Why can't i initialize variables in anonymous inner class?

I have a problem with NullPointerException when i try to access variables from object i initialized in inner class.But inside the inner class it has all the elements set,and everything is fine.  public class FirebaseConnectionStream extends FirebaseConnection {      private Object DownloadResult;     public void publish(String path,Map<String,Object> map){         try{        DatabaseReference ref = database.getReference(path);        ref.updateChildren(map);      }     catch(Exception e){         e.printStackTrace();     }  }  public <T> PortfolioInfo download(String path,final T object){      try{         DatabaseReference ref = database.getReference(path);         ref.addValueEventListener(new ValueEventListener(){              @Override             public void onCancelled(DatabaseError arg0) {                 // TODO Auto-generated method stub              }              @Override             public void onDataChange(DataSnapshot arg0) {                  try{                 DownloadResult = arg0.getValue(object.getClass());                 PortfolioInfo p = (PortfolioInfo) DownloadResult;                 System.out.println(p.getId()); // This line here works?                 }                 catch(Exception e){                     e.printStackTrace();                 }             }            });     }     catch(Exception e){         e.printStackTrace();     }     return (PortfolioInfo) DownloadResult; // But this one does not?      }  }


How to completely remove and reinstall Ubuntu?

I want to reinstall Ubuntu, but I also want all information and settings to disappear. So everything looks like the first time I installed it. Is it possible to do so via Terminal? Or what are the steps I should follow?


When ArrayList Matched Element Found If condition not run

In android coding i have two different arraylist. i have matched both arraylist elements. But my problem is that when my matched data found  in loop, if statement not running. this is my code  for (int i = 0; i < mname.size(); i++)  {     if(i<jsonArray.length())     {      JSONObject jo = jsonArray.getJSONObject(i);      String paid = jo.getString("name");      instname.add(paid);      }      else      {      instname.add("0");      }      System.out.println(instname.get(i)+ "  " + i );      for(int j=0;j<mname.size();j++)      {          System.out.println("instname "+i + "  " + "mname  "+j);          if(instname.get(i) == mname.get(j))          {              System.out.println("instnam=" + instname.get(i));              System.out.println("mem="+ mname.get(j));              pay = instname.get(i);              break;          }      } }   Here in code mname and instname is arraylist. mname has 2 names, 'name1' and 'name2' and instname hase 1 name, 'name2'. In my logcat result like      name2  0     instname 0  mname  0     instname 0  mname  1     0  1     instname 1  mname  0     instname 1  mname  1   instname 0 and mname 1is true matched data contains both name2, but my if condition not run. it results pay = null


During the battle scene in Avengers: Endgame, Thor summons Stormbreaker when he's being beaten up by Thanos. Before it reaches Thor, Thanos simply grabs Stormbreaker mid-air with his bare hands and then attempts to drive it into Thor's heart.   How could Thanos wield Stormbreaker? Is he worthy too?


how to create progress bar when running command that take time   for example ( this take 10 min )   cat GTTfiles* > GTTcentos7.tar.gz   so during that CLI is working how to create some progress that show process is running?  example of output ,  ( only example , we will happy to get other ideas )   |..........                             |


Is a left invertible element of a ring necessarily right invertible?

Let $R$ be a unitary ring and let $a,b \in R$ such that $ab=1$.  Does it imply that $a$ is invertible?  The definition of invertible element requires that $ab = ba = 1$, so I guess it doesn't imply that a is invertible, but I didn't manage to find a unitary ring in which this happens.


Weird pixels showing where window controls should be after suspend

Was doing some development using a Java library and started getting a buffer overflow error that I thought was being caused by an Nvidia driver update so I started fooling around with those a bit and now I've got an odd error that shows up.  Basically if I put my computer into suspended mode (running Ubuntu 16.04 LTS), I have the following odd pixel stuff showing up:    As you can see, this could prove rather annoying.  The problem doesn't appear if I have the windows in full screen mode, only in windowed mode.  I've tried running a purge on the nvidia stuff and reinstalling the nvidia-375 package as well as going into the addition drivers option and trying different items listed there.  However, nothing appears to be working.  There's also a problem where opening anything new freezes the monitor where it opens.  I'm at a loss of what else to do about this so any suggestions would be greatly appreciated.


How to get a "Times New Roman" font in a LaTeX pdf document?

The package mathptmx is giving "Times Roman" font. Instead, I need "Times New Roman" font in my LaTeX pdf document.


Can I use RHEL Virtual Datacenter License with vCenter Server Essentials (Essentials Kit)

Does somebody use RHEL Virtual Datacenter License with vCenter Server Essentials?   I cannot get a clear answer from our RHEL Partner, as well as I cannot find it clearly stated somewhere on the WEB. I know that virt-who will work with the normal vCenter Server, however I am not sure about  vCenter Server Essential version at all...


Disk Utility: Invalid Disk Label @ cksum mismatch

I have a WD external hard drive. I've been running the routine tests to make sure all my stuff is safe lately. In Disk Utility, I did Verify Disk on both the disk itself as well as the main partition, which is in the encrypted HD format.  I ran across this error on the partition:     Invalid Disk Label @[number] cksum mismatch   Which didn't seem very good. Resources online have close to no information, and I don't know what this is. It went away after I scanned again, but that is a common occurrence and other posters said that I should keep an eye on it.  I ran Repair Disk and it went without a hitch, but Verify Disk after that still showed the error.  I ran SMART Utility with the SAT-SMART Driver to enable SMART on external USB drives, it passed with 0 bad sectors and stuff.  Any ideas?  MacBook Air - Mavericks 10.9.5


I just have heard a song "Heart Don't Lie". And I'm curious to know, how has it used? grammatically.      "Heart Don't Lie"      "Heart Doesn't Lie."


Is restricting identifiers to alphanumeric words enough to prevent SQL injection?

I need to use dynamic table names which can't be provided as parameters in prepared statements. I figured that if I restrict identifier names to alphanumeric + underscore only, then there is no way some sql could be injected, right?  here's the check function:  function is_safe_identifier($s) {     return preg_match('/^[a-zA-Z0-9_]+$/', $s) == 1; }


Is a Bundle whose Fibers are Homeomorphic a Fiber Bundle?

To avoid problems with the notoriously inconsistent notation/formalisms of geometry, I will define bundles and fiber bundles (as I call them) below:   We define a bundle $E \xrightarrow{\pi} B \ $ as a triplet $(E, B, \pi)$ with $E, B$ topological spaces and $\pi: E \to B$ a continuous surjection. We further define the fiber at $x \in B$ as the set $\pi^{-1}(\{x\})$. A Fiber bundle is a 4-tuple $(E, B, F, \pi)$ with $E, B, F$ topological spaces, $\pi: E \to B$ a continuous surjection, together with a local trivialization $\{(U_i, \varphi_i)\}$, where $\{U_i\}$ is an open cover of $B$ and $\varphi_i: \pi^{-1}(U_i) \to U_i \times F$ is a homeomorphism such that $\text{proj}_1 \circ \varphi_i \equiv \pi \ $ on $\ \pi^{-1}(U_i)$.    Now, in a lecture series on differential geometry that I am watching, bundles were defined in much the same way except that topological spaces were replaced by topological manifolds. No complaints here. However, a fiber bundle was subsequently defined as a bundle $E \xrightarrow{\pi} B \ $ such that all of the fibers $\pi^{-1}(\{x\})$ were homeomorphic to some common topological manifold $F$—with no mention of the local triviality condition.     My question is: In the case of topological manifolds, does this condition naturally induce the locally trivial condition that appeared before? Does it for general topological spaces?   My intuition is that it does not for general topological spaces: Clearly, there exists a family of homeomorphisms $\varphi_x: \pi^{-1}(\{x\}) \to \{x\} \times F$, and for any $U \subset B$, we can glue these maps together to obtain $\varphi_U: \pi^{-1}(U) \to U \times F$ defined point-wise by $\varphi_U(y) := \varphi_{\pi(y)}(y)$. It's easy to see that this map is bijective independent of $U$, but I see no reason to suspect bi-continuity even with "nice" choices in $U$ as—roughly speaking—we don't have any information about how this map behaves when moving transverse to the fibers. Perhaps this construction is too artificial, but it seemed compelling enough to me.  In the case where the base space, total space, and common fiber are topological manifolds, I wouldn't be surprised if the chart maps could be used to construct a local trivialization but I'm not sure how to explicitly construct it at the moment.


How to get required parameters from a stored procedure in C#

When we try to execute a stored procedure without sending values to it's required parameter , it gives an error like below.      I wanna know, is there any way to problematically capture the all parameters for a given stored procedure ?  Eg: Parr[] string =  GetSpParameters("StoredProcedureName); //I need to develop the "GetSpParameters" function.  Thanks.


How can I write % into an auxiliary file? % will not work, because LaTeX thinks that I start a comment with it (in the main file, not in the auxiliary file!), and \% will write \% into the file. How can it be accomplished?   \documentclass{article} \begin{document} \newwrite\outfile \immediate\openout\outfile=example.dat \immediate\write\outfile{%}% will not work, of course, but neither \% \immediate\closeout\outfile \end{document}


How can change 12000 user role into contributor by sql

We have about 12000 users who doesn't have any roles. we need to change them to "contributor". How can I change them to "contributor"? Should I do on database? if so, which fields I need to update?  I try this code :-  INSERT IGNORE INTO an_usermeta (user_id, meta_key, meta_value) SELECT DISTINCT u.ID, 'wp_capabilities', 'a:1:{s:11:"contributor";b:1;}' FROM an_users u   But when go to wp-admin i don't see any user for contributor role Thanks,


I know the basic difference of static class, we can't instantiate this and other,but i'm little bit confused why we use this means which scenario we need static class. when i search lot of this then i'm getting more confused.  please help me.


