the quality.  I would be very grateful if you could share your inputs and any documentation/research paper/reference you may have.


Useless prompt when trying to delete answered question?

If you try to delete an answered question, the site asks if you are sure about it. However, even if you click yes, it will just tell you that you can't delete it because it's an answered question. Why is there a prompt in the first place if it can't be deleted anyway?


Login page ERROR: Cookies are blocked due to unexpected output

I have a WordPress website that I recently discovered had this error on the login page:     ERROR: Cookies are blocked due to unexpected output. For help, please   see this documentation or try the support forums.   I can only access the login page from wp-login.php, since /wp-admin/ displays a blank white page.  I've searched the web and tried many things with no success:   Removing ?> and space at end of the functions.php Ensuring both functions.php and wp-config.php had no spaces at beginning or end of file Opening wp-config.php and functions.php in Notepad++ and converting to UTF-8 (people recommend 'without BOM' but that is only an option in the newest version of Notepad++ - I'm guessing UTF-8 does that now) I've set WP_DEBUG to true and have received no errors in debug.log,  except for 2 that relate to when I hadn't fully uploaded some files. That particular error mentioned nav-menu.php; this confirmed that it is reporting errors, just not related to my login issues I renamed each plugin folder with _tmp at the end to try and rule out any plugins causing the problem I also renamed the plugins folder to rule out all plugins at the same time   Given these things I've tried, and that I'm not receiving any PHP errors, what else could I try?


What is the best practice to assign php variable to javascript variable?

I have some code like this    var minAmountPay =  <?php echo $this->chat['Current']['admin'] >= 1 ? 1 : $this->minAmountPay; ?>;   var userId = <?php echo $this->currentUserId?>;   I use ZF and I have a lot of javascript code in my action files. I want to create js-files for each action and do minifications of this files. But I can't create js-file because I have assigning php variable to javascript variable.  Maybe I need to use some javascript framework for this purposes?


The expression "It's all up hill from here!" and "It's all down hill from here!" mean that things will only get better or things will only get worst.  Metaphorically going uphill can provide for a better position, while going down hill is easier.  Which expression represents which way?


c# Check if process is running and act properly

To check if an application is running and continue or return back to your previous condition this should make your life easier in order not to exit from any of your current processes    protected override void OnFormClosing(FormClosingEventArgs e)         {             Process[] pname = Process.GetProcessesByName("ConsoleApplication");             if (pname.Length == 0)             {             }             else             {                 MessageBox.Show("You cannot exit until the process has finished");                 e.Cancel = true;             }          }


I know that we need to win 2 of 3 games to rank up, rigth? like form silver 2 to silver 1.  Is it possible to rank down? like silver 1 to silver 2? There any matches that we need to win to stay in that rank?


The sentence is   Travellers  ________________ their reservation well in advance if they want to fly during winter vacation.  Which is suitable to complete this sentence. Please give some explanation so that I can understand.  1. had better to get  2. had better get


Why would an electron in an orbit be accelerating continuously and would thus radiate away its energy and fall into the nucleus in a classical model?

I was reading this answer by madame anna v:      You are right, the planetary model of the atom does not make sense when one considers the electromagnetic forces involved. The electron in an orbit is accelerating continuously and would thus radiate away its energy and fall into the nucleus.      One of the reasons for "inventing" quantum mechanics was exactly this conundrum.      The  was proposed to solve this, by stipulating that the orbits were closed and quantized and no energy could be lost while the electron was in orbit, thus creating the stability of the atom necessary to form solids and liquids. It also explained the lines observed in the spectra from excited atoms as transitions between orbits.    But I don't understand one assumption: Why would an electron in an orbit be accelerating continuously, and would thus radiate away its energy and fall into the nucleus in a classical model?  Also in a planetary model, would planets also be accelerating and thus fall into the sun?   I mean for example: a planet would accelerate towards the sun, but because it will then have bigger velocity, it will escape a little bit the sun, and then it will accelerate towards the sun... and the whole process repeats again. But, why wouldn't that be true for an electron and proton?  Thank you.


