Show that the $n$th derivative of $f(x)$ is zero for all $n \geq 0$.

Let $f:\mathbb{R} \rightarrow \mathbb{R}$ be defined by $f(x)=e^{-\frac{1}{x^2}}$ for $x \neq 0$ and $f(x)=0$ for $x=0$.   I want to show that $f^{(n)}(0)=0$ for all $n \ge 0$. That is, the $n$th derivative at $x=0$ is zero for all $n \ge 0$.   Any hints on how to get started? Thanks.


I got a flat/puncture on my bike tube, how can I fix it myself without going to the nearest bike shop? What kind of equipment would I need?


Intersection of cyclic subgroups: $(x^m) \cap (x^n) = (x^{lcm(m,n)})$

This group theory problem has stumped me. I want to prove that if $G=(x)$ is a finite cyclic group that $(x^n) \cap (x^m) = (x^{\operatorname{lcm}(m,n)})$ for all integers $m$ and $n$, where $(x)$ is the group generated by $x$. Thoughts?


integration of $\sin^3(x)/x^3 $ from $0$ to infinity.Can it be solved using laplace or fourier transform?

Integration of  $\sin^3(x)/x^3 $ from $0$ to infinity. Can it be solved using Laplace or Fourier transform ?


How many binary equivalences are there on a $3$ element set?

Given the set $A=\{1,2,3\}$  How many different binary equivalence relations can be formed?  Can I list all of them?  Furthermore, how will this answer change as I add more elements to the set?


Differences between anti-bioterrorism organizations in the resident evil universe

What is the difference between the anti-bioterrorism organizations in the resident evil universe [BSA,D.S.O,TerraSave]?


Am I able to fit 20x2.4 tires on my 20x2.175 Bmx rim? I dont know if im able to fit that type of tire beacause I want street tires


In how many ways can n couples (husband and wife) be arranged on a bench so no wife would sit next to her husband?  I thought about this:  (Total amount of ways to sit 2n people in 2n sits)-(Using inclusion and exclusion to find that at least 1 wife sits next to her husband) And i get:  Let $A_1$ be the attribute where at least 1 wife sits with her husband, Then we "merge" up the husband and wife into a one person. We have $\binom n1$ ways to choose $1$ couple out of $n$ couples, And we are left with $2n-1$ to place $2n-1$ 'people' so we get $(2n-1)!$ and so on, And on a general note:  $(2n)!-(2\binom n1(2n-1)!-2^2\binom n2(2n-2)!+...2^k(-1)^k\binom nk(2n-k)!)$ And a bit simplified:  $(2n)!-(\sum_{k=1}^n2^k(-1)^k\binom nk(2n-k)!$)  Since i don't have answers to this question i wanna know if i did something wrong? Did i even look at the question right?


Adding the source code to eclipse does not showing .java files

I have attached the source code of rt.jar file ie src.zip to my Eclipse.  My problem is that, After adding the source code of rt.jar to eclipse, when I open any class,for Example "String" class, The eclipse itself showing ".class" file for "String" only,It does nopt showing ".java" file for "String".  How can I see the ".java" file?


Why can I use a function before it's defined in JavaScript?

This code always works, even in different browsers:  function fooCheck() {   alert(internalFoo()); // We are using internalFoo() here...    return internalFoo(); // And here, even though it has not been defined...    function internalFoo() { return true; } //...until here! }  fooCheck();   I could not find a single reference to why it should work, though. I first saw this in John Resig's presentation note, but it was only mentioned. There's no explanation there or anywhere for that matter.  Could someone please enlighten me?


Is there a closed formula for:  $\sum_{i=1}^{N}{\binom{i+k}{i}}$   ( k is a constant whole number )


Purchase domain and web-hosting from different company

I know that it is possible to purchase domain from one company and web-hosting from other, but I have never done that yet. Its first time I am doing it so I want to do it in correct way.   I have domain registered within company A. And I have now purchased web-hosting from company B. From my understanding all I have to set are domain name servers for my domain in company A pointing to DNS servers of company B.  But how the company B knows that I am real owner of this domain. What If someone already purchased web-hosting for this domain in company B. It means that I would not be able then to purchase webhosting from this company for my domain? Or how does it work?


