Does Linux have the capability to use "junctioned" symbolic links? I'm not sure if this is an actual term or not, so let me explain the concept.  I have a git repository containing all my configuration dot files in ~/dotfiles. I use symbolic links into this directory in order to "activate" them. For example, by executing ln -s ~/dotfiles/bash/bash_profile ~/.bash_profile to produce the link:  ~/.bash_profile -> ~/dotfiles/bash/bash_profile   However, I find myself in a situation where I want to combine the contents of multiple files. For example, I want the ~/.bash_profile symbolic link to point to two separate files, one for each project. E.g.:  ~/.bash_profile (1) -> ~/dotfiles/bash/bash_profile (2) -> ~/dotfiles/proj/bash_profile   I know I can simply concatenate the two files (e.g., cat ~/dotfiles/{bash,proj}/bash_profile > ~/.bash_profile), but if I can do the same thing with symbolic links, I would prefer to.  I imagine that if such a feature exists (Nix is pretty huge), then under the hood it would have to map the two different files together, hiding all sorts of complexities under the hood (mapping file offsets of all non-first "mapped" files, locking all files when writing to the junctioned symbolic link, etc, etc).  If such a feature doesn't exist, are there are plans to implement it?

Is there a way of creating a filesystem object akin to this:  mknod files p cat file1 file2 ... fileN > files   but such that it can be seeked in, as if it were a regular file?


I wonder how async call works when looping through html elements with jquery. I know that async call doesn't stop iterating when server call is being made. That means, script is immediately iterating over next element in sequence, even if response from call is not yet finished.  My problem is, that on each call I have different values set, like this:  $(".businessUnit").each(function (index) {       var $element = $(this);       var iUCBU_KEY = $element.prop('data-iucbu_key');       var iENTE_KEY = $element.prop("data-iente_key");  $.ajax({       method: 'post',       url: '/CodeBase/LoadInsertCATETE_BASE1/',       data: {         iUCBU_KEY: iUCBU_KEY,         iENTE_KEY: iENTE_KEY       },       success: function (response) {         //will there be $element from sequence when call was made?           $element.find('input.price').val(response.price);        },       error: function (response) {        }     });       });   Which $element will be updated? Will it be $element from which call was made or $element in which iteration is currently? Response from server can take a few seconds, so iteration can go several elements further in between call - response.

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


In Wireframe and Solid view modes, there's this "cone" of visibility that extends out from one of the cameras and clips all the objects in the scene:  It does not move at all when I switch cameras or move the camera. I've tried clearing the camera border but it had no effect. It doesn't appear in Material Preview or Rendered modes. How did this show up, and how can I make it go away?

When looking at my objects in 3d view I'm seeing a gray cone that seems to be hiding other objects.   Can anyone help me turn this off and explain what it is please.  Screenshots attached.


I was watching Hawking (2004 film) and in the movie, Hawking has a sudden insight that all the matter and energy observed in the known universe may, in fact, have sprung out from nothing (singularity) during the Big Bang event—an insight which later on goes to become the main subject of his thesis.  But this completely flies in the face of the laws of conservation of matter and energy. What gives?

Did the law of conservation of energy apply to the earliest moments of the Big Bang? If so, what theoretical physics supports this?   I hear that Einstein's theory of relativity disputes the law of conservation of energy- so does that mean the law is false, or only some aspect of it?


I was working on this project, and out of the blue, when I right click, Blender crashes. It only happens in this project, and I'll attach the project.I'm fairly new to Blender. This started occurring after a test render

Essentially, my problem is that i am trying to render a scene, however, blender crashes on me early during the render. I only have about 14 total objects in the scene. (It's not that complex) I tried to render a different blender file which was bigger than the one that i am having problems with, and the scene renders just fine. There is no difference in the render presets for both of these files. However, i still cannot render the other scene. It gets to preparing scene data, but then it crashes.  Thank you.


we  know that new Instance()  subclass in java , the first recursive call will be the parent class constructor,If the parent class is an abstract class,will be Calling its constructor? if this true ,Means that the parent class will be instantiated？ But the abstract class can not be instantiated,Who can explain this question. Thank You.

Can an abstract class have a constructor?  If so, how can it be used and for what purposes?


Is this better to have 2x2gb DDR3 RAM in both of the slot or single 4GB DDR3 RAM in single slot in laptop? Which way is right to increase my laptop perfromances, what should I do for best and fast performances?

I'm building a Core  system which supports dual-channel memory (up to 16 GB in four DIMMs), my target is 8 GB. From the performance perspective, is it better to have two times 4 GB or four times 2 GB?


I’d like to prove:     Let $G$ be a group and $m,n$ two relatively prime numbers. If $x^my^m=y^mx^m$ and $x^ny^n=y^nx^n$ for all $x,y\in G$, then $G$ is abelian.   Thanks for help in advance.

Let $(G,.)$ be a group and $m,n \in\mathbb Z$ such that $\gcd(m,n)=1$. Assume that $$ \forall a,b \in G, \,a^mb^m=b^ma^m,$$ $$\forall a,b \in G, \, a^nb^n=b^na^n.$$  Then how prove $G$ is an abelian group?  Some context: Some of these commutation relations often imply that $G$ is abelian, for example , or . This looks like another example of this phenomenon, but the same techniques do not apply.


If not, then what's the minimum? I have seen an 800 watts setup but I guess that's too much.

Note: This is intended to become a canonical post.  I got a dedicated graphics card of type XXX and it claims I need at least a YYY Watt PSU.   How big does my PSU really need to be?


I use 17.04 and rc.local is gone(I couldn't do it with rc.local anyway).  I just want this two commands to run at the startup;  cd Folder python3 file.py   That's it. I looked all the similar answers here but I couldn't make it.  Thank you so much!

How can I run scripts automatically when Ubuntu starts up so I don't have to run them manually after startup?


just wondering how to sum stereo to mono signal? I am aware that you can use resistors in series to the left and right outputs of say a Bluetooth receiver module but when i do this, the channel does sum but the quality is horrendous on the high frequencies, sounds like a low bit rate mp3? Does anyone have a solution to this? The parts that i am using is a sure 30watt mono amp, and a sure Bluetooth receiver module 4.0 aptx etc... Thanks i would really appreciate this as i have been pulling my hair on this speaker build

this is my first question and I am very much a beginner in electronics so I apologize if this is a too stupid question.  I have Atari punk console and another small homemade audiomaking circuit. These two have mono audio signals as outputs and I would like to combine these as one in the simplest possible way. I know next to nothing about audio processing but I believe that the strength of the two signals is roughly the same.  What would a neat solution be? It would be really nice if I could extend the solution later on to more than just two signals but thats not really important.  Any hints, references, guides, links or ideas would be highly appreciated.


In diatomic lattice vibration, acoustical phonons correspond to vibration. But I could not understand the relevance of term optical in this context.

Why do we have two different types of phonons, ? Why are they called optical phonons?


Explanation of what I'm trying to communicate:  Suppose that there is an object, Vinegar (say).  And we're marinating chicken before roasting it. If vinegar was added to the marinade then the roast turns out to be good. If it wasn't, then it's going to be smelly and "rubbery".  Now let's say that I didn't know this and some person X found out about the requirement of vinegar and informed me.  My sentence:  "Today, I added a new ingredient, Vinegar, in the marinade, whose absence causes chicken to be smelly, found by person X".  Is the above sentence correct? It feels somewhat off. I have 2 queries regarding this:  1) Is the phrase "whose absence" correct? If not then what other phrase can we use in its place?  2) Is there a better way to frame this whole sentence rather than breaking it into smaller sentences (for the sake of improving grammar)?

We lit a fire whose fuel was old timber wood.   Is the word whose referring to fire, an inanimate object, correct in this sentence? Or is there a more appropriate word?


$$ \lim_{(x,y)\to(0,0)}{\frac{x^2y}{x^2+y^2}} $$  If you substitute in $(0,0)$ for $x$ and $y$. It becomes $$ \frac{0}{0} $$ usually you would apply the L'Hopital's rule. However, I think it is not possible with the multivariable equation.  If I cannot apply the L'Hopital's rule here, what should be my first step in solving this limit?

Could anyone help me with this  Find $$\lim_{(x,y) \to (0,0)} \frac{3x^2y}{x^2+y^2}$$ if this limit exists  I tried using the squeeze theorem, but I could not find a suitable expression for the squeeze theorem as I could not find any number that allow me to squeeze the limit in between and cancel the denominator


I am inserting data in database dynamically without assigning column in code. This works fine if I don't bind. But, when I tried to bind, it doesn't work    Working fine      $id = $_POST["id"];     $text = $_POST["text"];       $column_name = $_POST["column_name"];       $result = $con->query("UPDATE menu SET $column_name=$text WHERE id=$id") OR die($con->error);       echo "Data updated";   But it doesn't work.  $result = $con->prepare("UPDATE menu SET :column_name=:text WHERE id=:id")or die($con->error);             $result->bindparam(':id',$_POST['id']);             $result->bindparam(':text',$_POST['text']);             $result->bindparam(':column_name',$_POST['column_name']);             if($result->execute()){                 echo "Data Updated";             }

Why can't I pass the table name to a prepared PDO statement?  $stmt = $dbh->prepare('SELECT * FROM :table WHERE 1'); if ($stmt->execute(array(':table' => 'users'))) {     var_dump($stmt->fetchAll()); }   Is there another safe way to insert a table name into a SQL query? With safe, I mean that I don't want to do  $sql = "SELECT * FROM $table WHERE 1"


I am using Ubuntu Desktop 14.04 LTS on an Acer Aspire-5742G with Intel Core i3 processor, 8 GB RAM, 640 GB HDD and nVidia GeForce 520M with 1GB memory.  I ran BleachBit with sudo permissions form the terminal. In the GUI that opened I checked all of the features in the left panel of the program, except those for which the system said they would take a long time to perform. I noticed that it deleted some files from the system folders, but I ignored that. After that I did a   sudo apt-get update && sudo apt-get upgrade   and I rebooted my system.  Immediately after I logged in I got a black screen and the only thing I could do was to open a console by pressing Ctrl+Alt+F1. I pressed Enter, it asked me for my log in credentials. Then I typed in DISPLAY and got the following error:  Cannot start X server - error/display.c/DisplayImageCommand/428   Please tell me what sequence of commands should I enter to fix this. If you need additional information, please ask. Although, I am still able to log in from the guest account.  Thank you in advance!

