Why is finding $M$ eigenvectors on smaller matrix valid?

I am following  on face recognition. In "calculating eigenfaces" section, the authors present a solution for the problem of calculating a very big matrix:   Let $A_{N^2\times M}$ be an $M$ sized dataset, where each column in an $N\times N$ image. Instead of calculating the $M$ large eigenvectors of the $N^2\times N^2$ co-variance matrix they calculate the $M$ eigenvectors of $L=A^TA$ matrix which is of size $M\times M$.    Why is this a valid\good enough solution? What are the criteria for a largest vector? larger in which seance?


ModernCV banking style default space between address and phone

Moderncv has a line of empty space between address and phone/email, like this:   MWE:  \documentclass[12pt]{moderncv} \moderncvstyle{banking} \name{Sherlock}{Holmes} \address{221B Baker Street}{London}{U.K.} % Your current address \phone[mobile] {+44~(0)71234 00000}    % Your mobile phone number \email{superdetective@mail.com}  \begin{document} \makecvtitle \end{document}   How do I remove/decrease that space by shifting the phone and email line up?


How do I embed a gather environment within a custom environment?

I've tried defining the following custom environment, but I get errors:     \begin{gather} ended by \end{solution}   etc...   Here's a MWE showing my problem:  \documentclass{article}  \usepackage[fleqn]{mathtools}  \newenvironment{solution}{%  <-Solution   \par\addvspace{1em}   \itshape{Solution:}\par\begin{gather}}   {\end{gather}\par\normalfont\hfill\qed\par\addvspace{\medskipamount}}%  \begin{document}   \begin{gather}     testing   \end{gather}    %% This does not work:   \begin{solution}     testing   \end{solution} \end{document}


Will making new chat rooms take a part of your reputation?

I have just earned the privilege of making new chat rooms. Because of this i want to know that will making new chat rooms take a part of my reputation. I know that chats which follow from discussions don't take some part of your reputation as it follows from a question but what about the rooms which are made on your wish?  Here by taking a part of your reputation i mean like what happens when you cast a bounty a part of your reputation goes into that bounty. Does the same think happen in making chat rooms?


Having installed Ubuntu 11.10 with whole disk encryption and LVM, I need to provide a way for users to easily change LUKS passphrase.  Preferably, this should be done using GUI tools, thus, enabling novice users to perform this basic task.


Triangle Inequality of the Cartesian product with Max function

Let $(X,d)$ be a metric space.  Define $$d'((x,y),(z,w))=max\{d(x,z),d(y,w)\}.$$   I'm trying to prove the triangle inequality for this, but really don't have a clue how.  Any tips or suggestions would be greatly appreciated!


Dicas para instalar skype no 64bits  Gostaria de instalar o skype 64bits e inicializá-lo junto com o sistema.  Além disto gostaria de deixar links para fazer ligações com atalhos visíveis com imagem  Machine-translation to English:     Tips to install skype on 64bit      I would like to install skype 64bit and initialize it with the system. In addition you want to make links to make calls with visible shortcuts with image.


Is an irrational to an irrational rational?

I am working on this logical proof for class and trying to either prove or disprove that an irrational to an irrational power is also irrational. Please don't answer the problem for me but I'm completely stuck on how to begin. Any hints would be appreciated.


I'm having some trouble proving the following proposition:  Let $a,c \in \mathbb Z\setminus\{0\} $ and $k \in \mathbb Z$, then:$$\gcd(a,ak+c)=\gcd(a,c)$$  If $D_a$ and $D_c$ are the set of all numbers that devide $a$ and $c$ respectively I was able to prove that, if $\lambda := \gcd(a,ak+c)$ then $\lambda \in D_a \cap D_c$, but now, I can't arrive at the conclustion that $\max(D_a \cap D_c) = \lambda$. How can I conclude this proof?


How to override the DHCP-provided nameserver?

I (think) that I've configured a static IP address in /etc/network/interfaces:  # The primary network interface  auto eth0  iface eth0 inet static     address 10.1.1.2     netmask 255.255.255.0     network 10.1.1.0     broadcast 10.1.1.255     gateway 10.1.1.1   And I change the file /etc/resolv.conf to include the desired nameservers.   Then I restart networking sudo /etc/init.d/networking restart  But after some hours resolv.conf always reverts back to the DHCP nameserver.   I should also say that this is Ubuntu Server with only l0 and eth0 interfaces.


let $f,g:R\to \mathbb{Q}$, show that $f=g$.

Let $R$ be a ring, $\mathbb{Q}$ be the field of rational numbers, and $f,g: R \to \mathbb{Q}$ be homomorphisms such that $f(n)=g(n)$ for all $n\in \mathbb{Z}$, where $\mathbb{Z}$ is the ring of integers, show that $f=g$.  (Hint: first show $f(1/n)= g(1/n)$ for all $n \in \mathbb{Z}$)


I have just started learning Cryptography.I looked on the Wikipedia and found topics like "Public key Cryptosystem","Symmetric Cryptography" ,"Cryptanalysis" etc.  Below this in the reference section there are enumerous papers .I just wonder if there are any books available in this section which will deal with the topics mentioned above .  Also what are the prerequisites in learning this subject?  Please help me in finding some good books in this subject.


Trends data from Twitter Search API in JSON.  Grabbing the file using:  $jsonurl = "http://search.twitter.com/trends.json"; $json = file_get_contents($jsonurl,0,null,null); $json_output = json_decode($json);   How do I work with data from this object. As an array? Only really need to extract data from the [name] values.  JSON object contains:  stdClass Object (     [trends] => Array         (             [0] => stdClass Object                 (                     [name] => Vote                     [url] => http://search.twitter.com/search?q=Vote                 )              [1] => stdClass Object                 (                     [name] => Halloween                     [url] => http://search.twitter.com/search?q=Halloween                 )              [2] => stdClass Object                 (                     [name] => Starbucks                     [url] => http://search.twitter.com/search?q=Starbucks                 )              [3] => stdClass Object                 (                     [name] => #flylady                     [url] => http://search.twitter.com/search?q=%23flylady                 )              [4] => stdClass Object                 (                     [name] => #votereport                     [url] => http://search.twitter.com/search?q=%23votereport                 )              [5] => stdClass Object                 (                     [name] => Election Day                     [url] => http://search.twitter.com/search?q=%22Election+Day%22                 )              [6] => stdClass Object                 (                     [name] => #PubCon                     [url] => http://search.twitter.com/search?q=%23PubCon                 )              [7] => stdClass Object                 (                     [name] => #defrag08                     [url] => http://search.twitter.com/search?q=%23defrag08                 )              [8] => stdClass Object                 (                     [name] => Melbourne Cup                     [url] => http://search.twitter.com/search?q=%22Melbourne+Cup%22                 )              [9] => stdClass Object                 (                     [name] => Cheney                     [url] => http://search.twitter.com/search?q=Cheney                 )          )      [as_of] => Mon, 03 Nov 2008 21:49:36 +0000 )


Will clearing image cache delete images from gallery?

I have an OPPO A3s where there is an option to clear image cache approx. 900 mb. size.  I want to know if clearing it will delete my pictures or not?


If determinism is true, what was the first event? Is time infinite?

How can all events be causally related if there is no initial event?


Android: Attempt to invoke virtual method 'android.content.ContentResolver android.content.Context.getContentResolver()' on a null object reference

I am trying to call the startListening() method from SpeechRecognizer. I am calling the method from a class that is not directly linked from the MainActivity layout, but extends Activity and is instantiated by the MainActivity class. I understand what a null object reference is, however I don't see where the null object reference is coming from...  Here's the code:  public class VoiceRec extends Activity implements View.OnClickListener {      private String command;     private TextView outputText; //TODO:temporary for testing     private Button speakButton;     private SpeechRecognizer voicerecognizer;     private String packageName;      private RecognitionListener voiceRecListener = new RecognitionListener() {          @Override         public void onReadyForSpeech(Bundle params) {             Log.d("VoiceRec", "onReadyForSpeech");         }          @Override         public void onBeginningOfSpeech() {             Log.d("VoiceRec", "onBeginningOfSpeech");         }          @Override         public void onRmsChanged(float rmsdB) {             Log.d("VoiceRec", "onRmsChanged");         }          @Override         public void onBufferReceived(byte[] buffer) {             Log.d("VoiceRec", "onBufferReceived");         }          @Override         public void onEndOfSpeech() {             Log.d("VoiceRec", "onEndofSpeech");         }          @Override         public void onError(int error) {             Log.d("VoiceRec", "error " + error);             //mText.setText("error " + error);         }          @Override         public void onResults(Bundle results) {             ArrayList data = results.getStringArrayList(SpeechRecognizer.RESULTS_RECOGNITION);             for (int i = 0; i < data.size(); i++) {                 Log.d("VoiceRec", "result " + data.get(i));              }             //mText.setText("results: " + str);         }          @Override         public void onPartialResults(Bundle partialResults) {             command = new String();             command = partialResults.getString(SpeechRecognizer.RESULTS_RECOGNITION);             outputText.setText(command);         }          @Override         public void onEvent(int eventType, Bundle params) {             Log.d("", "onEvent " + eventType);         }     };      public VoiceRec() {         voicerecognizer.setRecognitionListener(voiceRecListener);     }      //for testing with button and output only, remove later     public VoiceRec(Object...args) {         voicerecognizer = SpeechRecognizer.createSpeechRecognizer(this);         voicerecognizer.setRecognitionListener(voiceRecListener);          speakButton = (Button) args[0];         speakButton.setOnClickListener(this);          outputText = (TextView) args[1];          packageName = (String) args[2];      }      @Override     public void onClick(View v) {         Intent vrintent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);         vrintent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL, RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);         vrintent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, packageName);         vrintent.putExtra(RecognizerIntent.EXTRA_MAX_RESULTS, 5);         voicerecognizer.startListening(vrintent);     } }   So the error occurs with the OnClick method when I call voicerecognizer.startListening(vrintent). I had this method working when all the code was in the MainActivity class originally, so I do not know how to fix this error. I assume it has to do something with context, but I am relatively new to this so any help would be appreciated!


Why are proofs not written as collections of logic symbols but are instead written in sentences?

Mathematical proofs are written as sentences and not as collections of logic symbols. Through logical operations, it is much easier for me to visualize what the symbols are trying to tell us rather than English text filled with grammar. This is my personal opinion, others may have different opinions. I just asked  on another website to find out logical mistakes in  which is entirely done in the language of propositional logic. Some people suggested to write it down in sentences in English. Is there any kind of tragedy in writing proofs as collections of logic symbols?


PCA: violation of the normal distribution assumption

I try to understand why normal distribution is an assumption for PCA and what might happens when it is violated. I found one answer on this plattform and a lot of different answers in literature. It varies between "there is no need for normal distribution as long as the data variables are linear correlated " and "normal distribution is essential, if violated PCA can go really wrong". I would be really happy if somebody could explane the connection between normal distribution and PCA.