Command substitution in for loop not working

I want to keep all files not ending with .bat  I tried   for f in $(ls | egrep -v .bat); do echo $f; done   and  for f in $(eval ls | egrep -v .bat); do echo $f; done   But both approaches yield the same result, as they print everything. Whereas ls | egrep -v .bat and eval ls | egrep -v .bat work per se, if used apart from the for loop.  EDIT  It's interesting to see that if I leave out the -v flag, the loop does what it should and lists all files ending with .bat.    Feel free to edit the question title, as I was not sure what the problem is.  I'm using GNU bash, version 4.1.10(4)-release (i686-pc-cygwin).     EXAMPLE  $ ls -l | egrep -v ".bat" total 60K -rwx------+ 1 SYSTEM SYSTEM 5.3K Jun  6 20:31 fsc* -rwx------+ 1 SYSTEM SYSTEM 5.3K Jun  6 20:31 scala* -rwx------+ 1 SYSTEM SYSTEM 5.3K Jun  6 20:31 scalac* -rwx------+ 1 SYSTEM SYSTEM 5.3K Jun  6 20:31 scaladoc* -rwx------+ 1 SYSTEM SYSTEM 5.3K Jun  6 20:31 scalap*   Command is working, but not in the for loop.  $ for f in $(ls | egrep -v .bat); do echo $f; done fsc fsc.bat scala scala.bat scalac scalac.bat scaladoc scaladoc.bat scalap scalap.bat scalac scalac.bat scaladoc scaladoc.bat scalap scalap.bat   DEBUG $ set -x  mike@pc /cygdrive/c/Program Files (x86)/scala/bin $ for f in $(ls | egrep -v .bat); do echo $f; done ++ ls -hF --color=tty ++ egrep --color=auto -v .bat + for f in '$(ls | egrep -v .bat)' + echo fsc fsc + for f in '$(ls | egrep -v .bat)' + echo fsc.bat fsc.bat // and so on


Is there an Extended Backus–Naur form (EBNF) that covers all of English?

Is there an  (Extended Backus–Naur form) that covers all of English, and if so, what is it?


Is there a way to zip all files in a given directory with the zip command? I've heard of using *.*, but I want it to work for extensionless files, too.


Strange side effect between amsmath, hyperref and cleveref

This issue seems rather exotic, but I encountered it in a medium-sized document, and it took me a while to indentify which particular combination of packages was responsible.  When I load amsmath, cleveref and hyperref (implicitly via pdfcomment), ref/autoref to an equation no longer work, i.e., LaTeX throws an Reference ... on page 1 undefined error. See the following MWE:  \documentclass[12pt]{scrartcl}  \usepackage[ngerman]{babel} \usepackage[utf8]{inputenx} \usepackage[T1]{fontenc} \usepackage{lmodern}  \usepackage{amsmath}  %% Hyperlinks %\usepackage[breaklinks]{hyperref} \usepackage{cleveref} %% implicitly loads `hyperref` \usepackage{pdfcomment}  \begin{document}  \section{Test} Etwas Fülltext, bevor die Gleichung kommt: \begin{equation} E_\mathrm{kin} = \frac{m}{2} v^2 \label{eq:kinErg} \end{equation} Jemand fand heraus, dass \autoref{eq:kinErg} gilt.  \end{document}   If I include hyperref explicitly, then everything works except I get . Not a deal breaker, but I'd prefer to avoid it and just use hypersetup for the additional options for hyperref.  Also, if I omit amsmath, everything works, too. I suppose that each package partially overwrites each other's settings...  If this is a bug, then where should I report it?