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I know is not possible to send a personal message to another user. What I would like to do would be to inform a user that I am rolling back an edit he made and explain him the reasons for doing so. But in this specific case, the user didn't write any comment or answer to the question, so I do not have a way to communicate with him. Is it possibly to send a message to a user who edited a question / answer?  Note: I know there exists .

How do the comment replies (aka "pinging users") work?  Who can I send an @reply to? How do I respond to a specific user when entering my comment? Will they be notified? What do people mean when they talk about "pinging" another user?  Related:


I have class date which just simply creates an arrayList of days of the week.  import java.util.*;  public class Date {      public static final String[] daysofTheWeek = {"Mon" , "Tue" , "Wed" , "Thurs" , "Fri" , "Sat" , "Sun"};     private String dayofweek;     private int day;     private int month;      public int getDate() {         return this.day;     }      public int getMonth() {         return this.month;     }      public Date(String dayofweek, int day, int month) {         this.day = 1;         if (day >= 1 && day <= 31) {             this.day = day;         }          this.month = 12;         if (month >= 1 && month <= 12) {             this.month = month;         }          this.dayofweek = "Mon";         if (isValidDOW(dayofweek)) { // why is this in the parameters?             this.dayofweek = dayofweek;         }     }      // must validate is DOW      //  TRUE/FALSE is the day of the week matching?     public boolean isValidDOW(String d) {     for (int i = 0; i < dayofweek.length(); i++)         if (d.equals(daysofTheWeek[i])) { // why i?             return true;         }         return false;     }      // to string     public static String monthToString(int i) {         switch(i) {             case 1: return "January";             case 2: return "Feb";             case 3: return "March";             case 4: return "April";             case 5: return "May";             case 6: return "June";             case 7: return "July";             case 8: return "August";             case 9: return "September";             case 10: return "October";             case 11: return "November";             case 12: return "December";             default: return "Invalid Month!!";         }     }      public String toString() {         return this.dayofweek + "," + Date.monthToString(this.month) + " " + this.day;     }      public String getDayOfWeek() {         return this.dayofweek;     } }   Now I am trying to get all days ( Say, return number of times sundays pop up). I tried using a loop to go through and count everything, but I am getting a null pointer exception. I've been looking at this for a while, and can't figure out whats wrong with it. Can anyone guide me in the right direction?  import java.util.*; /**  * ArrayList example  */ public class Calendar {      private ArrayList<Date> Schedule;      public ArrayList<Date> sundays(String dayofweek) {         ArrayList<Date> app = new ArrayList<Date>();         for (Date entry : Schedule) {             String d = entry.getDayOfWeek();             if (entry.getDayOfWeek() == dayofweek) {                 app.add(entry);             }             else if (app.size() == 0) {                 return null;             }         }         return app;     } }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I have a VPS with ubuntu linux on it.  $ ssh ghopper@XXX.XXX.XXX.XXX ghopper@XXX.XXX.XXX.XXX password:  Welcome to Ubuntu 16.04.5 LTS (GNU/Linux 4.4.0-134-generic x86_64)   * Documentation:  https://help.ubuntu.com  * Management:     https://landscape.canonical.com  * Support:        https://ubuntu.com/advantage New release '18.04.1 LTS' available. Run 'do-release-upgrade' to upgrade to it.  Last login: Wed Sep 19 16:52:58 2018 from 178.140.210.120 ghopper@114744:~$ env  LC_PAPER=ru_RU.UTF-8 XDG_SESSION_ID=409 LC_ADDRESS=ru_RU.UTF-8 LC_MONETARY=ru_RU.UTF-8 TERM=xterm-256color SHELL=/bin/bash SSH_CLIENT=XXX.XXX.XXX.XXX 51616 22 LC_NUMERIC=ru_RU.UTF-8 SSH_TTY=/dev/pts/0 USER=ghopper LC_TELEPHONE=ru_RU.UTF-8 MAIL=/var/mail/ghopper PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games LC_IDENTIFICATION=ru_RU.UTF-8 PWD=/home/ghopper LANG=en_US.UTF-8 LC_MEASUREMENT=ru_RU.UTF-8 SHLVL=1 HOME=/home/ghopper LOGNAME=ghopper SSH_CONNECTION=XXX.XXX.XXX.XXX 51616 XXX.XXX.XXX.XXX 22 XDG_RUNTIME_DIR=/run/user/1000 LC_TIME=ru_RU.UTF-8 LC_NAME=ru_RU.UTF-8 _=/usr/bin/env ghopper@114744:~$ tail -n 16 ~/.bashrc function color_my_prompt {     local __user_and_host="\[\033[01;32m\]\u@\h"     local __cur_location="\[\033[01;34m\]\w"     local __git_branch_color="\[\033[31m\]"     local __git_branch='`git branch 2> /dev/null | grep -e ^* | sed -E  s/^\\\\\*\ \(.+\)$/\(\\\\\1\)\ /`'     local __prompt_tail="\[\033[35m\]$"     local __last_color="\[\033[00m\]"     export PS1="$__user_and_host $__cur_location $__git_branch_color$__git_branch$__prompt_tail$__last_color " } color_my_prompt  export IGNOREEOF=10  export LC_CTYPE=en_US.UTF-8 export LC_ALL=en_US.UTF-8   The problem is that there aren't colors in the terminal. At all!  But, after I run /bin/bash they appears.  ghopper@114744:~$ /bin/bash ghopper@114744 ~ $ env LC_PAPER=ru_RU.UTF-8 LC_ADDRESS=ru_RU.UTF-8 XDG_SESSION_ID=409 LC_MONETARY=ru_RU.UTF-8 SHELL=/bin/bash TERM=xterm-256color IGNOREEOF=10 SSH_CLIENT=XXX.XXX.XXX.XXX 51616 22 LC_NUMERIC=ru_RU.UTF-8 SSH_TTY=/dev/pts/0 LC_ALL=en_US.UTF-8 USER=ghopper LS_COLORS=rs=0:di=01;34:ln=01;36:m ... 0;36:*.xspf=00;36: LC_TELEPHONE=ru_RU.UTF-8 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games MAIL=/var/mail/ghopper LC_IDENTIFICATION=ru_RU.UTF-8 PWD=/home/ghopper LANG=en_US.UTF-8 LC_MEASUREMENT=ru_RU.UTF-8 PS1=\[\033[01;32m\]\u@\h \[\033[01;34m\]\w \[\033[31m\]`git branch 2> /dev/null | grep -e ^* | sed -E  s/^\\\\\*\ \(.+\)$/\(\\\\\1\)\ /`\[\033[35m\]$\[\033[00m\]  HOME=/home/ghopper SHLVL=2 LOGNAME=ghopper LC_CTYPE=en_US.UTF-8 SSH_CONNECTION=XXX.XXX.XXX.XXX 51616 XXX.XXX.XXX.XXX LESSOPEN=| /usr/bin/lesspipe %s XDG_RUNTIME_DIR=/run/user/1000 LESSCLOSE=/usr/bin/lesspipe %s %s LC_TIME=ru_RU.UTF-8 LC_NAME=ru_RU.UTF-8 _=/usr/bin/env   How can I get colored terminal by default?

When I connect over ssh to remote hosts everything is just a single font/color. I would like to have colours like I do locally e.g. green for executable and blue for symlinks etc. And such that when I run $ git diff on the ssh host it shows me diff with colours =)


I want to copy the text from function parameter, with other text after it  I tried making textarea element for only read and hide it,and put text in it but it didn't work    function Copy(str) {   const AllWord = str + "

Copied From HERE";   var el = document.createElement('textarea');   el.value = AllWord;   el.setAttribute('readonly', '');   el.style = {     position: 'absolute',     left: '-9999px'   };   document.body.appendChild(el);   el.select();   document.execCommand('copy');   document.body.removeChild(el); }  Copy("CopiedText");     I expect it to copy "CopiedText"

What is the best way to copy text to the clipboard (multi-browser)? I have tried: function copyToClipboard(text) {     if (window.clipboardData) { // Internet Explorer         window.clipboardData.setData("Text", text);     } else {         unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");         const clipboardHelper = Components.classes["@mozilla.org/widget/clipboardhelper;1"].getService(Components.interfaces.nsIClipboardHelper);         clipboardHelper.copyString(text);     } }  But in Internet Explorer it gives a syntax error. In Firefox, it says unsafeWindow is not defined. A nice trick without using :


We know that when light passes through a black hole it bends. But I couldn't understand why? As light is composed of photons and we know that photons are massless, we also know that gravity and mass relation, .      How can photons experience gravity? What is making them to bend their path?   What I thought (may be pure nonsense) is due to the nature of spacetime itself, which decides the trajectory around the black hole. Not exactly the mass affected by gravity. This is how I explained it to myself or convinced myself. But I have no background to defend it.  Forgive me, I have no background in GR (General Relativity). If this can be answered more on physical ground without invoking more maths(little or most necessary maths is good).(How to explain this to Ist year undergrad, if he/she ever ask me?)

Light is clearly affected by gravity, just think about a black hole, but light supposedly has no mass and gravity only affects objects with mass.  On the other hand, if light does have mass then doesn't mass become infinitely larger the closer to the speed of light an object travels. So this would result in light have an infinite mass which is impossible.  Any explanations?


I would like to know if Java code is decompilable? Because I am doing an app for Android and i'm wondering if using the mysql connector is safe or not?  Talking about the java code into an android application.  Thanks for your answers.

What program can I use to decompile a class file? Will I actually get Java code, or is it just JVM assembly code?  On Java performance questions on this site I often see responses from people who have "decompiled" the Java class file to see how the compiler optimizes certain things.


I am looking for a package to monitor bandwidth consumed by one particular app, e.g., the data of a Zoom meeting. i need to track that consumption. Can someone suggest any software that you know.

Is there a graphical data counter for Ubuntu that records how much uploaded/downloaded data was used and bandwidth being used and total amounts, filtering it by application?


For example, in "to see", what part of speech is "to"?

