i having a value transfered from another fragment to this fragment(mentioned below) and the data is transfered successfully but i when tried to get the data through the bundle it generates an error, and i tried but can't resolve it  help me, Thank you!  Fragment code:  public class BusinessDetail extends Fragment {      String value1;     Bundle bundle;     private TextView headlineSecond;     private TextView authorSecond;     private TextView detailsSecond;     private List<StringList> s;      public BusinessDetail() {     }      public void receiveValue(StringList value, int positionValue) {   bundle = new Bundle();         bundle.putString("news", value.authorName);         BusinessDetail detail = new BusinessDetail();         detail.setArguments(bundle);       }      @Override     public View onCreateView(LayoutInflater inflater, ViewGroup container,                              Bundle savedInstanceState) {         View view = inflater.inflate(R.layout.fragment_business_detail, container, false);          headlineSecond = (TextView) view.findViewById(R.id.id_headline_second);         authorSecond = (TextView) view.findViewById(R.id.id_author_second);         detailsSecond = (TextView) view.findViewById(R.id.id_details_second);           value1 = getArguments().getString("news");         authorSecond.setText(value1);         return view;     }}   Error:            java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.os.Bundle.getString(java.lang.String)' on a null object reference               at com.bulletin.theinvincible.bulletin.BusinessDetail.onCreateView(BusinessDetail.java:50)               at android.support.v4.app.Fragment.performCreateView(Fragment.java:2184)

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


How do you explain the concept of spin in QM to a 14-year old teen, and why it isn't a vector as in the classical notion of angular momentum?

I often hear about subatomic particles having a property called "spin" but also that it doesn't actually relate to spinning about an axis like you would think. Which particles have spin? What does spin mean if not an actual spinning motion?


I'm getting a quite curious error when displaying text on a webpage. I'm working on converting a set of pages from ISO-8859-15 to UTF-8. As I'm getting texts from various sources on that page, I'm using iconv to convert from ISO-8859-15 to UTF-8.   $arbeitstext=iconv("ISO-8859-15", "UTF-8", $arbeitstext);  I'm also setting the page header of the page with  header('Content-Type: text/html; charset=utf-8');  and the page in question is saved (and converted) as UTF-8 via notepad++.  So far so good - the output of, for instance, ä, ö, ü alone works fine. In combination with ` however, (`ü) it results in lots of Ã characters.   I'm depending on combinations such as     `ü, `Ü, `$,`&,´§,  etc. for another function, (replacing them with different strings), so this is quite an issue for me.   My firebug log suggests that the page-header is correctly set as utf8. The SQL Database from where I'm getting my texts is also set as UTF-8. What am I missing?

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I have tried to download a 8GB ISO image file. Unfortunately the file system was FAT32 on the pendrive. Max file size was only 4GB. The download process was aborted at a point, but as I used wget for download, I got a partial file. Then I examined the incomplete file, for its size, and I continued the download with cURL, explicitely defining the byte range. After successful download I have two separate file parts. Question is, how can I handle them as one: some kind of virtual join, or kind of mount, without copying them really together. I have no free space for phisically joining them on hard disk, this is why I downloaded them onto a 16 GB FAT32 pendrive.

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


I opened my Frank DeLoupe.app application and it asked for permissions. A window popup that I almost always click allow. This time I clicked deny, and now the color picker is not working.  How can I give this app permission?  I've tried adding the app to the accessibility whitelist (preferences > Security and privacy). That made no difference.   (The problem is that when I open this color picker, it doesn't "see" the screen I am on)

So I upgraded to Mojave recently and I got some app permission popups requesting access to system events, etc.  I didn't recognise some of these the apps and didn't allow access.  Now it turns out that this is being used by xcodebuild and it is failing.  How can I reset all these app permissions. So that I get the popup again and I can allow this time.  PS: I'm not asking about file permissions.


There is the template I have to use for a papaer and it looks like this:  \documentclass[a4paper,11pt]{article}  \usepackage{graphicx}  %%% for including graphics \usepackage{url}       %%% for including URLs \usepackage{times} \usepackage{natbib} \usepackage[margin=25mm]{geometry}  \title{Example Paper for IWCS} \date{}  \author{Example Author}  \begin{document} \maketitle \thispagestyle{empty} \pagestyle{empty}  \section{Introduction}  \end{document}   But I have to insert an abstract and when I do it using abstract{} the margins of the page changes. Any ideas how to have an abstract and maintain 2.5cm margins at the same time?      The minimal working example is:  \documentclass[a4paper,11pt]{article}  \usepackage{graphicx}  %%% for including graphics \usepackage{url}       %%% for including URLs \usepackage{times} \usepackage{natbib} \usepackage[margin=25mm]{geometry}  \title{This is the Title of the Paper} \date{} \author{Author Author}  \begin{document} \maketitle \thispagestyle{empty} \pagestyle{empty} \abstract{The term "domestic dog" is generally used for both of the domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, a "powerful dog breed".[6] The term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce ("finger-muscle").[7] The word also shows the familiar petname diminutive -ga also seen in frogga "frog", picga "pig", stagga "stag", wicga "beetle, worm", among others.[8] The term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary, reflecting the role of the dog as the earliest domesticated animal. }  \section{Introduction} The term "domestic dog" is generally used for both of the domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, a "powerful dog breed".[6] The term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce ("finger-muscle").[7] The word also shows the familiar petname diminutive -ga also seen in frogga "frog", picga "pig", stagga "stag", wicga "beetle, worm", among others.[8] The term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary, reflecting the role of the dog as the earliest domesticated animal.  \end{document}

In the article class, it seems that using the abstract environment has an effect to the rest of the document. More precisely, it seems that it redefines the \linewidth, which equals \textwidth without abstract, is smaller with the abstract. My feeling is that \linewidth is redefined for the abstract environment, but the value is not reseted at the end of the abstract.  Here is a minimal example:  \documentclass{article} \begin{document} \abstract{This is an abstract. This is an abstract.}\bigskip  This is text. This is text. This is text. This is text. This is text. This is text.\\  \rule{\textwidth}{3em} \rule{\linewidth}{3em} \end{document}   The output is not the same if you comment the \abstract line or not.  Do you have the same problem as I do when you compile (if not, I will upload some PDF files to show)? Is this a (known) bug in LaTeX2e? How can we circumvent the problem?  Note: I compile with the pdflatex command, and I use pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian).


I am getting null pointer exception in below code as I mentioned in comment.  I am confused why its so and need help.  Does the list of people is null ?   I am trying to display list of people and someone please explain how this  execute() works in active android.  Thanks.  @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_show_all);          mListAll = (ListView) findViewById(R.id.list_all);         mTextEmptyList = (TextView) findViewById(R.id.list_empty_message);         mInflater = LayoutInflater.from(this);         initListWithData(); //null pointer     } private void initListWithData() {     ArrayList<Person> people = new Select()             .all()             .from(Person.class)             .execute();  //null pointer     mAdapter = new SunilListAdapter(this);     mAdapter.setData(people);     mListAll.setAdapter(mAdapter);     mListAll.setEmptyView(mTextEmptyList);     mListAll.setOnItemClickListener(this);  }   person class   package com.example.model;      import java.io.Serializable;     import com.activeandroid.Model;     import com.activeandroid.annotation.Column;     import com.activeandroid.annotation.Table;      //Notice how we specified the name of the table below     @Table(name = "Person")     public class Person extends Model implements Serializable{          // Notice how we specified the name of our column here         @Column(name = "personName")         public String personName;          // Notice how we specified the name of our column here         @Column(name = "personAge")         public int personAge;          @Column(name = "personScore", onDelete = Column.ForeignKeyAction.CASCADE)         public Score personScore;          public Person() {             // Notice how super() has been called to perform default initialization             // of our Model subclass             super();         }          public Person(String personName, int personAge, Score personScore) {             super();             this.personName = personName;             this.personAge = personAge;             this.personScore = personScore;         }          @Override         public String toString() {             // TODO Auto-generated method stub             return "Name: "                     + personName                     + " Age: "                     + personAge                     + " "                     + personScore;         }     }   initalize MyApplication.java  package com.example.sinildatabasetest;  import com.activeandroid.ActiveAndroid; import com.activeandroid.app.Application;  public class MyApplication extends Application{      public static final String TAG = "SUNIL";     @Override     public void onCreate() {         // TODO Auto-generated method stub         super.onCreate();          ActiveAndroid.initialize(this);     }  }


I am looking to install Linux on a new laptop I have, with only 64gb of storage.  I am curious if there are any sources that compare the base install size of various distros.  I am not looking to go off the beaten path, so I am really only considering maybe Lubuntu, Xubuntu, or Ubuntu Mate. I might consider Ubuntu 18.04 with minimal install, but I only have 4gb ram as well, so I rather avoid gnome.  Is there any hard data (besides recommended storage size) that I can look into?

For a given hardware configuration, how do I find out if Ubuntu will run on it? What considerations should I take into account when choosing an Ubuntu version and  such as:    with a lighter desktop than the usual Gnome and Unity  with the even lighter LXDE desktop   Obviously Ubuntu does not run on some processor architectures. So how do I go about choosing the right version and derivate. How can I find out the minmal system requirements?


Which of these should I use?      My test result should be done by last Wednesday.   or     My test result should have been done by last Wednesday.   What is the difference in meaning?

Non-native speakers often get confused about what the various tenses  and aspects mean in English. With input from some of the folk here I've put together a diagram that I hope will provide some clarity on the matter.  I offer it as the first answer to this question. Consider it a living document. Input is welcome, and good suggestions will be  incorporated into the diagram.    Nota bene: What this is not is a discussion of whether there are  more than two tenses in English. , to which this question is not intended to supply arguments one way or the other.  Here, the aim is to provide an overview of what constructions English-speaking people use for conveying information about actions referring to past, present, and future, and to provide it first and foremost to precisely the people who are likely to use "tense" as a catch-all term in their search, rather than to linguists who know better.  Breaking News There is now an excellent ELU blog article titled  . It is highly recommended reading.


I have two line layers of the exact same features but I suspect there is a difference in some of geometry between the two. Is there a way to simply detect change between the two layers? I am not interested in the attribute change; I simply want to see the areas where there is a difference between the two layers.

I am using  to update the roads in OpenStreetMap. I have a copy they published last year and one that was just published, and I would like to find all the LineStrings that have either had their attributes or their geometry changed. This will assist me in making sure all the new and modified streets are updated in OpenStreetMap. The street segments should have a unique identifier, so my only thought is to write a Python script which opens both Shapefiles, finds any segments in the new that aren't present in the old (added segments), and the reverse (removed segments), and then loop over matched pairs comparing their constituent coordinates to see if anything has changed. Is there a way to do this using QGIS?