What is the correct way to pronounce such complicated combination of sounds when not pausing for breath? As an example, how would one pronounce something like "The Eighteenth century"?


I'm trying to do the following..     if "ps | grep -e file" then       true;    else       false;   What would I need to do to make the string n the if statement execute the linux command listed?


I asked a similar question a few months back about  but this time I'm asking "what is a toxic link?". You read all over the internet that you should disavow your toxic links with little information what actually classifies as a toxic link.  Sadly most of the information will class toxic links simply because they are self created when in fact this can be actually bad advice. Links on social networks, github, WordPress plugins directory, start-up sites, some infographics, citations and so forth generally are self created and those shouldn't be deleted. Some advice includes penguin only cares about links that are not "nofollowed" the rest are ignored (some of the most respected SEO'ers have said this).  Other links could include blog comments using your brand or business name to relevant blogs that actually improve their relevancy and improves the user experience. So then... the idea of this question to have quality answers based on what you have read and what have you learned, and possibility switch this question to a wiki community question once established.   Ideal answers should be somewhat in depth, for example blog comments links are bad is a little board, because using your real name may be acceptable etc, using the name field is bad but in the body is ok, partial keyword matches are ok, exact are bad etc. But by no means am I expecting anyone to spend the next week writing a 100,000 word answer.


Copy table cell to clipboard with double click anywhere on its row (Javascript)

We have a table with n rows. If you double-click any row, you copy the value of the last column of this row to the clipboard. I think it's a useful functionality but I'm not able to implement it. Any suggestion?  I've tried things similar to:


Why is the date in my menu bar transparent?

Late at night, my menu bar looks like this:  Does anyone know why the date is transparent? It's really hard to read like this. Can I turn this off?


Can multinomial distribution be simulated by a sequence of binomial draws?

I wonder if single multinomial distribution (I will use the notation from JAGS/WinBUGS, but in fact, this is principial thing rather than of particular language)  x[] ~ dmulti(p[], N)   would give the same result as a sequence of binomial draws:  x[1] ~ dbin(p[1], N) x[2] ~ dbin(p[2]/(1 - p[1]), N - x[1]) x[3] ~ dbin(p[3]/(1 - p[1] - p[2]), N - x[1] - x[2]) ... x[K] <- N - x[1] - x[2] - ... - x[K - 1]   Is it totally equivalent? Or did I miss something?


Writing first $5$ terms of recurrence relation

How do I write the first $5$ terms for this recurrence relation?  $$S_0=2\\ S_n=S_{n-1}^2 +S_{n-2}^2+\ldots+S_0^2$$  Since I can't substitute $S_0$ directly?


We have a CentOS server for our web startup hosted on softlayer.com. Knowing how secure Linux is even without anti-virus programs: Do I still need to install McAfee as advertised in softlayer's site ()? Is it worth installing? What benefits will it provide me?   Thanks!


Compute the limit:  $$\lim_{n\to\infty} \left(1+\frac{1}{n}\right)\left(1+\frac{2}{n}\right)^{\frac{1}{2}}\cdots\left(1+\frac{n}{n}\right)^{\frac{1}{n}}$$


unable to display chinese character using PHP

$sql="SELECT * FROM customers";  if ($conn_id=odbc_connect("testconn","user1","user1")){   echo "connected to DSN: $dsn <br>";    if($result=odbc_do($conn_id, $sql)){   } }   I have a database which is utf-8,I am using the below PHP code,it is not displaying the Chinese character.I have tried with other ODBC clients,connecting to same odbc datasource and they are able to display Chinese character.I have tried suggestion mentioned here But still I am not able to display Chinese character