Reopen note:  There is a quite finite and modest amount of evidence in the literature about this issue, which members can record here as they see fit. Less than there is for example about what a noun is or what a verb is, or how to tell what the Subject of a sentence is. It's a simple question, that people need to be able to get answered on a site such as this. It is of continuing interest as more recent questions such as  attest to. The fact that people disagree about the outcome of the evidence does not mean that there is too much evidence to be documented. Quite the reverse. They disagree because there is relatively little evidence altogether. However, it is seriously interesting evidence.   The question   What part of speech is to as in:   I need to know. To err is human, to forgive divine. What am I to do?   This question is not really about the difference in meaning between the examples. It is a question about what grammatical or syntactic reasons we have to classify this item as a particular part of speech. If arguing that it is 'its own part of speech', I'd like to know what grammatical - but not historical - reasons you have for your claim.   Just to clarify, I'm not asking about what assignment any particular authority or publication gives it. I'm interested to know the reasons why. Your own personal insights are also very welcome.  If you're a grammar anorak - like me - then you may want a list of the contenders out there from other grammarians. In no particular order:   preposition subordinator non-finite auxiliary verb modal verb inflectional element   Can you help?


Below is the command I'm running grep -i -e "useCss()|useXpath()" abc.txt  abc.txt contains below text .useCss() .useXpath()  I'm getting output blank but when I run one by one without pipe its giving the output. grep -i -e "useXpath()" F:\abc.txt  output .useXpath()  Similarly I can get output for useCss but when I try to run both them in an or condition it returns null, could someone please help me what's wrong? Thank You!!

I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I want to know how to protect my website from hacker. I am a php-mysql developer. For fetching data from database i always use mysqli. For prevent my website from sql injection i always use  $db->real_esacpe_string() function of php. For prevent my website from XSS(Cross site scripting) i used this function  function parsing($text) { global $db;         $text=$db->real_escape_string($text);  $text= @trim($text);        $text= strip_tags($text);  if(get_magic_quotes_gpc()) {             $text= stripslashes($text);         }     $text=str_replace('<','',$text);     $text=str_replace('>','',$text);           $text=htmlspecialchars($text, ENT_QUOTES, 'UTF-8');     return($text); } $name=parsing($_POST['name']);   Any suggestion from your side is welcomed. Thanks in advance.

If user input is inserted without modification into an SQL query, then the application becomes vulnerable to , like in the following example:  $unsafe_variable = $_POST['user_input'];   mysql_query("INSERT INTO `table` (`column`) VALUES ('$unsafe_variable')");   That's because the user can input something like value'); DROP TABLE table;--, and the query becomes:  INSERT INTO `table` (`column`) VALUES('value'); DROP TABLE table;--')   What can be done to prevent this from happening?


I'd like to compress some files for http distribution, but found that .tar.gz keeps the user name and user ID and there doesn't seem to be any way to not do that? (There is a --numeric-owner option for tar which seems to ignore the user name, but still keeps the user ID.)  Doesn't that mean that .tar.gz is a poor choice for file distribution as my system probably is the only one with my user ID and my user name? Is .7z a better format for file distribution, or do you have any other recommendation?

I have a tarball and the files it contains do not have the right user and group ownership. Files are owned jenkins:jenkins and I'd like them to be owned naftuli:othergroup.   Is there a way for me to edit the tarball in place so that the files it contains become owned by naftuli:othergroup?   The problem I'm facing is that at the time of the tarball creation, the jenkins user doesn't have permissions to chown things to different users and groups. At the time of extraction, I will have permissions to create those files as the users mentioned, so I need to edit the user ids and group ids within the tarball.


Getting c:/mingw/bin/../lib/gcc/mingw32/8.2.0/../../../../mingw32/bin/ld.exe: main.o:main.cpp:(.text+0x2b): undefined reference to (insert my methods in ComplexNumber.cpp) when compiling using a makefile after the G++ main.o ComplexNumber.o -o output is being ran.  I have tried checking online for places I may have missed a  and used my other header files I have done in the past for reference to check for errors there, but I have had no luck. I am using cygdrive on windows to compile, but have also tried just using mingw on regular command prompt as well.   Header File: '''''''''''''  #include <stdio.h>   #ifndef COMPLEXNUMBER_H_ #define COMPLEXNUMBER_H_    template<typename T>  class ComplexNumber {      public:         // a is a real number, b is a complex number         T a;         T b;         ComplexNumber();         ComplexNumber(T, T);         void toString();     ComplexNumber operator +(ComplexNumber<T>& c);     ComplexNumber operator *(ComplexNumber<T>& c);     bool operator ==(ComplexNumber<T>& c); };    #endif /* COMPLEXNUMBER_H_ */   ''''''''''''''  ComplexNumber.cpp ''''''''''''''  #include <iostream> #include <stdlib.h> #include <ctime> #include "ComplexNumber.h"   using namespace std;   template <typename T>      ComplexNumber<T>::ComplexNumber()     {} template <typename T> ComplexNumber<T>::ComplexNumber(T a, T b) {     this->a = a;     this->b = b; } template <typename T> ComplexNumber<T> ComplexNumber<T>:: operator +(ComplexNumber& c) {     ComplexNumber <T> temp;      // adds the complex numbers, (a+bi) + (c+di) = (a+b) + i(c+d)     temp.a = this->a + c.a;     temp.b = this->b + c.b;     return temp; } template <typename T> ComplexNumber<T> ComplexNumber<T>:: operator *(ComplexNumber& c) {     ComplexNumber<T> temp;      // multiplies complex numbers, (a+bi) + (c+di) = (a*c-b*d) + i(a*d + b*c)     temp.a = (this->a * c.a) - (temp.b * c.b);     temp.b = (temp.a * c.b) + (temp.b * c.a);     return temp; } template <typename T> bool ComplexNumber<T>:: operator ==(ComplexNumber<T>& c) {     ComplexNumber<T> temp;      // compares complex numbers to see if they're equal, (a+bi) == (c+di) -> if (a==c) & (b==d)     if (temp.a == c.a && temp.b == c.b)     {         cout<< "The complex numbers are equal."<<endl;         return true;     }     return false; } template <typename T> void ComplexNumber<T>::toString() {      cout<< "("<< this->a<< " + "<< this->b<< "i)"<<endl; }   MakeFile: ''''''''''''''  all: ComplexNumber ComplexNumber: main.o ComplexNumber.o     g++ main.o ComplexNumber.o -o output main.o: main.cpp     g++ -c main.cpp ComplexNumber.o: ComplexNumber.cpp     g++ -c ComplexNumber.cpp clean:     rm *.o output   ''''''''''''''

Quote from :     The only portable way of using templates at the moment is to implement them in header files by using inline functions.   Why is this?  (Clarification: header files are not the only portable solution. But they are the most convenient portable solution.)


From what I understand, if I get insurance from my work the amount I pay is pre-tax (correct?).  Is there any way for my work to allow me to purchase my own insurance on the exchange with money that is pre-tax?  At a previous job I had used a cafeteria plan to pay for certain medical expenses pretax.  Could something like this be used to purchase healthcare on the exchange?

I would like to continue paying for health insurance with pre-tax dollars.  But, according to , buying healthcare through the Affordable Care Act (Obamacare) requires post-tax dollars.   Is the article accurate, or can I continue to use pre-tax dollars to pay for health insurance?


I have 2 disks: one with Windows and second split into 2 partitions, on one I have Ubuntu and on the second one I have some more space for Windows' files. I've accidentally deleted all Windows' files: both from disk with main system and partition from other and I want to recover them. Using this:  I found out that all or most of the files are still there and I can recover them (well, I haven't written anything on them after deletion so it should be this way I guess), but I wonder if I could recover whole Windows. It would be nice as I don't have Windows key at the moment and need Windows a bit. After some research I've found TestDisk, but I'm not sure if I can recover it with this and how.

About two weeks ago I had a problem with my PC that my brother wrote a question about at .  I still haven't solved the problem, so my PC is unusable now.  Now I think that it would be simpler to re-install both Win7 & Ubuntu than repair them, but there're some data on their partitions. I want to recover this data.  These partitions are not mountable for some reason. I don't know why.  sudo fdisk -l about the problematic partitions:     Device    Boot      Start         End      Blocks   Id  System /dev/sda1            2048     147912703    73955328   83 Linux /dev/sdb2            206848   174079999    86936576    7  HPFS/NTFS/exFAT   And in GParted:      And the error of the mount command:  Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   And the exact same message for /dev/sda1  How can I recover my data from those HDDs?  EDIT     I have tried to specify the type of the drive:  $ sudo mount -t ext4 /dev/sda1 /olddisk mount: wrong fs type, bad option, bad superblock on /dev/sda1,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so $ sudo mount -t ntfs /dev/sdb2 /olddisk NTFS signature is missing. Failed to mount '/dev/sdb2': Invalid argument The device '/dev/sdb2' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?   EDIT     sudo ntfsfix /dev/sdb2 returns:  Mounting volume... NTFS signature is missing. FAILED Attempting to correct errors... NTFS signature is missing. FAILED Failed to startup volume: Invalid argument NTFS signature is missing. Trying the alternate boot sector Unrecoverable error Volume is corrupt. You should run chkdsk.


I need to breakup a file into two separate files based on a particular line for example:  . . sc_outfifo 0.000E+00 0.000E+00 0.000E+00 0.000E+00 1.586E-02 1.586E-02 1.586E-02 Fub_Level_DACGE(%) PS0_SI.0 PS0_SI.0 PS0_SI.0 PS1_SI.0 PS1_SI.0  siunit 98.91 98.81 98.91 90.06 96.37 81.37 81.37 16655 . .   So all the lines above Fub_Level_DACGE(%) goes in one file and the rest including Fub_Level_DACGE(%) goes in another file. Any idea how it can be done?

How to split a large file into two parts, at a pattern?  Given an example file.txt:  ABC EFG XYZ HIJ KNL   I want to split this file at XYZ such that file1 contains lines up-to XYZ and rest of the lines in file2.


I am upgrading from Ubuntu 14.04 to 16.04. When I tried to upgrade it threw errors about not enough memory space. After searching on the web I found out deleting old kernel helps. I deleted old kernel, and was successful in freeing up space. However, the upgrade still needs more space (more than 3 GB). How can more space be made available?. My partition is of 19GB

I'm using Ubuntu 11.04 and I want to free up some space in my root directory, which is overloaded. I especially want to change the path used for installing applications (they are getting installed directly to the root drive).  Another consideration is that I'm working on a MySQL database server. The server is installed in the root directory itself, so I don't want to  risk losing any data.  Please give me some tips to help sort out this problem.