I have a scenario where In my table there are lots of duplicate value. lets's say.  SID|LOTID|TEST 1    45    A 1    45    B 1    45    C   I want a mysql query which  can provide me output like this.  SID|LOTID|TEST 1    45    A,B,C

Using MySQL, I can do something like:  SELECT hobbies FROM peoples_hobbies WHERE person_id = 5;   My Output:  shopping fishing coding   but instead I just want 1 row, 1 col:  Expected Output:  shopping, fishing, coding   The reason is that I'm selecting multiple values from multiple tables, and after all the joins I've got a lot more rows than I'd like.  I've looked for a function on  and it doesn't look like the CONCAT or CONCAT_WS functions accept result sets.  So does anyone here know how to do this?


For a phrase such as the following:      each apple and each orange   Is it correct to use "has" or "have" when describing properties of both apples and oranges?

I am reading a book that contains the following text.      A square matrix P is said to be a permutation matrix if each row and each column of P contains a single element 1, and the remaining elements are zero.   My questions are:     why is "contains" used? why not "contain"? Since there is a "and" before "contains".   why not "zeros" for the last word in the sentence?


When I compress my QGIS file with the folder containing all my shapefiles, how can I maintain the paths?  For example, I made a map on QGIS using a large amount of shapefiles. Once done, I save my QGIS file to  C:\Users\Workcomputer\Desktop\New_folder  From there I compress the shapefiles and the QGIS file located in \New_folder and send the newly made .zip file to myself by email or dropbox.  However, when I download and uncompress the .zip on a different computer, the QGIS file is empty, and I have to re-path all the shapefiles, because they are now located in  C:\Users\Homecomputer\Desktop\New_folder   instead of   C:\Users\Workcomputer\Desktop\New_folder  Is there anyway to short-cut having to do this?

Is there an option in QGIS to save the project with the data source being a relative path?  I don't see the option here. QGIS Wroclaw1.7.3


I have two different computers, running Ubuntu 18.04 Both computers have two cores running at 100% for process that I do not know of.

What should I do if my Windows computer seems to be infected with a virus or malware?  What are the symptoms of an infection? What should I do after noticing an infection? What can I do to get rid of it? how to prevent from infection by malware?   This question comes up frequently, and the suggested solutions are usually the same. This community wiki is an attempt to serve as the definitive, most comprehensive answer possible. Feel free to add your contributions via edits.


I am having no idea how I can solve this problem.  I need help!  Here's the problem  $2x^4+x^3-11x^2+x+2 = 0$  I am learning Quadratic Expressions and this is what I need to solve, and I can't understand how :C

By using the substitution $p=x+\frac{1}{x}$, show that the equation $$2x^4+x^3-6x^2+x+2=0$$ reduces to $2p^2+p-10=0$.  I can't think of anything that produces a useful result, I tried writing p as $p=\frac{x^2+1}{x}$ and finding areas to substitute but have come with no progress. Could someone offer a slight hint on how to proceed?  Thanks


I would like to know if anyone could recommend a book that deals more with the practical issues around conducting a meta-analysis?  Thanking you in advance  Andrew Vitiello

A (non-statistician) colleague has been encountering meta-analyses in papers he reviews for medical journals and is looking for a good introductory level treatment so he can educate himself.  Any recommendations?  Favorites?  Books, monographs, nontechnical survey articles would all be fine.  (Yes, he's familiar with the Wikipedia entry and other stuff readily accessible by a Google search, such as .)


I have a blog post on my site, and then a few months later I got asked by another (much larger) website, if they could put that same post on their website as a guest post.  Seeing as their site is much more popular than mine, I agreed to it, as I was keen to get some extra traffic and publicity.  But could this have affected my search engine ranking due to duplicate content? I was thinking this wouldn't be an issue, because Google indexed my post a few months before the duplicate post was added to the other website.  But I have noticed a drop in my traffic over the last couple years. I suspect there could be a number of reasons fo this, but I am wondering if this could be one of them.

This is a general, community wiki question regarding duplicate content.  If your question was closed as a duplicate of this question and you feel that the information provided here does not provide a sufficient answer, please open a discussion on .     What does Google consider to be duplicate content? Will the way I am presenting my content result in a duplicate content penalty? How can I avoid having my site's content treated as duplicate content?


How do I construct uncountably many non isomorphic ordering of natural numbers?

I would like to find a way to construct uncountably many non-isomorphic linear (total) orderings of natural numbers (as stated in the title).  I've already constructed two non-isomorphic total orderings. They are $$ 1 < 2 < 3 <\ldots\\ 1 > 2 > 3 >\ldots $$ where "$<$" and "$>$" are  strict total ordering relations.  Thanks in advance for your help.


Guys i'm new to awt library. I'm try to build a simple GUI using java awt.  I want to build something react with button thing.   enter codepackage chapter19; import java.awt.*;  import java.awt.event.*; class Gui05 extends Frame implements ActionListener,ItemListener{ private static final ItemEvent ItemEvent = null; TextField[] tfs;// south Button[] bts; //North TextArea ta; Checkbox[] cbs;// east3 Button bt;  Gui05(){     super("Compound Layout");      create();     allocate();     button(null);   } private void allocate(){      this.setLayout(new BorderLayout(5,5));     Panel cp = new Panel();     cp.setLayout(null);     ta.setSize(400,300);     ta.setLocation(20,20);      this.add("Center",ta);      for(Button b: bts){     // panel 이란 컨테이너를 사용해야 한다      Panel np = new Panel();     np.setLayout(new GridLayout(1,4,5,5));     for(Button t: bts){         np.add(t);       }     this.add("North",np);      Panel sp = new Panel();     sp.setLayout(new GridLayout(1,2,5,5));     sp.add(tfs[0]);     sp.add(tfs[1]);     this.add("South",sp);        Panel ep = new Panel();     ep.setLayout(new GridLayout(2,1,5,5));     Panel ex = new Panel();     ex.setLayout(new GridLayout(3,1,5,5));     //ex.add(bt);     //     for(Checkbox t: cbs){         ep.add(t);       }     ep.add(ex);     ep.add(bt);     this.add("East",ep);     this.setSize(500, 430);     this.setResizable(false);      }        }     private void create(){     tfs = new TextField[]{new TextField(),new TextField()};     bts = new Button[]{new Button("NEW"), new Button("OPEN")      , new Button("CLOSE"), new Button("EXIT")};        ta = new TextArea();     cbs = new Checkbox[]{new Checkbox("red"),new Checkbox("yello"),new      Checkbox("green")};     bt = new Button("enter");     bt.addActionListener(this);      addWindowListener(             new WindowAdapter()             {                 public void windowClosing(WindowEvent e){                      System.exit(0);                 }             }             );       this.setSize(1000, 800); }  public void button(ActionEvent ie){       String arg = bt.getActionCommand();     if(arg == "enter"){         System.out.println("checking..");         Checkbox tempcbs = new Checkbox("red");         //System.out.println("arg2..."+arg2);         if(tempcbs == cbs[0]){             System.out.println("red is printing...");             setBackground(Color.red);          }       }  }     //public void stateChange(ItemEvent ie){     //String arg = bt.getActionCommand();     //System.out.println("arg..."+arg);    //} @Override public void itemStateChanged(ItemEvent e) {     // TODO Auto-generated method stub  } @Override public void actionPerformed(ActionEvent e) {     // TODO Auto-generated method stub  }         }         public class GuiEx05 {             public static void main(String[] args) {             new Gui05().setVisible(true);          }    } here   and this part   enter code here public void button(ActionEvent ie){       String arg = bt.getActionCommand();     if(arg == "enter"){         System.out.println("checking..");         Checkbox tempcbs = new Checkbox("red");         //System.out.println("arg2..."+arg2);         if(tempcbs == cbs[0]){             System.out.println("red is printing...");             setBackground(Color.red);          }   its printing "checking.." even though i did not click the enter button and I want to check checkBox's text is match with 'red','yello' string. how to do this?

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I would like to know how to add inclined lines in Matrix

Is there a way to create a new command with 9 arguments ({a_{11}},{a_{12}},{a_{13}},{a_{21}},{a_{22}},{a_{23}},{a_{31}},{a_{32}},{a_{33}}) that has as output a matrix with the Sarrus Rule? For instance: to obtain     just use the command that we will call sarrus:  \sarrus{-k}{k-1}{1}{0}{k-1}{k}{2}{0}{1}.   If it is possible i want to use the command sarrus in math mode just like matrix for istance.


This is sample of my code am just to pull contacts from the phone book, but line  if(phone.getCount() > 0)   it produce some error which says nullpointerException, below is the my logic from the java file  StringBuilder builder = new StringBuilder();     ContentResolver contentResolver = getContentResolver();     Cursor phones = contentResolver.query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,null,null,null,null);      if (phones.getCount() > 0)     {         String name = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));         String phoneNumber = phones.getString(phones.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));          while (phones.moveToNext())         {              if(name!=null)             {                 builder.append(namecsv).append(name);                 builder.append(phonecsv).append(phoneNumber);             }         }      }      phones.close();      nameArray = nameCsv.split(",");     phoneArray = phoneCsv.split(",");      ArrayAdapter <String> adapter = new ArrayAdapter<String>(this,android.R.layout.activity_list_item,android.R.id.text1,nameArray);     contactViewer.setAdapter(adapter);

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


I am a GIS Specialist with an Earth science/geography background, and about 8 years experience using both ArcGIS and QGIS.   I have written small snippets of Python code to help myself with basic tasks such as editing attribute tables or displaying map labels and symbols in interesting ways.    I have also used ModelBuilder tools in ArcGIS to automate tasks and simple work flows. But I would really like to learn more about computer programming in general.   I am planning to take a 24-hour ESRI classroom course on "Geoprocessing Using Python" next month. But what can I do over the next few weeks to get better at programming, in preparation for the class?    I really want an online course or textbook that is for beginners, that focuses on things like loops, if/then/for statements, etc.  I never seem to learn much at all from those "here is the code, type it in, it will do x" tutorials.    I think I really need something that is a combination of theory and practical knowledge. A focus on Python and/or GIS is of course a bonus.    Any suggestions?

In your opinion, what is the best book/site to learn Python with GIS goals in mind?  By "best", I mean:   not very long (book) easy to understand (book/site) good practical examples (book/site)   For answers specific to learning how to use the ArcPy site-package for Python to customize ArcGIS for Desktop there is a separate Q&A:


It seems that the former is US English, while the latter BR English.   What do you native speakers think of it?