On sites with new responsive theme, word wrap on long titles breaks in the middle of a word

For sites that have the new responsive theme enabled, where the "Ask Question" button is in line with the question title on question pages, the word wrap on long titles is not working correctly.  It will break a word across two lines.  Here is an  from Personal Finance and Money:  Maximum width, left nav hidden:   Narrow width:   This is also happening on beta sites.  Here is an  on Sports:    These screenshots were all taken on Firefox, but I am seeing the same problems in Chrome and Internet Explorer.  One more example:


Apparently it means there is a dungeon around but I can never find any?  If it does mean dungeons how far away will it trigger?


How do you compare two folders and copy the difference to a third folder?

You've got three folders:   folder current, which contains your current files folder old, which contains an older version of the same files folder difference, which is just an empty folder   How do you compare old with current and copy the files which are different (or entirely new) in current to difference?    I have searched all around and it seems like a simple thing to tackle, but I can't get it to work in my particular example. Most sources suggested the use of rsync so I ended up with the following command:  rsync -ac --compare-dest=../old/ new/ difference/   What this does however, is copies all the files from new to difference, even those which are the same as in old.  In case it helps (maybe the command is fine and the fault lies elsewhere), this is how I tested this:   I made the three folders. I made several text files with different contents in old. I copied the files from old to new. I changed the contents of some of the files in new and added a few additional files. I ran the above command and checked the results in difference.   I have been looking for a solution for the past couple of days and I'd really appreciate some help. It doesn't necessarily have to be using rsync, but I'd like to know what I'm doing wrong if possible.


What is the result of $ \lim_{n \rightarrow \infty} \frac{ 2^n }{ n! } $ and why?

What is the result of the next limit: $ \displaystyle\lim_{n \rightarrow \infty} \frac{ 2^n }{ n! } $  Why (theorem)?


What is an efficient means to serve a dynamic website globally, in terms of latency?

We're using Amazon's AWS infrastructure. At one time, we did have a load-balanced setup across geographic regions, and our database cluster was divided between those regions. To reduce costs for the time being, and to solve some clustering issues we were having, we cut back to using regions inside the US only. Our latency in other regions is now totally horrible.  Using a CDN for assets (images, files) will satisfy our file-serving needs, but our site is extremely dynamic in nature with pages saving data frequently. This is definitely a First World Problem and one that's come about since the advent of AJAX. Surely, we do not need to re-invent the wheel.  Is using other regions in AWS the only option, and will we have to suck up the less-than-desired database clustering issues? Or... is there a better way?  Also, if we went with distinct architecture in each region, i.e. different database, is there an efficient means to keep data in sync between separate clusters. We're using Percona, for the record.


$\lim_{n\rightarrow\infty} \int_n^{n+1}\frac{\sin x}x \, dx$

I am asked to calculate $\displaystyle \lim_{n\rightarrow\infty} \int_n^{n+1}\frac{\sin x} x \, dx$.  Before letting the $\lim$ to confuse me I used integration by parts, but it didn't get me far.  Any hint?


I am converting a GPX file to shapefile using OGR in Python. After converting it to .shp the time field only show 'date' and it excludes the time part. What could be problem in converting.


n=5   for i in {1..$[n]}   do         echo $i   done   it gives:  {1..5}   But I think it should output:  1 2 3 4 5   Why it gives such a strange output?


How to solve for $u(x, y)$ satisfying $u_x + u_y = 1$.

I apologise, since this question does already exist. But I cannot for the life of me understand how it is solved. Could anyone provide me with a simplified version of the solution?


I have been reading quite a lot on the subject in the past hour and I don't seem to be getting an answer, just about amps. I have a 2 watt rated ball valve, and I have a 12v dc 1 amp power supply. W = a * V. So 12 watts power supply? Would it burn out the ball valve?


How to make print() accept the user input in same line?

When i  am tying to take user input in python then it is taking input in next line but I want ti to take input in same line. How to achieve that?   I am taking input like this  print("Enter your name:",end=" ")   It is showing on console as  Enter your name: Ankit   but I want it as  Enter your name:Ankit


Why is there a “problem of time” in Quantum Gravity?