Find $\lim_\limits{x\to\infty} \frac{1+\sqrt2+\sqrt3+...+\sqrt{n}}{n\sqrt{n}} $

Evaluate the limit:  $$\lim_{x\to \infty} \frac{1+\sqrt2+\sqrt3+...+\sqrt{n}}{n\sqrt{n}} $$  Am I right in saying that we can apply Stolz-Cesaro to find limit of $\lim_{x\to\infty} \frac{\sqrt{n+1}}{(n+1)\sqrt{n+1} - n\sqrt{n}}$ which is $\lim_{x\to\infty} \frac{1}{(n+1) + n\sqrt\frac{n}{n+1}}$ = $0$ ? My bad. $\lim_{x\to\infty} \frac{\sqrt{n+1}}{(n+1)\sqrt{n+1} - n\sqrt{n}}$ = $\lim_{n \to \infty} \dfrac{\sqrt{n+1}[(n+1)\sqrt{n+1}+n\sqrt n]}{(n+1)^3-n^3}$ = $\lim_{n \to \infty} \dfrac{(n+1)^2+n\sqrt{n(n+1)}}{3n^2+3n+1}$ =$\lim_{n \to \infty} \dfrac{n^2+2n+1 + n^2\sqrt{1+\frac{1}{n}}}{3n^2+3n+1}$ =$\frac{2}{3}$


Science fiction/fantasy novel about a god returning to Earth to reclaim his powers

I am looking for a book that I read back in the 90's about a guy who's lost his memory and figures out, eventually, that he's a god and part of the universal battle between good and evil, or maybe chaos and order (no, it's definitely not Chronicles of Amber, although some of the story line is similar). My memory seems to think that he fights as an indestructible flying golden/metal lion or something similar at times. I also seem to remember that he loses his first major battle and has to go off for a long time to heal before he comes back and eventually prevails.   I was thinking it was a story by Roger Zelazny, but I don't see anything in his bibliography that fits exactly. Also, the gods are part of a pantheon — I just can't remember which.


Does $\langle u,Tu \rangle=0$ imply that $T=0$?

I have this simple question :     for an operator $T$ in a complex  Hilbert space we have:    $\langle u,Tu \rangle =0$ for all $u$ in this Hilbert space. So does this imply that $T=0$? If yes, how to prove it?


Let $(a_n)_{n \in \mathbb{N}}$ be an infinite positive sequence of integers. Assume that $f(\lambda) = \sum\limits_{n=0}^{\infty} a_n \lambda^n$ is finite for any $\lambda \in [0, \lambda_0)$. Does this necessarily imply that $f(\lambda)$ is also continuous in $(0, \lambda_0)$, or might something strange happen?


I'm just wondering how I can round off decimals to the nearest whole number. So the problem is that I'm using Round(Total / i, 0) code, but when the value is something like .5 decimals, it doesn't round off. Example: The value is 92.5, but the result only shows 92, not 93.


Environment variable with different value

I operate a windows system with several applications, that all need a special home variable.  But if I set this "home" variable, all applications use the same value. Is there a way to set this variable independent of application?


How to extract the Videostream without audio from MP4?

how to xtract the Videostram from an MP4file with ffmpeg? I was lookig but did´nt find anything. All i founded was m4v to mp4 not otherwise. best regards


Python: Is there a different between ' and " in strings?

In PHP there is a difference:  $var='text'; '$var' → $var "$var" → text   In some other languages:  'c' → single char "string" → multiple chars   and in Python?


I have been studying SDL for a few weeks and I have succeeded in making a 2D Ping-Pong game, but  I want to get started in 3D development, and I'd like to know if SDL is capable (and suitable) for 3D game development, or I must use OpenGL?


Let $f(x) = |x|$ for $x \in [-1,1]$ and extend $f$ to all of $\mathbb R$ by requiring $f(x+2)=f(x)$. Prove that $|f(x)-f(y)|\le|x-y|$ for all $x$ and $y$.   This is easy to observe on a graph but my proof is long and a bit tedious. Just curious if there is a quick/elegant way?