..$ sudo apt-get install apache2 Reading package lists... Done Building dependency tree        Reading state information... Done The following extra packages will be installed:   apache2-data Suggested packages:   apache2-doc apache2-suexec-pristine apache2-suexec-custom apache2-utils The following NEW packages will be installed:   apache2 apache2-data 0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded. Need to get 250 kB of archives. After this operation, 1,194 kB of additional disk space will be used. Do you want to continue? [Y/n] y WARNING: The following packages cannot be authenticated!   apache2-data apache2 Install these packages without verification? [y/N] y Err http://archive.ubuntu.com/ubuntu/ utopic-security/main apache2-data all 2.4.10-1ubuntu1.1   404  Not Found [IP: 91.189.91.13 80] Err http://archive.ubuntu.com/ubuntu/ utopic-security/main apache2 i386 2.4.10-1ubuntu1.1   404  Not Found [IP: 91.189.91.13 80] E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/a/apache2/apache2-data_2.4.10-1ubuntu1.1_all.deb  404  Not Found [IP: 91.189.91.13 80]  E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/a/apache2/apache2_2.4.10-1ubuntu1.1_i386.deb  404  Not Found [IP: 91.189.91.13 80]  E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? chumpen@chumpen-Lenovo-G480:~$


Explain the following JavaScript statement?

var ninja = (function(){     function Ninja(){};     return new Ninja(); })();   Why is the function above encapsulated in parentheses and why is there a (); at the end?  I think it's a constructor function because of the (); at the end, but why is the object wrapped in parentheses?


"I found that, on average, there are...." or "I found, on average, that there are..."?

So if you couldn't figure out the question from the title, does the subordinating conjunction (the word "that") precede or succeed the extra information between the commas?


This question arose while reading Velleman's How to Prove It in section 2.3. For context, the definition of ∩F is { x |∀A ∈F(x ∈ A)}={ x |∀A(A ∈F → x ∈ A)} and ∪F is { x |∃A ∈F(x ∈ A)}={ x |∃A(A ∈F∧x ∈ A)}. F is a family of sets.  The question, however, doesn't have much to do with these definitions than it does with the title and a more generalized issue of these two statements when used with respect to sets. Why is the definition for ∩F defined as ∀A(A ∈F → x ∈ A) but not ∀A(A ∈F∧x ∈ A)? Aren't they both saying checking for the same conditions: that A belongs to F and x belongs to A?   I understand why they aren't the same by transforming the definition for ∩F into a logical statement:  ∀A(A does not belong to F or x belongs to A), which is obviously different than ∀A(A ∈F∧x ∈ A).     I suppose I just need some convincing in some way other than a logical statement.


Why are negative counts in the achievement dialog sometimes shown, but not always?

Close voters:   does not address the question "When are negative counts in the achievement dialog supposed to be shown in the top row?  They are shown sometimes, but not always."  Negative counts aren't shown in the achievement dialog's top row:  - Update: sometimes, negative counts are shown in the achievement dialog's top row:  so the behavior seems inconsistent. When are negative counts in the achievement dialog supposed to be shown in the top row?


Null Pointer Exception in creating an instance

I have an exception and I don't know how to solve it.  Person a = new Person(); Scanner in = new Scanner(System.in); System.out.println("Please type name: "); String name = in.nextLine();   It says there's an exception in the first line. The following code is the default constructor.  Person(){          this.name = "No_Name";          this.surname = "No_Surname";          this.number = "No_Number";          this.personalCode = "No_personalCode";          this.dateOfBirth.set(Calendar.DAY_OF_MONTH, 1);          this.dateOfBirth.set(Calendar.MONTH, Calendar.JANUARY);          this.dateOfBirth.set(Calendar.YEAR, 1900);      }   Class person full code:  import java.util.Calendar; public class Person {      String name;      String surname;      private String number;      private String personalCode;      private Calendar dateOfBirth;         Person(){          this.name = "No_Name";          this.surname = "No_Surname";          this.number = "No_Number";          this.personalCode = "No_personalCode";          this.dateOfBirth.set(Calendar.DAY_OF_MONTH, 1);          this.dateOfBirth.set(Calendar.MONTH, Calendar.JANUARY);          this.dateOfBirth.set(Calendar.YEAR, 1900);      }      Person(String name,String surname,String number,String personalCode,Calendar dateOfBirth){          this.name = name;          this.surname = surname;          this.number = number;          this.personalCode = personalCode;          this.dateOfBirth = (Calendar) dateOfBirth.clone();       }       Person setName(Person a, String name) {          a.name = name;          return a;      }      Person setSurname(Person a, String surname) {          a.surname = surname;          return a;      }      Person setNumber(Person a, String number) {          a.number = number;          return a;      }     Person setpersonalCode(Person a, String personalCode) {         a.personalCode = personalCode;         return a;     }      String getName(Person a) {         return a.name;     }     String getSurname(Person a) {         return a.surname;     }     String getNumber(Person a) {         return a.number;     }     String getPersonalCode(Person a) {         return a.personalCode;     }     Calendar getDateOfBirth(Person a) {         return a.dateOfBirth;     } }


I use yakuake as drop-down-terminal in Ubuntu 16.04. Whenever I click on a link on the console to open it in browser, it opens in the default kde-browser webbrowser-app. I tried to uninstall webbrowser-app, but that would uninstall those packages too: libunity-webapps0 unity-tweak-tool unity-webapps-common unity-webapps-service webapp-container         I am not sure, if I still need them. How do I change the default browser in yakuake?


Close a selectbox when clicking outside of it

I've created a cool select box in Angularjs , all the codes works fine with no problem , the only problem that I'm facing with no luck to solve it is this :   Let say below is my select box markup :
     Title    <input type="text" ng-model="q">

{{r}}

   So far it works and and when I click on this div or any child of it ( lets say that title element) , the ul will toggle show and hide.  Problem :   When I click outside of this div ( anywhere outside ) I want this select box to be closed ( isOpen=false) , I know that I have to catch the document.click event and do something with that , but I'm not sure how to use it.


Is a keyring necessary for programs to store passwords?

I just downloaded Ubuntu 13.04 earlier and was trying it out.  At least I know you can surf all installed applications with the dash home if you click the icons at the bottom, you're not forced to memorize all the names of everything.  Anyway...  I'm used to Windows, where programs have their own ways of storing passwords--and they do, and I've never had a hard time.  It makes me comfortable.  I'm very *un*comfortable with the idea of something storing pretty much ALL my passwords, I prefer them to be separate entities.  Is a keyring really necessary for programs like Chrome and Firefox?  Can I just disable the keyring altogether and still have Chrome remember my passwords, or when I use Ubuntu, will I forever have to type a password for it to automatically type a password?  To me, typing a password so I don't have to type a password just doesn't make any sense.  I'm confused.  I never remember having to do this when I installed Linux before.  And yes, I have the login password the same as the keyring password but I still have to log into both each time.


Questions got serial down-votes, revenge?

While I'm reviewing my profile, I did notice a strange behavior especially on my 0 votes questions:     As you can note here, 4 votes down on the 4 so different questions in 1 minutes, that target my 0 votes questions to be -1 fo all, which this is an annoying part here!  I don't really bother myself with this, but still, I want to understand how to prevent that or report that.  I tried to find a question similar to this, but I found nothing talking about this case exactly, (or I was searching for incorrect words).  Any explanation and how to report this? Especially that down caster seems smart guy trying to avoid the auto-detect system of stack overflow system.


Example where schema are better than multiple databases

In several database systems (e.g., PostgreSQL and MS SQL Server) there is a concept of schema. There are many questions out there asking what schema are and how they are used; here is a . Usually the answer boils down to "namespace" and "permissions". However, what remains unclear to me is why a schema has any advantage over just adding a new database. A different database allows one to have both separate namespaces and permission assignments.  Can someone provide an example in PostgreSQL where multiple schema in a single database provide an advantage over multiple databases without schema? From a purely organizational perspective they appear equivalent.


Parallel Universe Moving Backwards in time

We know that different parallel universes- if they truly exist - are governed by different sets of laws. But, Could there be a parallel universe that is moving back in time(?) - in different direction the flow of time in our universe?


Is there a way to determine if an recipient email address is invalid

With the mailing application I'm working on, I catch SendFailedException to handle validation of recipient email addresses. After reading a bit more though, I learned that catch blocks are quite expensive. It made me wonder if there was any way to determine if an address is invalid before the message is sent. This is more of an optimization problem of sorts.


Prove there is no simple group of order $729$

Let G be a group of order $729$.   $729 = 3^6$ so by Sylow's Theorem G has a Sylow $3$-subgroup of order $729$. And there are $x$ of them. $r \equiv 1 \pmod 3$ and $r\ |\ 1$. So $x=1$? Is this correct?


1. You roll five fair, six-sided dice. What is the probability that the sum of the five dice is 20?

I know we can try and count the number of ways that they can add to 20, however this is much easier when there is only 2 or 3 dice. I believe there is a way to do this using combinations but I am not sure. I thought it was a stars and bars, so I wrote out  20 like -> 1 + 1 + 1 + 1 |+ 1 + 1 + 1 + 1| + 1 + 1 + 1 + 1 + 1 + 1 |+ 1 + 1 + 1 |+ 1 + 1 + 1  Which makes a 20 choose 4, however, this is over counting as each block of 1's can't be greater than 6 or less than 1.   Thanks for your help


Case assignment rule is always executed in the test class

No matter what to do, the case is always assigned by the assignment rule!!  You can try the scenario and code which are attached in the post.  But, I have tried to execute the code in the developer console, and it is ok.  The whole test scenario is as below:  [Case assignment rule] <== only 1 rule for testing  Criteria:  ISPICKVAL(Type, 'Other')   Assign to:  Case default queue   [Testing class]  @isTest(SeeAllData=true) private class TestCases {   static testMethod void unitTest01() {     Case caCheck;     Case c = new Case();     c.Type = 'Other';     insert c;     caCheck = [ SELECT Id,Owner.Name FROM Case WHERE Id =: c.Id ];     System.assertEquals(caCheck.Owner.Name, Userinfo.getName()); // Owner is changed to 'Case default queue'   }   static testMethod void unitTest02() {     Case caCheck;     Case c = new Case();     c.Type = 'Other';     Database.DMLOptions dmo = new Database.DMLOptions();     dmo.assignmentRuleHeader.useDefaultRule= false;     c.setOptions(dmo);     insert c;     caCheck = [ SELECT Id,Owner.Name FROM Case WHERE Id =: c.Id ];     System.assertEquals(caCheck.Owner.Name, Userinfo.getName()); // Owner is changed to 'Case default queue'    } }   [Testing result]  2 errors:  1.  System.AssertException: Assertion Failed: Expected: Case default queue, Actual: Cray Kao Class.TestCases.unitTest01: line 9, column 1     2.  System.AssertException: Assertion Failed: Expected: Case default queue, Actual: Cray Kao Class.TestCases.unitTest02: line 20, column 1


How do I read the first line of a string?

my_string = """This is my first line, this is my second line, and...  ...this is my fourth line!"""   How can I store the first line of that (This is my first line,) into a separate string? I attempted to use .readline() from another similar question, however I get this error:  AttributeError: 'str' object has no attribute 'readline'


list of figures space after figure name?