In leetcode, for the add two numbers problem, I implemented the same algorithm both in Java and Scala. But Java version outperforms scala a lot. The runtime of java version code is 52ms while the runtime of scala one is 552ms. Why is there huge performance difference?  Codes are attached:  Scala version:  object Solution { def addTwoNumbers(l1: ListNode, l2: ListNode): ListNode = { var a = l1 var b = l2 var sum = 0 var digit = 0 var tenDigit = 0 val l3 = new ListNode var c = l3 while(a!=null || b!=null){    sum = (if(a==null)0 else a._x) + (if(b==null)0 else b._x) + tenDigit   digit = sum % 10   tenDigit = sum / 10    c.next = new ListNode(digit)   c = c.next   if(a!=null)a = a.next   if(b!=null)b = b.next  }  if (tenDigit > 0) {     c.next = new ListNode(tenDigit); }  l3.next  } }   Java version:  class Solution { public ListNode addTwoNumbers(ListNode l1, ListNode l2) { ListNode a = l1; ListNode b = l2; int sum = 0; int digit = 0; int tenDigit = 0; ListNode l3 = new ListNode(0);     ListNode zeroNode = new ListNode(0); ListNode c = l3; while(a!=null || b!=null){  sum = (a==null ? 0 : a.val) + (b==null ? 0 : b.val) + tenDigit; digit = sum % 10; tenDigit = sum / 10;  c.next = new ListNode(digit); c = c.next; if(a!=null)a = a.next; if(b!=null)b = b.next;  } if(tenDigit!=0){    c.next = new ListNode(tenDigit); } return l3.next; } }


I spend some weeks searching for potential answers for a similar problem without success. This happened after one of many MikTex updates I made but it is unclear to me the source of the problem. My yap.exe file has the date of 29 Oct'16, so this might give you some useful clue. I usually compile my documents to pdf and so I only use dvi and yap to do tests and quick debugging. In one such ocasion while opening the dvi with yap an error window open with the message "MiKTeX encountered an internal error." The report info is the following  MiKTeX Problem Report Message: MiKTeX encountered an internal error. Data:  Source: Libraries\MiKTeX\Core\Session\mfmodes.cpp Line: 50 MiKTeX: 2.9 OS: Windows 7 Professional, 64-bit, Service Pack 1, build 7601 Invokers: non-existing/explorer/TeXnicCenter SystemAdmin: yes PowerUser: no Root0: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 Root1: C:\Users\Myaccount\AppData\Local\MiKTeX\2.9 Root2: C:\ProgramData\MiKTeX\2.9 Root3: C:\Program Files (x86)\MiKTeX 2.9 UserInstall: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 UserConfig: C:\Users\Myaccount\AppData\Roaming\MiKTeX\2.9 UserData: C:\Users\Myaccount\AppData\Local\MiKTeX\2.9 CommonInstall: C:\Program Files (x86)\MiKTeX 2.9 CommonConfig: C:\ProgramData\MiKTeX\2.9 CommonData: C:\ProgramData\MiKTeX\2.9   The problem is the same regardless if I compile a document within TeXnicCenter or just try to open a dvi file directly from a directory or even if I just double-click on yap.exe. I guess there is no problem in compiling to a dvi document, just opening it.  Many thanks for your support


Git wrongly mark a file as deleted instead of rewritten

I'm doing several refactors on a project. So sometimes I need to rename the file extension, for example index.js -> index.ts, and change many lines on this file.  Because that git wrongly mark index.js as deleted and index.ts as a new file, that could be bad on code review and logs.  Is there some way to explicitly say to git "hey, I renamed index.js to index.ts"?  Edit  The approach using git add / git rm / git mv didn't work, because git still say that I created a new file and removed other.  Also I should not use two commits to that (one for rename and one for update its content), because the first commit will be broken, since the build steps for a .js file is different than a .ts file


"Please bring lots of $1.00s and $5.00s" or "Please bring lots of $1.00's and 5.00's"?


Stack Overflow chat application for mobiles

I am using an Android smartphone. I wanted to know if there is a mobile application through which we can use chat?


Wubi: request not supported when Installing to a partition, 13.04

When I use wubi.exe to install Ubuntu to a partition on another HDD I get this error ():  07-06 20:23 DEBUG  WindowsBackend: modify_bcd Drive(A: hd 129914.515625 mb free ntfs) 07-06 20:23 ERROR  TaskList: Error executing command >>command=C:\Windows\sysnative\bcdedit.exe /set {f544d06e-4e60-11e2-885c-a62c26d2ce07} device partition=H: >>retval=1 >>stderr=An error has occurred setting the element data.  The request is not supported.   What can I do? This is stopping me from installing Ubuntu/Linux. I chose 30 GB as the install size and I chose the correct partition etc.  It is ubuntu Desktop 13.04 by the way.


geting bone heat error when trying to parent to mesh

So I am new to all of this and at my wits end. I can't seem to get a rig to parent to the model mesh it gives me an error every time. I have tried everything that i have been able to find out about. i appended rig to other mesh so rig is fine.  Things I Have tried.   remove doubles recalculate outside remove all modifiers,vertex groups,shape keys,and UV data  corrected non manifold  applied decimate modifier removed all model acc (ie clothes) symmetrize model    Like I said I am new so maybe I overlooked something simple.


Let $X$ be a compact , metric space.  Assume that the closure of every each open ball it the closed ball with same center and radius.   Prove that any ball in this space is connected.


Should I use the rubber viewfinder cover?

A rubber viewfinder cover is connected to my camera strap.  What's it for, and when do I use it?  What happens to a photo if I don't use it?


I want to create a wave made out of particles/dots. The wave should look like this:  I tried to achieve this effect by adding an ocean modifier to a plane. Then I added a particle system to the plane but now I don't know how to go on. How can I make the particles lay on the 'ocean' and move when the ocean is moving? PS: I know there is a way to do this with a material in the Blender Render. But firstly I want to create the whole thing in Cycles and secondly I want to have particles.


If $X= \newcommand{\W}{\operatorname{W}}\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{\sqrt{A}^{.{^{.^{\dots}}}}}}}}}}} $ then what is the value of $X^2-e^{1/X}$ ?


What can be the general statements made, when two finite groups can be isomorphic to each other: $\mathbb{Z}_{pq}$ and $\mathbb{Z}_{p} \times \mathbb{Z}_{q}$  Say  $$\mathbb{Z}_{pq} \simeq\mathbb{Z}_{p} \times \mathbb{Z}_{q},$$  what are the conditions for $p$ and $q$ and their factorization relations?  How do we show this in the most elegant way? And the intuitive way?


How can I install gcc6.4, g++6.4 and cmake3 on Ubuntu 14.04? I want to rewrite below lines that run on Linux to be run on Ubuntu   $ yum install gcc64-c++ libcurl-devel $ export CC=gcc64 $ export CXX=g++64 $ yum install cmake3   I tried below commands on ubuntu  $ sudo add-apt-repository ppa:ubuntu-toolchain-r/test $ sudo apt update $ sudo apt install -y g++-6 $ sudo apt install -y gcc-6 $ gcc --version $ g++ --version $ export CC=gcc6 $ export CXX=g++6 $ gcc --version $ g++ --version   But version returned is   gcc (Ubuntu 4.8.4-2ubuntu1~14.04.4) 4.8.4   and  g++ (Ubuntu 4.8.4-2ubuntu1~14.04.4) 4.8.4    Although I expect to be 6.4  And when I tried to install cmake3   $ sudo apt-get update  $ sudo apt purge cmake*  $ wget http://www.cmake.org/files/v3.5/cmake-3.5.1.tar.gz  $ tar xf cmake-3.5.1.tar.gz  $ cd cmake-3.5.1  $ ./configure  $ make  $ sudo make install  $ cmake --version   It gave me an error in ./configure  CMake 3.5.1, Copyright 2000-2016 Kitware, Inc.  ---------------------------------------------  Error when bootstrapping CMake:  Cannot find appropriate C compiler on this system.  Please specify one using environment variable CC.


JavaFX unable to load scene after populating a comboBox

I am trying to create a GUI that could dynamically load a scene on a borderPane(user can change the scene by clicking on a button). and then I want to add a comboBox that is filled with some option from an observablelist but after populating the comboBox, the program unable to load the scene  I get this error when trying to load a scene  Caused by: java.lang.NullPointerException     at prototipegui1.FXMLDocumentController.cekSource(FXMLDocumentController.java:87)     at prototipegui1.FXMLDocumentController.initialize(FXMLDocumentController.java:39)     at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)     ... 50 more   it works fine before i add this   sourceCbx.setItems(sourceList);   package prototipegui1;  import java.io.IOException; import java.net.URL; import java.util.ResourceBundle; import java.util.logging.Level; import java.util.logging.Logger; import javafx.collections.FXCollections; import javafx.collections.ObservableList; import javafx.fxml.FXML; import javafx.fxml.FXMLLoader; import javafx.fxml.Initializable; import javafx.scene.Parent; import javafx.scene.control.ComboBox; import javafx.scene.input.MouseEvent; import javafx.scene.layout.AnchorPane; import javafx.scene.layout.BorderPane; import javafx.stage.Stage; import com.fazecast.jSerialComm.SerialPort;  public class FXMLDocumentController implements Initializable {      @FXML     private AnchorPane mainPane;     @FXML     private BorderPane fillPane;     @FXML      private ComboBox<String> sourceCbx;      private ObservableList<String> sourceList = FXCollections.observableArrayList();       @Override     public void initialize(URL url, ResourceBundle rb){         cekSource();     }     @FXML     private void Close(MouseEvent event) {         Stage stage = (Stage) mainPane.getScene().getWindow();         stage.close();     }     @FXML     private void Central(MouseEvent event) {         loadPane("FXMLcentral");     }     @FXML     private void Temperature(MouseEvent event) {         loadPane("FXMLtemperature");     }     @FXML     private void Proximity(MouseEvent event) {         loadPane("FXMLproximity");     }     @FXML     private void Electricity(MouseEvent event) {         loadPane("FXMLelectricity");     }     @FXML     private void Humidity(MouseEvent event) {         loadPane("FXMLhumidity");     }     @FXML     private void LoginRecord(MouseEvent event) {         loadPane("FXMLrecord");     }     private void loadPane(String pane){         Parent root = null;         try{             root=FXMLLoader.load(getClass().getResource(pane+".fxml"));         }catch(IOException ex){             Logger.getLogger(FXMLDocumentController.class.getName()).log(Level.SEVERE, null, ex );         }         fillPane.setCenter(root);     }     private void cekSource(){//masih mengganggu fungsi tombol lain         SerialPort[] portNames = SerialPort.getCommPorts();             for(int i = 0; i < portNames.length; i++){                 sourceList.add(portNames[i].getSystemPortName());             }           sourceCbx.setItems(sourceList);     }   }   After checking this  I get the solution   If(sourceCbx!=null){ sourceCbx.setItems(sourceList); }


How can we prove that we've discovered a strange attractor?

So,  has a strange attractor of the form:  $$x_{n+1} = a x_n + y_n$$ $$y_{n+1} = b + (x_n)^2$$  ...it precedes the graphic of a strange attractor itself  (the initial conditions are also given for the strange attractor).  My question is, how can we prove that this system defines a strange attractor?  Also, is there any way to get more exact values for the system - for example, more accurate numbers?  EDIT  I asked  for a general reference on chaos and strange attractors.  For this question (the current question), I'm wondering what exactly we need to do to prove that we have a strange attractor.  In other words, the last question was a reference request, and this question is the mathematics itself - how do we go about proving that we've found a strange attractor?


Should we introduce screen time to our 27 month old?

Somehow, my wife and I have made it through 27 months of virtually no screen time for our daughter.  We thought we were doing what's best for her, but we're starting to fear it's going to come back and bite us.  To elaborate...  My question is spurred by the fact that recently I let her use my phone on a video chat with Grandma and I had it locked completely down so she couldn't do anything.  This was the first time we had tried this, and after the call ended she carried my phone around for a half an hour refusing to part with it.  When I finally insisted on getting it back, it was the ultimate meltdown of her young life.  Both my wife and I were stunned.  It was not her first video chat, but the first chat where she got to hold the device solely herself. She could not manipulate the phone so to speak as all the controls were off, including the touchscreen.  She sees her parents, other adults, and some kids with electronics that she is not allowed to see or hold, though she desperately wants to.  By keeping screens from her so stringently, is she more likely to be obsessed with screen time later?  Would she be better off now if they had been a small part of her daily life from the get go?


How to fix the wrong number of unread emails flag in Outlook?