The word "Latinx" seems to be the English shorthand for saying "Latino and/or Latina", where Latino includes men and Latina includes women.   How does one pronounce "Latinx"?

More and more I see, especially in activist communities, Spanish-derived words ending in x or @ in order to neuter the gendering inherent in the original language. For example: latinx (or latin@) as opposed to latina and latino. How, though, are these endings pronounced? Please provide evidence of how this orthography is most commonly pronounced. Note 1: I recognize this is in an English Language site, rather than a Spanish language site, but this phenomenon is very much happening in English, albeit with Spanish loan words. Therefore the question is relevant to non-Spanish-speaking English speakers. Note 2: A question like this can lead to politically charged or, at least, sarcastic comments. Please refrain from bringing in your biases for or against. Note 3: This question is not seeking opinions as to how some people pronounce the suffixes. Answers should address evidence of a developing orthodoxy in pronunciation.


When looking at my total votes in the 'votes' tab (not the summary) on my profile on SO I saw that I had a total of 236 Votes Cast. However when I look at my badge progress of the Civic Duty badge it says that I votes 292 times:       Is there any logical reason for the count difference?

When I visit my profile page, in the Summary Tab it shows that "601 votes" have been cast. However, when I visit the "Votes Tab" I find that it shows "585 votes" have been cast (and I'm looking with "All" filter selected).  Here's a screenshot of my summary tab:    And here's another screenshot from my Votes Tab:   I just wanted to know what am I reading wrong in these two values? I referenced the following Meta posts but I don't think I could gather anything that closely relates to this. It would really be helpful if you can please let me of any specific meta posts that would help me understand this.


Maybe this is a trivial question, but I am struggling with it for a while.  I have an alkaline AA battery which is consuming 80mA for 8 seconds each 30 minutes. I need to calculate how many days it will last before reaching 1.1v. I know it depends a lot on the battery type, but let's say it is a Duracell battery.  I have problems in calculating the "average" consumption per hour, as the battery is drained for just 8 seconds (80mA) each 30 minutes.  Thanks for any help.

I would like to know how to calculate battery life when using an LED strip. The LED strip is powered by 8 AA batteries in series. LED Current Draw = 260 mA. LED power consumption: 3.1 W. LED Operating Voltage range: 9-14.8 VDC. Please see attached images for battery datasheet.  This is my calculation, but I'm not sure if it's correct:     Battery Life = (Battery Capacity)/(Load Current) = 2000 mAh /260 mA = 7.7 Hours   This is for one battery, and the lights are powered by 8 batteries, so is the total battery life = (7.7)x(8) = 61.6 hours ?


Let $I = \{a +\sqrt2b \in \Bbb Z[\sqrt2] : a\text{ and } b\text{ are both multiple of }5\} \subset \mathbb Z[\sqrt 2]$. I have shown that $I$ is an ideal.   Now I want to show that it is maximal. Since I can write   $$I = 5\mathbb Z[\sqrt 2] = \{ 5(x+y\sqrt 2): x, y, \in \mathbb Z\},$$  I guess $\mathbb Z[\sqrt 2] / I\cong \mathbb Z/5\mathbb Z$. This is a field and thus $I$ is maximal. I am not sure about if the $\cong$ is true though.

Let $I = \{a +ib \in \Bbb Z[i] : a$ and $b$ are both multiple of $5\}$. Show that $I$ is an ideal of $\Bbb Z[i]$. Is $I$ a maximal ideal? And to find the numbers of elements of the quotient ring $\Bbb Z[i]/ I$.  I have shown that $I$ is an ideal of $\Bbb Z[i]$. But how to verify that $I$ a maximal ideal or not?   And to find the numbers of elements of the quotient ring $\Bbb Z[i]/ I$.   Is there any general way to verify when  $I = \{a +ib \in \Bbb Z[i] : a$ and $b$ are both multiple of $n\}$ will be maximal or not?


I want to keep track of a count variable inside the callback function for setInterval but the incremented value does not seem to pass down after each call. Here is my code:  var count = 0; function open_link(count) {     $("a")[count].click();     count++; } setInterval(open_link, 5000, count);   I was expecting that count will be 0, 1, 2 and so on but the value of count always stays 0. How can I update it?  Thanks.

What is the scope of variables in javascript? Do they have the same scope inside as opposed to outside a function? Or does it even matter? Also, where are the variables stored if they are defined globally?


my teacher told us to write a program that should give the length of a string after taking out the consecutive spaces, and only use one space. for example, if i write "hello(space)(space)(space)world" it should return "hello world" and the length should be 11. The problem is that i keep getting segmentation fault and i don't know why? can someone explain it to me? thanks by the way!  int limpaEspacos (char t[]){  int i, j, w=0; char c; for(i=0;t[i];i++){      t[w]=t[i];     w++;      for(j=i;t[j];j++,i++){          if (t[j]!=' ') {break;}        }     }    t[w]='\0';    return w; }   int main () { int a;  a= limpaEspacos ("b   ruh");  printf("%d\n", a );  return 0;  }

The following code receives seg fault on line 2:  char *str = "string"; str[0] = 'z';  // could be also written as *str = 'z' printf("%s\n", str);   While this works perfectly well:  char str[] = "string"; str[0] = 'z'; printf("%s\n", str);   Tested with MSVC and GCC.


When on the road, I would like to use my phone's LTE connection and tether it to my macbook.  However, I do not have an unlimited data plan, so I don't want the mac to download a bunch of stuff (OS X updates, Chrome updates, and so forth) and kill my monthly allowance.  As far as I know, when tethering from the mac side it looks like a regular wlan connection, so I am not sure if there is an easy way to do this. I use Little Snitch, so I was considering creating a restrictive profile there to block connections when in this mode. Is there an obvious way to do this that I am missing?

I'm being forced to use my Macbook more and more with my metered 4G connection. I really need to keep data usage limited. Windows has an  mode which really helps with this.   What's the best way to handle this issue in the OSX world? Perhaps some use of the firewall? Is there any sort of logging happening as to what is using the network?  Thanks for your help :-)


$\sum_n \exp(-n^{ 1/3})$ Should be convergent by ratio test. However it gives me that $a_{n+1}/a_{n}=\exp(n ^{1/3}-(n+1)^{1/3}) \rightarrow 1,n \rightarrow +\infty $ so the limit ratio test fails. Thank you for suggestions.

I have the problem to prove, that the following series converges:  \begin{equation} \sum_{n=1}^{\infty}\exp\left(-n^{\varepsilon}\right), \end{equation} where $\varepsilon > 0$.  I tried everything. I tried the ratio and root test, but I don't come to a solution. Can someone help me?  Thanks!


I have below query in perl DBI -  $query = $dbh->prepare(     "SELECT * FROM domain WHERE domainname = ? AND servicename = ?"); $query->execute( $domain, $service );   where the servicename can be case insensitive i.e if my existing service name is 'Storage' then it should fetch the result for 'storage' also.  I tried below code -  query = $dbh->prepare(     "SELECT * FROM domain WHERE domainname = ? AND servicename = lower(?)"); $query->execute( $domain, $service );   But it is not working for servicename = 'storage'.  Any pointer where i have missed?

I'm running a MySQL database locally for development, but deploying to Heroku which uses Postgres. Heroku handles almost everything, but my case-insensitive Like statements become case sensitive. I could use iLike statements, but my local MySQL database can't handle that.  What is the best way to write a case insensitive query that is compatible with both MySQL and Postgres? Or do I need to write separate Like and iLike statements depending on the DB my app is talking to?


I get random Strings as input and all I want is to get the ENGLISH words for keyword search app apart from the punctuation marks () or word dividers ( say, white space, multi-white spaces ). This issue is that I won't know the basis for spiting the Strings. For example, if I get a String "FLORENCE - FIRE/TOMORROW", I would like to get String array as {"FLORENCE", "FIRE", "TOMORROW" }. Besides, sometimes it also happen that a single word will come, say, "MELBOURNE" and just need to get the array as {"MELBOURNE"}. Capital letters has nothing to do with the question.  How can I do this ?

Does anyone know of a Java library that handles finding sentence boundaries? I'm thinking that it would be a smart StringTokenizer implementation that knows about all of the sentence terminators that languages can use.  Here's my experience with BreakIterator:  Using the example : I have the following Japanese:  今日はパソコンを買った。高性能のマックは早い！とても快適です。   In ascii, it looks like this:  \ufeff\u4eca\u65e5\u306f\u30d1\u30bd\u30b3\u30f3\u3092\u8cb7\u3063\u305f\u3002\u9ad8\u6027\u80fd\u306e\u30de\u30c3\u30af\u306f\u65e9\u3044\uff01\u3068\u3066\u3082\u5feb\u9069\u3067\u3059\u3002   Here's the part of that sample that I changed:   static void sentenceExamples() {    Locale currentLocale = new Locale ("ja","JP");   BreakIterator sentenceIterator =       BreakIterator.getSentenceInstance(currentLocale);   String someText = "今日はパソコンを買った。高性能のマックは早い！とても快適です。";   When I look at the Boundary indices, I see this:  0|13|24|32   But those indices don't correspond to any sentence terminators.


I'd like to search for a certain string in all system man pages, but I only want to get a list of the man pages where this text appears.  The first 2 pages of results Google returned do not provide the answer I'm after, if at all such an answer exists.  Let me explain:  I'd like to see all man pages where the word hairpin appears.  I proceed to type man -K hairpin, and the contents that appear are akin to me having typed man nmcli.  When I exit this man page via q, the following then appears on my screen:  --Man-- next: bridge(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]   From here, I can continuously type Ctrl+D and eventually return to the command prompt with the following displayed above the prompt:  --Man-- next: bridge(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: lldptool-evb22(8) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: systemd.network(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: nm-settings(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: nm-settings-ifcfg-rh(5) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ] --Man-- next: systemd.directives(7) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]   What I'm asking is, is it possible to get a listing of the man pages where hairpin appears such as below?:  man -<some-option> -K hairpin nmcli(1) bridge(8) lldptool-evb22(8) systemd.network(5) nm-settings(5) nm-settings-ifcfg-rh(5) systemd.directives(7)   Edit: Searching Google using a sentence doesn't always return the results where the specific query is addressed.  This is obviously the case for this question, as pointed out by several that it is indeed a duplicate.  However, it would be best not to delete it as it shows the specific output returned on Ubuntu systems.  A user on Ubuntu may benefit from this question.  Edit 2: Searching for skip (Ctrl-D) now has this question appearing in the first page of Google results where previously nothing was returned!