I have seen many sentences like this:     "Capitalism, Socialism, and Anarchism"   and this:     "She was happy, and cheerful"   Do we have to use a comma before "and", or is it incorrect?  If it is not, then why?


I'm on Lesson 28/28 of Getting Started with Programming of Codeacademy's Javascript tutorial. I want to create a program in which a prompt comes up where I enter a quantity and if the quantity is   var numberOfLessons = prompt("How many lessons have you taken?")  if(numberOfLessons===28) {     console.log("I finished my first course!") }  else if(numberOfLessons<28) {     console.log("Do more lessons!") } else if(numberOfLessons>28) {     console.log("Do less lessons D:") }   When I run the program, if I input a quantity less than 28, then the proper "Do more lessons!" comes up. However, with ===, if I input 28, then console.log doesn't output anything. It's completely blank. However, if I use == in line 3, instead of ===, then inputting "28" into the prompt returns the proper "I finished my first course!"  var numberOfLessons = prompt("How many lessons have you taken?")  if(numberOfLessons===28) {     console.log("I finished my first course!") }  else if(numberOfLessons<28) {     console.log("Do more lessons!") }  else if(numberOfLessons>28) {     console.log("Do less lessons D:") }   Why is it that == works but === doesn't? My first thought (or, rather, my friend's first thought) was that it's because numberOfLessons is a variable and === requires the types of the two things being compared to be the same, and a variable is not the same as a number. But, in that case, why would it work for the "else if" statement where > is being used?

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


A simple maybe 8th or 7th grader question, but I can't really get over it. Elastic collision: momentum is conseved and so is the kinetic energy whereas in an inelastic collision, momentum is conserved but not the energy. Although I don't get it why is momentum of a closed and isolated system is supposed to be constant/conserved just accounting to the fact that system is closed (no mass enters or leave it) and isolated (no net external force) but, ok, let me accept this for a minute and think about how is it possible that momentum is conserved but the kinetic energy of system changes as happening in an inelastic collision.  I mean since both quanties depend on velocities of object initially and finally, both of them should act alike. If one changes, other does too. If one doesn't, other doesn't as well.

In inelastic collisions, kinetic energy changes, so the velocities of the objects also change.  So how is momentum conserved in inelastic collisions?


Let $M$ be a closed subspace of a Hilbert space $H$. Let $P$ be the orthogonal projection on $M$. I was told to find the eigenvalues and eigenvectors of $P$ and moreover say when it is compact.  Since $M$ is closed we have $H\cong M\oplus M^\perp$ and this is an eigenspace decomposition so $P$ has eigenvalues $1,0$ and eigenvectors the elements of $M,M^\perp$ respectively. Is there any formal explanation I emphasize in the infinite dimensional case?  If $M$ is finite dimensional $P$ is finite rank so compact. I don't see anything but that...

Suppose that we have a Hilbert Space $H$ and $M$ is a closed subspace of $H$. Let $T\colon H\rightarrow M$ be the orthogonal projection onto $M$.   I have to show that $T$ is compact iff $M$ is finite dimensional.  So if we assume that $M$ is finite dimensional then $\overline{T(B(0,1))}$ is a closed bounded set in a finite dim vector normed space and so it is compact. Which gives that $T$ is compact.  But I am unsure how to prove that if $T$ is compact then $M$ is finite dimensional?  Thanks for any help


I need some information. I intend to travel to Canada from 13-29 October. I am a Pakistani national and I am traveling from Germany to Calgary by KLM Airlines. My passport validity is until 12 January and my visa validity is until 11th January. Can I travel with my existing passport or should I renew my passport?

I am traveling from Boston to Canada by cruise ship. The first port of arrival is on July 30 and the last port in Canada is on August 4. Then I'm flying on August 5 from Montreal to California. My passport is valid until August 20th. Will I have a problem?


I noticed that I do not get a compiler error for the following code. Instead the program hangs. Why is that so?  class GLvector { public:   static GLvector CrossProduct(const GLvector &V1, const GLvector &V2);  // ..  GLvector v; v.CrossProduct(foo, bar);

Here is a little test program:   #include <iostream>  class Test { public:     static void DoCrash(){ std::cout<< "TEST IT!"<< std::endl; } };  int main() {     Test k;     k.DoCrash(); // calling a static method like a member method...      std::system("pause");      return 0; }   On VS2008 + SP1 (vc9) it compiles fine: the console just display "TEST IT!".  As far as I know, static member methods shouldn't be called on instanced object.   Am I wrong? Is this code correct from the standard point of view? If it's correct, why is that? I can't find why it would be allowed, or maybe it's to help using "static or not" method in templates?


Excerpt from a mathematical proof by contradiction involving discrete variables that serves to prove by contradiction that predicate P(n) is true for all nonzero integers n.     If n belongs to set C i.e. n >= c, then P(n) is false.      This implies the contrapositive,      If P(n) is true, n has to not be a part of set C i.e n < c.   Question is, why is the above implication immediately valid? Am I not assuming that n cannot take on 2 values simultaneously -- n being both >= c and < c, thus P(n) being both true and false simultaneously? What is the basis behind a predicate (or any proposition) being either true or false?    Also, if you don't mind, please do let me know if I am using some terminologies (i.e. discrete, predicate, contrapositive, assume) wrongly. I am extremely new to discrete mathematics and could really use some extra guidance.   Thank you.

Excerpt from a mathematical proof that serves to prove by contradiction, using the Well Ordered Principle, that predicate P(n) is true for all nonzero integers n.     If n belongs to set C i.e. n >= c, then P(n) is false.      This implies the contrapositive,      If P(n) is true, n has to not be a part of set C i.e n < c.   I know that the above implication is valid but why so? How should I know that n cannot take on 2 values simultaneously -- n being both >= c and < c, thus P(n) being both true and false simultaneously? (Yes I am thinking Dialetheism, maybe even quantum logic but I know nothing other than that quantum logic defies certain aspects of propositional logic.) What is the basis behind a predicate (or any proposition) being either true or false? Or would the simultaneity be possible just that I wouldn't be dealing with a proposition to begin with?  Also, if you don't mind, please do let me know if you feel my understanding of concepts and terminologies (i.e. discrete, predicate, contrapositive, assume) are erroneous. I am extremely new to discrete mathematics and could really use the extra guidance.  Thank you.


I was wondering about the appropriate way to use an image hosted by another website as a teaser image in my own website. For example, if I am aggregating articles from sources including the NYTimes, can I present a teaser or thumbnail from the NYTimes website as part of the link/teaser summary on my own site?  What steps would I need to go through such as getting permission or attributing the primary source?

Lets say I write a blog post about the new Batman movie or a the new Grand Theft Auto game and i decide to use the boxart/poster or a wallpaper as the main image for the blog post,  can I be sued for breach of copyright on this image?  Im pretty sure Warner Bros are going to be hunting anyone down even if it is legal, but is this actually legal? If i buy the DVD or Game and take a picture of it, is this my copyright? When a trailer gets released and put on youTube, can i take a screenshot of this video and use this as an image?  It seems people can get rightly screwed for this, so I would like to know where i stand on this sort of thing.


If the word isn’t specific, so need ’a’. Or If the word isn’t common, so need ’the’.  Which way your mental process works?

I can’t for the life of me figure out where to use a and where to use the — and where there is no article at all. Is there a simple rule of thumb to memorize?   The standard rule you always hear:     “If a person knows which item you are talking about then use "the"   . . . doesn’t clear things up for me, as I have no idea whether or not they know.


Asked to prove that for $n \in \mathbb{Z^+}$:  $\sqrt{1}+\sqrt{2}+...+\sqrt{n}\ge\frac{2}{3}n\sqrt{n}$ by mathematical induction.  My inductive hypothesis is then:  $\sqrt{1}+\sqrt{2}+...+\sqrt{k}\ge\frac{2}{3}k\sqrt{k}$  I've come to this step:  $\sqrt{1}+\sqrt{2}+...+\sqrt{k}+\sqrt{k+1}\ge\frac{2}{3}k\sqrt{k}+\sqrt{k+1}$  I know that I want the RHS to read $\frac{2}{3}k\sqrt{k+1}+\frac{2}{3}\sqrt{k+1}$ but I'm not sure how to get from the last line to this line while ensuring the inequality still holds ... What am I missing?

Assumption: $\sqrt{1}+\sqrt{2}+\sqrt{3}+...+\sqrt{k}\ge\frac{2}{3}k\sqrt{k}$   Prove true for $n=k+1$ $$\sqrt{1}+\sqrt{2}+\sqrt{3}+...+\sqrt{k}+\sqrt{k+1}\ge\frac{2}{3}(k+1)\sqrt{k+1}$$  I'm upto :$$\sqrt{1}+\sqrt{2}+\sqrt{3}+...+\sqrt{k}+\sqrt{k+1}\ge\frac{2}{3}k\sqrt{k}+\sqrt{k+1}$$after which I'm stuck.


I have some figures that should take turn showing up below itemized text. The problem is referencing to these figures later on becomes impossible no matter how many recompilation. How should i correct it?  \documentclass{beamer}  \setbeamertemplate{caption}[numbered] \begin{document}  \begin{frame}     \frametitle{Title}     \begin{itemize}[<+->]         \item ABC         \item XYZ         \item DEF     \end{itemize}     \begin{overprint}         \onslide<1>             \begin{figure}[h]                 \centering                 \caption{ABC}                 \label{fig:ABC}                 \includegraphics[width=\textwidth]{ABC}             \end{figure}         \onslide<2>             \begin{figure}[h]                 \centering                 \caption{XYZ}                 \label{fig:XYZ}                 \includegraphics[width=\textwidth]{XYZ}             \end{figure}     \end{overprint} \end{frame}  \end{document}

For space reasons I want to break up the contents of an itemize list into separate slides, which I have been doing without much problem using \only.  However, the following minimal document complains that the label eq:formula is not defined:  \documentclass{beamer} \begin{document} \begin{frame}{Title}  \begin{itemize}  \only<1>{   \item Item 1.  }             % Comment   \only<2>{     % these lines   \item Item 2, with equation   \begin{equation}    \label{eq:formula}    xyz   \end{equation}    \item Item 3, with reference \eqref{eq:formula}.  }  \end{itemize} \end{frame} \end{document}   As you can see, it is clearly defined.  The problem goes away if you comment out the marked lines (thus, printing everything on one slide).  I see using \tracingmacros that there is a serious redefinition of \label in beamer, and as such it appears that this is a bug with detecting what slide the label is printed on.  Is that right, and what is the solution?