I have an annoying problem in Outlook 2013. My inbox is flagged with "1" unread message, but this is not the case. Even when I empty my inbox folder, this bold "1" stays next to my folder, new as it contains a new message.  I've tried to "empty" it, to "clean" it, to "mark all as read" it. Nothing works.  Any tips?


I hope you're doing great. I want to set the color properties (for example blue) of the cite command in Beamer (citep and citet) but I don't know how. How can I do it? That is my code.  \documentclass[xcolor=dvipsnames,t]{beamer} \definecolor{mikadoyellow}{rgb}{1.0, 0.77, 0.05} \definecolor{yaleblue}{rgb}{0.06, 0.3, 0.57} \usetheme{warsaw} \usefonttheme{serif} \setbeamerfont{section in head/foot}{family=\sffamily} \setbeamerfont{subsection in head/foot}{family=\sffamily} \setbeamerfont{author in head/foot}{family=\sffamily} \setbeamerfont{title in head/foot}{family=\sffamily} \setbeamercolor*{palette primary}{use=structure,fg=black,bg=red} \setbeamercolor*{palette quaternary}{fg=white,bg=black} %\usepackage[spanish]{babel} \usepackage{multirow} \usepackage{ragged2e} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{gensymb} \usepackage{xcolor} \usepackage{hyperref} \justifying \usefonttheme{professionalfonts} \usepackage[none]{hyphenat} \usepackage{cancel} \usepackage{tikz} \usepackage[round]{natbib} \usepackage{color} \usepackage{colortbl} %\let\oldcite=\citet %\let\oldcite=\citep  %\renewcommand{\citet}[1]{\textcolor[rgb]{0,0,1}{\oldcite{#1}}} %\renewcommand{\citep}[1]{\textcolor[rgb]{0,0,1}{\oldcite{#1}}}  %\def\@citet#1#2{{\hypersetup{linkcolor=blue!black}[{#1\if@tempswa , #2\fi}]}}  \newcommand{\textunderscript}[1]{$_{\text{#1}}$} \setbeamersize{text margin left=20pt,text margin right=20pt}  \title[Title 2]{Title}    \author{Author}  \date{\today}   \begin{document} \sloppy { \addtobeamertemplate{headline}{% \setbeamercolor{section in head/foot}{use=palette quaternary, fg=palette     quaternary.bg} }{} \begin{frame} \titlepage \end{frame} } %-------------------------START----------------------------   \section{Problem definition} \subsection{Introduction} \frame{ \citep{Ansari2014} and \citet{Ansari2014} }    \begin{frame}[allowframebreaks] \bibliographystyle{apalike} \bibliography{ref_qualify} \end{frame} \end{document}   Thanks in advance


So I had to switch SharePoint from one server to another.  Our network guy installed SharePoint onto a new server and I backed up and uploaded my stuff into the new server (with the same name as the original one).  Everything seems to be working alright except for the Business Data Connectivity Service.  I keep getting this error when I click on it:  The load balancer is not provisioned. Verify the load balancer was provisioned successfully before retrieving endpoint addresses.    I have tried stopping and starting the service, deleting and re-adding the service, changing the app pools and users it uses, restarting IIS, rebooting the entire server...  I'm at a loss right now and I'm not sure what to do.  Are there any other options or ideas out there that I can try?  EDIT  When I try installing the hotfix, it says that it is not applicable


Converting the beta coefficient from matrix to scalar notation in OLS regression

I've found for my econometrics exams that if I forget the scalar notation, I can often save myself by remembering the matrix notation and working backwards. However, the following confused me.  Given the simple estimation  $$\hat{y_i} = \hat{\beta_0} + \hat{\beta_1}x_{i1}$$  How do we get from  $$\boldsymbol{\hat{\beta}} = \boldsymbol{(X'X)}^{-1}\boldsymbol{X'y} $$  to  $$\hat{\beta}_1 = \frac{\sum_{i=1}^n(x_i-\bar{x})(y_i-\bar{y})}{\sum_{i=1}^n(x_i-\bar{x})^2} $$  I get stuck at  $$\hat{\beta}_1 = \frac{\sum_{i=1}^nx_iy_i}{\sum_{i=1}^nx_i^2}$$


Custom keyboard shortcut to print symbol

I'm trying to set a custom shortcut Alt + - [that's a hyphen] to print an em dash and can't get the right command. echo — doesn't work.  Any ideas what I can do?


I did dual boot with Windows 7 & Ubuntu 14.04. I get both in boot menu but can't boot into Windows 7. The primary drive where Windows 7 was configured now shows to be logical drive with all files in it. How to resolve it ?  This is what it shows:  irshad@irshad-desktop:~$ lsblk NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT sda      8:0    0 465.8G  0 disk      ├─sda1   8:1    0  58.6G  0 part /media/irshad/B2E08E69E08E339F     ├─sda2   8:2    0     1K  0 part      ├─sda5   8:5    0 195.3G  0 part /media/irshad/8E90A6A690A6946D     ├─sda6   8:6    0 182.8G  0 part /media/irshad/7650B08250B04B1F    ├─sda7   8:7    0    25G  0 part /    └─sda8   8:8    0     4G  0 part      sr0     11:0    1  1024M  0 rom     I tried to run update-grub but I get the following result.  $ sudo update-grub  Generating grub configuration file ...  /etc/grub.d/06_custom: 31: /etc/grub.d/06_custom: function: not found  /etc/grub.d/06_custom: 34: /etc/grub.d/06_custom: save_env: not found  /etc/grub.d/06_custom: 36: /etc/grub.d/06_custom: Syntax error: "}" unexpected


Can we make closed:0 and is:answer work together so only answers are returned on open questions?

I'm not sure whether this is a bug or was planned, but I created a filter to return posts that meet the following requirements:   is:answer - The posts are answers only. hasnotice:1 - The posts have a post notice on them closed:0 - The questions are not closed.     The problem is that the first two filters work correctly if closed:0 is omitted. I get back answers with a post notice, but if I add closed:0 to try and filter out answers on closed questions, I end up getting questions themselves back in the search results.  It would be helpful if it were possible to return answers that are on open questions, since answers on closed questions are arguably a different matter.  In short, can we make closed:0 and is:answer work together so only answers are returned on open questions?


Prime spectrums bijection but not homeomorphism

Let $f$ be a homomorphism from commutative ring $A$ to $B$.  Suppose $f$ induces a bijection between $\operatorname{Spec} B$ and $\operatorname{Spec} A$.  Must $\operatorname{Spec} A$ and $\operatorname{Spec} B$ be homeomorphic?  Are there any counterexamples？(The topology is Zariski topology)


I would like to align some statements so that it's more pleasing to the eye. I have the following code, where the first version the two statements are not aligned. I use \phantom to force alignment but this introduces necessary space. It would be nice to place some text within a specified maximum width, but I don't know if this is possible with LaTeX. This is the MWE:  \documentclass{article}  \usepackage[noend]{algpseudocode} \usepackage{algorithm} \usepackage{algorithmicx}  \newcommand*\Let[2]{\State #1 $\gets$ #2}   \begin{document}  \begin{algorithm}[!h]   \caption{Integration } \begin{minipage}{\textwidth}  \begin{algorithmic}  \Let{$\mathbf k$} {$ \mathbf k + j  \mathbf w \left[ i \right] \mathbf B $}  \Let{$\mathbf r $} {$ \mathbf r - j   \mathbf w \left[ i \right]  \mathbf B$} \end{algorithmic} \end{minipage} \end{algorithm}  \begin{algorithm}[!h]   \caption{Integration } \begin{minipage}{\textwidth}  \begin{algorithmic}  \Let{$\phantom{\mathbf{r}}\mathbf k$} {$ \phantom{\mathbf{r}} \mathbf k \phantom{-}+ j  \mathbf w \left[ i \right] \mathbf B $}  \Let{$\phantom{\mathbf{k}}\mathbf r $} {$ \phantom{\mathbf{k}} \mathbf r \phantom{+}- j   \mathbf w \left[ i \right]  \mathbf B$} \end{algorithmic} \end{minipage} \end{algorithm}  \end{document}   which produces


Initial value problem $t\frac{dx}{dt}=x+\sqrt{t^2+x^2}$

Another question on ODEs, this time just wondering how I should start with this one. $$t\frac{dx}{dt}=x+\sqrt{t^2+x^2}, \qquad x(1)=0.$$ It looks like a linear ODE and so after playing around with it I eventually got $$\frac{dx}{dt}-\frac{2}{t}x=\frac{dt}{dx}$$ to which I multiplied the integrating factor $$I(t)=t^{-2}=\frac{1}{t^2}.$$ This in turn gave me $$\frac{x}{t^2}=\int{\frac{1}{t^2}t'dt},$$ and then I used integration by parts to get $$\frac{x}{t^2}=\frac{-1}{t}+C.$$ Applying the initial conditions gave me $$x=t(t-1).$$ The answer in the book is however $$x=\frac{1}{2}(t^2-1).$$  Where did I go wrong? What should I do to solve this problem? Thanks.


When logging into my Ubuntu instance I get the message *** System restart required ***. I am running a server and uptime is very important for me.  How can I know why the restart is required? I have setup automatic security updates and I suspect one of those updates requires a restart. I only want to restart the server if the updated software is relevant to my setup.


Why does the sum of the reciprocals of factorials converge to $e$?

I've been asked by some schoolmates why we have $$ \sum_{n=0}^\infty \frac{1}{n!}=e.$$ I couldn't say much besides that the $\Gamma$ function, analytic continuation of the factorial, is defined with an integral involving $e$. Then I also know that actually $$ \sum_{n=0}^\infty \frac{x^n}{n!}=e^x.$$ Is there a reason for these facts?  P.S. I added the tag "intuition", please remove it if you think it is not pertinent.


Is the result of the product of metric tensors $\eta^{\mu\nu} \eta_{\mu\nu} = 1$?   If so how would I prove this?  I know that tensors are represented as matrices but I don't know how I'd prove this (if it is true).


I have 41 GB of space on my E:/ drive. Is it sufficient to install Ubuntu? My Windows XP is installed in C:/ drive. Is it OK for dual boot? Should I install Ubuntu (I am installing using Live CD). I don't want to lose my Windows option.


If I have Greek Visa, can I use it to visit other Schengen countries after my arrival in Greece

I am planning to travel to Greece so I want to know if I can visit other Schengen countries with the visa and also by train from Greece after my arrival in Greece


How to use getters and setters? Semi question: How to create structure to easily retrieve data?  After setting the data in setter I can't retrieve it from the getter.  The structure is as follows:   Interaction - parent class with getters and setters                                              Dictionary, CategoryInteraction, WordsInteraction - subclasses    Here is my code:  public class Dictionary extends Interaction {      private String resource = "/home/kjlk/IdeaProjects/Jdf/src/fdf/res";     private File resourceFile = new File(resource);     private Scanner scanner;     private LinkedHashMap<Integer, String> categories;      public void getCategoriesFromDictionary() {         Interaction interaction = new Interaction();         try {             scanner = new Scanner(resourceFile);         } catch (FileNotFoundException e) {             e.printStackTrace();         }         categories = new LinkedHashMap<>();         int categoriesCount = 1;         while (scanner.hasNextLine()) {             String line = scanner.nextLine();             if (line.startsWith("_")) {                 categories.put(categoriesCount, line);                 categoriesCount++;             }         }         scanner.close();         setCategories(categories);     } }  public class Interaction {      private LinkedHashMap<Integer, String> categories;       public LinkedHashMap<Integer, String> getCategories() {         return categories;     }      public void setCategories(LinkedHashMap<Integer, String> categories) {         this.categories = categories;     } }  public class CategoryInteraction extends Interaction {      public void printCategories() {         LinkedHashMap<Integer, String> categories = getCategories();         for (Integer key : categories.keySet()) {             System.out.println(key + ": " + categories.get(key));         }         System.out.println();     } }   I'm getting NullPointerException for:  LinkedHashMap<Integer, String> categories = getCategories();   Thank you in advance! Please do not refer me to answers for NPE! The idea points to the working structure.