It’s often said that the problem of time exists because time is treated as absolute in quantum mechanics but not so in General Relativity, see e.g. . However Quantum Field Theory merges QM with Special Relativity, which treats time as relative (time dilation, etc). What actually leads to the problem of time in Quantum Gravity?


Adding weird symbol to URL stops PHP line

So basically it is like a PHP game, where you have garage and when you buy cars they go to that garage and there is a list of them in there, also there is a button with url http://localhost/garage?active=58(58 being a car ID.) this button switches car and makes it active, you can race using that car with other people. HOWEVER, when you add a weird symbol to the url (ex.:active=58@) , it deactivates all cars, because php code stuck at:   Here, it does not recognise the car id and stops here:  $setinactive = mysql_query("UPDATE user_cars SET active='No' WHERE userid='$userid' and carid='$activenow'");    When without symbol, it ordinary proceeds to this line and sets choosen id car active:  $setactive   = mysql_query("UPDATE user_cars SET active='Yes' WHERE userid='$userid' and carid='$carid'"); }   I know its bad coding, but is there any simple fix to this?


Can I connect through LAX to PDX without going through quarantine?

California recently issued a 14 day quarantine for preventing the spread of COVID-19. I plan on flying in from a different country, doing immigration and the taking the next flight to PDX. Can I do that and not get quarantined in California? Bonus Question: If I were to fly back from California, can I take my flight out from Cali to my home country without going through quarantine. Say, arrive on day N and then fly out on day N+1 without doing the 14 day quarantine.


Evaluate $ \lim_{n\to\infty} \frac{(n!)^2}{(2n)!} $

I'm completely stuck evaluating $ \lim_{n\to\infty} \frac{(n!)^2}{(2n)!} $ how would I go about solving this?


Derivation of formulas in Doppler‘s effect in light

I was wondering how was the formula for Doppler effect in light i.e. $f=\sqrt{\frac{(1-v/c)}{(1+v/c)}}f$ was derived. I understood how it is derived for sound but I am unable to understand how it is derived for light . I read a few books but they were difficult for me to comprehend.A little hint of derivation would also do.


How can I tell if another instance of my program is already running?

How do i tell if one instance of my program is running? I thought I  could do this with a data file but it would just be messy :(  I want to do this as I only want 1 instance to ever be open at one point.


After nearly two weeks of testing, STM32L MCU suddenly stopped working. It is not recognized by ST-LINKv2 debugger (tried connecting using stlink under Linux and STM's ST-LINK utility under Windows).  MCU power is OK, ground and SWD pins are connected.   I did not do anything special with device when it suddenly stopped working software does not redefine SWD pins device is powered from battery, so do not expect that MCU was burned by some voltage spike MCU was bought from local reseller that seems to have original parts (but not sure) although present on schematic, quartz crystal and capacitors are not soldered. Device is driven from internal clock (HSI).   It seems that MCU is dead. The only explanation that come to my mind is EMI.  Please help to understand what could be the source of problem.


Intersection of nested closed bounded convex sets in Euclidean space

I read that in a complete Euclidean space - i.e. a normed real space with the norm induced by the scalar product - any sequence of nested bounded non-empty closed convex sets has a non-empty intersection, but I can't manage to prove it to myself. Has anybody any ideas or links to online proofs? Context The space is not assumed finite dimensional. At the point where I am in the text, Kolmogorov and Fomin's, they haven't defined a Hilbert space yet. I have not yet learned about the weak topology and reflexivity.


Syntax to transfer from remote to local scp by leapfrogging onto another host?

I am trying to copy files from a remote server to my local server, however, my remote server first requires me to connect to an intermediate host and then leapfrog onto the actual server from there. I am wondering how would I go about copying files from my remote server to my local machine with the scp command using this leapfrogging technique?  So first I have to connect to intermediate server, then from there I want to connect to my actual server.