Sometimes I need to look up certain words through all the manual pages. I am aware of apropos, but if I understand its manual right, it restricts search to the descriptions only.     Each manual page has a short description available within it. apropos searches the descriptions for instances of keyword.   For example, if I look up a word like 'viminfo', I get no results at all...  $ apropos viminfo viminfo: nothing appropriate.   ... although this word exists in a later section of the manual of Vim (which is installed on my system).      -i {viminfo}                When  using  the  viminfo file is enabled, this option sets the filename to use, instead of the default "~/.vim‐                info".  This can also be used to skip the use of the .viminfo file, by giving the name "NONE".    So how can I look up a word through every section of every manual?


I have a solution that is being installed in an enterprise environment. The solution and its deployment guide are designed to installed on a RHEL7/CentOS7 server with SELinux enabled and components being installed to locations according to the Filesystem Hierarchy Standard.  One of the clients however has surprised us by stating that all 3rd party solutions must be installed to a /apps directory since they back this up according to policy.  To avoid deviation for this specific client, since it would require significant modifications to the solution, we decided the best approach would be to create a new directory in the /apps directory for /optand create symlinks upfront from the true /opt and apply the same SELinux content to it (usr_t) e.g.:  ls -laZ /appl/opt drwxr-xr-x. root     root     unconfined_u:object_r:usr_t:s0   . drwxr-xr-x. root     root     unconfined_u:object_r:default_t:s0 .. drwxr-xr-x. product product unconfined_u:object_r:usr_t:s0   product  la -laZ /opt drwxr-xr-x. root root system_u:object_r:usr_t:s0       . dr-xr-xr-x. root root system_u:object_r:root_t:s0      .. lrwxrwxrwx. root root unconfined_u:object_r:usr_t:s0   product -> /apps/opt/product/   Certain components of the product are accessed via Apache HTTPD and require the httpd_sys_content_t context to be applied to them.  The files are located at /opt/product/wwwstatic/ (which in reality is /apps/opt/product/wwwstatic/).  The deployment guide specifies the following commands to run:  semanage fcontext -a -t httpd_sys_content_t "/opt/product/wwwstatic/*" restorecon -Rv /opt/product/wwwstatic   which restores the contexts on a standard installation but in this environment, because of the symlinks, it fails.  If you modify the commands to include the /apps directory it works but deviates from a generic approach.  The contents of /etc/selinux/targeted/contexts/files/file_contexts.local is:  # This file is auto-generated by libsemanage # Do not edit directly.  /appl/opt/.*    system_u:object_r:usr_t:s0 /appl/srv/.*    system_u:object_r:var_t:s0 /opt/product/wwwstatic/*    system_u:object_r:httpd_sys_content_t:s0   Is there a means of modifying the arguments to semanage or restorecon commands so that this will work for symlinks (as well as normally) or have I a fundamental misunderstanding of how SELinux applies file contexts?  I believe this question differs from  since it is about applying contexts to files in subdirectories from symlinked directories instead of applying contexts to the symlink file itself.

My apache DocumentRoot /var/www is a symbolic link to another path. The target has the appropriate file context label (httpd_sys_content_t) so that apache can read it with SELinux enabled. However, the symbolic link itself is labeled with var_t.  [root@localhost var]# ls -lZ lrwxrwxrwx. root root unconfined_u:object_r:var_t:s0 www -> /srv/www   I need to relabel the symbolic link with httpd_sys_content_t.  Running chcon with the -h option initially seems to work:  [root@localhost var]# chcon -h -t httpd_sys_content_t /var/www [root@localhost var]# ls -lZ lrwxrwxrwx. root root unconfined_u:object_r:httpd_sys_content_t:s0 www -> /srv/www   However this does not survive a relabel:  [root@localhost var]# restorecon -Rv . restorecon reset /var/www context system_u:object_r:httpd_sys_content_t:s0->syst em_u:object_r:var_t:s0   Using semanage does not relabel the link itself; just the target:  [root@localhost var]# semanage fcontext -a -t httpd_sys_content_t /var/www [root@localhost var]# restorecon -Rv . [root@localhost var]# ls -lZ lrwxrwxrwx. root root unconfined_u:object_r:var_t:s0 www -> /srv/www   semanage does not have the -h option.  How can I get semanage to set the label of the link itself so it remains as httpd_sys_content_t after a relabel?


I want to wrap this rope, based on curve around cylinder:

I have searched everywhere on the web for a way to do this, but I can’t find anything. Someone have any ideas for doing this without using physical simulations? The operation should be this: the red wire passes through the blue object (which is static) and is anchored to the yellow object, which can rotate When the yellow object rotates, the wire wraps around the cylinder in a similar way to a fishing rod.


In the TV series Glitch, we see several people returning from the dead. Most of them, especially those that have been dead longer, have some difficulty remembering their past lives.  In the second episode, "Am I in Hell?", Vic has a car accident near the cemetery the risen came from. We're made to believe he has now risen too.  In a later episode, doctor Elishia McKellar confirms that he has died and immediately come back to live during the accident, although it's unclear how she knows that.  Vic shows a complete change of character after his accident. Also, he seems to heal at extraordinary speed.  Has Vic risen?

In the TV series Glitch, we see several people returning from the dead.  We see Vic, a police officer,      getting in a car accident and seemingly .   Afterwards, he behaves very strange. He searches for the doctor and the risen, whom he seems to know a lot about, sometimes even more than they know themselves.      He rekills Maria by breaking her neck.   And he threatens the other risen.  Most of the risen, especially those that have been dead longer, have some difficulty remembering their past lives. Vic on the other hand, seems to remember fine but to have a complete change of character instead.   Why is he after the other risen? How does he know so much about them? Why did he have such a change of character?     Yes, these are several questions, but they are closely related, so I opted to ask them in one question.


I currently have an app in C#/WPF, and I have a manual on how to use it in pdf, and I'm thinking of adding a button that when clicked open the manual ... How can I do this?

Any ideas how to display a PDF file in a WPF Windows Application?     I am using the following code to run the browser but the Browser.Navigate method does not do anything!  WebBrowser browser = new WebBrowser(); browser.Navigate("http://www.google.com"); this.AddChild(browser); // this is the System.Windows.Window


Why isn't $1^{\infty}$ considered as equal to $1$ but is said to be an indeterminate form in limits?

From : In calculus and other branches of mathematical analysis, an indeterminate form is an algebraic expression obtained in the context of limits. Limits involving algebraic operations are often performed by replacing subexpressions by their limits; if the expression obtained after this substitution does not give enough information to determine the original limit, it is known as an indeterminate form.    The indeterminate forms include $0^{0},\frac{0}{0},(\infty - \infty),1^{\infty}, \ \text{etc}\cdots$   My question is can anyone give me a nice explanation of why $1^{\infty}$ is considered to be an indeterminate form? Because, i don't see any justification of this fact. I am still perplexed.


I just finished making a form in Cognito and would like to know if it is possible to receive a submission by email? If not is there an alternative way that I could send the responses by email?   Also wanted to ask if there is a way to collect data from the submissions we get.

It says that Cognito Forms can send email notifications when a form is submitted. Where would I find those email notification settings?   I would like for my website clients to be the recipients of those email notifications. Do they have to have an account or a verified email address?   Also, is the form data included in the email notification? Also, is there an advantage to using the WordPress Plugin vs the regular embed code?


I'm stunned by this behavior, and can't seem to pinpoint what's causing the issue. I'd consider myself fluent in Python, but I'm completely at loss here. >>> board = [[0]*3]*3  >>> board [[0, 0, 0], [0, 0, 0], [0, 0, 0]]  >>> board[1] [0, 0, 0]  >>> board[1][1] 0  # Expected behavior: [[0, 0, 0], [0, 1, 0], [0, 0, 0]] >>> board[1][1] = 1  # Actual behavior: >>> board [[0, 1, 0], [0, 1, 0], [0, 1, 0]]  Running Python 3.9.5 on arm64 macOS 11.4 % python3 --version Python 3.9.5

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


All neutrino knows which of the 3 flavours they must be upon their creation, however their mass becomes uncertain... why is that? isn't mass supposed to tie to which ever flavours like for example an electron neutrino has a mass of say x electron volt and tau neutrino y electron volt but clearly this is not the case. So my question is what is it that are oscillating their flavour or mass?

Neutrions are produced and detected as flavor eigenstates $\nu_{\alpha}$ with $\alpha=e, \mu, \tau$. These states have no fixed mass, but are the combinations of three mass eigenstates $\nu_{k}$ with $k=1, 2, 3$, with mass $m_1$, $m_2$ and $m_3$, respectively. My questions are:  a) do neutrinos travel from source to the detector as flavor eigenstates or mass eigenstates?  b) is it possible to know which mass eigenstate the neutrino is in?


I have looked on the internet and no one can tell me why  needs eleven dimensions?

Some theories have more than 4 dimensions of spacetime. But we only observe 4 spacetime dimensions in the real world, cf. e.g.  Phys.SE post.   Why are the theories (e.g. string theory) that require more dimensions taken seriously by scientists?  Is there any proof that these extra dimensions exist? Is there a simple layman's explanation for the need [or strong hint] for extra dimensions?


I know that in context of time, if for example it is: 1:45 then I should say: "It is a quarter to two". But my question is about "half" in such context, for example, in case of 1:30. Should I say "It is a half past one."? I'm asking it because I didn't notice that people use this article in context of time.

I usually say “It’s a quarter past” (for instance) “five”.  But I think I’ve heard (or read) “It’s quarter past ...”, too, with no indefinite article: is that correct?  Which is more common (if both constructions are in use)?  Is the omission of the article more colloquial (informal, popular, whatever)?  Is there a difference between British and American English?  Thank you very much.