Error when trying to install listings package in MikTex

I'm trying to install the 'listings' package through MiKTeX package manager and I get the following error:  MiKTeX Problem Report Message: parse error - unexpected end of input; expected '}' MiKTeX: 2.9 OS: Windows 7 Enterprise, 64-bit, Service Pack 1, build 7601


Registration form in a popup window (colorbox or jQuery ui)?

How to embed a registration form in a popup window?  I would like to use Colorbox or jQuery UI:  drupal_add_library('system', 'ui.dialog');


How can I tell if a journal is reputable?

In a lot of research you have to site sources from a "reputable" journal. I've seen journals that have opened simply to post that bigfoot exists and won't take anything other than more or less garbage papers. Not to mention the problem with people "fixing" data to make their paper look legitimate when it's not.  How can I tell if the journal (and subsequent articles) I'm looking at is reputable?


I want to put two <div>s next to each other. The right <div> is about 200px; and the left <div> must fill up the rest of the screen width? How can I do this?


Isomorphism theorem: $\mathbb{Z}[i]/(i+4) \to \mathbb{Z}/17\mathbb{Z}$

Show that $\mathbb{Z}[i]/(i+4) \to \mathbb{Z}/17\mathbb{Z}$. I know that I have to use the first Isomorphism theorem to proof this. Therefore I have to introduce a morphism $\phi : \mathbb{Z}[i] \to \mathbb{Z}/17\mathbb{Z}$ and show that the $\ker \phi = (i + 4)$. But how is the morphism defined in this case? $\mathbb{Z}[i]$ is defined as $\mathbb{Z}[i]=\{a+b i \mid a, b \in \mathbb{Z}\}$.


Removing columns in a SpatialPolygonsDataFrame in R?

My spatial polygon data frame (SPDF) contains too many columns (variables) and I want to remove most of the columns entirely.   I know how to do this with a regular data frame in R, but I am unsure how to do this when dealing with object of class SpatialPolygonsDataFrame?


Why does the beef I cook never come out tender?

I have tried cooking beef (mostly London broil type) so many times... And it never comes out tender! I've tried different methods... Temperatures... Everything! It always comes out tough and chewy. I thought maybe it was the type of meat I was using, but I had my mother cook the same exact type of beef at her house... & it came out perfectly. I asked her how & she said she just does it! And she sautéed it on the stove... I did the same thing a week later, & it turned out bad. What am I possibly doing wrong?


Why is the equation of state only a function of three variables?

Wikipedia says about the equation of state as:  For a given amount of substance contained in a system, the temperature, volume, and pressure are not independent quantities; they are connected by a relationship of the general form ${\displaystyle f(p,V,T)=0}$  But why are there only three variables in the equation of state? Why can't say entropy and other state variables be a part of the equation of state?


Numbering sections independent of chapters numbering

Is it a way to create a document in such a way that the numbering of the sections is independent of that of the chapters?  e.g.:    Chapter 1    section 1    section 2 Chapter 2    section 3    section 4    section 5 Chapter 3    section 6    section 7


Analytical solution of a convergent series

Which is the analytical solution of the infinite sum  $\frac{1}{1+1^{2}}+\frac{1}{1+2^{2}}+\frac{1}{1+3^{2}}+\frac{1}{1+4^{2}}+\cdots$?


How do I send a file with FileZilla from the command line?

I have a batch file that builds an application, and then I want to upload it to an FTP server from the command line.   Considering I do the upload manually with , is there a command line for it to upload files?  I am limited to Windows.


Plot three dimensional surface plot using (x,y,z) coordinates


Getting all the values from a entity reference field (Drupal 8)

I'm trying to figure how I can get all the values inside an entity reference field  As shown in this image, I have an entity field called Target Participants(field_program_participants) with multiple values.    I have tried to output the values using node.field_program_participants.entity.label, but it only outputs one value.     How can I output all the values inside the field


Solve recurrence relation $a_n = 3 a_{n - 3} + a_{n-1} + 2 n$

I am not able to solve the above recurrence relation which involves $n$. The initial conditions $a_0 = 1, a_1 = 2, a_2 = 3$, for $n \geq 0$. Please try to give closed form in terms of arbitrary $a_i \geq 1 $ for $i \geq 0$


Wavelength of light too long to measure electron position in double-slit experiment?

I'm a mathematician, so I am not familiar with experimental physics.  I am watching MIT course on Quantum Mechanics, and they describe the two-slit experiment with electrons passing through the slits.   Here is my question: How do we measure the position of an electron with a light source?  AND, why does longer wavelength mean we can't be as accurate in our measurement of the position.  What is the apparatus?  How does this actually work in a lab?  What I describe below is described in the video at 59:50 ()  They talk about trying to "cheat" and observe which slit the electron went through.  They say to shine very weak light at the electrons before they pass through the slit.  Sure, the light will impart some momentum and alter the path of the electron a little bit, but if the light is low energy enough, we could perhaps know which slit it went through, yet not change the diffraction pattern by very much.  Great!  Except weak light means low frequency, long wavelength.  Then they say that long wavelength means we can't tell which slit the electron went through.  We need wavelength on the order of the distance between the two slits to know which slit it went through.  But increasing frequency by this amount is just enough to wash out any interference pattern at all, and so our experiment fails.  My question:  How do we measure the position of an electron with a light source?  AND, why does longer wavelength mean we can't be as accurate in our measurement of the position.  What is the apparatus?  How does this actually work in a lab?


Proving that a function is constant from functional equation

$a,b \in (0,1)$ and $f:[0,1] \to \mathbb R$ is continuous functions s.t. $ \int_0^x f(x)dx=\int_0^{ax}f(x)dx+ \int_0^{bx}f(x)dx$ . Knowing that $a+b=1$, we have to prove that $f$ is constant.  Using the derivative,we get: $f(x)=af(ax)+bf(bx)$   I managed to do it for the case $a=b=1/2$, but I don't know how to make it with $a,b$ arbitrary and $a,b \in (0,1)$ $a+b=1$


Appeal to Pity? 'don't give me a ticket. My parents will take the car away from me and my life will be miserable.'

Source: p 214, With Good Reason, An Introduction to Informal Fallacies (2000 6 ed) by      Fallacy: Appeal to Pity   Definition/Hints: Seeking to persuade not by presenting evidence    but by arousing pity   [1.] Example/Method: "Please, officer, don't give me a ticket. My    parents will take the car away from me and my    life will be miserable."    If the Conclusion is:           I am not guilty of a ticket.   Then 2 is an AtP because criminal guilt is an independent conclusion and question from emotional misery due to the ticket.   Don't give me a ticket.    Then how is 1  an Appeal to Pity (abbreviated to AtP)? Is not 1 a Valid Syllogism as follows? 3 differs from the Protasis of 4, and so 4 and 5 would not apply.   If an officer gives me a ticket, then my parents will take the car away from me. If my parents will take the car away from me, then my life will be miserable.


Name change on French passport. Will there be issues coming into the US?

A friend came to the US last year and was harassed at immigration for no reason. It's suspected because of the new administration, and also racial profiling based on his name and skin color.  He is a French citizen and holds a French passport. He recently changed his first name and has a new passport with the name change. Do you know if there will be issues, since during his last visit to the US he had a different name? What shows up in the computer when he comes through immigration? He's concerned he will be turned back or have issues since his last record of entry has a different first name. Do you know what paperwork he should bring to show proof of the name change? Everything he has is written in French. Thank you.


Repeat a command every x interval of time in terminal?

How can I repeat a command every interval of time , so that it will allow  me to run commands for checking  or monitoring  directories ?   There is no need for a script, i need just a simple command to be executed in terminal.


inner and outer margin misplacement in book

I am using the book style \documentclass[11pt,openright]{book} but the title, index starting and all the capters have larger margin in the right proper of documents opening on the left. I tried to change the option to \documentclass[11pt,openleft]{book} but there is no change on the page positioning.  Another option is to change the margins definition using this:  \usepackage[a4paper,inner=3.5cm,outer=2.5cm]{geometry}   but it seems like an improper work-around to me. I'm sure there is a way to properly set it from the book class already.  Is there any other parameter to tune? or sould I apply the geometry solution and forget aobut it?


Prove that R is an equivalence relation on S.

let $S$ be the union of disjoint sets $A_1, \dots , A_k$. Let $R$ be the relation consisting of pairs $(x,y) \in S \times S$ such that $x,y$ belong to the same member of $\{A_1, \dots, A_k\}$. Prove that $R$ is an equivalence relation on $S$.  To answer the question I did the following, I am not sure if it is correct.  Reflexive   For any $x \in A_i$, $(x,x) \in R$ and this also hold for any $y \in A_i$, so therefore reflexivity holds  symmetry  For any $x,y \in A_i$ where $x = y$, then $(x,y)=(y,x) \ in R$ therefore symmetry holds  Transitivity  given $(x,y),(y,z) \in R$ then $x=y$ and $y=z$ so therefore $x=z$ and Transitivity holds  I don't know if the above counts as a valid proof but that is what i was able to come up with.


How is the joint state of these qubits derived?

Can someone show to me the steps to derive the joint state at the bottom of this image, please?   I tried to follow his explanation but I didn't get the same results… This is taken from the lecture notes of Ronald de Wolf in case it may help


As a mod when should I vote to close content that is not flagged?

I know mods are supposed to step in to quickly close seriously problematic posts and otherwise allow the community to vote to close a post.  But what about when there are four close votes on a question, and I personally feel the question should be closed but isn't worthy of mod super-mega closing? Should I cast the final vote like a normal user (even though it's technically binding) or should I sit back and wait  for the community?  For me the problem is complicated because on UX.SE we hover close to the point where there's not enough high-rep activity to quickly close posts and I was one of those high rep users that used to VtC.  Should I always treat my mod close vote as binding and reserve it for extreme situations, or should I treat my close vote as "normal" when it's the fifth and final vote anyway?