Restricted logins with automatic full permission in databases

My scenario: I have some groups with full - and inappropriate - access to all Sql Server instances. I want to change that.  My Plan: Give full and automatic access to all databases (it is customer databases and this groups must be allowed to change any property if necessary).  Restrict permissions on Instance Level, because this groups should not be allowed to do any unexpected change on instance properties.  I don't want to create a user in databases, because our external customer could drop the user ( they have db_owner permission )  Someone have any idea? Tks


Flagging a comment on a grayed-out answer is acting weird

When flagging a comment on an answer scored -3 or lower (so it's grayed out), if you move your mouse off of the answer/flag dialog the flag dialog grays out as well and hides under things.    In this example on Puzzling.SE, the bottom of the flag dialog snuck under the spoiler on the answer below. It's a little more drastic when the answer is at the bottom, though, such as in this example on Scifi.SE:    In this case, the flag dialog hides under the place where you write your own answer.  I assume this is not intended behavior.


is ∀x∃y(Lxy) and ∃x∀yLyx provable from each other?

The proof I have is :  $\begin{aligned}1&\ &\forall x\exists yLxy\\   2&\ &\exists y\ \text{(Lay)}\ \forall E_1\\  3&\ &\text{Assume Lab}\\   4&\ & \forall y Lyb\ \forall I_3∀yLyb\\  5&\ &\exists x\forall yLyx \exists I_4\\  6&\ & \exists x\forall yLyx ∃x∀yLyx\ \exists E_2 ∃, 3–5 \\\end{aligned}$  But I don't know if steps 4 and 5 are proper application of the universal and existential introductions.


Declaring javascript object method in constructor function vs. in prototype

In creating javascript objects, I can put a method declaration either in the constructor function or in the prototype.  For example, say I want a Dog class that has a Name property and a Bark method.  I can put the declaration of the Bark method into the constructor function:  var Dog = function(name) {     this.Name = name;     this.Bark = function() {         alert(this.Name + " bark");     }; }   or I could put in as a method on the prototype object:  var Dog = function(name) {     this.Name = name; }  Dog.prototype.Bark = function() {     alert(this.Name + " bark"); };   When I instantiate objects of type Dog, both approaches seem to work fine:    var dog = new Dog("Fido"); dog.Bark();  //Both approaches show "Fido bark"   Should I prefer one of these approaches over the other?  Are there any advantages to using one over the other?  Behind the scenes, do these two approaches end up doing exactly the same thing?  Which approach do most people tend to favor?  Thanks for the help.


Is it possible to add the Rhythmbox volume controls in the Sound Menu?

I can see Rhythmbox pause/play controls in Sound Menu. But I also want the Rhythmbox volume slider controls (as opposed to master volume controls). Is it possible to add them under sound menu or are there any alternatives? (I'm on Ubuntu 12.04). I saw some articles about "Panflute" but it seems to have been abandoned.


Finding the Moment Generating Function of $X^2$ when $X\sim N(0,1)$

If $X\sim N(0,1)$, integrate to find the moment generating function of a random variable $X^2$ and identify the distribution of $X^2$ using the moment generating function. $$E\left[e^{tX^2}\right]=\int_{-\infty}^{\infty}{e^{tx^2}e^{-x^2}\over{\sqrt{2\pi}}}dx$$ which reduces to $$=\frac1{\sqrt{2\pi}} \int_{-\infty}^{\infty}{e^{tx^2}e^{-x^2}}dx =\frac1{\sqrt{2\pi}} \int_{-\infty}^{\infty}{e^{x^2(t-\frac12)}}dx$$ and thus I am stuck. I'm sure there must be some trick to this (like completely the square for the mgf of a standard normal variable X) but I can't figure out what it might be. Any hints?


deleting and------ does it seem strange only to me?