A few years back, my parents gave me a Windows 8 laptop. After years and years of messing with the poor thing, I got it to a hardly working point, and it seemed Windows hardly even worked on it anymore. Because of this, I attempted to factory reset my laptop, just for the same weird errors and glitches to show up. Finally, I installed Ubuntu, and the errors stopped. After using the laptop for a year now, I still hardly know how to use Ubuntu, and I think that I should switch back to Windows 8 and attempt to fix it's problems. I was wondering if it is possible to get Windows 8 back on my Ubuntu for free? Thanks -Aiden


Determine if the statements are true. If they are true prove it, and if they are false, give a counterexample.

a) Let $a$ be an odd integer.  If $2^a \equiv 1\ (\text{mod}\ n)$, then $ \varphi(n)|a$.  b) Let $p$ be an odd prime. There exists $a \in \mathbb{Z} >0$ with $\varphi(a) = 2p$.  I think a is false and b is true, but I'm not sure. I'd appreciate any help, thanks!


Bring all windows of the same application to front on focus in Unity

I am essentially trying to replicate the default window management behavior of macOS in Ubuntu since I've gotten so used to it over the years.  When a window of an application in macOS gets focus (either by clicking on it directly, clicking on it in the launcher, or selecting it with the app switcher Alt+Tab), all other windows of the same application are brought to the foreground. In Unity, however, only the focused window is brought to the front.  Is there a setting to achieve the desired behavior? Maybe in ccsm, unity-tweak-tool, gconf-editor , etc.?  I am aware that clicking on the application icon in the launcher twice will open up an overview of all open windows. This is not the behavior I want since I do not want any animation and I do not want the windows to change their position. I simply want them to move to the foreground.


The Arch Linux Wiki page on Zsh has an example that gets key sequences from terminfo in it.  typeset -g -A key  key[Home]="${terminfo[khome]}" key[End]="${terminfo[kend]}" ...   But how would I get ones with modifiers? Specifically Alt+j and Alt+k.  Thank you.


May I speak English in the chat related to a localized site? For example, may I speak English in Stack Overflow in Russian chat? And is there any rule about it? P.S. I guess I may because a chat is not a part of a particular site.


Find $ \lim\limits_{{n \to \infty}} \frac1{2^n} \sum\limits_{k=1}^n \frac1{\sqrt{k}} \binom nk$

Find $$\lim_{n \to \infty} \frac {1}{2^n} \sum_{k=1}^n \frac{1}{\sqrt{k}} \binom{n}{k}.$$  First time I thought about Stirling's approximation but didn't get anything by applying it. I would also think about a Riemann Sum, but no idea how to rewrite...  The answer is $0$.


How to find the directory on which a particular command is executed?

I already installed nautilus-open-terminal package. So i can openup terminal from any directory. Like that i opened a terminal from a directory(i forgot it's path) and executed apt-get download vlc command.  We all know, apt-get download command will download the package to the current directory itself. Because of I forgetted the directory path, i don't know where these packages are located.  I tried history command, it shows only the below commands.    1986  man cdrecord  1987  cd foo-bar  1988  history  1989  apt-get download vlc   It failed to mention the directory on which a particular command(apt-get download vlc) is executed. If it displays the directory, it will be easy to find the location of downloaded pacakges.    1989  ~/Desktop  apt-get download vlc   Is that possible to make history command like above? Is there any way to find the directory on which a particular command is executed?


Is there a command line tool to bulk extract images from a pdf?

I have a pdf catalog that was given to me from a client in pdf format. They don't have the images but they're in the pdf. Is there a way to extract all images from a pdf using a command line tool while preserving it's original file names? I reviewed this question here:   but it's for individual images.