F12/F2 not working & Lenovo logo not showing after installing Ubuntu (Single-boot)

I have a Lenovo Edge 15, of which I installed Ubuntu on (removed Windows).  I have to access the BIOS. However, the F12 key won't open it, and the Lenovo logo won't even display. Instead, it goes directly to Ubuntu asking me for my password to decrypt the system.  I need help accessing BIOS  EDIT: It seems the BIOS itself maybe messed up. When I press F2, I get a black screen, and it stays there until reboot


Is there a word for a job title that are based on doing busy work

Is there a word for a job title that doesn't actually contribute to increasing productivity in an organization and is redundant, wouldn't matter if this positions were vacant and even if you make them disappear.  A loose example would be document controller working for a very small valued and magnitude project where responsibilities of this position could have been easily accomplished by a coordinator in excess to his own. but a inexperience first timer project manager (nepotism) utilized his bookish idea to employee another inexperienced incompetent document controller.


My friend let me start a character in Assassin's Creed Odyssey on his profile to see if I liked it. I did in fact like the game so I ordered it in the mail. Is there a way for me to transfer my progress to my account?


How to move system clock time forward/backward?

I know commands for setting specific time and/or date, but can't find ones which move the time relative to the current time.  What are the commands to move the time forward/backward x seconds/minutes/hours? (And possibly also days/months/years?)


How do pump spells interact with damage at end of turn?

My friends recently got into a heated argument over a rules interaction. One player had a 2/2 creature, and responded to the opponent's Lightning Bolt targeting it with a Mutagenic Growth. The player casting Lightning Bolt claimed that the creature died later, because the pump spell wore off at the end step, but damage was not removed until the cleanup step. I am the most experienced player of our group and told him that is sort of right, but state based actions are not checked at that time, so the creature lives. What actually happens here?


Extract substring after delimiter using GNU awk or awk

I would like to extract substring after colon delimiter for my practical needs using GNU awk utility. For example I can extract the temperature of hdd value using cut as follows  hddtemp /dev/sda | cut -d ':' -f3   The same example written in sed  hddtemp /dev/sda | sed 's/.*\://'   For glory of Saint Completeness and GNU Trinity (awk, cut, sed) I wonder, can GNU awk do such thing?  Sample input: /dev/sda: ST500LT012-9WS142: 47°C  Required output: 47°C


MikTex 2.9 Installation Error: File name database capacity exceeded.

I am trying a complete installation of MikTex 2.9, using 64 bit installer, from a recently downloaded local package directory, all latest versions.  During installation, I run across this error "File name database capacity exceeded."  Does anybody know a solution to this problem. My complete log file can be viewed at


Going through minimized windows in Ubuntu dock

I've been using Elementary OS for years, and now I am back to Ubuntu 18.04.  In such a distro there is a very useful function, which is that if one has several minimized windows of the same software (e.g. several PDFs documents) one can show them one by one via scrolling in the dock icon (moving the mouse wheel or moving two fingers on the touchpad).  The function doesn't work in Ubuntu. Is there any way to make it work? And if not, is there a less cumbersome way to go through the minimized windows than right click -> All the windows?


What does the value of a probability density function (PDF) at some x indicate?

I understand that the probability mass function of a discrete random-variable X is $y=g(x)$. This means $P(X=x_0) = g(x_0)$.  Now, a probability density function of of a continuous random variable X is $y=f(x)$. Wikipedia defines this function $y$ to mean      In probability theory, a probability density function (pdf), or density of a continuous random variable, is a function that describes the relative likelihood for this random variable to take on a given value.   I am confused about the meaning of 'relative likelihood' because it certainly does not mean probability! The probability $P(X<x_0)$ is given by some integral of the pdf.  So what does $f(x_0)$ indicate? It gives a real number, but isn't the relative likelihood of a specific value for a CRV always zero?


Can you use marinade twice if it was first used on precooked meat?

I made precooked frozen meatballs in the crockpot with jelly and honey BBQ sauce. It was really yummy and was wondering if the sauce that's leftover would be ok to marinate some ribs in?


Time needed for a meteorite to reach the Earth surface

I was wondering how to calculate the time needed for a meteorite to reach the surface of Earth given its distance from the surface. The mass of the meteorite is much smaller than that of the Earth, but the distance from the Earth doesn't allow easy approximations, let's say that the distance from the surface of the Earth is three times the radius of the Earth.


How can I install the most used plugins like flash player and mp3 in Ubuntu?


Is $\langle a, b \mid baba^{-1}\rangle$ truly isomorphic to $\langle a, c \mid a^2c^2\rangle$?

Kosniowski's A First Course in Algebraic Topology sure claims that $$\langle a, b \mid baba^{-1}\rangle$$ and $$\langle a, c \mid a^2c^2\rangle$$ are isomorphic to each other (see ch. 23 "The Seifert- Van Kampen theorem: I Generators", pages 178-179), and I'm not doubting the proof since it seems to be correct, and this claim is also found in other sources (online or not).  But... how CAN it be true? As far as I know, $\langle a, b \mid baba^{-1}\rangle$ is the fundamental group of the Klein bottle. An exercise found in another chapter of Kosniowski's very book even challenges the reader to prove that this group is isomorphic to a certain group $G$ generated by two transformations $$a(z) = z + i$$ and $$b(z) = \overline{z} + \frac{1}{2} + i$$ of the complex plane, and by looking at it geometrically it's pretty obvious that all elements $a^m(z)b^n(z)\in G$ are distinct from each other.  I'm actually trying to show that this group is indeed isomorphic to $\langle a, b \mid baba^{-1}\rangle$ right now... and not only can't I do it because there's no guarantee that $a^hb^i \neq a^jb^k$ whenever $h\neq j$ or $i\neq k$ (not as far as I know, at least), but now I've even learnt that this group is supposed to be the same as $\langle a, c \mid a^2c^2\rangle$, where elements like $a^4c^4$ and $a^2c^2$ are clearly the same!  I'm really clueless as to what's going on here. Did I somehow misunderstand how group presentations even work, or what?


How to permanently disable monitor power saver using the command line?

I have tried as following:  1. Turn off: export DISPLAY=:0.0 && xset dpms force off  2. Turn on: export DISPLAY=:0.0 && xset -dpms   Which works but that is a temporary solution, which does not fix my problem yet. When i reboot system it start again and again the same auto turn off mode.   How can i now remotely using SSH turn it off forever?  IMPORTANT:  - KIOSK (ATM machine will use this option) - 24/7 advertising display/slides will use this   Optional Note: this guide i followed   , but permanent solution did not worked.


What is the correct and better language code format in URL and hreflang?

From SEO perspective, which language code format in the URL is better and more correct? www.example.com/en-US www.example.com/en_US    Is the second format valid for the attribute hreflang in <link rel="alternate".....>? According to , the first format en-US is always described.   I have already done my website with the second format en_US. Is it worth to move to the first format if it is a better one.  [UPDATE]  Rather than trying to find an answer to choose underscores or dashes in URL, I would like to know about the correct language code usage in URL. For example, as I already used the en_US format, what is the correct usage?  <link rel="alternate" href="http://www.example.com/en_US" hreflang="en_US" />  <link rel="alternate" href="http://www.example.com/en_US" hreflang="en-US" />


My function that returns first and last index of a chosen real number in an array executes but doesn't always work

I'm trying to define a function prem_dern that returns the first index and last index of an input real number ( by the user ). When executing, the intitializing part works fine but not the prem_dern function ( program exits right after compiling. The program doesn't return any errors when compiling.Here is what I did : #include <stdio.h> #include <stdlib.h>  void prem_dern(float t[], int n, float r) {        int i,j;     printf("donner le reel pour savoir les positions ");     scanf("%f",&r);     for(i=0;i<n;i++)     {         if (t[i]==r)printf("la premiere position %d:",i);          break;     }     for (j=n-1;j>0;j--)     {         if(t[j]==r) printf("la derniere position %d:",j);         break;     } } int main() {   int i,n;     float r;     float t[100];     printf("donner le nombre des elements : \n");     scanf("%d",&n);     for(i=0;i<n;i++)     {         printf("donner un element :");         scanf("%f",&t[i]);     }     prem_dern(t,n,r);     return 0; }


Award bounty points when I blew up the original question?

I posted this SO question:   I put a bounty on the question and got some very reasonable suggestions, though nothing that led to an actual solution to my problem. (It's been a fairly painful week.)  I "solved" my own problem with a fairly significant architectural change to the way I'm storing user data. It's not a solution to the original problem; it's totally changing what the problem was. Feel free to read the thread for the gory details.   What's the etiquette regarding the outstanding bounty points? Should I let them expire? Award them to the highest voted answer? Give them to the one that caused me to think about how to re-attack my problem in a different way - but didn't provide details of the eventual answer?  Haven't found a meta thread that deals with this specific philosophical dilemma...


Where does OS X store your current desktop picture? I read somewhere else that it was in /Library/Caches/com.apple.Desktop. But I don't have that directory.


This question has been asked a lot, but for reason I cannot get it to work. I'd like to include a .eps image in my document - I am using pdflatex in TeXMaker. Below is the input (I am providing the whole preamble incase there is some interference.   \documentclass[11pt]{article} \usepackage{times} \usepackage{graphicx} \usepackage{epstopdf} %converting to PDF \usepackage{amssymb} \usepackage{amsmath} \usepackage{mathtools} \newcommand{\HRule}{\rule{\linewidth}{0.5mm}} \usepackage[parfill]{parskip} \setcounter{secnumdepth}{5} %how deep sections are numbers \usepackage{float} \usepackage[font={sf,footnotesize},labelfont=bf, justification=justified, singlelinecheck=off]{caption} \usepackage[font=footnotesize]{subcaption} \usepackage[scaled]{helvet}  \usepackage{titlesec}  \usepackage[T1]{fontenc} \usepackage[export]{adjustbox} %for large figures \usepackage{upgreek} \usepackage{microtype} \usepackage{setspace} \singlespacing \usepackage[defaultlines=4,all]{nowidow}  \includegraphics[scale=1]{/../model_1_2.eps}    The error I get is:      ! Package pdftex.def Error: File `/model_1_2-eps-converted-to.pdf' not   found.See the pdftex.def package documentation for explanation.Type H    for immediate help.... .../../model_1_2.eps}   I hope someone can help.


Is it possible to check where an alias was defined?

An alias, such as ll is defined with the alias command.  I can check the command with things like type ll which prints  ll is aliased to `ls -l --color=auto'   or command -v ll which prints  alias ll='ls -l --color=auto'   or alias ll which also prints  alias ll='ls -l --color=auto'   but I can't seem to find where the alias was defined, i.e. a file such as .bashrc, or perhaps manually in the running shell. At this point I'm unsure if this is even possible.  Should I simply go through all files that are loaded by bash and check every one of them?


What is the first reference in Sci-Fi to a touch-screen computer interface?

I know in TNG that all computer interfaces are now touch-screen, and that got me thinking: when was the first reference to touch-screen computer interfaces in Sci-Fi made?


I'm trying to create an interpolation map visualizing the global distribution of genetic markers - basically replicating the attached map. Can it be done in QGIS 3.8 (Zanzibar)?  I installed QGIS 3 but don't see the 'Interpolation plugin' as downloadable (experimental & deprecated plugins enabled). Is it unavailable or found elsewhere?


Geometric interpretation of Electromagnetism

For gravity, we have    General Relativity, which is a geometric theory for gravitation.  Is there a similar analog for Electromagnetism?