I am using a template to write my  thesis and I got something like that which is shown in the image when it automatically generates list of figures. How can I fix that? I am also enclosing the part which I believe is the source of problem in the class file.    \newcommand\listoffigures{% \if@twocolumn   \@restonecoltrue\onecolumn \else   \@restonecolfalse \fi \chapter{\listfigurename}% \vspace{10pt}   \@mkboth{\MakeUppercase\listfigurename}%           {\MakeUppercase\listfigurename}% \@starttoc{lof}% \if@restonecol\twocolumn\fi }   All the packages I use is:  \usepackage{subfigure} \usepackage{graphicx} \usepackage{epsfig} \usepackage{amsmath} \usepackage{amsfonts} \usepackage{verbatim} \usepackage{array}  \usepackage{setspace} \usepackage{balance} \usepackage{picins} \usepackage{eqparbox} \usepackage[export]{adjustbox}   There is also something defined like this on the beginning of the latex class file that I am using.    \def\ext@figure{lof}   Please show me which parts do I need to change in order to give some space between figure names and the explanations? I am good at programming but no clue about latex at all. Please state which parts do I need to change clearly.  A working example of the template for thesis can be downloaded from below:    (I have edited the post according to the comments)  Thanks


Is it true that $\sum_{n = 0}^\infty \frac{a_n}{n}$ is also convergent?

Let $\{a_n\}_{n = 0}^\infty$ be a sequence of real numbers such that the series $\sum_\limits{n = 0}^\infty |a_n|^2$ is convergent.  Is it true that $\sum_\limits{n = 0}^\infty \dfrac{a_n}{n}$ is also convergent?  My try:  Since $\sum_\limits{n = 0}^\infty |a_n|^2$ is convergent,   $$\begin{align}\lim_\limits{n\to \infty} |a_n|^2=0 &\implies \forall \epsilon >0 \quad \exists N\in \mathbb N \quad \forall n>N \quad|a_n|^2<\epsilon \\ &\implies \forall n>N \quad |a_n|<\sqrt \epsilon \\ &\implies -\sqrt\epsilon<a_n<\sqrt \epsilon  \end{align}$$  Hence $\lim _\limits{n\to \infty} \dfrac{a_n}{n}=0$.  Now $S_n=\sum_\limits{i=1}^n \dfrac{a_i}{n}\implies |S_n|\leq \sum_\limits{i=1}^n \dfrac{|a_i|}{n}\leq \sum _{i=1}^n |a_i|$.  Am I heading in the right way or there is any counter-example? How to complete the proof from here?  Please help.


Show that an inequality is true using mathematical induction and the mean value theorem

A question in my math book is: "Use mathematical induction to show that:  $$e^x>1+x+\frac{x^2}{2!}+...+\frac{x^n}{n!}$$  if $x>0$ and $n$ is any positive integer."  Apparently the solution involves applying the Mean Value Theorem on:  $$g(t)=e^t-1-t-\frac{t^2}{2!}-...-\frac{t^{k+1}}{(k+1)!}$$  Then:   $$\frac{g(x)}{x}=\frac{g(x)-g(0)}{x-0}=g'(c)$$  Then it states that $g'(c)$ is positive.  QUESTION 1: why is $g'(c)$ positive?  QUESTION 2: how would one answer (in small understandable steps) the original question of my math book? I don't fully understand the method used.  Thanks!


My laptop has a slightly obscure wifi card and I can't install a driver from the driver management or the USB, and I don't have ethernet. Instead, I found a driver online and it worked on a Live USB because I could install gcc from the USB. However, when I actually installed the OS, I could not start the driver or install gcc!  So, how do I install gcc from a USB or ISO in Kubuntu 15.10.  EDIT:  Another solution I'm open to is to download the packages outside of Kubuntu and then use dpkg -i to install them. In that case I would need someone to list the needed packages and where to download them.


When a battery is your power source, what is ground?

For the sake of not incorrectly connecting my power supply and damaging my board I'm going to ask a relatively dumb question. Is ground on my board the negative terminal on my battery? Explicitly should I connect the ground to the negative terminal of the battery?


Error Updating: izx/askubuntu/ubuntu xenial Release' does not have a Release file

I am performing an update and its failing on the following:  The repository 'http://ppa.launchpad.net/izx/askubuntu/ubuntu xenial Release' does not have a Release file..   Running a local Ubuntu server 16.04


Does the derivative of a continuous function goes to zero if the function converges to it?

Physicist here. I am puzzled by a question: looking at a continuous function $g :\mathbb{R} \rightarrow \mathbb{R}$ that goes to zero at infinity, I am interested in the behavior of its derivative $\beta = g'$. Precisely, does it go to zero too? By writing on paper it looks like: $$ \beta(+ \infty)=\text{lim}_{x\rightarrow \infty}\text{lim}_{h\rightarrow 0} \frac{g(x+h)-g(x)}{h}$$ And if I can invert the two limits, I get what I expect: $\beta(+\infty)=0$, so I was curious about the hypothesis behind this permutation. Is the requirement of continuity enough? Thanks.


Is the possessive of "one" spelled "ones" or "one's"?

I've been confused about this as long as I can remember. Should it be:     One should do ones duty.   or     One should do one's duty.   I'm guessing it should be the latter. But that doesn't sit well with the possessive pronoun 'its'. For example:     It is its own purpose.   vs.     It is it's own purpose.   Here, the former seems clearly correct.


My questions concerns a chapter in Michael Spivak's math book Calculus. On page 81, Spivak talks about finding a coordinate axes for a plane P that intersects a cone. What I don't understand is the part where he talks about a point in that plane having a certain first coordinate with respect to the newly created axes; he labels this as x. This same point has αx+β its first coordinate relative to the standard axes with which we are familiar. I don't understand where he got the αx+β. I really hope someone clears this up for me. Here is a quote from that page dealing with conic sections: "Now we have to choose coordinate axes in the plane P. We can choose L as the first axis, measuring distances from the intersection Q with the horizontal plane (Figure 5); for the second axis we just choose the line through Q parallel to our original second axis. If the first coordinate of a point in P with respect to these axes is x, then the first coordinate of this point with respect to the original axes can be written in the form αx+β for some β. On the other hand, if the second coordinate of the point with respect to these axes is y, then y is also the second coordinate with respect to the original axes."


Does a filament of lamp still have resistance when no current flows, and if yes, why?

Does a filament lamp still have resistance when no current flows?


I am trying to see if I can have a specific Hosts file that only a Proxy Server application on my machine will use while the remainder of the machine uses the normal proxy server.  For example, I want to take (and this is JUST AN EXAMPLE) www.cnn.com and map it to 127.0.0.1. However, I only want this to happen when connected to a proxy server application running on my machine.  Then I would configure Firefox to use the Proxy Server while IE doesn't use the Proxy server.  Could I use something like Fiddler, Charles, or some other Proxy/Debugger and have only that application use a custom Hosts file?  Why? This allows me to compare the live web site with what I have developed locally. Trust me, I need the host name mapping for a reason. I'm using HTML from the live site with local CSS changes. I need to compare those CSS changes to what is in Production environment.


Contents in pdf reader use a "greeklish" display when writing greek

I am creating a greek document using package babel. The main problem is that the contents the pdf viewer creates are not displayed in greek, but in "greeklish".  Okular    Adobe Reader    At first I thought that it was Okular's issue but I get the same behaviour on adobe reader and adobe acrobat, so I don't think that has to do with the reader.  My TeXLive version is TeX 3.14159265 and I am using pdfLatex.  A simple code is  \documentclass[11pt,a4paper]{book}  \usepackage[english,greek]{babel} %\usepackage[utf8]{inputenc} \usepackage[iso-8859-7]{inputenc} \usepackage{kerkis} \usepackage[pdfencoding=auto]{hyperref} %\usepackage[unicode]{hyperref} \usepackage{bookmark}  \begin{document}  \tableofcontents  \chapter{Περίληψη} %  \begin{otherlanguage}{greek} % \addchap{\texorpdfstring{Per'ilhyh}{Περίληψη}} % Per'ilhyh % \end{otherlanguage}   \section{Πρώτη Ενότητα}   \section{Δεύτερη Ενότητα}  \chapter{Δεύτερο Κεφάλαιο}   \section{Πρώτη Ενότητα}   \section{Δεύτερη Ενότητα}  \chapter{Τρίτο Κεφάλαιο}   \section{Πρώτη Ενότητα}   \section{Δεύτερη Ενότητα} \end{document}   I've tried to use options unicode or pdfencoding=auto to the hyperref package, but without any luck. I've also changed the encoding from iso-8859-7 to utf8 but I get an error     ! Argument of \UTFviii@three@octets has an extra }.   &lt;inserted text&gt;                    \par    l.13  \chapter{��������}         Runaway argument?   Any idea why is this happening and how to fix it?


Why is the write command not working with a generated string vs pre-generated string?

The issue I'm having is that when I write a pre-generated list of strings using the .write() function, it works without an issue, but when I try to generate a list of numbers as strings and use .write() with them, it says I cant use a list and that it must be a string. import csv def makeFile():     fileName = "m11prog2.csv"     outputData = ['#ENG101-04 Module 11, Program 2\n', 'Noah Sickels\n', '\n', 'x,x^2\n']     newData = []     with open(fileName, 'w') as f:         for i in range(1, 1001):              #dataStr = f'{i}, {i**2}\n'             dataStr = ''+str(i)+','+str(i**2)+'\n'             newData.append(dataStr)         outputData.append(newData)         for data in outputData:             f.write(data)  What I don't understand is why the .write() is letting me write the first list 'outputData' to the file, but not the newData to the file, when they are the same type of list.


Are there any effect of Sun to the tide?

The Earth is rotating for the Sun's gravitational field. Like a free falling object Earth should feel zero gravity to the Sun. So why there are effect of Sun to the tide?


What is the identity of in - "after" or "within"?

This is really controversial in a lot of countries where English is not a native language. I will be there in 5 minutes. Identity A: I will be there after 5 minutes. Identity B: I will be there within 5 minutes. or "in" is different from A or B and has its own something (like nuance difference) ?


Using rc.local to start server and then launch web-application?

I'm running into issues when I try to start a server via Python program, and then open its web-app. I'm not able to get it to open the server and then also open the web-application.  I tried to modify rc.local to the following before exit 0:  sudo python /home/pi/Program/program.py & sudo bash chromium-browser --kiosk https://127.0.0.1:8081/   I also tried to use bashrc to do this, but while I was able to run server on bootup with rc.local, I wasn't able to run it with bashrc on bootup. Only once I run LXTerminal was it able to open the server. On rc.local, the opposite problem. Can run server but not browser.  I am able to boot the python program on its own, and the webpage on its own (but obviously it gives address not found, since there is no server), but not the two together.   I tried to modify rc local to bin/sh -e but this didn't work still.   I am running Rasbian Os.  I am unable to work with what was said in the post that was suppose to answer my question. The answer only tells you what you should be doing, which is what I already know, start the browser after GUI, but it doesn't tell me how to do it. It also doesn't solve my problem of the server having to be up and running before I start the browser. May I also mention how I tried many methods but none of them worked... I tried to edit autostart as well bashrc.


how to run command line python scripts within my code

there are some scripts that you have to run them from command line like   python run.py -u alex__a -p 123 -v -f  I want to work with them inside my code I don't know whats the name of them so I wasn't able to google about my question . sorry if it't so simple


Why does blender erase transforms after inserting a keyframe?