Within a couple of days I could stand, even make two, three steps.   It is the original sentence. And I have a strong belief that the and is deleted as below.     Within a couple of days I could stand, (and) even make two, three   steps.   "And" is deleted, but I do not know why that is possible. This seems to be a very unusual situation to me, because if "even" was not there, this sentence would just sound off to my ear. What's more, "stand" and "make" are two verbs, not adjectives. So what rule or usage makes it possible to delete "and"?


Is there a criterion to differentiate "thriller" from "horror"?

The genres, in my opinion, have a very slim boundary separating one from another. I see a lot of movies being categorized as thriller or horror almost interchangeably, which might seem like lack of thought or criteria. However, is there a true criterion used to differentiate between the two film genres?


Novel about a man who has his car stolen and is cryogenically frozen with his cat?

So this is a bit of a memory game of my behalf, but I'm trying to remember the name of a (presumably) Sci-Fi novel with only a recollection of the following:   A man owns a (yellow?) car parked outside his house along with a cat The car goes missing or is stolen The man decides to be cryogenically frozen for 75 (fairly sure, could be 50?) years along with his cat (I might be muddling up novels but I'm sure there was a cat...?) He takes a walk along the street X years in the future when he wakes up and the currency he has in his pocket is now worthless   I don't think I got that far into the book and all the above happened relatively early.  I read it about 10 years ago and at a guess, it's an 80's novel - all of the above details might be inaccurate, but I'm certain about the cryogenic freezing and the currency aspects.  I'd be surprised if this one gets anywhere!


How to calculate the sum of the infinite series $\sum_{n = 0}^\infty \frac{n}{2^\sqrt{n}}$

How do you calculate the sum of an infinite series like  $$ \sum_{n = 0}^\infty \frac{n}{2^\sqrt{n}}$$  //EDIT  //Ignore  I searched up how to find this with infinite geometric series solution which was  $$\frac{a}{1-r}$$  $a$ being first value and $r$ being common ratio. But I could not find common ratio.   Please give me common ratio of this series.  //Ignore  I have also tried limits like  $$ \lim_{a \to \infty} \sum_{n = 0}^a \frac{n}{2^\sqrt{n}} $$  but they don't actually give me a solid answer.  Correction  Prove this infinite series is convergent.


Trouble removing filestream file / filegroup

My database was originally using filestreams in one table.  For reasons that I won't go into here, we decided to stop using filestreams.  I therefore wrote a migration to copy the filestreamed table into a new table that doesn't use filestream, I dropped the old table and renamed the new table.  All good so far.  Now I want to drop the filestream file and filegroup.  And SQL server won't let me:     The file 'MyFilestream' cannot be removed because it is not empty.   I ran the following query:  select * from sys.tables t  join sys.data_spaces ds on t.filestream_data_space_id = ds.data_space_id  -- and ds.name = 'MyFSGroup'   Even commenting out the ds.name filter, I get zero records back.  Like , I ran this query:     exec sp_helpfilegroup 'MyFSGroup'   and got back:  groupname    groupid    filecount ---------    -------    --------- MyFSGroup    2          0   I've Googled all over for solutions and workarounds.  So far as I can tell, there is no table anywhere in the database that is still using this file - but I still cannot drop it.  I have tried restarting the SQL service, too, but it's not to be fooled.  How do I find out what is still using the filestream file, and how do I drop it?  EDIT: ooh, here's a thought: the database has "Full" recovery model.  Could that have something to do with it?


Bash aliases/functions and command line options

I want to set an alias to start nedit together with command line option -noautosave (due to text files up to 500MB). What seemed to be easy:  alias nn="nedit -noautosave $1 &"   just raises some error "Permission denied" of a different file and another error about unexpected EOF while looking for matching "'" and "unexpected end of file".  One solution I found after a Google Search would be to check the quotes, but I can't see any possible errors with them.  I also tried declaring a function:  function nn () { nedit -noautosave $1 &}   which also failed with same errors.