I am writing this query to find duplicate CTN Records in table1. So my thinking is if the CTN_NO appears more than twice or higher , I want it shown in my SELECT * statement output on top.  I tried the following sub-query logic but I need pulls     SELECT *          table1     WHERE S_IND='Y'      and CTN_NO = (select CTN_NO                       from table1                      where S_IND='Y'                        and count(CTN_NO) < 2); order by 2


Number of permutations $\alpha\in S_{n}$ with $\alpha^{2}=1$

This question is from Rotman's book An Introduction to the Theory of Groups.  How many $\alpha \in S_{n}$ are there with $\alpha^{2}=1.$ (Hint. (ij)=(ji) and (ij)(kl)=(kl)(ij))  My try: 1) There is identity permutation.  2) Transpositions: $\dfrac{n(n-1)}{2}$. ($2$ comes from the repetition in the transposition $(ij)$)  3) Product of two disjoint transpositions: $\dfrac{n(n-1)(n-2)(n-3)}{8}$ ($8$ comes from $2$ repetitions from the first transposition $2$ from the second and $2$ from the permutation of the two transpositions)  Even if my caslculations are correct I don't know how to get a closed formula for the summation.  I want to find the closed formula for the sumation and not counting the number of products of disjoint transpositions such that $\alpha^{2}=1$.  I am not a student, I'm just an old guy who likes to study Mathematics. I think I can live without knowing how to find the closed formula. Thanks for your hints.


Where does the chat get the thumbnail on Wikipedia links from?

Starting , we kind of wondered how the chat selects the preview picture. But with , we changed our direction: where does the chat get these pictures from? The displayed pyramids picture is nowhere to be seen on the page itself (unless I overlooked something)!


Expected number of tries before all elements of sample space have occurred.

We have a bag with 4 balls, one white, one black, one blue and one red. We are drawing balls with replacement. Find the expected value of the number of tries needed to draw all four colours.  More general: We have a uniform discrete distribution. What is the expected value of the number of tries needed until all elements of the sample space have occurred.


How to read papers without falling into a rabbit hole?

Often while reading a paper, I will see a citation that that seems more relevant than my current one. I'll switch to the new paper, only to experience a similar feeling. Or maybe I need to look something up on Wikipedia. An hour later, I'll still feel as if I didn't really digest anything. I will have skimmed 2-4 papers' introductions and conclusions, scratched some notes on the side, and generally feel overwhelmed.  Is this a bad habit? An abnormal feeling? How have others dealt with this to become more productive readers?  I'm fairly new to research, if that matters.


Is it possible for moderators to convert a comment into an answer?

Looking at the  to the Q there would be a fitting answer.  It would be a nice feature for Moderators to be able to convert comments to answers (and more often vice versa).  Possible or not?


Is my question suited for SO, if not where should I ask it?

I am planning to make an application to digitize and organize documents that a company, or forum, etc may have.  The first thing that came to my mind was:   How should I look for possible competitors that already have their product on the market?   To see what I am against, so I believe this question would be rather flamed if posted on the SO.  Other things I was thinking of:   Once I know about the other companies doing this same application I am planning, what should I consider before taking the step to do it or look for something else? Is there a public or a good resource where I should look first about the type of application I am planning to create? Would SO be a good place for this sort of questions or where should I go with those question I have?   Just wanted to add here since I stated on the comment answer below, that what concerns me the most is the attitude of the community whenever a post that may not suit it or is subjective or don't suit it at all, people go all out to bang it with negative votes without leaving a comment or giving the moderators a chance to move it, hence why I asked here first.  PS: hope I didn't do anything wrong by posting this here as well. If I'm missing a tag please let me know to added to it, I wasn't sure of what other tags I should use here.


In PHP, how do you change the key of an array element?

I have an associative array in the form key => value where key is a numerical value, however it is not a sequential numerical value. The key is actually an ID number and the value is a count. This is fine for most instances, however I want a function that gets the human-readable name of the array and uses that for the key, without changing the value.  I didn't see a function that does this, but I'm assuming I need to provide the old key and new key (both of which I have) and transform the array. Is there an efficient way of doing this?


I saw  got  from , but the question was put on hold and the user got one downvote from it. How could he get ten reputation from it?


Regression changing of dependent variable

In regression model with random regressors  $$y = a + bx + e$$  can I change the equation to  $$x = (-a/b) + (1/b)y + (-1/b)e$$  and consistently estimate $(1/b)$ with OLS?


Passing an Array to Different Class...Netbeans Java

A.java  public Class A {          String a,b;         public static void setArray(String[] array)//This is where i want the array to come         {                array[0]=a;                array[1]=b         } }   B.java  public class B {          String[] arr1 = new String[2];         arr1[0]="hello";         arr1[2]="world";         public static void main(String[] args)               {                 A a = new A();                 a.setArray(arr1);//This is from where i send the array               } }   I am trying to send an array from one class to another class


Why are best practice questions not well-received?

In my programming journey, I have been able to solve problems by writing spaghetti code and copying and pasting it through out my solution, as long as it works.  So not so long ago, I reached a stage where I was more interested in solving problems in accordance with best coding practice, creating maintainable code rather than a quick fix.  However, in my search for help I have also noticed negative reactions to best practice questions (downvoting). Yes, I do agree these questions fall into the XY problem spectrum.  However, I don't understand how one is expected to improve his skills and coding ability by not receiving such help?  Why are best practice questions not welcome on Stack Overflow?


Excluding some of the commands from being getting stored in bash history

Is there any way to exclude commands like rm -rf, svn revert from being getting stored in bash history? Actually I, by mistake, have issued them a number of times even though I have no intent to do, just because I am doing things quickly and it happened. Hence results in lost of lots of work I have did so far.


If $f: [0, a] \to \mathbb{R}$ is continuous and $1$-to-$1$ with $f(0) = 0$, how do see that $$\int_0^{f(a)} f^{-1}(t)\,dt + \int_0^a f(t)\,dt = af(a)?$$


Simple Expected Value Of Continuous Variable Question

The normal expected value that I am used to is the following with $f(x)$ as the probability density function:  $E[X] = \int_{-\infty}^\infty{xf(x) \, dx}$  My basic probability textbook is doing a basic proof with a nonnegative random variable $Y$ that begins:  $E[Y] = \int_0^\infty{P\{Y > y\} \, dy}$  Can someone explain this to me? Why does this expected value definition hold? Where does it come from? This doesn't make intuitive sense to me. I imagine that I'm missing something obvious?


CSI image resolution enhance: How real is it?

So I watched the following .  In the clip, using what seems to be the recording from a standard bank camera, they zoom in at least 100, and see the image of the culprit in the reflection of the eye of the girl.  Now, I thought this was completely ridiculous, so much so that I thought it was actually really funny.    However, my friend argued that there are very good tricks for image enhancement, such as "super resolution" a procedure where multiple frames of a video to produce a much higher single resolution image.   He did think the show bends the truth quite a bit, but how much?  Honestly, I don't actually know anything about these things, so my question is:     How good is modern image resolution enhancement?  Also, how far off are the CSI television programs?    Thank you,  Remark: This is  on the Skeptics site.  I was told I might receive better answers here.


Implementing meaningful equals method for non-static inner classes

I am currently wondering if there is a good way of implementing an equals method for a non-static inner class in Java. I basically a class Foo with an inner-class Bar like this:  public class Foo {    private final String foo; // constructor omitted    public /* non-static */ class Bar {      private final String bar; // constructor omitted      @Override     public boolean equals(Object other) {       return other != null && other.getClass() == getClass()         && ((Bar) other).bar.equals(this.bar)         && Foo.this.equals(Foo.((Bar) other)); // Will, of course, not compile.     }   }    @Override   public boolean equals(Object other) {     return other != null && other.getClass() == getClass()       && ((Foo) other).foo.equals(foo);   } }   My classes are a lot more complex in reality and I want to reuse the Foo#equals method from within Bar#equals in order to save me a lot of code. I am now considering to make the "inner-class-relationship" explicit in order to being able to refer to the "outer" class. However, then I have to add accessor methods manually and I want to avoid this. I cannot get rid of the feeling that there should be a Java approach of doing this.


Maximum number of $0.5$ cm diameter circles that can fit in a $5$ cm $\times$ $5$ cm square

This is an aptitude question which looked simpler to me than it actually is and got me stuck. The question asks:     What is the maximum number of cylindrical pencils of $0.5$ cm diameter that can be stood in a square shaped stand of $5$ cm $\times$ $5$ cm cross-section?   I am aware of hexagonal packing but i really don't know how to get the answer which says it should be $105$ pencils.  EDIT  A link to this question already asked  found later.


I would like to put an address in my document as follows:  |                             | |                     Name    | |                     Street #| |                     City    | |                     ZIP     | |                             |   where the | mark the left and right page borders. I would like the items of the address (Name, Street etc.) to be left-flushed, but the box right-flushed so that the longest item touches the right page border.  Is there a simple way to accomplish this?


Can a  (complete determinism) ever be compatible with quantum mechanics?


How to become competitive for PhD in data science?

I want to apply for Ph.D at a good Western university (e.g., in the UK or US) in data science. I have a master's degree (no thesis) and only one publication in a local journal. Will I be competitive for such spots? If not, how can I improve my profile?


Why doesn't raggedright work in the last column of a tabular (with package array)?

Here's my MWE:  \documentclass{article} \usepackage{array} \begin{document}  \begin{tabular}{>{\raggedright}l>{\em}l} A & B \\ E & F \end{tabular}  \begin{tabular}{>{\raggedright}l>{\raggedright}l} A & B \\ E & F \end{tabular} \end{document}   I want to make all the columns of the table \raggedright (in the real example then the columns are of X variant and I'm using tabularx, but the error shows up in the above).  Using the \array package I appear to be able to successfully insert \raggedright in each column except the last.  What's going wrong here?  (If there's a better way of making all columns of a table \raggedright then I'd be happy to know that as well.)


$f(0)=g(0)$ and $f'(x) \leq g'(x) ~\forall~ x \in \mathbb{R} \implies f(x) \leq g(x) ~\forall~ x>0$

Here's a problem which I thought to be lacking an additional condition. So I imposed the condition and presented my solution. Please check whether it can be done without the additional condition. Thank you.     The Problem : Let $f,g:\mathbb{R} \to \mathbb{R}$ be differentiable. Assume that $f(0)=g(0)$ and $f'(x) \leq g'(x) ~\forall~ x \in \mathbb{R}$. To show that $f(x) \leq g(x) ~\forall~ x \geq 0$.   If we impose the condition that $g'(x) \neq 0 ~\forall~ x>0,$ then it is a quick consequence of .  For every $x > 0, \exists c \in (0,x)$ such that $$\frac{f(x)-f(0)}{g(x)-g(0)}=\frac{f'(c)}{g'(c)} \tag{1}$$  The right hand side of $(1)$ is $\leq 1$ because of given assumption. Coupled with the fact that $f(0)=g(0),$ we have the desired result. $\blacksquare$  What can I do when $g'(x)=0$ at some points of $(0,\infty)??$


Trying to perform kernel density analysis but obtain: 'error all input points identical' or 'error in executing grid expression'

I am trying to perform a density analysis of a point shapefile on ArcMap. I am unsure of what to insert for population field. I've tried the actual number of people in the census tract where my point is and also tried adding a column to insert count (of points), so that each point has a count of 1. I have also left it as None. Neither works.  I get 2 types of errors:   all input points are identical errors in executing grid expression


Weird limit $\lim \limits_{n\mathop\to\infty}\frac{1}{e^n}\sum \limits_{k\mathop=0}^n\frac{n^k}{k!} $

$$\lim \limits_{n\mathop\to\infty}\frac{1}{e^n}\sum \limits_{k\mathop=0}^n\frac{n^k}{k!} $$  I thought this limit was obviously $1$ at first but approximations on Mathematica tells me it's $1/2$. Why is this?