I have a default cube. I would like to animate it. For example I would like to make it rotate around the Y axis. I add a rotation keyframe (I) at frame 0 and at the last frame I add another rotation keyframe. Then, I set the yellow Transform Rotation Y field to 180°.  And instantly, 180° rotation disappears and no rotation occurs when playing animation. Why does Blender erase the keyframe settings? And how should I make this work properly?  In fact, I am trying to go trough  and my object doesn't behave in the mentioned way. When I move/rotate/scale my cube, the F-Curves are not updated. What I might be doing wrong?


How can i share ubuntu's intertet to iphone via USB

Can anyone help me reverse tethering from linux to iphone 5.


when I was doing c program in Ubuntu 12.04 , there is a font configuration warning shown by terminal. What should I do?  shayna@shayna-Vostro-3446:~$ gedit hello6.c Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-garuda-synthetic.conf", line 9: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-garuda-synthetic.conf", line 21: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-kinnari-synthetic.conf", line 9: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-kinnari-synthetic.conf", line 21: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-loma-synthetic.conf", line 12: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-umpush-synthetic.conf", line 9: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/89-tlwg-umpush-synthetic.conf", line 21: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 9: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 22: Having multiple <family> in <alias> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 22: Having multiple <family> in <alias> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 22: Having multiple <family> in <alias> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 26: Having multiple <family> in <alias> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 31: Having multiple values in <test> isn't supported and may not works as expected Fontconfig warning: "/etc/fonts/conf.d/90-fonts-nanum.conf", line 40: Having multiple values in <test> isn't supported and may not works as expected shayna@shayna-Vostro-3446:~$ gcc hello6.c -o hello6 shayna@shayna-Vostro-3446:~$ ./hello6 shayna@shayna-Vostro-3446:~$


Return value of member function using "this"

In the following class definition:  #include<iostream>   class Test  {  private:    int x;    int y;   public:    Test(int x = 0, int y = 0) { this->x = x; this->y = y; }    Test &setX(int a) { x = a; return *this; }    Test &setY(int b) { y = b; return *this; }    void print() { cout << "x = " << x << " y = " << y << endl; }   };    I don't understand why we should put an * in front of this in the setX or setY functions. I know this is a pointer to the current object and the * returns the pointed object, but since there is a & in the functions' return values, which means that the function returns a reference to a Test object. Then, shouldn't the return variable also be a reference (that is a pointer), like this:  Test &setX(int a) { x = a; return this; }   ?  As an alternative, I believe  Test setX(int a) { x = a; return *this; }   would also be correct because the return value is not a pointer, but the pointed object, which of type Test (and not of type pointer to Test: Test&).  Why, if it's the case, are they not correct?


how to find information about not installed packages

I am very curious to know how it would be possible to find the name of a particular program installer package (before installing the program itself)  based on the subject my interest and the way to obtain information about it via the command line.  The only link that I have found is , and it would not work in Ubuntu.  Would you help me discover how to find for example the packages that install music players?


So now when the new Lollipop is on it's way we all have our feeds filled with magazines or sites telling us how awesome LG or Samsung is to release Lollipop so soon.  My question is,  Why is this such a hard thing to do?  How come it's much easier to switch from Windows to Linux on a PC? Or even switch hardware product and download a driver? Why aren't the drivers or hardware products in our phones compatible with every operating system or phone model just like a PC?  Okay, screen sizes may differ, but a vibrator will still work as a vibrator.  YElp!


error no such partition. Grub rescue mode

I want to remove the ubuntu operating system from my laptop so I formatted the ubuntu drive (previously had dual booting)  But now I run in grub rescue mode. I checked the other forums and tried the set root and set prefix with all the drives but it still shows file system not found.   Can someone help me so that I can normally boot my win 8.1 which is already loaded ?


I am looking for an adjective, similar to "holding a grudge"

I am looking for an adjective that describes a person who is not willing to forgive or excuse someone's faults or wrong-doings from the past (other than "unforgiving"). For the ones who speak German, that word would be "nachtragend".


How can I track a bug that caused a crash and was reported via apport / whoopsie?

It used to be that when a program crashed, especially when a user was using a pre-release of Ubuntu, apport could be used to open a bug report.  The user could then track the bug, see if it affected others, help fix it, etc.  As of Precise 12.04, this behavior and workflow changed.  As I discovered in , by default apport no longer opens a bug report (and it is awkward but not impossible to get it to do so).  At the same time people are noticing a new "whoopsie" process, as described at .  After some more googling, I dug this blueprint up, which describes the whole process: .  (It didn't mention whoopsie or daisy, so I added them - please correct me if I got it wrong).  Wow - this sounds like great work to streamline and improve the crash reporting process.    I'm left with this question: how does a user learn what the status of the problem is? The blueprint now has this requirement     The user should have some way to check back on the status of their crash report; e.g. have some report ID they can look at to see statistics and/or any associated bug #. E.g. provide a serial number at time of filing that they can load via a web page later on.   which seems unimplemented.  Is there anything available in the meantime?  And how does a developer get into the game?  Going to  just provides an "Incorrect Content-Type" error message.  Finally, I suggest documenting the apport behavior changes in the Release Notes.  It should be of interest to anyone who has been trying to help out Ubuntu.


How does a battery ( primary cell ) work?

I'm having an hard time understanding primary cells. There are plenty of videos and explanations about the reactions that happen inside the battery, but you must have a strong background in chemistry to really understand them. Instead, I would love to have a description that abstracts from the chemicals details, and still manages to explain its basic working princeples! I would like it to address the following questions/doubts:     Electrons flow form higher potential to lower potential so, when you buy a  battery, is an electric field already there, before connecting it to a wire? (I presume yes) So,How is this field created? Are the electrons at the top and the protons at  the bottom, or just electrons at the top and the bottom is neutral? How are electrons kept together in the same place before connecting the battery  to the wire? What does prevent them to flow inside the battery? How does the battery pump up the electrons? and at which rate? What makes it burn out? and after many cycles does it burn out?       I know there are a lot of questions but my mind is exploding. I don't expect everything to be abstracted from the chemicals but as long as you can through analogies, or intuitive principles, i'd love that. Anyway the main intent of the answer must be addressing the doubts listed.


I'm trying to make this test method work.      //test @isTest  private class CoreValuesExtTestClass {     static testMethod void validateCoreValues() {        Core_Values__c cv = new Core_Values__c(Account__c='6', HSE__c='6', Professionalism_Integrity__c='6', Quality_Accuracy__c='6', Technology_Innovation__c='6', Value_for_Money__c='6', Timeliness__c='6');        System.debug(cv.Account__c + cv.HSE__c + cv.Professionalism_Integrity__c + cv.Quality_Accuracy__c + cv.Technology_Innovation__c + cv.Value_for_Money__c + cv.Timeliness__c);         // Insert book        insert cv;         // Retrieve the new book        cv = [SELECT Account__c, HSE__c,Professionalism_Integrity__c,Quality_Accuracy__c,Technology_Innovation__c,Value_for_Money__c,Timeliness__c FROM Core_Values__c WHERE Id =:cv.Id];        System.debug(cv.Account__c + cv.HSE__c + cv.Professionalism_Integrity__c + cv.Quality_Accuracy__c + cv.Technology_Innovation__c + cv.Value_for_Money__c + cv.Timeliness__c);         // Test that the trigger correctly updated the price        System.assertEquals('6', cv.Account__c);        System.assertEquals('6', cv.HSE__c);        System.assertEquals('6', cv.Professionalism_Integrity__c);        System.assertEquals('6', cv.Quality_Accuracy__c);        System.assertEquals('6', cv.Technology_Innovation__c);        System.assertEquals('6', cv.Value_for_Money__c);        System.assertEquals('6', cv.Timeliness__c);     } }   for this class  public class CoreValuesExt {     ApexPages.StandardController sc;     public boolean readonly {get; set;}     public Core_Values__c cv {get; set;}     public integer countEdit = 1;     public string buttonValue {get; set;}     public integer recordScan;      public CoreValuesExt(ApexPages.StandardController sc)     {         this.sc = sc;         cv = new Core_Values__c();         cv.Account__c = sc.getid();          readonly = true;         buttonValue = 'Edit';         recordScan = [SELECT COUNT() FROM Core_Values__c WHERE Account__c = :cv.Account__c];        if (recordScan != 0){        cv = [SELECT id, HSE__c, Professionalism_Integrity__c, Quality_Accuracy__c, Technology_Innovation__c, Timeliness__c, Value_for_money__c FROM Core_Values__c WHERE Account__c = :cv.Account__c];         }      }      public ApexPages.PageReference Save()     {         return sc.Save();     }      public void ApplyAction()     {         countEdit++;         Integer modolus = Math.mod(countEdit, 2);         String total = cv.HSE__c + cv.Professionalism_Integrity__c + cv.Quality_Accuracy__c + cv.Technology_Innovation__c + cv.Value_for_Money__c + cv.Timeliness__c;         if(modolus == 0)         {             readonly = false;             buttonValue = 'Save';         }         else         {             if(total != 'nullnullnullnullnullnull')                {             if (recordScan == 0){             insert cv;             readonly = true;             buttonValue = 'Edit';             }             else             {             update cv;             readonly = true;             buttonValue = 'Edit';             }             }         }        } }   Unfortunately, the tests pass nothing, how do I make this work. Any help would be appreciated, thanks


I'm using SharePoint Online modern UI.  And, I want to hide Quick edit, Sync, Export to Excel, PowerApps, Automate from my site.  Please check below picture.   Could you tell me how to hide that menu?