Phishing site uses subdomain that I never registered

I recently received the following message from Google Webmaster Tools:     Dear site owner or webmaster of ,      [...]      Below are one or more example URLs on your site which may be part of a   phishing attack:            [...]   What I don't understand is that I never had a subdomain repair.gotgenes.com, but visiting it in the web browser gives an actual  My DNS is , which does not list a repair subdomain. My domain name is registered with GoDaddy, and the nameservers are correctly set to NS1.AFRAID.ORG, NS2.AFRAID.ORG, NS3.AFRAID.ORG, and NS4.AFRAID.ORG.  I have the following questions:   Where is repair.gotgenes.com actually registered? How was it registered? What action can I take to have it removed from DNSs? How can I prevent this from happening in the future?   This is pretty disconcerting; I feel like my domain has been hijacked. Any help would be much appreciated.


Why am I required to do something to first time posts?

What is required from me in reviewing a post? There is a similar question on    I clicked on  and see many first time posts. I see I have 2 options:    I'm done  Not sure.    I'm done is grayed out. I don't understand why as this actually now forces the post to be edited or voted up when in many cases neither of these are applicable.   So, I guess by voting up is a good way to start - it rewards new posters for good questions and makes them feel welcome - and what happens -- I'm limited to X number of votes a day (up voting and down voting). Currently there are 2.1k posts on Super User which need reviewing and with these limitations I expect it will take some time (although I use Super User, it's applicable to all sites on SE).   I don't think writing a comment saying 'well done for a good post' is useful either for future visitors (IMO it also may impact SEO but we won't discuss that here) but it adds 'noise'.  Any thoughts on this, have I missed the point?


I’m using Git in Android Studio 4.0.1 for the first time since I have learned Git. Initially I have 2 branches (master and dev) First I made a commit in master. Then I created a new dev branch and checkout in dev, I added a new file without committing it When I switch to master I expect not to see the new file created in dev inside the Android project view of the master branch. Seems that if I commit in dev then correctly isn’t in master. Why I continue to see it before committing ? Thanks all.


I am running an application which needs to be restarted everyday. I am noticing that when I close this application and I run "free -m" It says:             total       used       free      shared       buffers        cached  Mem:      1009        863        146       0            16             815  -/+ buffers/cache:    31         978 Swap:     0           0          0   How come I only have 146mb free? It is the only application I am running and when I restart the whole system I have 980mb free.


Number of ones in Binary matrix multiplication

Consider a binary matrix $\mathbf A_n$ corresponding to values $0$ to $2^n-1$ where each row represents a length $n$ binary representation of a real number. For example, for $n=3$ we have  $\mathbf A_3=\begin{bmatrix}      0   &  0   &  0\\      1    & 0  &   0\\      0   &  1  &   0\\      1   &  1   &  0\\      0   &  0  &   1\\      1  &   0   &  1\\      0   &  1  &   1\\      1  &   1    & 1 \end{bmatrix}.$  Consider two arbitrary non-zero binary vectors $\mathbf v_1, \mathbf v_2$ of length $n$ (column vector) such that $\mathbf v_1\neq\mathbf v_2$. Now, assume $\mathbf u_1=\mathbf A\mathbf v_1$ (mod $2$) and $\mathbf u_2=\mathbf A\mathbf v_2$ (mod $2$) . I can verify for an arbitrary $n$ that $\mathbf u_1.^*\mathbf u_2$ (element-wise multiplication) has always $2^{n-2}$ ones. For example, for $\mathbf A_5$ and $$ \mathbf v_1=\begin{bmatrix}0,\ 0,\ 1,\ 1,\ 1\end{bmatrix}^T, \mathbf v_2=\begin{bmatrix}0,\ 1,\ 0,\ 0,\ 0\end{bmatrix}^T $$ We have  $$ \mathbf u_1.^*\mathbf u_2=\begin{bmatrix} 0\     0\     0 \    0 \    0  \   0\     1 \    1\     0 \    0 \    1  \   1 \    0  \   0 \    0  \   0 \    0 \    0\     1\  1\     0 \    0  \   0\     0 \    0\     0 \    0 \    0 \    0 \    0\     1\     1\end{bmatrix}^T $$ of length $2^5$ which has $2^{5-2}=8$ ones. I am looking for an analytical way to prove this.