Affiliation of an Undergraduate Student: Paper Publication

I'm an undergraduate student, and I'm working on a (physics) project with one of my supervisors. We hope to complete the project soon and submit it to various journals for publication.  Most journals require the affiliation of the authors. Since I am an undergraduate student, I'm not affiliated with/hired by a university's department, per say. How would I ho about filling in the affiliation section (in my case)? Should I be leaving it blank?


Doesn't this LED created by MIT violate the second law of thermodynamics?

Here is the article I am referring to:   In their own words (or at least the article writer's), "it appears to draw in heat energy from its surroundings ... it begins to cool down, stealing energy from its environment to convert into more photons."  Well, there we have it. In the simplest case, you could use this device to pump heat from cold to hot, by simply aiming the light from the LEDs onto a dark surface. This obviously shouldn't be possible.  What am I missing?


How to close, minimize, and maximize a specified window from Terminal?

I am running Ubuntu GNOME 15.10 with GNOME 3.18 and I am wondering if there is a way from Terminal to close, minimize, unminimize, maximize, and unmaximize specified windows?  Note - I've looked at  - I am asking how to do it from Terminal... Not how to add the buttons... The buttons are already there, I don't need to add them.


I have just made this in illustrator. I made a path and used gradient across the stroke, but this highlighted area appeared. So, how can I fix it using photoshop or illustrator ?


PHP - What is the real use of base64_encode function

I have been using json_encode, url_encode and many other functions suffixed with encode in php. However, I have never seen real use case or atleast learn from anywhere what base64_encode does. Inspecting its output,I realize that it uses Character set [A_Za-z0-9] to encode data.  //sample output  TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlz IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2Yg dGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGlu dWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRo ZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=    So the question is. What does base64_encode aim to solve when we already have a myriad of text encoding functions.


Let me easily get the souce code for my comments after the 5 minute edit grace period

When I start hunting for "duplicate pools", and I want to make a single comment with links to the entire pool.  If often happens that I make a comment, only to find another item of the duplicate pool the following day.  So what I'd like is to:   take the source of the old comment (THIS is what is missing) add the new link to it post the updated list delete the old one   in order to concentrate the links further.  I understand that putting and edit button on uneditable comments may be bad, but I wish there was a way to get that source easily.  The only way I see currently is with the SEDE.  Maybe enable the edit button, but if it is clicked add a huge alert: "You can't edit anymore!!!".  Some other mechanism would be fine as well.


Which is correct: "a same" or "the same"?

He and I share a/the same book.   The book hasn't been mentioned before. So which one is used with "same", "a" or "the"?   Because the book hasn't been mentioned before, I want to use "a".  Because I remember that "same" is always used with "the" in front, I have to use "the".


Why isn't maximum current forced upon a circuit by a power source?

I asked a similar question  about this, but I still don't  quite understand.  Say I grab onto two wires from a standard 120V 20A wall socket. I would fry. I would have 20A at 120 forced on my body.  But, when speaking in terms of circuits, as in my linked question, if I have a power supply outputting 100mA maximum at 5v, for some reason my device only gets exactly what it needs? Why is this?  Most things flow from an area of high concentration to low concentration, taking the path of least resistence. If you connect two wires to a power supply, why don't the maximum number of electrons want to go through your circuit?  If current behaves this way...why do you have to regulate voltage?


Using \left( \right) in different lines in align environment

I would like to produce an equation over two lines with a bracket opening in the first line and closing in the second line. Unfortunately, however, using the "\left" and "\right" commands (to have the size of the brackets automatically adjusted) leads to an error.  \begin{align*} L &= \left[ \frac{a}{b} \\ &+ a \right] \end{align*}   I would be very grateful for any advice on how to solve this problem! :)


"One fifth of the population is children" or "are children"

Which is correct:        One fifth of the population is children.   One fifth of the population are children.


Prove/Disprove $\lim \sup a_n = -\lim \inf -a_n$

Prove/Disprove $$\lim \sup a_n  = -\lim \inf -a_n$$  Intuitively it seems like a proof, as $\sup(a_n)=-\inf(-a_n)$ and then taking the limit from both sides, but it is informal and I am not sure that it is correct.


I just created three albums at iCloud.com that I'd like to give other people read access to. The information  describes only how to create a new shared album, but the albums I want to share have already been created.   The people I'll be sharing with don't have Apple devices.  I'm used to cloud storage facilities such as Google Drive or Dropbox that make it easy to create a link to something in the cloud so that the link can be sent to others. Isn't there a way to do this for iCloud?


Commutation relation for general case $[a^n, \bar{a}^m]=?$

I want to find some formula related with  \begin{align} [a^n, \bar{a}^m]=? \end{align} with $[a,\bar{a}]=d$ for some constant number $d$.   Note here $[A,B]= AB-BA$. $i.e$, $[ , ]$ is usual commutator.   First after some computation i obtain  \begin{align} &[a,\bar{a}^m] = m \bar{a}^{m-1} [ a ,\bar{a}] \\ & [ a^n, \bar{a}] = n a^{n-1} [ a,\bar{a}] \end{align} By applying some formula like $BAC-CAB$ rule.   I want to obtain some formula related with $[a^n, \bar{a}^m]$, but it seems my formula dosen't seem nice,   Do you have any idea or guess for the form of $[a^n, \bar{a}^m]=$?    Consider the case for  \begin{align} [a^2, \bar{a}^2] &= [a,\bar{a}^2]a + a[a,\bar{a}^2]  \\ &=  ([a,\bar{a}]\bar{a} + \bar{a}[a,\bar{a}])a + a( [a,\bar{a}]\bar{a} + \bar{a}[a,\bar{a}]) \\ & = [a,\bar{a}]2(\bar{a}a+a\bar{a}) = [a,\bar{a}] 2( [a,\bar{a}] +2\bar{a}a) = 2 [a,\bar{a}]^2 + 4 [a,\bar{a}] \bar{a}a  \end{align}


I want to sum up all values in the cells of the rows and write the aggregated value in the bottom of the  table.  I use this code  double Sum[] = new double[sheet.getRow(0).getLastCellNum()]; for (int i = 1; i < LastCellNum; i++) {     Sum[i - 1] = 0;      for (int j = 1; j <= LastRowNum; j++)     {         cell = sheet.getRow(j).getCell(i);         if (cell != null)         {             try             {                 Sum[i - 1] = Sum[i - 1] + cell.getNumericCellValue();             }             catch (NumberFormatException | NullPointerException ex)             {                 //Handle NumberFormat and NullPointer exceptions here             }             catch (Exception ex)             {                 //Handle generic exception here}             }         }     }     System.out.println(Sum[i - 1]);   The code works properly and it could even print the Value of Sum, but after that I have java.lang.NullPointerException. All the selected Cells in my file are either empty or contain numbers.


I know p7zip package is not installed by default on Ubuntu 18.04. Still Nautilus is able to create 7z archives. How is this possible?


novel about man awakening in the future on a planet with intelligent forest and feline-humanoid species

I read this story/novel in the 1970s.  My recollections are : A man wakes up thousands of years in the future, on a planet which turns out to be Earth (maybe).  The man had been somehow petrified, and awakened, due to electricity or lightening. The planet has beings which are feline-like and also canine-like (and I think the two species were in conflict with each other). The man has a romantic situation with one of the cat-ladies. There is some influence of a giant intelligent tree which governs and permeates the planet. The man was considered a deity because he awoke from stone (not sure about that part though). Thanks for any help finding if this was a real book or my imagination.


Word for "moving up one conceptual level"

Bats and rats are mammals. 1 and 2 are positive integers. Oaks and maples are trees. Carrots and cake are food.   I seek a word to describe this, the process of finding a concept that encompasses several given concepts. Is there such a word?


Java beginer - Arrays - how to print a sorted array?

Problem: when printing a sorted array with data type "int" it is returning funny character "[I@edf4efb". It looks like the address of the array  Question: how to print a sorted array?  Code listed below:  import java.util.Arrays;  public static void main(String[] args) {   int [] sa = {8,200,10};   Arrays.sort(sa);   Arrays.sort(sa);   System.out.println(sa); }   Actual result: [I@edf4efb  Expected result: 8, 10, 200


Does gravity act in the centre of the Earth?

If we we dig a hole from north pole to the south pole of the Earth and we throw a ball in this hole where would it stop? Will it come back on the surface or it will stop at the centre?


Volume preserving procedural mesh deformation

I'm having difficulties trying to create a procedural mesh that deforms on impact. The deformation is meant to look and feel like metal when it is being forged. Since this is less of an aesthetic feature and more of something that would affect gameplay directly, it needs to be somewhat accurate. This means that volume of the mesh should be preserved (at least visually) such that the mesh does not gradually get too much smaller.  What I have tried:  1) Applying force on every vertex, based on the force and distance from impact point  foreach (Vector3 vertexPos in vertexList) {     vertexPos += (force / distanceToImpactPoint.sqrMagnitude) * impactDir; }   This led to the entire mesh gradually becoming smaller (as mentioned earlier)  2) Take into account the dot product between the impact direction and vertex normal for each vertex, as well as lerp between impact direction and normal (to simulate sides of objects bulging out when compressed  foreach (Vector3 vertexPos in vertexList) {     float attenuatedForce = (force / distanceToImpactPoint.sqrMagnitude);     float nDotD = Vector3.Dot(impactDir, currVertexNormal);     vertexPos = attenuatedForce * nDotD * Vector3.Lerp(impactDir, currVertexNormal, nDotD); }   This led to mesh completely splitting apart for anything that has hard shading (as there  are duplicate vertices where the edges are, and also artifacts on smooth shaded objects.  Hard Shading:    Soft Shading (sort of works, but lots of artefacts and not volume preserving)   Also, both methods break completely if force is applied to an edge.  Does anyone know of a more elegant solution to do this?


How can I update an object with another object?  for example   master = { name: "John", email: "j@j.com" }  child = { phone: "888-333-3999" }   How can I  update master with child?  Output of master need to be   { name: "John", email: "j@j.com", phone: "888-333-3999" }   Also, this is a node.js JavaScript, I don't want to use jQuery.


A file in a directory has a Group ID "501" After checking /etc/group, Group ID "501" was not found how is that possible ?


How Long Will This Battery Keep My Fridge Powered For?