Finding solutions to equation of the form $1+x+x^{2} + \cdots + x^{m} = y^{n}$

Exercise $12$ in Section $1.6$ of Nathanson's : Methods in Number Theory book has the following question.         When is the sum of a geometric progression equal to a power? Equivalently, what are the solutions of the exponential diophantine equation $$1+x+x^{2}+ \cdots +x^{m} = y^{n} \qquad \cdots \ (1)$$ in integers $x,m,n,y$ greater than $2$? Check that    \begin{align*} 1 + 3 + 3^{2} + 3^{3} + 3^{4} & = 11^{2}, \\\ 1 + 7 + 7^{2} + 7^{3} &= 20^{2}, \\\ 1 + 18 +18^{2} &= 7^{3}. \end{align*}   These are the only known solutions of $(1)$.      The  doesn't reveal much about the above question. My question here would be to ask the following:   Are there any other known solutions to the above equation. Can we conjecture that this equation can have only finitely many solutions?   Added: Alright. I had posted this question on  some time after I had posed here. This user by name  had actually given me a link which tells more about this particular question. Here is the link:


Images in reopen review (side-by-side view) are larger than column width

I was reviewing  and noticed that the side-by-side view is rendered incorrectly.   The images are too large, the one in the left column overlaps with the right column and the one in the right column extends into the sidebar.    This behaviour has been confirmed in Firefox and Chromium browsers by me and various other users.  It's probably caused by these not matching styles:  #revisions .sidebyside-diff > div {     width: 330px !important; }  #revisions .sidebyside-diff > div img {     max-width: 410px; }


I'm using the circuitikz library to draw some circuits. To connect two nodes with a square angle, there is the possibility to use |-, as in the MWE below for the connection of (a) with (b). However, sometimes I don't like the way circuitikz connects the nodes (e.g. it sometimes draws line overlapping with other lines in large circuits), so in some cases I'd like to specify the coordinates where the square angles are inserted (e.g. sometimes I'd like to have two right angles as in MWE 2) or I want to insert a circle at a particular node and so on.  In the MWE, node (a) is connected with nodes (b), (c), (d) and (e).   The connection with (b) is fine. For the connection with (c), I've inserted a circle, and the line after the circle doesn't start immediately at the circle but with some horizontal space inbetween. Same problem with node (d), but without the circle. Finally, I wanted to connect (a) with (e) by going further up (to (0,5)) and then from there to the right and down to (e). However, this isn't working properly either.   Any ideas how I can solve at least some of these problems?  \documentclass{article} \usepackage{tikz} \usetikzlibrary{positioning} \usepackage[european]{circuitikz}  \begin{document}  \begin{circuitikz} \draw  (0,0) node (a){a} (1,1) node (b) {b} (2,2) node (c) {c} (3,3) node (d) {d} (3,4) node (e) {e}  (0,2) node (crossa) {} (0,3) node (crossa2) {} (0,5) node (crossa3) {}  (a) |- (b) (a) to[short, -*] (crossa) (crossa) -- (c) (a) -- (crossa2) |- (d) (a) -- (crossa3) |- (e)  ;\end{circuitikz} \end{document}


Can't install/uninstall packages in Debian

I'm trying to install/uninstall packages in Debian but getting errors.    I can't remove or add any package, always getting the error.   I tried:  apt-get --remove purge package apg-get remove package dpkg -r package


Expression Functions for Lightning Web Components

How can expression functions similar to Visualforce and Lightning Aura Components be achieved within lightning web components?   For example, <template if:true={index % 5 == 0}>
</template> expression index % 5 == 0 is not compyling at all.  accountList.html  <template>     <template if:true={accounts.data}>         <template for:each={accounts.data} for:item='item' for:index='index'>                                       {item}         </template>     </template> </template>   accountList.js  import {LightningElement, wire} from 'lwc'; import getAccounts from '@salesforce/apex/TestController.getAccounts';  export default class AccountList extends LightningElement {      @wire(getAccounts) accounts;  }   Since LWC doesn't support Expression Functions, I'd like to know how to implement them.


My understanding of colour is that atoms in a particular object will absorb certain wavelengths of electromagnetic radiation, and the scattered wavelengths give the object its colour. The absorbed wavelengths contribute to lattice vibrations, increasing the kinetic energy and raising the objects temperature. Is this correct?  What is the sequence of events when a solution of particular atoms is sprayed through a Bunsen burner? I don't understand this. In this case is the colour seen a result of electrons moving up and then back down energy levels?


Why does the experience-to-next-level not change between some levels?

At every level from 1st to 11th, the experience needed to reach the next level (from the current level) increases every level. However, this pattern gets broken for most of the later levels:   Going from 10th to 11th takes 21,000xp (= 85k - 64k), but 11th to 12th takes only 15,000xp! (= 100k - 85k). Both 13th and 14th level only take extra 20k experience each, i.e. the amount needed doesn't increase between those two levels. Levels 16 and 17 similarly only need 30k experience each, and 18 and 19 only need 40k experience each.   Why does the last half of the experience chart have some of these levels maintain the same experience costs, and even briefly decrease the experience cost for 12th level?


I've been trying to master the croissant for the last 3 months, and right now I really want to have the honeycomb view inside of it. Unfortunately, this was the maximum that I have reached:  How to come to this point?  PS: Right now doing a recipe that I make a dough (flour, water, sugar, salt, yeast), put in the fridge. After 1h, laminate the dough, chill, laminate again. Let it overnight before final stretch and croissant shape. Let it rise for 2 hours before going to oven.


How do I become a 'Good Sport' and what rewards can I receive?

I received an in-game notification saying, "If you are a 'Good Sport' you will receive periodic rewards".  (see picture below)    How do I become a 'Good Sport & what rewards can I receive?  How often will I receive rewards?  I did get a notification when I accidentally blew up someone else's car, saying [something along the lines of]: "You blew up someones car.  You are a Poor Sport."  I also saw an in-game message that mentioned [something like] "If you are a Poor sport, you will play with other poor sports"


Does Sylvester Rank Inequality holds for a matrix over finite field?

Given $A$ and $B$ are matrices over finite field $\mathbb{Z}_p$ ($p$ is a prime number), does this statement holds ? $$\operatorname{rank} A + \operatorname{rank}B \leq \operatorname{rank} AB + n.$$


Should "discussion" tag gold badge holders be able to dupe-hammer questions on Meta?

This topic , but I observed it as an issue on main Meta as well.  Ordinarily, holders of gold tag badges have the privilege of "dupe-hammer" (binding VTC vote as a duplicate) on questions that have a tag they have the gold badge in.  The rationale for the privilege is that, for a subject matter tag, having a gold badge is indication of subject matter expertise, and thus likelihood that the holder is expert enough to figure out if something within said area of expertise is a duplicate.  However, this rationale breaks completely for  meta-tag on Meta sites. There are no "experts" in "discussion", as a subject matter topic, and therefore nobody is 5 times more qualified than an average VTC-privileged community member to decide whether something is a duplicate just because it is tagged as .


Ubuntu 18.04's installation/boot freezes

Story  A year ago, I got a new laptop ASUS TUF Gaming FX505, Windows 10 wasn't really easy to use so I switched so I decided to install Ubuntu 18.04 on it with a USB Key alongside of Windows 10. I had some various issues because the BIOS is not well suited for that kind of application, but it worked fine at the time.  This week, I ran into major issues and needed to re-install Ubuntu 18.04 because I'm not able to boot, (anyway, I was planning to re-install it because I had some issues) but now, the USB Key I used to install Ubuntu doesn't work anymore!  Issue  When trying to boot from the USB Key, it gives a terminal-like screen with four option,  Try Ubuntu, Install Ubuntu and some others options I don't remember. When I select one of thoses two options, it tries to boot from the USB Key, at this point, it either freezes like that:  Or if I selected the Try Ubuntu option, I get a frozen desktop, but the mouse is free. Or if I selected the Install Ubuntu option, I get a frozen desktop again but with the download Ubuntu dialog box, empty, there is just the language selection visible, oh and everything is frozen of course! But the mouse is free.  Now, to shut-off Ubuntu, it also doesn't work! I'm forced to do a long push on the power button to turn off Ubuntu.  So, I can't run any command in the Terminal.  Remember that it worked a year ago but not now!  What I tried to do  • I downloaded a new .iso of Ubuntu 18.04 and used Startup Disk Creator (on another PC) on the USB Key that used to work. Unfortunately, it didn't worked. • Then I did it on a better USB Key. And got the same issue. • Eventually, I tried on another computer, and it was working, there was no issues like that. I guess which my computer doesn't like Ubuntu... • I looked on Internet and found some solutions, but some needed to press the Shift key but when I do that, it does absolutely nothing, and pressing Esc just switches between the boot screen or the boot terminal where I can't input any command. So no solution found on any other posts. • I tried to boot with nomodeset but I can't even get the Live session.  Computer Specs  ASUS TUF Gaming FX505, laptop including:   An Intel Core i7 8750H CPU (6 cores for 12 threads at 2200MHz) A NVIDIA GeForce GTX 10-Series GPU 8GiB of memory A 1TB HDD on and a 256GB SSD   Credits: The image above was took from this post: .


If a ring element is right-invertible, but not left-invertible, then it has infinitely many right-inverses.

Let $A$ be a ring and $a\in A$ an element that has a right-inverse but does not have a left-inverse. Show that $a$ has infinitely many right-inverses.


I have been unable to run apt get update command properly due to many errors that seem to suggest some repositories are unavailable. I tried 'apt-get clean' but it did not help. I have the following message (Ubuntu 18.04) Err:13 http://uk.archive.ubuntu.com/ubuntu bionic amd64 Contents (deb)                                           File has unexpected size (39528051 != 92769273). Mirror sync in progress? [IP: 2001:67c:1360:8001::23 80]   Hashes of expected file:    - Filesize:92769273 [weak]    - SHA256:5b4dd447bb35deb5a446cef9b30cbc78dde20bd58598bee8e9744c97c370e667    - SHA1:542e69afb40e026121a9d9ff31ed5649486d73cb [weak]    - MD5Sum:f1ffee77dbd97765067212ecec7a977a [weak]   Release file created at: Thu, 23 Jul 2020 07:19:14 +0000 Hit:16 http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic InRelease                                 Get:15 http://uk.archive.ubuntu.com/ubuntu bionic i386 Contents (deb) [56.1 MB]                                    Err:15 http://uk.archive.ubuntu.com/ubuntu bionic i386 Contents (deb)                                                 Err:17 https://cloud.r-project.org/bin/linux/ubuntu eoan-cran35/ Release                                             404  Not Found [IP: 2600:9000:2131:9000:6:c2d3:f940:93a1 443] Hit:18 http://ppa.launchpad.net/thopiekar/miraclecast/ubuntu bionic InRelease Hit:19 http://ppa.launchpad.net/ubuntuhandbook1/avidemux/ubuntu bionic InRelease Err:11 https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ InRelease   The following signatures were invalid: EXPKEYSIG 51716619E084DAB9 Michael Rutter <marutter@gmail.com> Reading package lists... Done  E: The repository 'https://cloud.r-project.org/bin/linux/ubuntu eoan-cran35/ Release' no longer has a Release file. N: Updating from such a repository can't be done securely, and is therefore disabled by default. N: See apt-secure(8) manpage for repository creation and user configuration details. W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/ InRelease: The following signatures were invalid: EXPKEYSIG 51716619E084DAB9 Michael Rutter <marutter@gmail.com>  Could I ask what I should do to fix this please?


What are all the invertible elements in $\mathbb{Z_m}$ for $m = 30$?

How can I know all of the invertible elements? Is it just all of the numbers that are relatively prime to 30?


When is the omission of relative pronouns acceptable?

So I learned that I tend to forget and unconsciously omit relative pronouns from my sentences, because apart from the fact that the meaning of some clauses without them remain clear and obvious, I find that relative pronouns make sentences superfluous. Instead of writing “the meat that are chilling in the freezer are spoiled”, I write “the meat chilling in the freezer are spoiled.” Or, “I believe it's true” instead of “I believe that it's true.” I find that many people do this, too. At first, I thought it's grammatically incorrect and is not acceptable in formal writing, but I recently came across a professional article that did the same thing. I'm just wondering whether it was a mistake or the editors deliberately left it that way because it's not really incorrect. So my question is, is the omission of relative pronouns acceptable? Or better yet, are relative pronouns always necessary?


Once I nest buttons within another element, I can no longer toggle to "hide" them using my previous CSS?