In his Tractatus logico-philosophicus, Wittgenstein uses an unusual numbering system for paragraphs, here's how he describes it.     The decimal figures as numbers of the separate propositions indicate the logical importance of the propositions, the emphasis laid upon them in my exposition. The propositions n.1, n.2, n.3, etc., are comments on proposition No. n; the propositions n.m1, n.m2, etc., are comments on the proposition No. n.m; and so on.   Example    Ideas  I see two ways of designing such architecture. The first is the one proposed by the author of the plain Tex question that I cite below (that uses up and down). The other is to create a proposition environment.  \begin{proposition}     Proposition 1     \begin{proposition}         Proposition 1.1     \end{proposition}     \begin{proposition}         Proposition 1.2         \begin{proposition}              Proposition 1.21         \end{proposition}     \end{proposition} \end{proposition} \begin{proposition}[0]     Proposition 2     \begin{proposition}         Proposition 2.0         \begin{proposition}              Proposition 2.01         \end{proposition}     \end{proposition} \end{proposition}   Notes   I don't mind about working with commands or environments, I'm just looking for a practical solution. I am aware that  exist but I guess the use of LaTeX can simplify macros.


Change Mac Address permanently inside /etc/network/interfaces

QUESTION:  How might I be able to specifically change the Mac Address of the enp3s0 and wlp2s0 interfaces through the /etc/network/interfaces file? What code would I have to include inside? I have been trying for some time now without success sadly enough.    ELABORATING:  So I found this great article online explaining how to change a Mac Address permanently through the /etc/network/interfaces file on my Ubuntu.  In the article, it says:      On Debian, Ubuntu, and similar systems, place the following in the   appropriate section of /etc/network/interfaces (within an iface   stanza, e.g., right after the gateway line) so that the MAC address is   set when the network device is started:      hwaddress ether 02:01:02:03:04:08   Source:  -WikiBooks  Now when I use the following code:  cat /etc/network/interfaces   I get the following output  # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback   And when I do ifconfig on my ubuntu, I get back 3 different interfaces:   enp3s0 lo wlp2s0   I would like to change the mac address of all of my interfaces (enp3s0, wlp2s0) (lo is loopback so no need there), but I am unfamiliar with the commands in the /etc/network/interfaces file. I have been looking at tutorials online though I can't seem to get stuff right, and my computer even started acting very strangely a few times afterwards.


I am trying to get a document to be able to pass through some AJAX and jQuery and I just keep getting the C:\fakepath\ when attempting to pass it through. I know this is a security feature within browsers, but I haven't found a way to get past it, so that it passes the doc.  Here's my code, and jsfiddle.  <form method="post" action="contact.php" name="contactform" id="contactform" enctype="multipart/form-data"> * FBN Document <input name="fbndoc" type="file" id="fbndoc" size="30" value="" />     jQuery(document).ready(function () {  $('#contactform').submit(function () {      var action = $(this).attr('action');      var values = $.map($('[name^="attribute"]'), function (elem) {         return {             name: elem.name,             value: elem.value         };     });        $("#message").slideUp(750, function () {         $('#message').hide();          $('#submit')             .after('')             .attr('disabled', 'disabled');          $.post(action, {             firstname: $('#firstname').val(),             lastname: $('#lastname').val(),             email: $('#email').val(),             contactphone: $('#contactphone').val(),             values: $('values').val(),             fbn: $('#fbn').val(),             fbns: values,             fbnnumber: $('#fbnnumber').val(),             fbnaddress: $('#fbnaddress').val(),             fbncity: $('#fbncity').val(),             fbnstate: $('#fbnstate').val(),             fbnzip: $('#fbnzip').val(),             owneraddress: $('#owneraddress').val(),             ownercity: $('#ownercity').val(),             ownerstate: $('#ownerstate').val(),             ownerzip: $('#ownerzip').val(),             businesstype: $('#businesstype').val(),             otherField: $('#otherField').val(),             commencedate: $('#commencedate').val(),             fbndoc: $('#fbndoc').val(),             comments: $('#comments').val(),             form_type: $('#form_type').val(),              verify: $('#verify').val()         },          function (data) {             document.getElementById('message').innerHTML = data;             $('#message').slideDown('slow');             $('#contactform img.loader').fadeOut('slow', function () {                 $(this).remove()             });             $('#submit').removeAttr('disabled');             if (data.match('success') != null) $('#contactform').slideUp('slow');          });      });      return false;  });  });   jsfiddle can be found here:


Finding invertible elements in $\mathbb{Z}/m\mathbb{Z}$

Can anyone show me how to find invertible elements in $\mathbb{Z}/m\mathbb{Z}$, $m$ is say $28$?  Also I'm not very clear about what it mean by 'invertible element in $\mathbb{Z}/m\mathbb{Z}$'


Intuitionistic proof of $\neg\neg(\neg\neg P \rightarrow P)$

How do you prove $\neg\neg(\neg\neg P \rightarrow P)$ in intuitionistic logic?   I know this statement to be intuitionistically provable because of Glivenko's theorem. However, I wish to prove it intuitionistically.  The relevant axioms I happen to be using are: (1) $\neg P = P\rightarrow\bot$ and (2) $\bot \rightarrow P$.


How do I combine two or more images to get a single pdf file?

Say I have some image files (for instance, the result of scanning some sheets) and I want to combine them into a single pdf file, each image on a different page. Is there a faster / more convenient way than converting each one to a pdf file and then combining those (say, as explained )? Or, if this is more or less how it is to be done, which is the most intelligent and less tedious possible way to do it?


Completing the count of characters in every line with dots

I would like to know how to count the characters in every line in a text, then subtracting this number from a threshold represents the maximum number of characters allowed per line, after then I would like to fill the gaps between the maximum number of characters and the count of characters with dots. For example:  Unix was  originally meant  to be a  co nvenient p latform for progra mmers developing software to  be run on it and on other  systems, rather than for non- programmers. [7][8] The system grew larger  as the operating system star ted spreading in a cademic circ les, as users add ed their own tools to th e system and shared them wi th colleagues.   The maximum number of characters over all the lines is /31/ in line#11. I would like the count of characters in every line to be /31/ by filling the empty spaces with dots, like this:  Unix was , ..................... originally meant , ............. to be a , ...................... co, ............................ nvenient p, .................... latform for progra, ............ mmers developing software to, .. be run on it and on other , .... systems, rather than for non-,.. programmers., .................. [7][8] The system grew larger,.. as the operating system star, .. ted spreading in a, ............ cademic circ, .................. les, as users add, ............. ed their own tools to th, ...... e system and shared them wi, ... th colleagues., ................   How can I do that in bash?


Referencing without captions appearing but keeping numbering

From what I understand, in order to refer to a figure in the text and be able to access it via clicking, I use \label{}, and then in the text I use \ref{}, with the same name inside.  What I would like is for the figure to not have the caption appear, but to keep the numbering. So that in the text, there is still "1" that I can click to jump to the figure, but for there not to be "Figure 1" or "Figure 1: etc". If I try including \caption*{} (as I've seen on other answers), the numbering goes away and is replaced with "??" which is not what I want (although it still goes the picture when I click it).  I think getting rid of the caption package and associated uses of \caption{} would do the trick normally, but within the same document later on, I am planning on cross-referencing to figures in a document that uses the captions and the caption package quite heavily, so I figure I need to be able to have the caption package here.  Example code below:  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{caption} \usepackage{graphicx} \usepackage{hyperref}  \begin{document}  \section{Introduction}  Let's test this \ref{Fig:test}  \begin{figure}     \centering     \includegraphics[width=\textwidth]{example-image-a}     \caption{}     \label{Fig:test} \end{figure}  \end{document}   Any help would be appreciated.


Breaking out of a mixture of for loops and if conditions

I have a piece of code which has several loops in it. By checking a condition (using an if statement) I want to come out of all the loops except the last one. Is there a way to do it without modifying much of my code as I have very less time to submit it.   for file in dirs:    ....    ....    #Opens a file in the directory    with open(path, 'rU') as csvfile:        ....       ....       ....       #Iterates over every row in the File       for row in csvreader:           ...           #If the data is insufficient, the next row will be iterated.            if len(Parameters)>15:                                  #If this condition is not satisfied then I need to go to the next iteration of the first 'for' loop           #Without Calculating the Average_Slip             ....           ....           Calculation_of_Slip()            #Because when all the rows are done iterating, Average_Slip encounters an error as the input values depend on the Slip.              #Instead I need to go to the next file in the directory     Average_slip(Slip_3MW,Slip_7MW,Slip_9MW,Counter_1, Counter_2, Counter_3, Counter_4)   I am sure I am missing something very simple but can anyone please help me.