I have an interesting mathematical/electrical dilemma and I'm not sure where to start.  I am considering buying  (specs on page).  I will be hopefully buying a battery pack with it to support a long-road trip (a few months) wherein I'll keep medication in the fridge (powered by the battery pack when parked and by the car when driving). The medication needs to be keep between 2 and 8 degrees C at all times.  Here's the  I'm thinking of getting:  Can someone please help me understand what I need to do in order to calculate whether or not this fridge + battery combo will work, and if so, how much time will I be able to power the fridge for.  Ideally, I need a combination of fridge and battery which will allow me to have the fridge constantly powered, assuming I sleep in the car for approx. 8 hours a night and drive for the rest of the day (although, there will be times which I'm away from the car during the day for several hours + times where I hope to have access to a wall outlet).   Specs:   Fridge:   Input voltage (AC 220-240 V Input frequency 50/60 Hz Rated input power (AC) 64 W Rated input power (DC) 46W DC12V/50W DC24V W Input voltage (DC) 12/24 V   Battery:   Capacity: 453Wh Battery Type: Lithium-ion Input Voltage: AC 110-220 V, 50/60 Hz; Solar Power: 18 V; Car Input: 12 V Output Voltage: AC 110V 60 Hz; DC Output: 4 * 12V 4 A (Max.10 A); USB Output: 4 ports: 2* 5V 2.1 A and 2* 5V 1 A Power Output: Rate 500 W Peak/Surge 1000 W


Should we search in answers too, to avoid asking a question about that same matter?

Can asking a question that has an answer in another question result in being duplicate? For example, imagine someone wants to ask if the recipe in  is really original or not. He tries to ask, but none of suggested questions tend to ask this exact question. But there's an  that is speaking about the same matter he wants to ask.


my client wants to print this photo on a poster of 10x4 meter board. i had all the files or I can make a new one too. please tell what should be the resolution and pixels etc.


How can I prove this Formula (about sum of r-combination of multiset)?

This is a formula about the binomial.I am so confused to prove it by combination way.  $${\sum _{r=0}^{k}{\binom {n+r-1}{r}}={\binom {n+k}{k}}}$$


If we increase the temperature of a volume of air it will rise up but if we look from molecular level, there kinetic energy has just changed but not thier weight so why they rise up and do not go in any other direction?


How to resurface questions that weren't answered

I'm sure that someone has brought this up before, but I can't find it. On some stack exchange sites, particularly smaller ones, not all questions get answered straight away. This means that a question which hasn't gotten answered will get less and less attention, making no-one answer it. Is there any way for these questions to be 'recovered' so that people can see them?  If someone is looking for a question to answer, they will look for the most recent questions on the site, or most recent on a tag, if it is a large site like stack overflow. This means people generally don't look at old questions, as they are probably already answered. How can these questions be resurfaced?  Also, people typically don't want to waste their time on answering that already has an answer, even if the answer is not accepted. This means that questions which have been answered, but with a bad answer, don't get the attention they need.  In short, how can we create an environment such that question answerers can see questions that should be seen?


GDBus.Error when trying to enable second screen

I connected an external screen to my laptop, but my desktop didn't automagically extend to it, as it used to do about a year ago (older version of Ubuntu).  I went to the display settings. The screen was listed there (correct resolution, brand name, etc.). But when i put the switch on 'on' and click 'apply', i get this error:   Failed to apply configuration: %s  GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface `org.gnome.SettingsDaemon.XRANDR_2' on object at path /org/gnome/SettingsDaemon/XRANDR   It's been like this for a few months now, but i'd really like to be able to use an external screen/beamer again.  Any ideas?  Thanks.


I'm pretty new to programming and made a few programs so far. I recently made a Calculator program and I hope you guys could tell me what I could do to improve. int firstNumber; string sign; int secondNumber; int answer;  Console.WriteLine("Input Number:"); firstNumber = Convert.ToInt32(Console.ReadLine()); Console.Clear();  Console.WriteLine("Input Sign:"); sign = Console.ReadLine(); Console.Clear();  Console.WriteLine("Input Second Number:"); secondNumber = Convert.ToInt32(Console.ReadLine()); Console.Clear();  switch (sign) {     case "+":         answer = firstNumber + secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case "-":         answer = firstNumber - secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case "*":         answer = firstNumber * secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     case "/":         answer = firstNumber / secondNumber;         Console.WriteLine(answer);         Console.ReadKey();     break;     default:         Console.WriteLine("Invalid Input");     break; }


Enqueue Stylesheets After Theme's "rtl.css"

I am currently developing a theme with internationalization support, and would like to load stylesheets after my theme's rtl.css (an alternative style.css loaded for languages with a right-to-left reading order).  I am familiar with enqueueing my stylesheets and controlling their load order with dependencies using the wp_register_style() and wp_enqueue_style() functions, however rtl.css is loaded automatically by WordPress whenever the locale's language direction is rtl, and there doesn't seem to be a way to specify the stylesheet as a dependency.  I know I can conditionally enqueue stylesheets using the is_rtl() function, however  these stylesheets' <link> elements are still printed out before WordPress automatically prints rtl.css's. I could also simply manually insert <link>s to the stylesheets that I wish to depend on rtl.css right after the call to wp_head() in my theme's header.php file, but I believe it's bad practice to do so, and I would like my theme to be commercial quality.  How can I load stylesheets after WordPress loads rtl.css?


I am working on a problem from Ideas, Varieties, and Algorithms:     Show that if $f \in \mathbb{C} \left[x_1, \dots, x_n \right]$ vanishes at every point of $\mathbb{Z}^n$, then $f$ is the zero polynomial.   My attempt so far:  This proof is by induction on $n$. Let $f \in \mathbb{C}\left[x\right]$ vanish at every point in $\mathbb{Z}$. Then, it must be identically the zero polynomial, as a polynomial of degree $d$ has at most $d$ roots. Hence, $f$ vanishes at every point at $\mathbb{C}$. Now, assume that $g \in \mathbb{C} \left[x_1, \dots, x_{n-1} \right]$ vanishes at every point in $\mathbb{Z}$. We may collect terms and rewrite $f$ as  $$ f(x_1, \dots, x_n) = \sum_{i=0}^m x^i_n g(x_1, \dots, x_{n-1}), $$ for some functions $g_1,\dots,g_n\in \Bbb C[x_1,\dots,x_{n-1}]$.  How do I proceed from here? I was trying to adapt an earlier proof with no success.


Error in file system, (30: Read-only file system)

I am very new to Ubuntu, and I don't know what I did but it shows this error today.   Error:Opening the cache  (E: Couldn't create temporary file to work with /var/lib/apt/list/us.archive.Ubuntu.com_Ubuntu_dists_xenial_InRelease - mkstemp (30:  Read-only file system)  E: The package lists or status file could not be parsed or opened.   I have tried apt-get update, but it shows that problem unlinking the file:  /var/cache/apt/pkgcache.bin - Remove Caches (30: Read-only file  system)  Problem unlinking the file /var/cache/apt/srcpkgcache.bin - RemoveCaches (30: Read-only file system)   W: Not using locking for read only lock file /var/lib/dpkg/lock   How can I proceed?


My professor wrote in an assignment that a random variable with an Inverse-Gamma 1 distribution has density function $$f_{ig}(\sigma|d,s) = C_g^{-1}(d,s)\cdot \sigma^{-(d+1)}\cdot \exp\left(-\frac{1}{2}\frac{s}{\sigma^2}\right)$$ where $$C_g(d,s) = \frac{1}{2}\cdot \Gamma\left(\frac{d}{2}\right)\cdot \left(\frac{2}{s}\right)^{\frac{d}{2}}.$$ This is quite different from the standard IG1 density. It does not appear to be a reparameterization or a form of the . If you plot it against a "normal" IG PDF with the same moments (mean = 0.5, SD = 2) the curves are quite different.  I find the $\sigma^2$ in the exponent to be particularly odd.  However, I'm not ready to say that this is a (massive) typo just yet. One reason is that - using this density as a prior - I get a posterior mode that is far less dependent on an initial guess than using the regular IG1 PDF.   One way to put my question, then, is: is this one of those optimization tricks of the trade or just a typo?  [Also: This is a prior density. So as long as this is proportional to a proper PDF I should be fine. (But I'll need to try to check that eventually.).]


How can I find which device is using all my network bandwidth?

Can someone please help me eliminate a problem within my house? There is a device in my house which continues to use all of my router's bandwidth.  How can I find which device it is which is using all of my bandwidth?  I have the Virgin Media Super Hub 3 Router.


Finding double integral using change of variables

Let $R$ be a region in $xy$-plane bounded by $y=x^2$ , $y=4x^2$, $xy=1$ and $xy=5$. Then find the value of the integral $\iint _R \frac{y^2}{x} dxdy$ I am not able to get any function of $x$ and $y$ in terms of $u$ and $v$ such that I can find limit of the integrals. Is there any other way to solve this?


How can I travel between Schengen countries with my new passport without a visa since I lost the old one with the visa?

I am a student here in Spain and I lost my passport with the Schengen visa, I got a new passport from the embassy but it’s without a visa and I am thinking of travelling somewhere in europe, how can I do that without the visa?


Can I change the font of the text-mode console?

I have a Unix-like OS installed without a windowing environment; i.e., just a text-mode console and no GUI.  Is it possible to change the font used by the console?  To be clear, I am not talking about the terminal emulator that comes with a desktop environment like KDE or GNOME.


How do I change from user to superuser (root)? What command do I use in the Terminal to switch to root? I have tried --help but I get lost with all the listed help. I'm looking for a recent download/install so I can use it.


Get no of days in current month in javascript

Is there any efficient way of getting the number of days in current month using JavaScript ?


Reducing the Tsunami impact using Nuclear bombs

I am a novice on this topic. However, I wonder if we use nuclear bombs against the tsunami, will it reduce the speed and impact of the tsunami. Is it possible to break the massive wall of waves using nuclear bombs? In other words, is it possible to create another opposite force which can neutralise/reduce the energy carried by Tsunami by creating an induced wave.


Many-To-Many Relation by storing comma-separated ids in a column?

Is it OK to sometimes instead of making a join table for a many-to-many relation, store the ids of entity A in a column of entity B? It would look something like this: // A id | name --------- 10 | foo 20 | bar  // B id | name | AIds ----------------- 30 | buzz | 10,20  I only need to know which A's are owned by B when looking at B, and not the other way around (and I can handle the logic in code, joins are not necessary). Hence the lack of a join table. Or are there some bad aspects to this I'm not seeing?


Are there any real life applications of Quantum Field Theory (QFT)

When searching for QFT's applications, most articles and answers tend to mention how it is used to expand our understanding of physics, e.g. with the LHC.   So I'm wondering if you know of any examples (outside of particle/theoretical physics) where QFT has been used to develop new forms of technology, products, new processes, etc.  Thank you for any replies


Proove that $\det(L_B) = \big(\det(B)\big)^n$, $\det(R_B) = \big(\det(B)\big)^n$.

Let $B \in M_{n×n}(\Bbb F)$. Deﬁne the  functions $L_B$ and $R_B$ by: $L_{B}(A) = BA$ and $R_{B}(A) = AB$. Prove that $\det(L_B) = \big(\det(B)\big)^n$, $\det(R_B) = \big(\det(B)\big)^n$.   $L_B$ and $R_B$ are linear transformations, thus can be represented by matrices. So the determinant of those functions exists.