Background to the question:   I have been writing a small program to solve the daily Reddit challenge (details of the challenge are posted  for those interested).  While doing so, I appreciate my design is not the best, but i opted to write a class as an interface for carrying out different operation in a specific order of +1, +number, -1 and -number. Then in my main code I simple called operation.calculate(baseNumber) or operation.incrementOperation() to move to the next designated operation. However I hit an issue when trying to implement the class which I can't understand why it won't work. The code I was trying to implement was:  class DesignatedOperation {  public:      DesignatedOperation() : operationId(0) {}     ~DesignatedOperation() {}      void incrementOperation()     {         operationId += 1;         if (operationId > 3) { operationId = 0; }     }      int calculate(int number)     {         int op1 = operations[operationId, 0];         int op2 = operations[operationId, 1];         return (op1 + number * op2);     }  private:      int operationId;     int operations[4][2] = { 1, 0, 0, 1, -1, 0, 0, -1 };  };   However I am not able to compile this as I get the error for the lines accessing the operations array with the square brackets:     a value of type "int *" cannot be used to initialize an entity of type   "int"   Now looking through examples for tutorials such as , I can't figure out why this is not working. Now as a workaround I found I could using a single dimension array changing the code to the following:  class DesignatedOperation     {  public:      DesignatedOperation() : operationId(0) {}     ~DesignatedOperation() {}      void incrementOperation()     {         operationId += 2;         if (operationId > 6) { operationId = 0; }     }      int calculate(int number)     {         int op1 = operations[operationId];         int op2 = operations[operationId+1];         return (op1 + number * op2);     }  private:      int operationId;     int operations[8] = { 1, 0, 0, 1, -1, 0, 0, -1 };  };   Question at hand  I know this appears trivial but I was trying to google if this is a specific issue with using multidimensional arrays in classes like this but I wasn't much luck working exactly what is going here, beside me missing an obvious mistake.   Not sure if anyone else has encountered this or knows the underlying reason why my code can't access the array?  I can change the code on those to lines to allow it to compile by de-referencing the array as if it was a pointer but this doesn't make sense to me as I have not declared operations as a pointer to an array and it's within the scope of the class. Running this compiled code produces garbage output, as I would expect.  Any pointer in the right direction would be really appreciated, Thanks.  For reference I am using Microsoft Visual Studio Community 15 (Microsoft Visual C++ 2015).

How does the comma operator work in C++?  For instance, if I do:  a = b, c;     Does a end up equaling b or c?   (Yes, I know this is easy to test - just documenting on here for someone to find the answer quickly.)  Update:  This question has exposed a nuance when using the comma operator.  Just to document this:  a = b, c;    // a is set to the value of b!  a = (b, c);  // a is set to the value of c!   This question was actually inspired by a typo in code.  What was intended to be  a = b; c = d;   Turned into  a = b,    //  <-  Note comma typo! c = d;


These methods rely on the below imports. These are old and from reading shouldn't be using it. This only works with java 6 anyway and I would like to get this updated to java 8.   Does anyone know how to get the PID in Java 8 on OS X ?  import sun.jvmstat.monitor.*; import java.lang.management.*;           public String getUsageDescription()         {             System.out.println("** Get Usage Description");             int pid = 0;             RuntimeMXBean rt = ManagementFactory.getRuntimeMXBean();             pid = Integer.parseInt(rt.getName().substring(0,rt.getName().indexOf("@")));             System.out.println("Run Time PID = "+pid);             return new String(getDeviceName()+" "+Integer.toString(pid));         }           public static boolean isPIDInUse(int pid)         {             try{                 String s = null;                 int java_pid;                 MonitoredHost host = MonitoredHost.getMonitoredHost(s);                 for(Object activeVmPID : host.activeVms())                 {                     java_pid = (Integer)activeVmPID;                     System.out.println("****************PID = "+java_pid);                     if(java_pid == pid){                         System.out.println("In Use\n");                         return true;                     }                 }             }             catch(Exception e)             {                 System.out.println("Exception:  "+e.getMessage());             }             return false;          }   Solution:   public static boolean isPIDInUse(int pid) {          try {              String s = null;             int java_pid;              RuntimeMXBean rt = ManagementFactory.getRuntimeMXBean();             java_pid = Integer.parseInt(rt.getName().substring(0, rt.getName().indexOf("@")));              if (java_pid == pid) {                 System.out.println("In Use\n");                 return true;             }         } catch (Exception e) {             System.out.println("Exception:  " + e.getMessage());         }         return false;     }

How do I get the id of my Java process?   I know there are several platform-dependent hacks, but I would prefer a more generic solution.


If a sentence has someone's initials as the last word, do I add a second period?  Example:  And that was the last they saw of T.J.  or  And that was the last they saw of T.J..

I always stumble when using abbreviations in a sentence, as they inherently contain a period in them. How do I use a comma or a semicolon after an abbreviation? How about a period?  E.g. (This is an example of my quandary)


I'd like to identify a fantasy novel I read, probably somewhere from the mid eighties to early nineties.  One problem is that I have read a lot of fantasy novels and it is highly likely that I will conflate parts of several novels if I say too much.  So, here is the one thing I remember that I want to know the story for:  A character on a quest of some sort got ill.  He had a cough that was accompanied by greasy smoke coming from his mouth.  He eventually died because of this.  Here are some other things that I believe came from the same story, but I cannot be sure.   Swords and sorcery story. The ill man and his party were travelling by boat at the time. The character was a villager (possibly a farmer or blacksmith). He was a major character, or at least a long standing character. As the illness progressed he may have had mushrooms appear on his tongue.   Thanks in advance for any help working this one out!  Rotty

I have vague recollection of a book (possibly a short series) that involved a bottle trap. When you interacted with the bottle, you were sucked into it and found yourself in a multi-level 'dungeon'. I think there might of been a bottle at that bottom to get yourself out. The same book might have had something about having slow conversations with stones, but it might not and I am really just interested in the bottle concept. It certainly was not written this century. If I had to guess, I would say the 80's, but that is only a guess.


Today I have noticed a subjective popup warning while asking a question on     I tried with a different wording for the same question but the result was the same    It's not site specific as I have tried the same on scifi.SE with same results.  I haven't seen it before, is it some new feature? And what is the algorithm for this popup to appear? Any guidelines for it?

(Catchy title, eh?)  I am asking the following on the photo.SE site:     How do you change from portrait to landscape in Lightroom   DANGER! DANGER! This appears to be subjective and is likely to be closed.  If I ask the following radically different question:     How do I change from portrait to landscape in Lightroom   ... there is no problem.  So, like the title says: Why is "you" subjective?  (And  where Jeff spills the regex)


I want to implement the addition and deletion of forms.Each new element contains two buttons to delete itself and add the same elements as itself.But in fact only the first one is valid, after the page is loaded itself. How can I fix it? Why?  Just started using jquery and javascript  JavaScript and Jquery code show below.    $(document).ready(function() {   var num_ac = 0   $(".add_ac").click(function() {     num_ac++     // Determine if the user enters a valid value     var select_option = $(this).parent().parent().find("select option:selected")[0].index;     var hr = parseInt($(this).parent().parent().find("input").val());      if ((select_option > 0) && (hr > 0)) {       var temp = $("#ac_row_1").clone().attr({         id: "ac_row_" + num_ac       });       temp.appendTo($("#activity_list"));     } else {       alert("Should input value");     }    })    // Can't delete the first one   $('.del_ac').click(function() {      var row_id = $(this).parent().parent().attr("id");     if (row_id !== "ac_row_1") {       $(this).parent().parent().remove();     } else {       alert("Cannot remove Because This is the first row")     }    })  })

       <select class="form-control ac_select">         <option value="0">Choose Activity</option>         <option value="1">Swimming</option>         <option value="2">Walking</option>         <option value="3">Runing</option>       </select>

              <input type="text" class="form-control" placeholder="Hour per week?" onkeyup="this.value=this.value.replace(/\D/g,'')">

       <button type="button" class="btn btn-danger del_ac">Delete</button>       <button type="button" class="btn btn-primary add_ac"> +Add</button>

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


I have a controller which use 12V 3A. And I got old laptop power supply which is 19V 3A what resistor I need to include to decrease the voltage from 19V to 12V but keep the same 3A? Or I need to use any diode? Here is the controller  I have a Power supply at 12V 1A, but doesn't start properly. Seems it is weak as current. The most strange thing is that when I test it with multi meter shows not 12V but 16V.

How would one go about using a 12 V DC power source to power something which needs 4.5 V DC using resistors? Is there a way to determine how much adding a resistor would drop the voltage?


Looking for one word with a negative connotation to describe "a cheap and dirty solution" in a professional (software) environment.   "The proposed solution is (a) ...."  Basicly synonyms of: "The proposed solution is shitty", "The proposed solution is bogus", "The proposed solution is bullshit".

I'm writing a technical document, and I need to convey the fact that we had to find a non-optimal, non-orthodox solution that was adopted as the best available alternative (a hack) to solve an otherwise problematic issue.  Please note that I refer to the positive meaning of "hack", and not at the negative one, as clarified in .  To me, "escamotage" doesn't sound really appropriate in a technical document, and "hack" seems a bit informal and not very "technical".  Is there a construction that can help?


Can the following case be assumed de facto thread-safe? The bool flag always starts at false and only goes one way to true or stays as is. I know it's actually not thread-safe, but is it possible to really break somehow?  In this case the async execution is even strictly ordered and never parallel.  bool cancelled = false;  await MyAsyncJob.Process(() => {     if (timeout)     {         cancelled = true;     } });  if (cancelled) {     DoSomething(); }

Is accessing a bool field atomic in C#? In particular, do I need to put a lock around:  class Foo {    private bool _bar;     //... in some function on any thread (or many threads)    _bar = true;     //... same for a read    if (_bar) { ... } }


I am looking to confirm the best practice of storing client / secret credentials for multiple environments for multiple external webservices within salesforce.   Below is the analysis I have done using custom objects, custom settings, custom metadata types, and named credentials for this objective.   Analysis:  Custom Settings are controlled by Profile or by User.   Whereas Custom Objects are controlled with object and field level security and access is controlled by sharing settings.   I have seen some users use custom settings for credential storage, I'm assuming the reasons for this is by using the .get methods on the custom setting it will not count against your SOQL query limits and due it being stored in the application cache it is faster to access. In addition, you don't have to worry about users accessing / modifying the credentials unless they have the system permission to view and modify custom settings.   If I have various credentials to the various endpoints for the same service. Ex: dev.mycompany.com/data/, uat.mycompany.com/data/, prod.mycompany.com/data/ that are not specific to the user or profile, I find it excessive to add each environment, its subdomain, and its credentials (client secret) to a new field on the custom setting. In this example, if I would have 3 x 2 fields (client and secret) + 3 x 1 field (subdomain) + 1 field to determine which endpoint to hit depending on type of salesforce instance I'm on (dev, partial, prod).   Whereas with the custom object, I would have four fields (client, secret, active(boolean for whether or not this should the endpoint to request data from), and subdomain) and 3 records.   In addition, there is Custom Metadata types, which seem to be more or less like custom settings, but are stored as metadata as opposed to a table structure like custom settings / objects for simpler migration from environment to environment.   As for security I could encrypt the custom object fields as I can encrypt custom settings fields, however Salseforce seems to advise against the use of custom settings or custom metatypes to store credentials and recommends named credentials (which don't fit my use case of client/secret) or encrypted custom fields, due to custom metadata and custom settings being public.   I noted that other stack articles, such as: , suggest using protected custom settings to accomplish this, however I believe this answer was before custom metadata types existed.   Summary / Question:   Knowing this, based on my understanding of these three options, I believe it makes the most sense to store the credentials in a custom object from a security perspective and custom metadata / custom settings from a deployment perspective.   Given that security concerns would be my first priority, I'm leaning towards custom objects visible and editable only by system admins.   Is my understanding correct, is there other considerations that I have not made but need to weigh in making this decision?