I have the following component:  <div aura:id="appr">     <ui:button aura:id="approveButton"  press="{!c.handleFirstPress}" label="Approve" /> </div> <div aura:id="subm" class="hide">     <ui:button aura:id="submitButton"  press="{!c.handleSecondPress}" class="hide" label="Submit" /> </div>   And javascript that utilizes the following CSS to toggle the buttons' visibility:  .THIS.hide { display: none !important; visibility: hidden !important; }  .THIS.show  { display: block !important; visibility: visible !important; }   Relevant Javascript:  handleFirstPress : function(cmp) {     var approveBtn = cmp.find("appr");     var submitBtn = cmp.find("subm");      $A.util.toggleClass(approveBtn, "hide");     $A.util.toggleClass(submitBtn, "show"); }   But when I wrap the component snippet in a another div, the CSS is no longer applied and the buttons remain visible even when I try to toggle their visibility.  <div class="foo" >      <div aura:id="appr">         <ui:button aura:id="approveButton"  press="{!c.handleFirstPress}" label="Approve" />     </div>     <div aura:id="subm" class="hide">         <ui:button aura:id="submitButton"  press="{!c.handleSecondPress}" class="hide" label="Submit" />     </div> </div>    Why does this happen?  Is it a lack in frontend knowledge, or lightning component related?  How can I solve it?  Thank you in advance!


I downloaded text editors (komodo, eclipse, sublime text, and medit). I opened the dash home but, they are in tar.gz format and are opening in archive managers as folders. How do I open them?  Thank you.


Is it possible to revise XYZ Math parametric equations without deleting the object and starting over?


Does the Favored Enemy feature count when using INT skills?

The Ranger's Favored Enemy feature gives Advantage to Intelligence checks when trying to remember information about your enemy. Does that count when making an Intelligence (History) check, for example?   My instinct says yes, but to my surprise the majority opinion seems to be that it only counts when making pure Intelligence checks.    Are not all skills checks Ability Checks by RAW? Does the Favored Enemy apply when using the skills associated with Intelligence?


Every time I try to update software I get the following: "Failed to download repository information" "Check your Internet connection" If I switch  to settings and close settings, after a moment I get: "The software on this computer is up to date".  The question: IS MY SOFTWARE UP TO DATE OR NOT?  \  Sorry if tags aren't appropriate I don't a good enough reputation    pierre@pierre-K54C:~$ sudo apt update [sudo] password for pierre:   Hit:1 archive ubuntu eoan InRelease   Ign:2 launchpad cairo-dock-team ppa InRelease   Get:3 security ubuntu eoan- InRelease [97.5 kB]         Get:4 archive ubuntu eoan-updates InRelease [97.5 kB]           Hit:5 launchpad nilarimogard webupd8 InRelease       Get:6 archive backports InRelease [88.8 kB]       Hit:7 launchpad noobslab icons InRelease Ign:8 launchpad screenlets-dev InRelease         Ign:9 launchpad screenlets InRelease   Err:10 http://ppa.launchpad.net/cairo-dock-team/ppa/ubuntu eoan Release     404  Not Found [IP: 91.189.95.83 80]   Err:11 http://ppa.launchpad.net/screenlets-dev/ppa/ubuntu eoan Release     404  Not Found [IP: 91.189.95.83 80]   Err:12 http://ppa.launchpad.net/screenlets/ppa/ubuntu eoan Release     404  Not Found [IP: 91.189.95.83 80]   Reading package lists... Done   E: The repository 'http://ppa.launchpad.net/cairo-dock-team/ppa/ubuntu eoan Release' does not have a Release file.   N: Updating from such a repository can't be done securely, and is therefore disabled by default.   N: See apt-secure(8) manpage for repository creation and user configuration details.   E: The repository 'http://ppa.launchpad.net/screenlets-dev/ppa/ubuntu eoan Release' does not have a Release file.   N: Updating from such a repository can't be done securely, and is therefore disabled by default.   N: See apt-secure(8) manpage for repository creation and user configuration details.   E: The repository 'http://ppa.launchpad.net/screenlets/ppa/ubuntu eoan Release' does not have a Release file.   N: Updating from such a repository can't be done securely, and is therefore disabled by default.   N: See apt-secure(8) manpage for repository creation and user configuration details.   pierre@pierre-K54C:~$ sudo apt dist-upgrade   Reading package lists... Done   Building dependency tree        Reading state information... Done   Calculating upgrade... Done   The following package was automatically installed and is no longer required:     catdoc   Use 'sudo apt autoremove' to remove it.    0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   pierre@pierre-K54C:~$     I hope this is complete I am limited to 8 links so I modified the good ones   I reinstalled Synaptic and reloaded: Looks like cairo dock team & screenlets are banished from Ubuntu being insecure  OK problem resolved, I've remove all check marks in settings other software and loaded the app with Synaptic. So thanks everyone


Is “You might could talk to her family” grammatically correct?

Following up my previous questions on the usage of the word / phrase ('banzai' and 'ring the cherries') in Thomas Harris' thriller, ”The Silence of Lambs,” I came across the following passage in the scene Stacy Hubca, an office clerk of Franklin Insurance Agency in Belvedere, Ohio answers to Clarice Starling, an FBI agent.     “She died. She went to Florida to retire and she died down there, Fredrica said. I never did know her. - - - You might could talk to   her family or something. I’ll write it down for you." - ibid Chapter 54.   Page 332.   As an only school textbook-based English language learner, it’s my understanding that an auxiliary verb (might) should be followed by a root of verb. What is the grammatical justification of the sentence, “You might could talk to her family or something”?  Though it "might could" be a midwest dialect, but what’s wrong with simply and normally stating “You might talk to her family” or “You could talk to her family”?


primes of the form $4k+3$ and sums of squares

It is well-known that if $p$ is a prime of the form $4k+3$ and $p|x^2+y^2$ then $p|x$ and $p|y$. I forget what is the name of this result, and where can I find a proof (please provide a link).


Problem with the latest MiKTeX pstricks update

I have just updated MiKTeX and have found that pstricks now appears to cause a problem. The error message I'm getting is     ("C:\Program Files\MiKTeX 2.9\tex\generic\pstricks\pstricks.tex"      ! Undefined control sequence.      l.31 \if@check@engine   Not sure what's happening here. If I stop pstricks from being loaded things work ok.  Is there a known problem with the latest pstricks?


Who are all of the companions and how do I get them?

I have quite the number of companions and I've just scratched the surface of Boston. I'm wondering if there is a definitive list of companions and information on how to get them all to join me on my crusade!


How to show $\int_0^1 f^3 dx < ( \int_0^1 f dx )^2 $

Assume $f$ is $C^1([0,1])$ and $f(0)=0$ and $ 0 < f' \le 1 $ then I want to show that $$\int_{0}^{1} f^3 dx < \left( \int_{0}^{1} f dx \right)^2 $$  my tries : I want to use a similar way like the proof of the poincare inequality   $f(x)^3=\int_0^1 3 f'(x) f^2 (x) dx $ now I use the bound of $f'$ and $f$ and Holder inequality and integrating from both side of the inequalities but i reach inequalities different of the asked one.    Can some one help me. thanks.


"The website encountered an unexpected error. Please try again later."

I get this error with Drupal 7.     The website encountered an unexpected error. Please try again later.   How can I get more information about this error? Is there any report or log to understand what happened? The PHP log doesn't report errors. How can I disable that message and have a more useful one for debugging purpose?


How to correlate scale and nominal variables in SPSS?

I want to run a test in order to identify if there is any correlation between the length of in-hospital stay (Scale) and the kind of the procedure (Nominal with three options; abdominal, cardiac and other). Can you provide me with the right test from the Analyze menu in SPSS ?


"Me" vs "I" - when it's correct to use "Me" and when it's correct to use "I"

I'm always confused when it's correct to use "Me" and when it's correct to use "I"?   Can I always replace "I" by "me" (not opposite)?  Some examples:  "Me and you went together there"  "I and you went together there"   For the moment I'm using me just in the end of the sentence or when I'm talking about me and someone else together. But I sometimes hear people that replace the two pronouns. Maybe here I'll solve the problem and I'll Know what is the correct way.


U.K. visitor visa denied for being unable to confirm provenance

My partner recently got refused a U.K. visitor visa thinking that he has not got access to these funds even though he provided bank statements dated back to 6 months, an employment letter, a salary letter which are all in his name so I’m not really understanding what more evidence he can provide to get approved in his net application


I've previously connected to a WiFi network on my iPhone but I have no way of finding out the password. Is there any way to recover the password after resetting my device to view saved WiFi passwords on the iPhone?


This morning suddenly after hours of work I found my self unable to access admin account, just a blank page without any info. The anonymous and authenticated users  are logged in normally without any problem , like usual..    The first reflex was to clear all the cache manually from the database,but this drove me to this issue:    Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 2006 MySQL server has gone away' in /home/www/includes/database/database.inc:2171 Stack trace:  #0 /home/www/includes/database/database.inc(2171): PDOStatement->execute(Array)  #1 /home/www/includes/database/database.inc(683): DatabaseStatementBase->execute(Array, Array)  #2 /home/www/includes/database/database.inc(2350): DatabaseConnection->query('SELECT expire, ...', Array, Array) #3 /home/www/includes/lock.inc(167): db_query('SELECT expire, ...', Array)  #4 /home/www/includes/lock.inc(146): lock_may_be_available('schema:runtime:...')  #5 /home/www/includes/bootstrap.inc(433): lock_acquire('schema:runtime:...')  #6 /home/www/includes/bootstrap.inc(455): DrupalCacheArray->set(Array)  #7 [internal function]: DrupalCacheArray->__destruct()  #8 {main} thrown in /home/www/includes/database/database.inc on line 2171   I tried to change the theme by removing it from the themes folder but nothing worked. Any Help please..


Recovering Grub after installing windows 8.1

I installed Windows 8.1 after Ubuntu 12.04.  Now, grub does not shows up any more! It's goes straight to Windows after turning my PC on.  Grub gone after installing Windows 8.1  Please tell me what should I do to turn grub back ?  Any helps would be awesome.


Copy of Stack Exchange network `dingding`

I just recently found the following link. I am not sure, is this the other network of Stack Exchange sitess or copy of it. Just have a look.  http://magento.dingding.in/


Is $\limsup_{n\rightarrow\infty}\frac{c_{n+1}}{c_{n}}=\limsup_{n\rightarrow\infty}\sqrt[n]{c_{n}}$ for a positive sequence $(c_{n})_{n\geq 1}$?