Are there any restrictions for drilling holes in solid lumber joists regarding how close to the ends of the joist?

I've read to not drill a hole greater than 1/3 the depth of the board (I want to drill a 3/4" hole in a 12" board for wiring, so that won't be an issue) as well as not to do it within two inches of the edges. Mine will be approximately 6" from one end.  Are there any restrictions as to how close to the ends of the board I can go with the hole?   Is the "end" of a joist, one of its "edges" (and therefore any holes must be 2" from the end)?


Place some xticklabels below and other above x-axis

here is a graph to demonstrate how signal sampling work:  \documentclass[french]{article}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc}  \usepackage{babel}   \usepackage{pgfplots} \usepackage{tikz} % State diagram  \usepgfplotslibrary{fillbetween} % For pgfplot integral \pgfplotsset{compat=1.12} % For pgfplot integral \usetikzlibrary{babel} % For pgfplot integral  \pgfplotsset{ standard/.style={     axis x line=middle,     axis y line=middle,     enlarge x limits=0.15,     enlarge y limits=0.15,     every axis x label/.style={at={(current axis.right of origin)},anchor=north west},     every axis y label/.style={at={(current axis.above origin)},anchor=north east},     every axis plot post/.style={mark options={fill=white}}     } }  \begin{document} \begin{tikzpicture}         \begin{axis}[             standard,             domain = 0:15,             samples = 16,             xlabel={$n$},             xmin=0,             ylabel={$x[n]$}]             \addplot+[ycomb,black,thick] {sin(2*180*x/13)};             \addplot[name path=f, domain=0:15, samples=100, color=blue] {sin(deg(0.485*x))};             \addplot[draw=none, name path = xaxis, domain=0:15] {0};             \addplot[orange!50] fill between [of=f and xaxis];         \end{axis} \end{tikzpicture} \end{document}   However, i would like to have the number 8, 10 and 12 above the y line, and all other number below. How can i do that ?


Extra square brackets and numbers when using automated link or add picture feature in questions and answers

I have recently noticed that when using the automated feature to add links, or to add images:    That instead of getting:  ![enter image description here][2]   You get:  [![enter image description here][2]][2]   And I often find the same with links too. This appears to be a bug as there is no functionality for these extra bits and they didn't used to appear.


Prove $x^5 + x^4 + x^3 + x^2 + 1 = 0$ has no rational solution  I want to prove it by Proof by Contradiction, but I am not sure how to proceed with the proof.


How to align the boostrap navbar to the center of the page

I have the following navbar using bootstrap  I have created it using the following code snippet (Here I'm using bootstrap version 3.3.5)

                     <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">                         Toggle navigation                                                                                </button>                     Home

About

           But I wanted center this navbar to the center of the page like below  I need to know how to do this using additional css styling .


Internet Archive Dump of StackExchange Data

The new dump of StackExchange data that has been posted on Internet Archive, does it contain previous snapshots of the data or does it just contain the snapshot at Jan 20th,2014. If it does not contain the previous snapshots (that were hosted on clearbits), does SO plan to put them on Internet Archive?  Thanks for all the help !