Where should the balance be between reputation of a question, and the jugment of high rep users and mods when in comes to deleting it?

I'm mostly active in Matlab related questions, and recently I checked the highest votes for that tag (disclaimer, I have a high ranking question there too). I have found that the #1 question:  was deleted. Now, I know and fully respect some of the users that gave the vote to delete, they are prominent people etc, but I still try to understand the following. When a question receives +139 votes, a record number for the matlab tag (I confess that I actually down-voted it), and also got 13 answers (with +129 votes the highest) with ~60K views, should a handful of individuals like myself and  more privileged user (like a moderators) be enough to delete it? Where's the weight of the many many peoples that up-voted it?  In this example, the question was first closed by a moderator for being not constructive (which I also agree with it, albeit many people thought otherwise). So far so good, there will be no more activity in that question. However, now that it is deleted, I started thinking whether this might miss the less formal side of SO, where users discuss broader issues. What should be the balance in your view?


How can I remove DisplayPort from audio devices?

When I connect my external monitor it shows up in the audio settings.   That makes zero sense, as this monitor does not have any speakers.  How can I prevent it from popping up as an audio output option?


Help, how can I show that [G: M] is finite and prime.

Let $M$ be a maximum subgroup of $G,$ that is, a proper subgroup of $G$ such that the only subgroups of $G$ that contain $M$ are $M$ and $G.$ It shows that if $M\underline{\lhd}G$ then $[G:M]$ is finite and prime.


Bijection between finite and infinite sequences over Reals.

So define the set of finite sequences to be $S={a_1,a_2,\cdots}$ where $a_k$ are in real numbers and only finitely many of them are non-zero. The set of infinite sequences is defined similarly except that we can have infinitely many non-zero terms. How do I prove that there does not exist a bijection between these two sets?


How to imagine the electromagnetic waves?

I've learned at school, that the electromagnetic radiation consists of photons. And all the frequencies of the wavelengths of photons define electromagnetic spectrum. The lower wavelengths are ionizing radiation. In the middle of the spectrum there is the visible light, and above that infrared, microwave, and radio waves.  But the thing nobody told me, is that: How is it possible to imagine a wave? I don't think, that the photon is physically moving sideways, and that is called the waving. But what is it then?  The explanation of the wavelength is, that it is a spatial period of the wave—the distance over which the wave's shape repeats. But what is this wave exactly? How can a single photon has it?


I accidentally deleted the /usr/bin directory. Using a bootable usb, is it possible to rescue my machine?


I'm writing a short story and was wondering which sentence is grammatically correct.      We lived in a cul de sac.   Or     We lived on a cul de sac.


Prime elements in $\mathbb{Z}/n\mathbb{Z}$

I'm tring to determine the prime elements in the ring $\mathbb{Z}/n\mathbb{Z}$.


Basically the title. The wavelength of light from the CMBR has expanded as the universe expanded and so it has lost energy since it is inversely proportional to the wavelength. Where did this energy go? It may have been asked before but I couldnt find it...


Why is the output different in both cases comparing floats

PYTHON PROGRAM:  a = 0.2 if a == 0.2:     print('*')   OUTPUT:  *   C PROGRAM:  #include <stdio.h>  int main(void)  {     float a = 0.2;     if(a == 0.2)     {         puts("*");     } }   OUTPUT:     Why is the output different in both cases? Is there a difference between the working of == operator?


Is it possible to get the exact Python code corresponding to a specific run of a tool in ArcToolbox? The reason I ask is that I want to replicate the function in a Tool in Python, and adapt it to my needs. I have tried some md tool for ncdf, which works in the GUI but not in python if I write the Python code by hand.