Let $\{x_n\}$ be a sequence of strictly positive real numbers. I want to show that   $$\lim \inf \frac{x_{n+1}}{x_n} \leq \lim \inf \sqrt[n]{x_n} .$$  I've tried and failed to assume the contrary to derive a contradiction. any hints?

If $(x_n)$ is any sequence of positive real numbers, then $$\lim \inf \dfrac{x_{n+1}}{x_n}\leq \lim \inf x_n^{1\over n} \leq \lim \sup x_n^{1\over n} \leq \lim \sup \dfrac{x_{n+1}}{x_n}. $$  I don't understand how am I suppose to use the hint nor what to do afterwards.  Hint: If $\lim \sup \dfrac{x_{n+1}}{x_n}-\infty$, right hand inequality is obvious. So suppose $\lim \sup \dfrac{x_{n+1}}{x_n}=M$. Then $\dfrac{x_{n+1}}{x_n}< M+\epsilon$ $\forall n\geq N$, i.e., $x_{n+k}\leq (M+\epsilon)^kx_n$ for all $k\geq 0$.


I use Japanese a lot. Is there a way I can just get Japanese to be in the document like latin characters? I don't want to have to use \begin{CJK}\end{CJK} everytime like in

I've recently started to use LaTeX but I've just encountered a problem, I tried searching it, although apparently no-one asked it before.  I'd like to write using Japanese input, but when I typeset, there can happen 3 things:   I get some error when compiling; I get question marks where Japanese stuff should appear; Nothing appears.   For example I had an example .tex file, compiled it and it worked, so I added some japanese in order to see "The author is [Japanese here]", but what I could see was "The author is [blank space]".  I've tried checking some guides, but I haven't found anything that could solve my problem (they are too old, or they don't talk about this at all).  Some minutes ago I tried compiling this:  \documentclass[12pt]{article}   \usepackage[T1]{fontenc}   \usepackage{CJKutf8}   \usepackage[romanian]{babel}   \usepackage[overlap, CJK]{ruby}   \usepackage{CJKulem}   \renewcommand{\rubysep}{-0.2ex}   \newenvironment{Japanese}{%   \CJKfamily{min}%   \CJKtilde   \CJKnospace}{}   \begin{document}   \parskip 3ex   \parindent 0pt   \begin{CJK}{UTF8}{}   \begin{Japanese}   ねこ    \end{Japanese}   \end{CJK}   \end{document}   It compiles fine but, still same problem, nothing appears when typeset, even if I should see "ねこ". There are many Linux guides, but I have a Mac and apparently, there aren't a lot around...   EDIT: A small add, if I get this to work, is the solution related to other asian languages such as Korean or Chinese?


I am new to strobes (studio lighting) in photography. I love the idea of blowing out the background, or making the image very emotive, with a dark black background for sports portraits.  However I am not sure what are the advantages of buying studio lighting specifically for photography over just high powered (very bright) lighting which you can buy from any light store or camping store?  I get that with studio lights you can attach wireless triggers and make the lights go off only when you click the shutter button, but other than that power/money/function wise what am I missing which makes strobes worth the money?  The only factors I can see are branding build quality, and maybe the ability /flexibility to use a wireless trigger (I have yong nuo Y622 C) over a cable when connecting your camera to your studio lighting (strobes)?  And obviously you would pay more for both the build quality and added functionality in the ways you can trigger the lights.  The only downside though that I can see to just using high powered lamps is the fact you wouldn't be able to control the light, only turning it on when you click the shutter button. Instead it would be always on or always off. (since there seems to be no standard for measuring light, specialy across disciplines, e.g. photography >> watt seconds?, cycling >> luminosity, building houses >> watts)  Other than that detractor there must be something I am missing on this topic. For photography lighting I would have though the higher the power or watt sec the better (it can light up more of a scene, and still work really well at night).

If one were to want to get started with studio photography (I'm thinking things like portraits, headshots, perhaps pets, etc) what would be the considerations in choosing whether to go with continuous lighting vs. strobes for the lighting equipment?


I know a lot of answers have been written about this but they all seem to be about how every file in Linux (even text files) are executable.  What I want is to compile code into machine code similar to a Windows .exe so that no one can tamper with my code. I'm not interested in interpreters either. Is there a straightforward answer to this?

I don't know what the exact executable file extension is. Is it .deb or .tar.gz?


$U(pq)$ is to be the units of $Z_{pq}$. I would assume that distinct prime factors would enable $U(pq)$ to always by cyclic. My professor alluded to the fact that this may not always be true. However, I am curious if this is always the case, since $U(p)$ is cyclic, given $p$ is prime.  What are your thoughts?

Prove that $U_{pq}$ is not cyclic if $p$ and $q$ are distinct odd primes.   I am a self taught person. I just learned this and tried this on my own and came up with this.  $x \equiv 1 \pmod{p}$ and $x \equiv -1 \pmod{q}$ has a solution $[a]_{pq}$, since $p$ and $q$ are relatively prime. Because $q$ is an odd prime, $[-1]_{pq}$ is not a solution, so $[a]_{pq}\neq [-1]_{pq}$. But $a^2 \equiv 1 \pmod{p}$ and $a^2 \equiv 1 \pmod{q}$, so $a^2 \equiv 1\pmod{pq}$ since $p$ and $q$ are relatively prime, and thus $[a]_{pq}$ has order 2.  Can someone please tell me if this proof this correct? Please help with proof as I learned it just now as a self taught person.


I am running Blender on a 2016 Macbook Pro that is not equipped for rendering. My renders are taking ages (6 to 8 hours to render wooden products on white background). I want to make interiors renders so I need to upgrade my setup. I am considering an external GPU for my mac but I don't now what solution to use for:  the enclosure hardware the graphic card  If you guys can help me on that, I would be really pleased Thanks

I am considering purchasing a Mac for my godson who will be using it to run Blender 2.8.  I know very little about this program.  All I can find are requirements for a Mac that will run earlier versions of Blender.  Would someone please recommend a list of requirements for a Mac (or a link to a list of requirements) that I could use to find a model that can run 2.8?  Thank you in advance for all your help! Sincerely, M. Lap


How would you show that $\lim_{n \rightarrow \infty} \ln(1/n) = -\infty$ using the definition of what it means to diverge to $-\infty$.  This is what I'm thinking, but is it right?  Let m be a real number. Then there exists $n_0 \in \mathbb{N}$ such that $n_0<m$. Let $n < n_0$ then $\ln(1/n) < n < n_0 < m$. Hence, $\ln(1/n) \rightarrow -\infty$

How would you show that $\lim_{n→∞}\ln(1/n)=−∞$ using the definition of what it means to diverge to $−∞$. If I plug in different $n$ I see that it goes to $−∞$, but I don't understand how to show this. Could someone please demonstrate?


I approached this inductively.  For n=1, $11^1-6=5$, which is divisible by 5.  For n+1, 11^(n+1) -6, there must be some trick with the factorization that I am missing. My first thought was to factor 11 out, but that ultimately lead  nowhere.   Thank you all for your time and assistance.

I am working on a problem I am pretty close to solving but I can't figure out the last part. I used some algebraic manipluation to break the problem down. The problem is:     Show that the following congruence is true      a^b = ((a mod n)^b) (mod n)      for any positive integers a, b, and n.      Hint: Number a can be written as a = q*n + r, where q = floor brackets a/n, and r = a mod n.   My attempt it:     (q*n +r)^b = ((a mod n)^b) * (mod n)      (q*n)^b + (a mod n)^b = ((a mod n) ^b) * (mod n)      (a)^b -(r)^b = ((a mod n) ^b) * (mod n)      (a)^b = modn  ----> divided by ((a mod n)^b)   Am I doing this correctly and if so how can I prove this is true? Is there a trick I am missing? I think that by simplifying it further I would just keep going in a loop.  Thanks!


Let X,Y,Z be independent, identically distributed random variables,each with density $f(x)=6x^5$ for $0\leq x\leq1$ and 0 elsewhere.I want to find the distribution and density functions of the maximum of X,Y and Z.  Answer:-I know by integrating density function, distribution function can be obtained.I computed CDF of maximum of $X,Y,Z=X^6$ and its PDF=$18*X^{17}$.  CDF of minimum of $X,Y,Z=1-(1-X^6)^3$ and its PDF is $6*X^5*3*(1-X^6)^2$

If an item follows normal distribution, average also follows normal distribution. What about minimum and maximum?


I am currently reading through a solution of the following problem and I am having a bit of trouble. The problem is as follows:     Let $S$ be a set and $F$ be the free group on $S$. Show that if $|S| > 1$, then $Z(F)$ is trivial.    In order to deduce a contradiction, suppose that $w \in Z(F) \setminus \{e\}$ (where $e$ is the identity element). Let $w = a_{1}^{\pm1} \cdots a_{n}^{\pm 1}$ be the reduced word expression for $w$. Since $w \in Z(F)$, we have  $$ \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)w = w\left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right). $$ Now the left-hand side reduces to  $$ \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)w = \left(a_{n-1}^{\mp 1} \cdots a_{1}^{\mp 1} \right)\left(a_{1}^{\pm1} \cdots a_{n}^{\pm 1} \right) = a_{n}^{ \pm 1}. $$ Comparing this to the right-hand side, we deduce that it must be the case that $a_{n}^{\pm 1}=a_{n-1}^{\pm 1} = \cdots = a_{1}^{\pm 1}$; so write $w = \left(a_{1}^{\pm 1}\right)^n$.    [Now every part of the proof makes sense to me thus far, but I do not see the rationale for the coming part.]     Since $|S| > 1$, let $b \in S$ be such that $a_{1}^{\pm 1} \neq b$. Then $wb = bw$ because $w \in Z(F)$, and so $\left( a_{1}^{\pm1} \right)^n b = b\left(a_{1}^{\pm 1} \right)^n$. However this implies that $a_{1}^{\pm 1} = b$, which is a contradiction.    I cannot see how to deduce that $a_{1}^{\pm 1} = b$ from $\left( a_{1}^{\pm1} \right)^n b = b\left(a_{1}^{\pm 1} \right)^n$. The solution says to consider the reduced words, but this does not seem to be very helpful considering $\left( a_{1}^{\pm1} \right)^n b$ and $b\left( a_{1}^{\pm1} \right)^n$ are already reduced.

How can I show that "A center of a free group that is non-cyclic is trivial" ?