I am again trying to understand what is the best possible option to securely making the apex callouts from a trigger to external application which supports OAuth2. I am not building any application/package here.  I am very new to Salesforce and the integration with external system, so pardon me if I am asking a very lame question. I am kind of stuck not able to understand what is the right choice for my scenario. The end point supports the grant type Client credentials grant_type=client_credentials client_id=clientId client_secret=clientSecret tenant_id=tenant_id resource=resource  As a POC I was able to harcode all the credentials in Apex and I was able to call external system with out any issues. As this not secure I tried exploring the options mentioned   I tried to use the named credentials but found that grant_type client_credentials is not supported as asked in the question  I tried to create the Custom metadata type and stored the credentials like below  but looks like I cannot store the credentials like above as they are not very secure. Read that I could also use a Custom object with the encrypted field also having the FLS to store these credentials and use it APEX Custom settings - I am not sure if I can use the Custom settings as when I tried to create a it I see the warning message where salesforce recommending to use the Custom metadata type   We dont have the platform encryption turned on in our ORg, should we enable that to created the encrypted fields on the Cutom metadta dattype/object/ settings encrypt it and when we reterive in apex should we be decrypting them? Please suggest me what is the best option to use here and also store the access token retrieved so I can use it until it expired.


Let $F[[x]]$ be the ring of formal power series in the indeterminate x with coefficients in F. Show that the field of fractions of $F[[x]]$ is the ring $F((x))$ of formal Laurent series.   I've been going in circles on this one for what seems like ever now! If anyone could lend me some insight I would be exceedingly grateful! Thanks!

Prove the field of fractions of $F[[x]]$ is the ring $F((x))$ of formal Laurent series.  $F[[x]]$ is contained in $F((x))$.  So there's at least a ring homomorphism that is injective.  Can also see it's injective because the kernel of such a mapping would be trivial because $0$ is the same in either. Not sure if showing they are isomorphic is the best way to do this.    $\displaystyle \sum_{n \ge N} a_nx^n \in F((x))$   Im not sure how I would define the mapping. maybe theres a better way


I'm thinking about getting an neutral density filter to shoot some silky waterfalls and smooths waves on the beach.  What would you recommend in terms of: 1. Brand - quality, durability, price 2. Darkness - what do I need to slow a direct sunlight shot (sunset, sunrise) down to 10-20s exposure? 3. Type - uniform or gradual?

I've seen a few related posts on the site but nothing specifically on this point:  I'd like to be able to take long exposure photos during daylight (like the examples in ). I'm told that you can do this by using a neutral density filter. So my question is: what is a neutral density filter exactly, and how is it used to achieve that smooth long exposure effect?


I was trying to access via Chrome's favourites links to an old question but when I try to do it, it says that the question is unavailable.  Seems that the user who asked it has deleted his/her account so the question is now also reachable with a Google search but not readable.  Is there any way to read a question even if the user who asked it deleted his/her account?  Thanks!  P.S.: Seems linke 10k+ rep users can read deleted questions. Does it concern also deleted users' questions? Should i be >10k rep?

What circumstances can cause a question or answer to be deleted, and what does that actually mean?    How can a post be deleted? When can't I delete my own post? Can I still see my post even after it's deleted? Can I see a list of my deleted posts? How can I undelete one of my posts? What does deletion mean for a post? How do votes to delete work? What are the criteria for deletion? What else should I know about deleted posts? If I flag my question with a request to delete it, what will happen?       For more information, see the articles about  and  in the .


In the total destructive interference of a wave, the peak of one wave, perfectly aligns with the trough of another wave (assuming they have the exact same amplitude and phase), causing the waves to cancel out (I know this is very difficult experimentally).  An example using water waves would mean the output is the still surface of water, using sound waves, you would get complete silence, using light, you would get darkened etc.   I have been trying to get my head around the idea of destructive interference causing energies to “destruct”, leaving “nothing” behind but I know this is against the first law of thermodynamics, which means energy cannot be created or destroyed.  Have I misunderstood something fundamental?   I’m trying to understand this somewhat philosophically using analogies.

What happens to the energy when waves perfectly cancel each other (destructive interference)? It appears that the energy "disappear" but the law of conservation of energy states that it can't be destructed. My guess is that the kinetic energy is transformed into potential energy. Or maybe it depends on the context of the waves where do the energy goes? Can someone elaborate on that or correct me if I'm wrong?


Consider this problem:  A stationary pulley carries a rope, one end of which supports a ladder with a man and the other end a counterweight of mass $M$. The man of mass $m$ climbs up a distance $l$ with respect to the ladder and then stops. What is the displacement of the centre of mass of the system?  Consider the counterweight, the man and the ladder to be one system. Their centre of mass doesn't accelerate if the external force on the system is zero, so the centre isn't displaced. What causes the acceleration in this case? Is it friction due to the pulley?

A pulley fixed to a rigid support carries a rope whose one end is tied to a ladder and a man and the other end to the counterweight of mass $M$. The man of mass $m$ climbs up a distance of $h$ with respect to the ladder and then stops. If the mass of the rope and the friction in the pulley axle are negligible find the displacement of the center of mass of the system.   My question is that the net external force on the system is 0 then why is there any displacement of centre of mass?


I have bought my TI5 compendium, is there a way I can level up my compendium by playing games and still be able to reach 250+ levels?

I've bought the "The International Five Compendium" for my friends and me, as there is a special thing where you will get more coins if there are five compendium owners in your team as well as a greater chance to level up. However, I'm not getting any points to level up; it feels ultra rare to get points. Are there any other ways how to level up?   Especially, is there any way that we can level up faster with a team?


i'm implementing google maps in an android project . But as soon as i moved my project into another PC machine i'm facing app crashs and this error message in my logcat console :  FATAL EXCEPTION: main Process: com.egsdigital.dolan, PID: 24887 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.egsdigital.dolan/com.egsdigital.dolan.Activities.MainPage_Pasenger}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setOnCameraChangeListener(com.google.android.gms.maps.GoogleMap$OnCameraChangeListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.google.android.gms.maps.GoogleMap.setOnCameraChangeListener(com.google.android.gms.maps.GoogleMap$OnCameraChangeListener)' on a null object reference at com.egsdigital.dolan.Activities.MainPage_Pasenger.onCreate(MainPage_Pasenger.java:178) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)  at android.app.ActivityThread.-wrap11(ActivityThread.java)  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)  at android.os.Handler.dispatchMessage(Handler.java:102)  at android.os.Looper.loop(Looper.java:148)  at android.app.ActivityThread.main(ActivityThread.java:5417)  at java.lang.reflect.Method.invoke(Native Method)   and here where the error points on:   map.setOnCameraChangeListener(new GoogleMap.OnCameraChangeListener() {         @Override         public void onCameraChange(CameraPosition position) {             LatLngBounds bounds = map.getProjection().getVisibleRegion().latLngBounds;             mAdapter.setBounds(bounds);         }     });   thanks so much.

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


I'm trying to wire two GFCI circuits sharing a neutral.  The line is coming in from a 2-pole circuit breaker.  I want to have two circuits at each location, each protected by a GFCI upstream.  Currently, I have it wired as shown below. If I reset 1 GFCI outlet, it works. When I try to reset both GFCIs, the first one trips.  What am I doing wrong?

In my kitchen, I want to replace a regular 120V receptacle with a GFCI-protected receptacle. The instructions describe what to do with a regular 2-wire + ground feed, with and without daisy chaining to other receptacles, but not how to do it with a 3-wire + ground feed. Please describe how I should connect the new receptacle.  Here's a diagram of how the non-GFCI receptacle is currently wired, in my best 6-year-old artistry:   I think it's connected this way so that each receptacle in the kitchen has their two sockets supplied by different breakers. At the service panel the circuit is controlled by a joined pair of 15A breakers. I assume the white and black are separate 15A lines and the red is a common neutral (?).  Here are the instructions for connecting in a 2-wire scenario.    How do I connect this? Or should I consult an electrician?  EDIT  From


I am using 18.04 version.  i wanted to install game war zone 2100  so i installed its dependencies and after that i am getting this error.  i cannot update the software center is not opening .  the synaptic package manager is also not opening. On the status bar the red minus icon appears as a error. i even cant upgrade. the apt update gives me this error.  Reading package lists... Done                                                  E: Failed to fetch http://ppa.launchpad.net/webupd8team/popcorntime/ubuntu/dists/trusty/InRelease  403  Forbidden [IP: 91.189.95.83 80] E: The repository 'http://ppa.launchpad.net/webupd8team/popcorntime/ubuntu trusty InRelease' is not signed. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. E: The value 'xenial' is invalid for APT::Default-Release as such a release is not available in the sources

When updating, I get the following error message:   W: The repository 'http://ppa.launchpad.net/mc3man/trusty-media/ubuntu xenial Release' does not have a Release file.   Here, I find another statement on this error:   This recommends removing certain PPAs; and, I'm not sure if I should do that since it might mean not getting the updates that I need.    Is this what I should do?