I was going through Theorem 3.39 from Baby Rudin page no 69. I will restate the theorem,  Given the power series $\sum_{n\geq0}c_{n}z^{n}$, put $\alpha=\limsup_{n\rightarrow\infty}\sqrt[n]{|c_{n}|}$ and $R=\frac{1}{\alpha}$(If $\alpha=0$, $R=\infty$ and vice-versa). Then $\sum_{n\geq0}c_{n}z^{n}$ converges if $|z|<R$ and diverges if $|z|>R$.  In the proof of the theorem, the root test is applied to individual terms in the power series. I tried the same using ratio test and the expression of reciprocal of the radius of convergence becomes $\alpha = \limsup_{n\to\infty}\frac{|c_{n+1}|}{|c_{n}|}$. Then using the inequality $\limsup_{n\to\infty}\frac{|c_{n+1}|}{|c_{n}|}\geq\limsup_{n\rightarrow\infty}\sqrt[n]{|c_{n}|}$, if it is followed strictly, there will be two distinct radius of convergence(let $R_{1}$ and $R_{2}$) and this cannot be the case, since the series will converge and diverge in an annular region with radius $R_{1}$ and $R_{2}$, by ratio test and root test. So, the only possible scenario can be the two are equal, implying equality holds in that inequality, i.e. $\limsup_{n\to\infty}\frac{|c_{n+1}|}{|c_{n}|}=\limsup_{n\rightarrow\infty}\sqrt[n]{|c_{n}|}$. But this looks so absurd since it makes the inequality totally meaningless. I am unable to figure out where is the gap in my thinking. Any help will be appreciated.


Why does my script work just in console?

I'm doing an easy note creator in JavaScript, just to improve my knowledge in web development.  So, I've almost did everything: but I've a problem:   if($("div").length != 0) $("div").click(function() {     for(var i = 0;i < $("div").length;i++) {     $("div").remove(); } });   If I open my page and I put it in console, it works.  If I put it in my JS file, the DOM doesn't load it.  Can I know why of that?    $("button.add").click(function() {   var text = document.querySelector("input").value;   var x = document.createElement("div");   x.innerHTML = text;   document.body.appendChild(x); });  if ($("div").length != 0)   $("div").click(function() {     for (var i = 0; i < $("div").length; i++) {       $("div").remove();     }   }); body {   background-color: lightblue;   margin: 5%; } input, button {   border: none;   padding: 10px;   display: block;   margin: 0 auto; } button {   background-color: #fff;   margin-top: 10px;   opacity: 0.9; } input:focus {   opacity: 0.9;   outline: none; } div {   background-color: #fff;   padding: 5%;   width: 10%;   color: #ccc;   display: inline;   transition: 0.4s; } div:hover {   background-color: #b71c1c; } <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <!DOCTYPE html> <html>  <head>   <meta charset="utf-8">   <meta name="viewport" content="width=device-width">   <title>Matteo Notes</title>   <link rel="stylesheet" href="C:\Users\User\Desktop\Dash\Notes\style.css">   <script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.1.1.min.js"></script> </head>  <body>   <input type="text" placeholder="Add...">   <button class="add">Add</button>   <button class="remove">Remove</button>   <script src="script.js" type="text/javascript"></script> </body>  </html>


When should we write "the" after "through"? For example, should we say "through internet" or "through the internet"? Thank you very much!


create a file in c++ like when you press right-click->new->new text document

What is the C/C++ command for creating a file in a certain directory with the name of a certain variable read from the keyboard ? For example: a text file with the name John previously read from the keyboard, the program will create the file John.txt


I've been living in Ireland for almost a year now and I start noticing they use the word "mens" a lot. I can see it used in:   Shops, to denote the area where you can find men's clothes In sport, when they talk about "mens team".    My guess is just that they are lazy about the use of quotes, so that mens should actually be men's. However, there may be some rule I'm not aware of. So, is "mens" only limited to Irish English? When I'm allowed to use it?


Close Vote Review Audits are too obvious

The other day, I got an obviously good question in a Close Vote Review.  Even if I didn't read the question,  is a bit of a giveaway.  Today I got one where   Also, on sites other than SO (where I understand the queues are huge), the number of reviews needed is often low enough (single digits) that you usually notice when you get an extra one.  I don't mind - I'm quite happy to get easy-to-pass audits - but maybe they could be a little harder...


What is the highest possible energy of a photon?

Are following suggestions ok to cap the energy of a photon?  When the photons have enough energy in a small enough volume to collapse into a black hole When the wavelength of the photons becomes the smallest possible. That is, some unit of space is indivisible and fundamental.


How can I have people log into my network and be directed to my website?

So what I am trying to accomplish is somewhat like Starbucks has, were you connect to there wifi, accept terms, then it directs them to there website. Can this be accomplished with a mobile hotspot?  Another thing is that when they try to go to another site it will be locked into my site, so while logged into my wifi they will only be allowed to access our website. Is this possible?  I am a mobile DJ that would like guest at any event to be able to access our site through there mobile and send the DJ a direct song request.


If $Z\subseteq Y\subseteq X$ and $Z$ is compact in $Y$, then $Z$ is compact in $X$

Let be X a topological space and let be $Z,Y\subseteq X$ such that $Z\subseteq Y$: so if Z is compact in Y then Z is compact in X.  To prove the assertion let be U an open cover of Z in X and we consider the open cover $\mathcal{U}'=\{U\cap Y:U\in\mathcal{U}\}$ of $Z$ in $Y$ -indeed $Z\subseteq\bigcup\mathcal{U}=\bigcup_{U\in\mathcal{U}}U\rightarrow Z=Z\cap Y\subseteq(\bigcup_{U\in\mathcal{U}}U)\cap Y=\bigcup_{U\in\mathcal{U}}(U\cap Y)=\bigcup\mathcal{U}'$- thus there exist $\mathcal{U}''\subseteq\mathcal{U}'$ such that $|\mathcal{U}''|<ℵ_0$ and $Z\subseteq\bigcup\mathcal{U}''$ and so $\mathcal{U'''}=\{U\in\mathcal{U}:U\cap Y\in\mathcal{U}''\}$ is an open and finite cover of Z in X -indeed $|\mathcal{U}'''|=|\mathcal{U}''|<\aleph_0$ and $Z\subseteq\bigcup\mathcal{U}''\subseteq\bigcup\mathcal{U}'''$- and so this prove that $Z$ is compact in $X$.  It is my proof correct? if not, how prove the assertion? could be that if is false?  Could someone help me, please?


"Post contains improperly formatted code" - Cannot find any misformatted code

I tried to post this exact answer on Stack Overflow, however it refuses to let me do so.  I tried searching around a bit, and found some people suggesting adding extra line breaks before code blocks. This didn't work.     You need to create a loop that goes through each possible value.   Often, you'd just use a for loop.  for($i = 0; $i < count($cars); $i++) {     if($cars[$i]['brand'] == "BMW")         echo $cars[$i]['color']; }       However, using a foreach loop is also an option, and it looks neater.  foreach($cars as $v) {     if($v['brand'] == "BMW")         echo $v['color']; }       See the array, for loop and foreach loop documentation for more   information      (link)   (link)   (link)   (Note that the (link)s down the bottom are links on Stack Overflow using the [text](link) method; I just couldn't post them here because of having under 10 reputation.)        I have almost no doubt that this is happening because I've done something wrong, but for the life of me I can't spot what it is.  Edit: Updates based on questions in the comments I receive this message exactly in a red box to the side of my answer:     Your post appears to contain code that is not properly formatted as code. Please indent all code by 4 spaces using the code toolbar button or the CTRL+K keyboard shortcut. For more editing help, click the [?] toolbar icon.   I'm on Chrome version 34.0.1847.116 m, Windows 7 64-bit.  Edit 2: As per Mat's suggestion, I tried putting all the links in an unordered list, with one blank line between them. This worked perfectly and the message was submitted.  I believe this question should remain as a bug report, as this sounds like a bug to me.


Find set with maximal cardinality given constraints

We are given a set $A = \{1,2,3 \:...\:256 \}$. I'm obliged to find such A', so:    $A' \subset A$  A' has the maximal possible cardinality A' contains no elements x,y which satisfy the following equality: $x = 2y$   I came up with some thoughts, but I'm not sure that my answer is correct, and I'm sure that the task could be solved in a more mathematically beautiful style.    My reasoning was the following:  1. First, pick up all odd numbers from set A. It makes 128 elements.  2. Then, pick all even numbers, which are large enough to not comply with the equation $x = 2y$. They are $\{130, 132\:...\: 256\}$. It adds 64 elements.  3. Then we note, that half of those 64 elements could be divided by 2 and some odd number from set A'. So we should only use those elements from previous step, which comply x div 4 = 0.  4. Also, we can include some even numbers, which are small enough to not have and greater match. They are $\{2, 4\:...\: 64\}$. We have to skip every second of them, to not create new matches. It gives us another 16: $\{4,8,12\:...\: 64\}$. Though, we have skip every second of them again, since they build pairs with themselves. It's 8 now: $\{4,12\:...\: 32\}$  5. Thus, we have 128 + 32 + 8 = 168, which is the maximal cardinality of A'.  I believe this solution lacks proof of maximality. So I would appreciate if you guys could prove my solution correct or erroneous or suggest more mathematically advanced way of approaching this problem (for example, I tried to look at elements of A as sequences of 8 bits, but it didn't help me much).


Taking a Desktop Computer Overseas - Options?

I am moving overseas for a few months and will be working remotely, which will require me to take my desktop computer.  What are the best methods to take a desktop computer overseas? What potential issues are involved?   Should I stuff the entire desktop into a hard-case samsonite luggage (and bubble-wrap/cushion it)? Should I remove sensitive parts and take those sensitive parts separately? Will the TSA say anything if I remove the GPU and CPU and take that with me as carry-on luggage?   Also, I hear that the TSA may open your checked-in luggage, and for desktops that they may remove the heatsink on the CPU. I do not want my CPU to get damaged, so in that case should I remove the heatsink, and CPU so that no one else has to do it?  Anything else to consider?


Number Theory: Prove for all $1\leq n \in \mathbb{N}$ $F_n \mid 2^{F_n}-2$ with $F_n$ is Fermat numbers Follow the following sections They will guide you in proof  Use polynomial division to prove that $2^{2^{n+1}}-1\mid2^{F_n-1}-1$.  Use polynomial division to prove that $F_n\mid2^{2^{n+1}}-1$.  Draw the conclusion from these two sections.   Attempt: if $2^{2^{n+1}}-1$ divide $2^{F_n-1}-1$ and $F_n$ divide $2^{2^{n+1}}-1$ so $F_n$ divide $2^{F_n-1}-1$ and i have no idea how to make it happen.


How can I ensure a service is disabled on boot?

For some reason I need to disable a system service on boot. In my case this is the Avahi Daemon. I just don't want it to start on boot.  In previous Ubuntu releases (e.g. 12.04) I could do  sudo update-rc.d avahi-daemon disable   However on 14.04 it shows  update-rc.d: warning:  start runlevel arguments (none) do not match avahi-daemon Default-Start values (2 3 4 5) update-rc.d: warning:  stop runlevel arguments (none) do not match avahi-daemon Default-Stop values (0 1 6)  System start/stop links for /etc/init.d/avahi-daemon do not exist.   And Avahi is started on boot. How can I disable this? I'm looking for a command line way of doing this.  And please care to explain what happened here? Some change in a recent Ubuntu release broke the use of update-rc.d? I suspect I'm missing something here.


Dual nationality (US/UK) visiting US but US passport expired, missed deadline to renew

I am a dual national with UK and US citizenship living in the UK. My US passport needed renewing and I sent it off. I apparently didn't enclose a picture, although I think it just fell out and missed the deadline to re-send the information. Mainly due to a medical condition, the approved courier company not arriving to collect the passport until 10.30pm (scheduled 7am-7pm) and I can't really justify the expense of paying again.   However, my aunt is unwell in the US and I'm wondering if I can apply for and travel on an ESTA using my UK passport?    It's not a confirmed trip, just more a question about the feasibility of visiting.