I`ve been coding some REST API tests, and i dont know either i wrote my test wrong or my POST method is invalid.  Im getting this error when i perform the test:      ERROR [2015-12-14 21:37:00,309] org.glassfish.grizzly.servlet.ServletHandler: service exception:   ! java.lang.NullPointerException: null   ! at resources.ActorResource.postActor(ActorResource.java:31) ...etc   and i have no idea where it came from. Actor object in the tests is properly initialized, it all should have worked fine.  Here is the post method :       @POST     @UnitOfWork     public Saying postActor(@HeaderParam("actorName") String name, @HeaderParam("actorBirthDate") String birthDate) {         Actor actor = dao.create(new Actor(name,birthDate));         return new Saying("Added : " + actor.toString());     }   And here is the test i wrote      @Test     public void postActor() {         when(movieDAO.create(actor)).thenReturn(actor);         final Response response = RULE.getJerseyTest().target("/actors").request().post(Entity.text(""));          assertThat(response.getStatusInfo().getStatusCode()).isEqualTo(Response.Status.OK.getStatusCode());         verify(movieDAO).create(actor);     }   EDIT Here`s Actor  initialization method      @Before     public void setup() {         actor = new Actor();         actor.setId(1L);         actor.setBirthDate("12-03-2014");         actor.setName("Karol Marks");     }   And Actor class   @Entity @Table(name="Actors") public class Actor {     private long id;     private String name;     private String birthDate;     private Movie movie;      public Actor() {     }      public Actor(String name, String birthDate) {         this.name = name;         this.birthDate = birthDate;     }      @Id     @GeneratedValue(strategy = GenerationType.IDENTITY)     public long getId() {         return id;     }      public void setId(long id) {         this.id = id;     }      @Column(name = "name", nullable = false)     public String getName() {         return name;     }      public void setName(String name) {         this.name = name;     }      @Column(name = "birthDate", nullable = false)     public String getBirthDate() {         return birthDate;     }      public void setBirthDate(String birthDate) {         this.birthDate = birthDate;     }      @ManyToOne(cascade = CascadeType.ALL)     public Movie getMovie() {         return movie;     }      public void setMovie(Movie movie) {         this.movie = movie;     }      @Override     public String toString() {         return "Actor{" +                 "id=" + id +                 ", name='" + name + '\'' +                 ", birthDate='" + birthDate + '\'' +                 '}';     }

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


I am using Windows 7 on my computer.  I use following browsers at a time:  Google Chrome  Mozilla Firefox  Now in my firefox browser, I have webpages running in more than 18 tabs & there is only 1 process for the entire firefox in the Task Manager. And they consume memory around 316004KB. And I have around 4 tabs opened in Google Chrome with 6 processes in the Task Manager? Why is it so?

I know that each new tab on Google Chrome have its own process, but I have 14 chrome.exe processes running actually as I can see it on the Task Manager, and only two tabs are opened on Google Chrome.    Could it be due to Chrome extensions? What other reason can open more chrome.exe process and how to avoid it?


What is the difference between the two synchronizations:  public synchronized void set (int i) {     this.i = i; }   and   public void set (int i) {        synchronized (this) {                this.i = i;          }     }

Can any one tell me the advantage of synchronized method over synchronized block with an example?


I got stuck on the following exercise:    Find a group $G$, a subgroup $N$, a subgroup of this subgroup $H$ such that $$ H \lhd N \lhd G \quad \text{but} \quad H \ntriangleleft G  $$    This is what I tried to solve it. I knew that   $\{e\} \ \neq \  H \neq N \neq G $ $G$ is not abelian.   I didn't know if a had to look for a finite group or rather an infinite one. I was thinking about taking $G= S_n$, $H = A_n$, and $|H| = \frac{n!}{4}$ for some convenient $n$. I hoped it would be easy to look for an even element $h$ of order $\frac{n!}{4}$, so that we can put $H = \langle h \rangle$. Do you think that it would be a good approach?

Suppose $G$ is a group and $K\lhd H\lhd G$ are normal subgroups of $G$. Is $K$ a normal subgroup of $G$, i.e. $K\lhd G$? If not, what extra conditions on $G$ or $H$ make this possible?  Applying the definitions, we know $\{ghg^{-1}\mid h\in H\}=H$ and $\{hkh^{-1}\mid k\in K\}=K$, and want $\{gkg^{-1}\mid k\in K\}=K$. Clearly, the best avenue for a counterexample is if $gkg^{-1}\not\in K$ for some $k\in K$ and $g\in G-H$.  If no such element exists, $\{gkg^{-1}\mid k\in K\}\subseteq K$ implies $\{gkg^{-1}\mid k\in K\}=K$ because if $k'\in K$, $gk'g^{-1}=k\in K\Rightarrow k'=g^{-1}kg\in\{gkg^{-1}\mid k\in K\}$.


possible duplicate of , but I think this question is more specific, and I can not find specific help in the above link. So I posted it.  I've ask a question here. . Now I want to give a bounty to it. I find this link , which is right below the comment area question , a link titled "eligible for bounty in 2 days". but I could not think how it offered any help.

It's possible to offer and award bounties of reputation on questions.   What is a bounty? How can I find questions that have a bounty attached? How do I start a bounty? When can I start a bounty? Why is the system requiring me to choose a bounty amount that's higher than the minimum? Can I use Markdown formatting in the bounty remarks? Can I edit the remark? How long is the bounty period? How do I award a bounty? Can I award a bounty to my own answer? Can I award a bounty to an old answer? If I offer a bounty on someone else's question, can I award the bounty to their answer? After awarding the bounty, can I remove it or move it to another answer at a later time? What happens if there's no answer after the bounty period? What happens if I feel my question is still unanswered? What is automatic awarding? Are bounty awards exempt from the 200 points/day reputation limit? How does Community Wiki mode affect bounties? How does user deletion or post dissociation affect bounties? Can I award a bounty to an answer from a deleted user or one where the author was dissociated? Can I offer a second bounty after the first one has expired? Can I raise my bounty? What happens if a bounty question is closed or deleted? Why can't I vote to close or migrate a bounty question? What happens if I delete my account while I have an active bounty? Do I keep an awarded bounty when I delete my answer? What happens if a question where I awarded a bounty later gets deleted or migrated? Can I cancel my bounty? Can I affect / divide / share part of my bounty to two (or more) users? How many outstanding bounties can a single user have?      See also:  in the Help Center


The repository 'cdrom://Ubuntu 18.04 LTS Bionic Beaver - Release amd64 (20180426) bionic Release' does not have a Release file. The CD is on an usbstick downloaded from Ubuntu. Now how do I manage to uptdate my system to 20.04?

Every time I try update (using sudo apt-get update) my Ubuntu I get this problem:  W: The repository 'cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1) xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. W: The repository 'ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu xenial Release' does not have a Release file. N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use. N: See apt-secure(8) manpage for repository creation and user configuration details. E: Failed to fetch cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)/dists/xenial/main/binary-amd64/Packages  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs E: Failed to fetch cdrom://Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)/dists/xenial/main/binary-i386/Packages  Please use apt-cdrom to make this CD-ROM recognized by APT. apt-get update cannot be used to add new CD-ROMs E: Failed to fetch ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu/dists/xenial/main/binary-amd64/Packages  404  Not Found E: Failed to fetch ppa.launchpad.net/kirillshkrogalev/ffmpeg-next/ubuntu/dists/xenial/main/binary-i386/Packages  404  Not Found E: Some index files failed to download. They have been ignored, or old ones used instead.   How can I fix it? I use Ubuntu 16.04 LTS


Let's say I have a creature in play that doesn't have summoning sickness anymore. My opponent then takes control of this creature (with for example ). Will this creature have summoning sickness again until next turn? Or will it not, because it was already on the battlefield?

Note: this is intended to be a canonical question about summoning sickness.  "Summoning sickness", broadly, is the rule that stops you from attacking or paying {T} costs with a creature that you just played. But how exactly does it work? How does it interact with other rules and effects?  For example, if I'm trying to figure out how a creature is affected:   Does the status matter (tapped/untapped, face down/face up, etc.)? What if it came into play, but I didn't cast it? What if it's a token? What if it was on the battlefield when my turn started, but it wasn't a creature? What if it stops being a creature? What if it's a creature and also another card type? What if it's a double-faced card that just transformed? What if it changes control? What if it's a copy of another creature? Which of the creature's activated abilities can I use? Are any of its other abilities affected? Can I tap the creature to pay a cost that is not a {T} cost?   (These examples are primarily taken from questions about summoning sickness that have already been asked on the site)


What does the not an answer flag mean? My interpretation is that this flag is intended for things which clearly are not answers. In other words, "this shouldn't exist, because it does not intend to answer the question". It's the difference between a value judgement ("how good is this answer?"), handled with voting, and a clear "this shouldn't exist (as an answer)". The latter is junk that either should have been something else (e.g. a comment, edit etc.) or is clearly worthless (e.g. spam). I think that downvoting is the mechanism for dealing with wrong answers, answers that answer the wrong question, or irrelevant answers. This is important because a moderator may not always have the context to know whether an answer is helpful or not, or may just be wrong. In my opinion, a mod should not be authorised to make such a unilateral value judgement. Is this correct? Are there circumstances where making a value judgement for this flag is acceptable? I'd like a canonical ruling or community consensus to point to for reference for such flag declines. (Context: I am a moderator on . I have a repeated mod flag where the OP believes I should delete  because it doesn't answer his question. However, I believe it is a good faith answer, and I'm happy to watch it stand or fall on its merit. It requires me to understand the question to know whether the answer is or isn't sufficient. I think it is outside of my jurisdiction as a moderator/ to act.)

What is the "Not an Answer" flag and what is its purpose? When should I use this flag? When should I not use this flag? But I'm still not sure if I'm using the flag correctly... An answer is "Not an Answer", but the flag was declined or disputed!   See also:


Is it true that, for a matrix $A \in \mathbb{R}^{n \times m}$ with $n<m$ (so with more features than samples), its covariance matrix is (or might be?) not positive semidefinite? If that's the case, can someone explain and prove it?

Let's say I have a $p$-dimensional multivariate Gaussian distribution. And I take $n$ observations (each of them a $p$-vector) from this distribution and calculate the sample covariance matrix $S$. In this , the authors state that the sample covariance matrix calculated with $p > n$ is singular.    How is it true or derived? Any explanations?


I encounter such an exercise question as below and have no clue so far.      Consider using decision trees/forests to implement Boolean functions,   i.e. classifiers from {0,1}n to{0,1}.      1) Give a good upper bound for the VC-dimension of decision trees with l leaves.      2) What is a good upper bound for the VC-dimension of a random forest   (thresholded linear combination of decision trees) with k trees where   each tree has l leaves?   For question 1), I understand the VC-dimension of a decision tree with l Leaves is at least l, but I cannot come up with the upper bound.