We're heading to NYC next weekend, for my five-year-old's birthday present (his request).  He's a very technically-minded child, and recently has loved asking questions about the history of buildings ("What is the tallest building", "What is the oldest building", "What was the tallest building before the Empire State Building", etc.).  He also likes to learn about materials and methods used to build things.    In Chicago, where we're from, there are excellent architectural tours that are led by boat down the river (which bisects the main part of the city).  Is a boat tour also the most effective way to see the NYC skyline and learn in detail about the history behind it?  I'd also welcome specific recommendations, to the extent that's on topic around here, for short to moderate length tours (probably not more than 1.5-2 hours).  For comparison, we did the Big Bus tour in London, and he tolerated that well enough, but by the end of it (90 minutes I think) was getting a bit bored.  For comparison, in Chicago the  is excellent, and the tour guide gives a lot of specific information that was news to me even after ten years' residence in the city and nearby suburbs, such as insights into the construction of specific buildings, the spats between different architects, and why certain buildings are constructed how they are.  Several competing companies offer similar tours.  While there are other methods to learn about the history of Chicago architecture, boat tours are the most efficient and primary method.  What I'm asking is whether this is also true in NYC or if walking/bus tours are better (or something else).

Every time I visit Chicago, I love taking one of the . These tours are excellent, run by enthusiasts, and take different forms. There are walking tours, an excellent riverboat tour, and several other options, as well. By far, it's the single best sightseeing tour of Chicago I've ever had.  Is there a New York City equivalent? I am having zero luck after a year, on and off, of searching. Short of buying a camera strap and a tour book, is there some sort of official architecture society tour that a sightseer or recent transplant could take of New York City? So far, I've found found food tours -- which, while awesome, aren't quite what I'm looking for.


I drag my feet on my floor, I hear static buildup/zapping sound in my earbuds and I get the device disconnected/connected system sounds from windows and all my mouse setting reset to factory defaults (scroll speed, pointer speed, etc)  If I open the mouse's control panel, everything returns to normal immediately.  I've tried all the combinations of moving the mouse to each of the USB ports, as well as plugging in my headphones into the back instead of the front panel.    Any other ideas on how can I keep from shocking my mobo through my ears each time I shift position?

Before opening a computer, I often hear advice to touch something that is "grounded"  - a computer case for example, or a heating element - to avoid damaging the sensitive electronic equipment through .  What exactly is true here, and what are the do's and don'ts.    Touching what objects will actually work, and what won't? If I touch a computer case, does it matter what it stands on, and whether it is connected to an outlet? What other ways are there to protect the equipment from a static discharge than touching something grounded? Are there common pieces of clothing that I shouldn't be wearing when working inside a computer, for example a woollen pullover?    There is a lot on Google, but there seem to be many contradictions and misconceptions out there, so I think this is a question worth having here.


Please forgive me if this is a stupid question as I have a very rudimentary understanding of physics.  I was reading about how the large hadron collider speeds up subatomic particles to near lightspeed and that the experimenters need to take the effects of time dilation into account because of this. This got me thinking and I came up with a strange thought experiment. Instead of subatomic particles, imagine we could send something like a small vehicle with a few people in it around the "track" (track seems like an inappropriate word but I'm not sure what it's actually called) at near light speed. So imagine they also have a high def webcam with them in the vehicle and that they wirelessly send a video to be broadcast on the internet. What would we see if we were to watch this video? Would they appear to us as if they were in super slow motion?

Consider a hypothetical situation: In which a time traveler travels in a spaceplane at close to speed of light circling the earth and I get a live telecast of inside of that plane to my television. How time dilation will effect him and what will I observe sitting next to the tv seeing him live. Considering time runs slower at speed of light, will he be looking like a slow motion video? (Or let he also watching live streaming of us at earth, what it will look to him) P.S. I'm not sure if it even makes some sense but if it does kindly explain in logical details. Sorry for the the bad english, I'm not a native speaker.


I would like to have two dryers in my laundry room. Can I run both off of the same circuit? Can the outlets be run in series? What upgrades do I need to make for this to work. I have room for another breaker in my box, which is in the same room. I am doing extensive work, including removing drywall, in the laundry room and now would be the time to make changes.  Thanks!

We are running a clothes dryer in the lower level of our home. We are installing a washer and dryer on our main level. Can I split the power feed between both dryers and what can I use and where can it be bought. We only want to run one dryer at a time when needed.


Generally finding a Residue of a function with $n^{th}$ order pole is done with  \begin{equation}\label{eq:1} Res(f(z),z_0) = \dfrac{1}{(n-1)!} \lim_{z \to z_0} \dfrac{d^{n-1}}{dz^{n-1}} (z-z_0)^n f(z) \end{equation}  For poles of $1^{st}$ order it's simply $ Res(f(z),z_0) =\lim_{z \to z_0}  (z-z_0) f(z) $. This can be written as $ Res(f(z),z_0) = \dfrac{g(z_0)}{h'(z_0)}$ if the original function was in the shape $\dfrac{g(z)}{h(z)}$  Now. I am looking for such an expression of $2^{nd}$ order poles. For the $1^{st}$ order case because $h(z)$ has zeros of 1st order so $h(z)$ can be written as $h(z)=h(z)-h(z_0)$ and $h(z_0)=0$.So it all falls on the same place and gives you the simplified equation for residue. But for $2^{nd}$ order pole there is much complication, i.e there is additional derivative term and I can't simplify.

Is there a good way to compute the residue of $f(z)=\dfrac{1+z}{1-\sin z}$ at $z=\pi/2$, which is a pole of order $2$?  Using the residue calculation formula yields  $$\text{Res}_{z=\pi/2}f(z)=\lim_{z\rightarrow\pi/2}\dfrac{d}{dz}\left(\left(z-\dfrac\pi2\right)^2f(z)\right)$$  The derivative is quite ugly, and calculating the limit requires L'Hospital probably twice (or more). The calculation is just too much. Is there a better way?


Prior to a black hole reaching sufficient (size ) to stop radiating light (due to excessive gravity ) would the speed of radiation of light slow smoothly down to zero (as the hole draws closer to the critical size)

We know that gravity speeds up a body; for instance, a meteor which enters the earth gets constantly accelerated up by earth's gravity. And from relativity we know that light bends near a massive body, because Newton's law of gravitation is just an approximation and actually gravity depends on energy and momentum. So my question is: If a ray of light is aimed exactly at the center of a body, then will it get accelerated like a meteor? And if does get accelerated, then won't it surpass the universal speed limit of 3,00,000 km/s (approx.)?


After shooting all day and viewing the images on the camera, when I put the card into my PC and tried to open it, I did not have all the images from today. I did have all the old images, from yesterday and older. Is there any where for me to look for these lost images and retrieve them??

I know this is not specifically a photography issue but since many of us with prosumer/professional-level DLSRs use Compact Flash cards, it is bound to happen to others as well.  I have a Sandisk 16GB Ultra card that occasionally had the camera reporting inability to access the card. I had to reinsert the card to continue using it. I was able to read the card and transfer the photo files to my computer drive. Today, the same thing happened again, just that nearing the capacity of the card, it failed one last time and the camera was subsequently unable to read it anymore. Despite reinsertion.  My other CF cards never once exhibited this problem, so it's pretty much isolated to this card.  The card is similarly unrecognisable on my computer CF card reader. I think the filesystem is toast, but I suspect the photo files are still intact. I would like to find ways where I can inspect the raw binary data in the card and hopefully recover the photos?


I deleted .aae files by mistake and all of my related photos are gone. How do I recover these missing photos?  iPhone 6, iOS 9.2.1

I was manually copying my photos from my iPhone 6 running iOS 9.3.1 onto my Windows 8 laptop and deleted all the .aae files associated with the various JPEGs before copying them over. I immediately found that the JPEGs associated with the .aae files were rendered unmovable and inaccessible.  I understand that .aae files are used to keep a history of photo modifications so that one can revert if one wants in the future, but I didn't think they were integral to accessing my JPEGs as I've been able to delete them AFTER transferring them to my laptop before without issue.  So now, I have a load of great pics I can't transfer and can't access.  I also tried unplugging and replugging my iPhone to my laptop, but now the once-inaccessible JPEGs seem to have totally gone.


yeah i know that the  sample rate is low, i increased it to 300 and it still was noisy, i think it has something to do with the indirect light, right?   I dont know if i need to give more info, im quite new to blender, like, a week new.  The project file is here:

I know that this question is a bit old or maybe overdone, but I'm running the latest edition of Blender and when I use the Cycles engine I get really fuzzy results and I can't find a simple, non-compromising solution to the quality.  I don't know exactly what I'm doing wrong here, but I'm sure others share my frustration.  Leaving everything in default settings, I started a new project and switched to the Cycles render.  I duplicated the cube and set colors for two Diffuse BSDF shaders, then went ahead and made walls and a floor all sharing the same diffuse shader.  I made two windows to emit blue light.  The screenshot has gaps between the walls because of the setup:  I'm aware that it's considered very incomplete and many have come to terms with some amount of noise, but is this normal?  Furthermore, with default settings or not, I can't change the amount of noise produced.  Supposedly, using "progressively refine" in the rendering tab should make it refine itself indefinitely, however Cycles only counts to 10 refines and then stops, creating a render which is a pixel-perfect match of the ordinary rendering method when it's completed.  I understand that there are tricks that can be used to reduce noise, but at the cost of extra processing time and usually small quality conflicts, like blurring.  My question essentially boils down to is this Cycles' current limit?


In my infinite wisdom, I deleted the file 'mpicc.openmpi' file in my /usr/bin/ folder by mistake.   I tried installing OpenMPI as well as GCC. But don't know how to get back to normalcy.  Can anyone please help me out.  Thanks.

Simple enough question: is there some shell command (or GUI method) I can use that, given the path to a file on my system, tells me what package put it there? Assuming the file did in fact come from a package, that is.  Bonus question: what if it's a file that isn't installed on my system? Is there, say, a website that will let me look up a file and see what packages, if any, provide it?


console.log([2] == 2) //returns true  console.log([2,3] == 2) //returns false  console.log([2] === 2) //returns false  console.log([2,3] === 2) //returns false   Can someone tell me what is happening behind the scenes in the above lines of code,how JavaScript Engine is performing these tasks

I'm using  to go through JavaScript, and it's returning many suggestions to replace == (two equals signs) with === (three equals signs) when doing things like comparing idSele_UNVEHtype.value.length == 0 inside of an if statement.  Is there a performance benefit to replacing == with ===?   Any performance improvement would be welcomed as many comparison operators exist.  If no type conversion takes place, would there be a performance gain over ==?