Javascript: Why is Math.floor(1.9) considered as 1 but Math.floor(1.9999999999999999) as 2?

Why is  Math.floor(1.9) considered as 1 but Math.floor(1.9999999999999999) as 2?  console.log(Math.floor(1.9));// result ==> 1; console.log(Math.floor(1.9999999999999999));// result ==> 2


$f: \mathbb{R^2} \to \mathbb{R}$ a $C^\infty$ function such that $f(x,0)=f(0,y)=0$ then exists $g$ such that $f(x,y)=xy\, g(x,y)$

I'm trying to solve the following exercise  Let $f: \mathbb{R^2} \to \mathbb{R}$ a $C^\infty$ function such that $f(x,0)=f(0,y)=0$ $\forall x,y \in \mathbb{R}$. Then there exists a $C^\infty$ function $g:\mathbb{R^2} \to \mathbb{R}$ satisfying $f(x,y)=xy\, g(x,y)$ $\forall x,y \in \mathbb{R}$  I thought first about expanding $f$ using the taylor theorem, we would have $$f(x,y)=f(0,0)+f'(0,0)(x.y)+\frac{f''(0,0)(x,y)^2}{2!}+r(x,y),$$ but $f(0,0)=0$ and $f_x(0,0)=f_y(0,0)=0$ since $f$ is zero on the $x$ and $y$ axis. $f''(0,0)(x,y)^2=f_{xx}(0,0)x^2+f_{xy}(0,0)xy+f_{yy}(0,0)y^2$, now we have a term that has a product of $x$ and $y$. But I don't know how (and if it is possible) to proceed from here.


Setting default values for columns in JPA

Is it possible to set a default value for columns in JPA, and if, how is it done using annotations?


losing ligatures when switching font series or color in the middle of a word

For pedagogical purposes, I would like to highlight some characters in a word, through bold or red color or whatever will work.  Because I use handwriting fonts (German Schulschriften wedn and French Cursive frcursive), I am bound to ligatures working well. Unfortunately, ligatures are blocked if you switch series or color in the middle of a word.  I would be happy with a XeLaTeX or LuaLaTeX solution. If needed, also with a PDFLaTeX solution. And as said, any kind of highlighting would be fine.  Here the MWE:  \documentclass[varwidth]{standalone} \usepackage[ngerman,frenchb]{babel} \usepackage{fontspec} \setmainfont{Linux Libertine O} \setmonofont[Scale=.75]{Linux Libertine Mono O} \setsansfont[Scale=MatchLowercase]{Linux Biolinum O} \usepackage{wedn} \newcommand{\schschrift}{\selectlanguage{ngerman} \wedn\upshape} \usepackage{frcursive}     \usepackage{xcolor}  \begin{document} \newcommand{\fex}[3]{#1\textbf{#2}#3} % \renewcommand{\fex}[3]{#1{\bfseries #2}#3}  { \schschrift \fex{W}{ö}{rter} -- Wörter } { \cursive \fex{incr}{oy}{able} -- incroyable }  \renewcommand{\fex}[3]{#1\textcolor{red}{#2}#3}  { \schschrift \fex{W}{ö}{rter} -- Wörter } { \cursive \fex{incr}{oy}{able} -- incroyable }  \renewcommand{\fex}[3]{#1#2#3}  { \schschrift \fex{W}{ö}{rter} -- Wörter } { \cursive \fex{incr}{oy}{able} -- incroyable } \end{document}   You can see that, in the first 2 lines, W and ö don't bind well, as well as the r and o + y and a, when put in bold or in red. Compare to the non-highlighted versions.


$1^3+2^3+...+n^3= $? How I can find formula

$1^3+2^3+...+n^3=$ has a formula which $(1+2+3+...+n)^2 $ or $[n(n + 1)/2]^2$ . We can verify with ınduction and I know how I can prove it. How we find what is the formula...  I tried like this $1^3+2^3+...+n^3= An^4+ Bn^3+Cn^2+Dn+E$ after a long process i found it this way $A=-299/54,$ $B=-4/9,$ $C=107/54,$ $D=4.$ And then I tried how can show that  But I didn't find Maybe The value of a,b,c,d is wrong  Can I get proof of this formula in this way or another way if we didn't know the formula, how would we get this formula


What are the criteria used to represent Stack Exchange sites on the sites page? (Grid view)

I noticed that  has been changed, and by default sites are shown by balloons.  What is not clear to me is why some sites are shown with a bigger balloon than other sites. For example, WordPress Answers has less questions, answers and users than Programmers, but its balloon is bigger. What are the criteria used to show the sites on that page?


My PC is a Dell approximately 7-8 years old running Ubuntu 16.10  I have watched tutorials on youtube and tried to install the ubuntu restricted extras to help make the install a bit easier to no avail.  When i type in the command   sudo apt-get install ubuntu-restricted-extras   It tells me to enter my password then nothing happens.   Can you help - How to install some type of flash on my desktop computer?


discard lines containing specific characters

How can I delete the lines from a file containing the character 'H'? The file contains the following column:  H1 N1 H2 C1 H3 H4 C2 H5 H6 N2 H7 C3 H8 H9 C4 H10 H11 N3 H12 C5 H13 H14 C6 H15 H16   Desired output is:  N1 C1 C2 N2 C3 C4 N3 C5 C6


What countries may be entered without visa by the holder of a South Africa refugee travel document?

What countries in the world may be entered without visa by a refugee carrying a South Africa travel document such as the one illustrated?


Upgrade from 16.04 LTS (32 bit) to 18.04 LTS

When I installed 16.04 LTS I used the 32 bit OS. I was unsure of the type of processor I had. Since then I've learned much, and my processor is definitely 64 bit (Intel® Core™ i3-3110M CPU @ 2.40GHz × 4 ) and I have 4Gb of RAM.  Q: Will I lose my data upgrading to 18.04 LTS because of the change from the 32 bit OS to the 64 bit OS?   I've done all the prudent steps of backing up my data. I'm concerned that the difference in OS will overwrite the file system because it will now be a 64 bit OS.


Is there any canon information about how gravity is controlled?

Ships of Star Wars all have artificial gravity even when within other gravitational fields. Some ships weaponize gravity to pull others out of hyperspace. Technology has clearly progressed to a point where organisms understand and can alter gravity at will. Is there ever any canon discussion of how they are able to do this? If there isn't current canon I'm also interested in Legends information on the development or implementation of gravity-altering technology. I'm thinking Ender in Exile esque, where Card explains how fractional lightspeed travel and instantaneous communication occurs to a relative degree of specificity--obviously not with real science, but with believable theories.


How to define and handle data smaller than 8 bits in C# struct

I'm using a C based native library named WinDivert via DllImport to handle packets in C#.  What would be the best way to define and handle (get, set) data which is  smaller than 8 bits in C# struct like the C style struct below without using bitwise operations?  Maybe MarshalAs attribute?  typedef struct {     UINT16 SrcPort;     UINT16 DstPort;     UINT32 SeqNum;     UINT32 AckNum;     UINT16 Reserved1:4;     UINT16 HdrLength:4;     UINT16 Fin:1;     UINT16 Syn:1;     UINT16 Rst:1;     UINT16 Psh:1;     UINT16 Ack:1;     UINT16 Urg:1;     UINT16 Reserved2:2;     UINT16 Window;     UINT16 Checksum;     UINT16 UrgPtr; } WINDIVERT_TCPHDR, *PWINDIVERT_TCPHDR;   Variables Reserved1, HdrLength are defined as 4 bits, and Fin, Syn, Rst, Psh, Ack, Urg are 1 bit, and Reserved2 is 2 bits in the code above.  Thank you in advance.


Hello guys the below given php code is mine i need to know it is vulnerable or not  $sql = "select Email,Password       from user where Email='$emailid'"; $ctr=0;              try     {        $result = $con->query($sql);        foreach($result as $row)        {                  $ctr++;      $pword = $row['Password'];      }    } catch(PDOException $e)   {       $errTyp = "danger";     $errMSG = "Something went  wrong, try again later...";   }  if($ctr == 0) { $errTyp = "danger"; $errMSG = "Invalid Username |  Password"; }  else {  if( $pword==$password ) {           $_SESSION['Id']=$emailid;    Here is my php login page code Just to confirm, how vulnerable is the above code to sql injection?


Is it discourteous to suggest a different answer be accepted?

Occasionally an answer could solve (or help solve) an asker's problem - and hence be accepted - but may not be beneficial to the community. In cases where the answer is simply too specific, this can be harmless (and often another responder will leave a more generalisable answer). But occasionally an accepted answer may actually be a bad idea for many users (even though it was helpful to the asker of the question). A fairly strident example  - note the comments on the accepted answer (basically it introduces a security vulnerability). In cases as pronounced as this, is it inappropriate or discourteous to drop a comment on the question suggesting another answer be accepted? Or is it expected that readers should always view several answers to minimise the risk of going by sub optimal information?


If $n\ge 0$, show $\sum_{k=0}^{n}  \binom{x+k}{k} = \binom{x+n+1}{n}$. Think as uses a well ordered set of naturals, induction can be used. Base case: $n=1$ Involves only single term, so trivial. Induction hypothesis: it is true for natural number $n$. So, $\sum_{k=0}^{n}  \binom{x+k}{k} = \binom{x+n+1}{n}$. Inductive step: need show for next natural $n+1$ $\sum_{k=0}^{n+1} \binom{x+k}{k} = \binom{x+n+1}{n} + \binom{x+n+1}{n+1} $. This should lead to : $\sum_{k=0}^{n+1} \binom{x+k}{k} = \binom{x+n+1}{n} + \binom{x+n+1}{n+1} \implies \binom{x+n+2}{n+1}$. Taking the LHS, get: $\binom{x+n+1}{n} + \binom{x+n+1}{n+1} = \frac{(x+n+1)!}{(n)! \, (x+1)!} + \frac{(x+n+1)!}{(n+1)! \, (x)!}$ Please help to proceed further, or suggest alternative approach.


I am copying the very first piece of code from  in order to create a glossary. While I get no problem in the compilation I do not get the "glossary part" that appears in the example. I literally copy paste.  Also, I want to create a document that only consists of a glossary of various terms. That is to put everything in alphabetical order (with the possibility to include references as well). How could I possibly do this? I tried some itemize options with alphabetical order but does not look that good.


Test Class is listed under Console Code Coverage section

I've noticed some unclear behaviors when writing Apex test class. Even though these are not blocking for my implementation, I'd like to know what is going on underneath.   When using class variables or methods that are not marked as testMethod, the test class is listed under normal apex class to be covered even it is annotated as @isTest. e.g.    If I remove the count variable and set the second method as a testMethod, the class will be removed from the code coverage list.  Q : What is the consideration for a class to be listed under this list? Fortunately it seems it's not counting for the org code usage though as I've checked.  P.S. : post has been updated as two different questions and the second one is moved