What is the  of a decision tree with k splits in two dimensions? Let us say the model is CART and the only allowed splits are parallel to the axes.  So for one split we can  and then for any labeling of the points we could get perfect prediction (i.e.: shattered points)  But what about 2 splits, or any general k?


Problem  Evaluate $$\lim\limits_{x \to 0} \frac{x-\sin\sin\cdots\sin x}{x^3},$$where $\sin\sin\cdots\sin x$ denotes n-fold composite sine function.  Solution  Consider applying Taylor's Formula with 3-order at $x=0$. We may obtain $$f_n(x)=\sin\sin\cdots\sin x=x-\frac{n}{6}x^3+\mathcal{O}(x^3).\tag{*}$$ To prove this, we can apply the mathematical induction. Let $n=1,$ then $$f(x)=\sin x=x-\frac{1}{6}x^3+\mathcal{O}(x^3),$$  It's true and shows that $(*)$ holds for $n=1$. Assume that $(*)$ holds for $n=k$. Then $$\begin{align*}f_{k+1}(x)&=\sin(f_k(x))\\&=x-\frac{k}{6}x^3+\mathcal{O}(x^3)-\frac{1}{6}\left(x-\frac{k}{6}x^3+\mathcal{O}(x^3)\right)^3+\mathcal{O}(x^3)\\&=x-\frac{k+1}{6}x^3+\mathcal{O}(x^3)\end{align*}.$$ This shows that $(*)$ holds for $n=k+1$. As a result, $(*)$ holds for all $n=1,2,\cdots.$ Now,let's go back to deal with the problem. $$\lim\limits_{x \to 0} \frac{x-\sin\sin\cdots\sin x}{x^3}=\lim\limits_{x \to 0} \dfrac{x-\left(x-\dfrac{n}{6}x^3+\mathcal{O}(x^3)\right)}{x^3}=\frac{n}{6}.$$  Please correct me if I'm wrong. Hope to see other solutions. Thanks.

The limit is   $$\lim_{x\rightarrow0} \frac{x-\sin_n(x)}{x^3},$$  where $\sin_n(x)$ is the $\sin(x)$ function composed with itself $n$ times:  $$\sin_n(x) = \sin(\sin(\dots \sin(x)))$$  For $n=1$ the limit is $\frac{1}{6}$, $n=2$, the limit is $\frac{1}{3}$ and so on.  Can we define a recurrent relation upon that given hypothesis? Also, how do I involve $n$ into calculation, because the final limit will depend on it?  Any suggestions on how to tackle this?  Thank you!


I have a huge issue right now. I can't visualise any real time render and eeve seems not to work. When I visualise the real time it is either gray or a bizarre texture. But in cycle it works fine. Need help.

I don't know why but now, when i go in material preview or rendered (in solid mode it works fine), my object is entirely gray, or invisible idk, because it has the same color of the background. I've been working for days on this project without having this issue, it suddenly showed up. I tried opening other old projects and suddenly they all do the same so i guess it is some blender program setting that applies for all the projects, but idk how it happened cuz i didn't change anything :/, anyone got any tips?


I made a little program in Java, and it run perfectly when I use the java -jar myFile.jar but when I use the "open with OpenJDK Java 7 Runtime" option, nothing happen.  I have no idea why it doesn't launch. If anybody got an idea... Thank you

I'm trying to run a jar application under Ubuntu, so I installed OpenJDK Java 7 Runtime, but when I open this application I got this message :     The file '/home/aimad/Programms/jMerise/JMerise.jar' is not marked as   executable.  If this was downloaded or copied from an untrusted   source, it may be dangerous to run.  For more details, read about the   executable bit.


I understand how redirecting output with > /dev/null causes it not to print to screen.   But for some reason this is not always enough, and some things still do get printed.  In those cases > /dev/null 2>&1 will achieve the desired result.  However this is a little confusing to me. Can someone break down exactly how this works?  What is particularly confusing is the &1 part. If I see & I think "run in background." Don't know what the 1 is for, what if it was a 2?

I am reading an article about   There is something about disabling automatically sending emails.        Disable Email By default cron jobs sends an email to the user account executing the cronjob. If this is not needed put the following   command At the end of the cron job line.  >/dev/null 2>&1       What is the detailed meaning for 2 > & and 1? Why putting this to the end of a crontab file would turn off the email-sending thing?


Let Q be the group of quaternions. Show that Aut(Q) is isomorphic to S4.  Any help here would be really appreciated!  (Also, sorry, I'm new, so I'm not really sure about how posting on here works.)

Let $Q_8$ be the quaternion group. How do we determine the automorphism group $Aut(Q_8)$ of $Q_8$ algebraically? I searched for this problem on internet. I found some geometric proofs that $Aut(Q_8)$ is isomorphic to the rotation group of a cube, hence it is isomorphic to the symmetric group $S_4$. I would like to know an algebraic proof that $Aut(Q_8)$ is isomorphic to $S_4$.


Equipment: Nikon D7000 with a 18-105mm lens that comes with it.  Level of photographer: novice   I've read that the aperture levels change depending on focus. Is there any way in manual mode to stop this?   I tried taking photos of some cardinals and had it originally set at f3.5 but when I looked my screen it was at f4.5 and I couldn't get it any lower.

Why does a camera's maximum (allowed) aperture get smaller when you increase its zoom?


I am trying to build a code but while using switch case this is showing an error like **A Constant value expected ** in my switch case. can not we write like this case "CRLR'" + CaseDetails.registerno + "' of '" +CaseDetails.year+"'- R ": CaseDetails.details = tabledata.LastChild.PreviousSibling.InnerText.Trim();in switch case? If no please let me know how to get non constant value in switch. this is my code       public CaseDetailsParser ParseCaseDetails(HtmlDocument htdocment)     {         CaseDetailsParser detailsParser = new CaseDetailsParser();         if (htdocment.DocumentNode.InnerText.Contains("THIS CASE IS NOT REGISTERED"))         {             return detailsParser;         }         var data = htdocment.DocumentNode.SelectNodes("//table").Where(x => x.Attributes.Contains("bgcolor") && x.Attributes["bgcolor"].Value == "Azure");         foreach (var value in data)         {             var rowvalue = value.ChildNodes;             foreach (var tabledata in rowvalue)             {                 var tdatas = tabledata.ChildNodes;                 if (tabledata.Name != "#text")                     switch (tabledata.FirstChild.NextSibling.InnerText.Trim())                     {                         case "Date of query :": CaseDetails.dateOfQuery = tabledata.LastChild.PreviousSibling.InnerText.Trim();                             break;                         case "Time :": CaseDetails.Time = tabledata.LastChild.PreviousSibling.InnerText.Trim();                             break;                         case "CRLR'" + CaseDetails.registerno + "' of '" +CaseDetails.year+"'- R ": CaseDetails.details = tabledata.LastChild.PreviousSibling.InnerText.Trim();                         //    break;                       }             }

When writing a switch statement, there appears to be two limitations on what you can switch on in case statements.  For example (and yes, I know, if you're doing this sort of thing it probably means your  (OO) architecture is iffy - this is just a contrived example!),    Type t = typeof(int);    switch (t) {      case typeof(int):       Console.WriteLine("int!");       break;      case typeof(string):       Console.WriteLine("string!");       break;      default:       Console.WriteLine("unknown!");       break;   }   Here the switch() statement fails with 'A value of an integral type expected' and the case statements fail with 'A constant value is expected'.  Why are these restrictions in place, and what is the underlying justification? I don't see any reason why the switch statement has to succumb to static analysis only, and why the value being switched on has to be integral (that is,  primitive). What is the justification?


i bought this new notebook (Acer E5-573G-58B7) with Windows 10. I'm trying to install Ubuntu and make a dual boot, so I followed this steps:   Download Ubuntu 14.04.03 LTS; Use one USB to make a boot device; Shrink my HD with other partition to install Ubuntu; Restart Windows and boot on USB; Install Ubuntu in the partition made before;   Untill now, no problems. The problem comes now.  When i restart my notebook it just go right to Windows, without GRUB or something, i searched a lot, and already disable SECURE BOOT and everything. And even if i hit F12 when computer starts to boot menu, that screen doesn't show the Ubunutu partition to select and i cant choose Ubuntu to start anyway.

I have an ACER Aspire laptop. Model number is E5-573G-56RG. I bought it only 15 days back. There is no DVD drive in it. I have tried various versions of Ubuntu- 14.04.2, 14.04.3, 15.10, 12.04.5. Tried disabling secure boot, fast startup. I current have Windows 10 Home and Windows 10 PRO (not-activated) installed with GPT partition in UEFI bios. I actually want only the Home edition and Ubuntu 14.04.3 (preferably because of LTS) or 15.10. In case more information is required, kindly ask me..  I tried installing through Wubi, when booting if I choose Ubuntu it automatically restarts and goes into Windows 10 Home! (I didn't have Windows 10 PRO at that time)  NONE OF THE SOLUTIONS I REFERRED HELPED ME.  I have spent 5 days (literally at least 20 hours reading all of them and trying out all kinds of editing in the grub command line, like removing quiet splash, adding and replacing with nomodeset, no splash, acpi_osi=off, acpi_osi=Linux, acpi_backlight=vendor,  acpi_backlight=legacy, noveau.modeset=0, i915.i915_enable_rc6=1 and such things! But I was not able to succeed installing which is why I doubt if there is some more thing to be done or know exactly what has to be done.


I'll be starting an HSA for the first time on Feb. 1.  I have significant medical bills for treatment in December. Can I deposit money into the HSA on Feb. 1 and then use the HSA to pay the bills for treatment in December?  Or can I only use the HSA to treatment after the HSA was started?

Let's say that in year A I had a medical insurance plan without an associated , and incurred some medical expenses (co-pays, deductibles). I didn't pay them that year; they may even have gone to collection.  In year B, I'm covered by a different medical insurance plan with an HSA. Can I use the HSA to pay the bills from year A? Or are the only eligible expenses incurred after the HSA plan's plan year begins? Or, worse, can I only pay a particular expense using money that was contributed before that expense was incurred?


I have encountered myself with the following exercise:     Let $\langle A, <_R\rangle$ and $\langle B, <_S\rangle$ be two linearly ordered sets so that each one is isomorphic to a subset of the other, that is, there exists $A'\subseteq A$ and $B'\subseteq B$ such that:      $$\langle A,<_R\rangle\cong\langle B',<_S\cap(B'\times B')\rangle\qquad\&\qquad\langle B,<_S\rangle\cong\langle A',<_R\cap(A'\times A')\rangle$$      Is it necessarily true that $\langle A,<_R\rangle\cong\langle B,<_S\rangle$?   The original statement talked about well-ordered sets, but that case is pretty easy, because supposing that $\langle B',<_S\cap(B'\times B')\rangle$ is not isomorphic to $\langle B,<_S\rangle$, the theorem of comparison between well-ordered sets assures that $B'$  with its restricted relation $<_S$ is isomorphic to an initial section of $\langle B,<_S\rangle$. But then, composing the unique isomorphism between $A$ and $B'$ with the restriction to $B'$ of the only isomorphism between $B$ and $A'$, we find that $A$ is isomorphic to a subset of $A$ with strict upper bounds (namely, the image of the element of $B$ that defines the initial section of $B'$ via the isomorphism between $B$ and $A'$) in the sense of $<_R$, which is absurd.  However, when the sets are not well-ordered, can we find a couple of linearly ordered sets that, although verifying the stated property, are not isomorphic to each other?  I have tried with some subsets of $\mathbb{R}$ and other subsets of $\mathbb{R}$, but it seems that they are all isomorphic to each other.  I ran out of ideas. Are there any counterexamples to this statement?  Thanks in advance for your time.  P.S.: I have thought, for instance, that a closed interval of $\mathbb{R}$ shouldn't be isomorphic to the whole $\mathbb{R}$. How can we prove this assertion?

If A and B are partially-ordered-sets, such that there are injective order-preserving maps from A to B and from B to A, is there necessarily an order-preserving bijection between A and B ?


I saw  question recently and I was wondering if a magic item, such as a , could be dispelled with dispel magic such that it would it lose the +1?  A common item would require a formula, 100 gp in components, and a minimum of a 3rd level spell caster with a similar spell to be made so it could be treated as a lvl 3 spell.    The  spell description states:     Choose one creature, object, or magical effect within range. Any spell of 3rd level or lower on the target ends. For each spell of 4th level or higher on the target, make an ability check using your spellcasting ability. The DC equals 10 + the spell's level. On a successful check, the spell ends.     So if somebody cast dispel magic on that Longsword +1 would its effects be negated, or would the caster lose a spell slot?

Does casting dispel magic on a plain +1 sword make it no longer +1?   Also does dispel magic work on a dragon slayer longsword such that it is no longer +1 and no longer does extra damage against dragons?


I want to cut a specific (but not very complicated) shape out of a sphere like so:    But the result is always bad looking due to tris and close proximity vertices.  The best I can get is using Edge Split:    Is there a way to get a clean result?  I've looked elsewhere and saw some people mention that this needs some manual work - how do I put in the manual work to make it look better?  I don't mind since my shapes are generally quite simple.

What are some good techniques to make a rounded/beveled hole in a non-flat surface? e.g. something like the :    The Boolean Modifier and the Knife project tool work well, but they create uneven topology that is difficult to bevel.    Image from the blender wiki


I am trying to get the separate RGB components from each element in a 2D color array,but it keeps throwing a NullPointerException and I am not sure why.  CODE:             Color[][] grid = new Color[MaxColors][MaxColors];      int R1 = 0;       for(int x = 0; x < N; x++){         for(int y = 0; y < N; y++){               R1 = grid[x][y].getRed();              /* do something with R1*/            }     }   I also tried to first add the colors to a list and and then convert it to a one-dimensional array. But I still get the same error.      List<Color> colorList = new ArrayList<Color>();      for(int x = 0; x < N; x++){         for(int y = 0; y < N; y++){               colorList.add(grid[x][y]);          }     }      Color[] SortColors = colorList.toArray(new Color[colorList.size()]);             for(int x = 0; x < SortColors.length; x++){          R1 = SortColors[x].getRed();        System.out.print(" " + SortColors[x]);        System.out.print(" " + R1);      }   It prints the following:  java.awt.Color[r=98,g=85,b=217] 98 java.awt.Color[r=254,g=110,b=177] 254Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException     at DrawGrid.ColourSorting.sortColours(ColourSorting.java:43)

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


If in a semigroup S,$ \ $ $ x^{k+1} = x $ for some  $k \ge 1$ and $xy^kx = yx^ky \quad  \forall x,y \in S$ then show that S is abelian.  I'm able to prove the following $\ x=x^3, \quad x^2y^2=y^2x^2=(xy^2)^2=(y^2x)^2 \ and \ x^k=x^2  \quad \forall x,y \in S$ I thought of proving  $x^2=y^2  \quad \forall x,y \in S$ and so S will have an identity element, but couldn't do it and don't know whether the approach is correct.

Let $S$ be a non-empty set and $n\in \mathbb{N}, n\geq 2$ a fixed integer. We consider an associative operation $"\cdot"$ on $S$ with the following properties:   $x^{n+1}=x, \forall x\in S$ $xy^nx=yx^ny, \forall x,y\in S$   Show that this operation is commutative. This problem has been given at a romanian contest. The proof uses very complicated substitutions and I am wondering if there exists an elegant proof of this. Thank you!


As I write my Bachelor thesis at the moment I tried to teach myself how to use Latex. But I am struggling a lot with my bibliography as I can not find a way to program it the way I want to:      Surname, N. und Surname, N. (year), Titel, .... other informarion   (The german word 'und' between the authornames is extremly important)  Sadly I could not find how to do that on the Internet or in other questions.  I recently tried alphadin and apalike. But with alphadin I get only Errors: (Package natbib Error: Bibliography not compatible with author-year citations.) and with apalike, with which i can compile my document, it does not look as I want it to. Besides that I always get that and between  names, which is not that practical as I write my text in german.  I put all my literature into JabRef.  my Code looks as following:   \usepackage[utf8]{inputenc} \usepackage[ngerman]{babel} \usepackage[T1]{fontenc} \usepackage[usenames]{color} \usepackage{graphicx} \usepackage{graphicx,caption} \usepackage{tabularx} \usepackage{amsmath} \usepackage{ulem} \usepackage{amsthm} \usepackage{amssymb} \usepackage{mathptmx} \usepackage{fancyhdr} \usepackage{a4} \usepackage{acronym} %\usepackage{epic} \usepackage{eepic} \usepackage{parskip} \usepackage{eurosym} \usepackage{array} \usepackage{pdfpages} %\usepackage{glossaries} \usepackage[authoryear]{natbib} %\usepackage{bibgerm} \usepackage[flushmargin, hang]{footmisc}  \begin{document} .... %-Literaturverzeichnis-------------------------------------------- %\nocite{*} %die Verwendung von bibtex ist Pflicht!!! \newpage \addcontentsline{toc}{section}{Literaturverzeichnis} \bibliography{Literatur} #so heißt mein JabRef File %\nocite{*} %\bibliographystyle{alphadidiEN} %bzw. unsrtdin, alphadin, abbrvdin  \bibliographystyle{alphadin} %\bibliographystyle{apalike} %plainnat statt plain %unsrtnat statt unsrt %abbrvnat statt abbrv %alphadidiEN statt alpha,  \newpage \end{document}   Most of the things with the % were given in the orientation file from my university.  I hope you can help me (and sorry for the trouble with the wrong language at first :) )

How can I change the citation conjunction from english "and" to catalan "i"?  Otherwise  Author = {Kirk, D. and MacPhail, A.},   would get cited as (Kirk and MacPhail, 2002) when it should be (Kirk i MacPhail, 2002).  When there are more than 2 authors I get et al. which is fine.  I've seen  and  which do not work with apalike style.  Also, I'd rather not use biblatex if possible.


Hi I have a 400*800 resolution video , I need a 800*400 video , So all i need to do is scale the video's with to 400 and change the y position so that I can see the scaled central part of the video. I have checked online but position is available only for overlays , I need for a single video

I have a html 5 video player which is 700px wide, 400px high. I'm trying to use avconv to use ffmpeg to resize (while retaining the aspect ratio) and making sure it fits into my player.  Input can be a file of any size, so I need to resize the larger ones but center the smaller ones with black bars. So far I've tried: -s and -aspect, I've seen pad being used with the -vf switch but don't understand how it works enough to get what I need.    This is a rough idea of what I need. I'm not sure if it's even possible. It's almost like CSS's max-width/max-height. I realise this may just be a jumble of words but if anyone happens to understand what I'm talking about, I'd appreciate help, Thanks.  avconv command:  avconv -y -i control.avi -vcodec libx264 -b 2000k -bufsize 20M -acodec aac -strict experimental -ar 44100 -ab 256k bigbuck_out.mp4


I have a file with the full path to an image on each line, all are jpg.  I want to resize every image/line in the file to 1024px in width, while keeping the aspect ratio for the height.  I simply want to overwrite the original file.  The main thing I'm having issue with is, I want to SHRINK only.  I do not want to enlarge images smaller than 1024px in width up to 1024px in width.  Here is the bash script I'm working with and just need help with the convert line as I have no experience with imagemagick.  #!/bin/bash  while read p; do   convert $p done < listofimages

I want to scale all images in a given folder to the same width (but different appropriately scaled heights). How can I do this using  a GUI-based or command-line tool?  For bonus points, is it possible to restrict which images are scaled based on their initial width (that is, only scale images that have a width > x and/or a width < y)?


Give an example of an ideal in the ring $\mathbb{Z} [x]$ is not principal. What kind of example would be the easiest?

Is $ \mathbb{Z}[x] $ a principal ideal domain? Since the standard definition of principal ideal domain is quite difficult to use. Could you give me some equivalent conditions on whether a ring is a principal ideal domain?


I'd like to create a simple line box that draws itself that I can import in Blender's VSE.   This can be done in after effects like in this video tutorial:   What methods would be best to recreate this and could I use such methods to creat other simple self revealing shapes a simple well?   Many thanks for any help!

Major Noob Question here but I want to create a 2d shape that seems to draw itself like in this video below:   I saw in KaptainKrisitan's videos and wanted to replicate in blender, but I don't have a clue how.


Currently I have something like this set up: B-R-R-R-C-R-R-R-C-R-R-R-C (etc...)  B stands for a redstone block, R stands for a repeater, and C stands for a command block.  I have a line like this (curling back once in a while, but not a loop) up to a minute -- but this method uses 120 repeaters at full delay. What circuit could I use to create something that behaves AS CLOSE AS POSSIBLE to what I have now, but taking up less space? Specifically:  1) Removing the redstone block power source won't stop the already-sent signal 2) Must have room for gradual command blocks (so at 20 seconds I could have a command block, at 30, at 35, etc...)  For specifics, this is my Deathmatch system in a vanilla Survival Games map. When the minute is over, it reaches command blocks which teleport everyone to one location. The admin in the match uses a command button in a /tellraw command to start the countdown for Deathmatch when (s)he deems it appropriate - this command sets a redstone block as the input. After it is placed, it remains placed for the rest of the game -- but I want to be able to destroy it while not stopping the minute countdown for debugging purposes. And, as it's a countdown, it needs to be able to send out a signal every second to command blocks for stuff like "15 more seconds until Deathmatch!"  Summary: I am looking for a delay as opposed to a timer. I do not want a signal that loops and am not looking for a necessarily long delay, I just want an accurate delay that is more efficient than using repeaters AND can support gradual output (IE at half delay an output, at three quarters, etc...) Hooking a timer up to an AND gate with the input won't work as far as I know (if you know a way please tell) because if the timer was half-passed when the input was given, then the "delay" would be half the intended time. And removing the input signal should NOT stop the delay from continuing. It also needs to be silent, as it is close to the surface, and non-laggy (no super-quick repeater loops).  I am asking for a very specific redstone circuit, I know.

I have recently found that my MC world does not auto-save (Don't answer on how to do that), so I have to /save-all every 5 minutes or so.  However, I have created a timer hooked up to a /save-all command block. Note that all repeaters are set to max delay.    Basically, what happens is, there is a redstone signal passing through the repeaters. When it reaches the end, it hits out a command block and loops around back to the starting which goes through the timer again.  I have timed this as 2:24.  Is there a much efficient design to the timer or any part of the structure? Is there also a way to increase the time without changing a major part of it?  Please don't suggest any latchology as I am terrible at it.


I use a string that contains \ in a sed expression and I want to keep it in the output of sed  $ A=w $ B="\ " $ echo word | sed "s/$A/$B/"    ord   I want to obtain \ ord instead of ord.  What is the most elegant way of doing it?

I have a script that reads a text stream and generates a file of sed commands that is later run with sed -f. The generated sed commands are like:  s/cid:image002\.gif@01CC3D46\.926E77E0/https:\/\/mysite.com\/files\/1922/g s/cid:image003\.gif@01CC3D46\.926E77E0/https:\/\/mysite.com\/files\/1923/g s/cid:image004\.jpg@01CC3D46\.926E77E0/https:\/\/mysite.com\/files\/1924/g   Assume the script which generates the sed commands is something like:  while read cid fileid do     cidpat="$(echo $cid | sed -e s/\\./\\\\./g)"     echo 's/'"$cidpat"'/https:\/\/mysite.com\/files\/'"$fileid"'/g' >> sedscr done   How can I improve the script to ensure all regex metacharacters in the cid string are escaped and interpolated properly?


Liverpool's players are skilled, so they .... the match easily.    will win are going to win   I had hard time answering this question in my final exam in the High School, my answer was the second. Some of my classmates said: "will win".

I know several questions were asked about the difference between "going to" and "will". Based on several answers (see, for instance, ,  and ), I understood that "will" is more spontaneous and "going to" is used with more planned actions.  So, it seems that everything is pretty fine. However, in , Kosmonaut has an answer in which he states: "Let's say that tomorrow you will walk your dog from 7 - 8 AM".  On the one hand, you probably planned to walk your dog long before and thus I should use "Let's say that tomorrow you're going to walk your dog from 7 - 8 am".   On the other hand, since I'm saying "let's say...", I'm deciding right now (thus, unplanned) that you will walk your dog. So, even though in this hypothetical situation you made a plan, I'm in a more spontaneous mood deciding right now that that's what you will do tomorrow, and, thus, I should use "will".  Which one (if any) of the above explanations is right?


I'm looking at some legacy code that looks like it was converted over from C to C++ and there are various classes that have public member variables and nothing else:  class sampleClass   public:     int fd;     customType clientHandle;     customType serverHandle; };   From my understanding struct = class with no functions and public members so is this virtually exactly the same as a struct for practical reasons?  What happens when the code is compiled.  Is it compiled down to the exact same "stuff" or do they get compiled differently

This question was .  Now I'd like to learn the differences between a struct and a class in C++. Please discuss the technical differences as well as reasons for choosing one or the other in OO design.  I'll start with an obvious difference:   If you don't specify public: or private:, members of a struct are public by default; members of a class are private by default.   I'm sure there are other differences to be found in the obscure corners of the C++ specification.


I failed . The original post is . I don't think this audit is good, because the question is clearly "too broad" and should be closed as such, and remain closed as such.   No harm is done, but I know that the posts that get put into audits are automated, here is a case where the automated process failed.  edit:  I also just failed  (). Clearly this should be closed as off-topic because it is about "general computing hardware and software".  I think there are probably a few problems with the reopen audits. Until they are fixed I am going to stop reviewing in that queue - because I fear the auto-ban might get me.  The point of my post (as it seems unclear to some):  I think these specific audits are on bad posts, and I think they should be removed from the selection of audits for this queue.

Some people are complaining about the automatically generated audits. They are based on close reasons and apparently are a little controversial :-)          etc   I propose that for "good reviewers" (definition TBD) an extra UI component be added to let the reviewer suggest this as an audit item. Possibly:   Reject and add as audit button (Close and add as audit, etc) checkbox next to Reject, Close, etc checkbox on the Reject reason, Close reason etc dialog (could get messy, and some actions such as Reopen don't involve a subsequent dialog) dialog after rejecting, closing, Recommend Deletion, etc   Further, after passing or failing an audit, we could ask "good reviewers" "was this a good audit"? Bad audits, whether auto-generated or human suggested, could be removed from use if enough "good reviewers" identified them as such.  Now, what's a good reviewer? I don't want to judge only on behaviour in the review queue. I think flagging well is a good sign. So is editing - maybe an edit-related badge? And yes, some number of reviews would be good. Maybe some ratio of pass to fail on review audits. But not JUST what we do in the queues.  (I first suggested this in my answer to  but I'm bringing it up as a feature request of its own and to apply to all the queues.)


A person watched 60% of a movie. Is it appropriate to say the person watched most of the movie?

In sentences such as the following, how is most best understood?       1) Most children do not like cauliflower.        2) Most of the balls in the bucket are red.   I suppose there are three or more possible interpretations for most in these sentences.     A) a plurality (at least one more than any other alternative)        B) a majority (more than half, even if barely more)        C) a comfortable majority (well more than half)   For sentence 1, interpretations A and B would be equivalent since there are only two alternatives.


Let $c \in \mathbb Z$ and $k=LCM(a,b)$.   Show that for every $a,b \in \mathbb Z$ \ {$0$} if  $a\mid c$ and  $b\mid c$ then also $k\mid c$.  Please dont give me the solution just a tip. My thoughts were that $c \ge LCM(a,b)$ so $c$ is a multiple of $k$ $\Rightarrow$ $c=LCM(a,b)*m$ with $m \in \mathbb N$. Then I have to look at to cases:   Case 1:  $c=LCM(a,b)$  then $a$ divides $c$, $b$ divides $c$ and then also $k$ divides $c$.   Case 2:  $c\gt LCM(a,b)$  a divides c and b divides c $\Rightarrow ax=c=by $ with $x,y \in \mathbb Z$ and a,b divides $LCM(a,b)$ then a,b divides also the multiple of $LCM(a,b)*ax*by*n$ with $n \in \mathbb N$.   Im pretty sure at Case 1 but not at Case 2. Does it make sense? please give me rate and a tip. Thank you!

Can't understand a proof: Let $a,b,c$ be integers. If $a$ and $b$ divide $c$, then $lcm(a,b)$ also divides $c$  Proof I've been shown:  Since $c$ is a common multiple of $a,b$, it means that $lcm(a,b) \leq c$.  So: $c=q\cdot lcm(a,b)+r$, $q \in \mathbb Z$ and $0\leq r \leq lcm(a,b)$  Since $c$ and $lcm(a,b)$ are common multiples of $a,b$, then so is $r$. But $m$ is the least common divisor, then it means $r=0$.   [Proof taken from: http://www.math.utah.edu/~wood/4400/hw1sol.pdf]  I cannot understand the last step... Why does it imply that $r=0$?   Thank you!


I have auto fill option activated on my chrome browser. I use Windows 7. I ma looking for the file that stores the data previously recorded as "Auto Fill" such as login username.  I know that such data is stored in C:\Users\Username\AppData\Local\Google\Chrome.  But there are so many files in it and I have already wasted a lot of time looking. Can some one point me in the right direction?

I know how to delete saved form data in Chrome, but I'd like to be able to see all of the entries stored for fields.   When I type a into a form, I get a list of a few items that I have typed before in that field which begin with a.   I would like to see a complete list, though.


I have been dealing with the concepts of physics and mathematics for a long time now. I am currently interested in understanding the concepts of Classical Mechanics at a deeper level, dealing with Lagrangian and Hamiltonian formalisms. Recently, a friend suggested a book on Classical Mechanics by V.I. Arnold. I am not sure if I have the prerequisites to start understanding the concepts in the book. Let me go ahead and state what I understand well so far. Classical Mechanics at the level of Kleppner and Kolenkow, Calculus at the level of G.B. Thomas, Linear Algebra, Concepts of physics at the level of University Physics and high school mathematics.   This course on Classical Mechanics is to be taken by me along with Differential equations (beyond what Thomas offers), Electrodynamics by Griffith and Complex analysis. I am skeptical about my current understanding being enough to start reading the book by Arnold.

So I am an undergraduate in Electrical Engineering. We had a course on Physics in our freshman year which is equivalent to Classical Mechanics I as taught in MIT. I am interested in studying advanced classical mechanics (which includes Lagrangian formulation and other stuff) as equivalent to Classical Mechanics lecture by Susskind. I wanted to know are they any prerequisites which I should know about before taking this course.   In general what are the prereqs for this course?


Here is my code:  \documentclass{article} \usepackage{tikz} \usepackage{hyperref} \begin{document}  \section{Hello} \subsection{Hello World}  \begin{figure} \centering \begin{tikzpicture} \node[circle,draw=black,minimum size=5cm]{}; \end{tikzpicture} \caption{Circle} \label{fig} \end{figure}  \pagebreak  \subsection{Hello Human} Figure \ref{fig} demonstrates a large circle.  \end{document}   Here is how the first page of the output looks like:  The figure has floated to the top. Is there a way I can ensure that the figure remains below section 1.1 while still be able to generate captions with figure numbers automatically and use them for cross-referencing?

Is there any package or a method to force LaTeX to keep floating environments like table and figure closer to where they are declared?


I was modeling a character head from an image background and have lost my image since I moved the blender file to another location . what do I do to make it come back instead of the pink colored area where my image should be ? thank you

I made a character, and its one of my first times texturing, and I saved my character into a new folder, and when I came back to the model ALL the textures were pink, I used to know what to do, but I stopped texturing, how do I bring my textures back?