Ignoring autocomplete='off' in chrome browser

once user choosing the auto filling option in chrome browser it will auto automatically change the value of this select box according the some deflate values in chrome browser so how can i stop this issue.  I have fond some solutions while i'm googling so it also not working. is there any other solution  1st option is put autocomplete="off"   2nd option is creating fake select box and put style="display: none;"  <form:select path="quote.toLocation[${varstat.index}]" multiple="false" cssClass="select_typ1 bigselect drpView_ti" cssErrorClass="errorInput select_typ1 bigselect" onchange="removeError(this);" cssStyle="margin-top: 0px;float: left;" autocomplete="off">                             <form:option value="">Please select destination</form:option>                             <form:options items="${countryList}" itemLabel="displayName"                                  itemValue="code" cssClass="countrySelectClass" />                         </form:select>


Is there a program that will help with fstab. Not sure how to mount a external harddrive with defualt options. Need help changing fstab for hdd. I screwed up editing mount options. Mounting with termimal this happens: mount /dev/sdc  mount: /dev/sdc: can't find in /etc/fstab.  Mounting with Disks this happens: Error mounting filesystem Error mounting system-managed device /dev/sdc1: unknown filesystem type 'nosuid,nodev,nofail,noauto,x-gvfs-show' (udisks-error-quark, 0) Error removing old /etc/fstab entry Didn't find entry to remove (udisks-error-quark, 0) Thank you.


bibliograpy (chapterbib) produces a [?] where the citation should be

first to all sorry for my english, isn´t me native language and is difficult for me. It´s the first time that i use this forum for that reason.  Now, i´ll try to explain my problem. I need to do multiple bibliographies, one for each chapter, and for it i´m using the package \usepackage[sectionbib]{chapterbib} (I'm using TexnicCenter), and using a file .bib  for each one of them.  After to compilate, in the end of each chapter appears the respective bibliograpy, but in the part of the text where's the cite (\cite{....}), in pdf file (Latex=>PDF) appears [?], even after two or three compilations.  Is the first time that i have this problem, but also is the first time that use \usepackage[sectionbib]{chapterbib}, so think that the problem is there, although the bibliographies are created in each chapter after compilation, means that files .bib are ok and to use \usepackage[sectionbib]{chapterbib} would be right, so i don´t know where is my mistake


I get "spam" emails advertising journals listed in Scopus. Can a Scopus journal be fake/predatory? Or does Scopus has enough strict conditions to list only reputable journals? Or do spammers lie about being listed there? My question is not about other criteria of fake/predatory and how to determined if a journal is predatory in general, but namely about whether this one criterion, presence in Scopus, is enough to decide if it is fake.


Substracting 2 Decimal Numbers from Database issue

$total_cost and $amount_paid value is 2028.36 as shown in the bottom right screenshot  // values are from database. both are type decimal 15,2  $balance = ($total_cost - $amount_paid);  the result is 2.2737367544323E-13  The result should be 0. I tried converting both to float. still doesn't work check screenshot below. I tried printing the value, the result shown in the bottom right corner.   Solved I did the calculation in the database level instead. $this->db->select('(SUM(ItemCost * OrderQty) - OrderAmountPaid) - Discount as Balance');


Why do my 50mm APS-C and 50mm FF lenses have the same angle-of-view on my APS-C camera?

This feels like it should be obvious, but I'm failing to figure it out.  I own a Sony a5100 -- an APS-C camera with a 1.6 crop factor.  I have long owned the SEL50F18, a 50mm f/1.8 lens designed for APS-C.  I wanted a slightly-more-telephoto lens to add to my kit, and after having tons of fun reading reviews, I decided to buy an old manual Minolta MC ROKKOR-PG 50mm f/1.4 and an adapter to E-mount.  It was cheap (about $75 for the set), and the idea of a fully-manual lens with some "character" sounded like fun.  Since the Minolta MC was for a 35mm film SLR, I anticipated the 1.6 crop factor making this lens have the same angle-of-view as an 80mm lens designed for APS-C (since the 50mm lens should produce an image circle much larger than my APS-C sensor)  The adapter is a cheap "Fotasy MD-NEX" adapter which has no optical elements.  So, I was very surprised when my gear arrived today and the new ROKKOR-PG produces images that have the same angle of view (or, at least, close enough that I can't tell the difference)  Where is the hole in my logic?  Why do these two lenses produce images with similar angle-of-view?


I want get the pathInof in my template twig :  How i can reach pathInfo please in my template ?


How to restrict SQL Server database access to application or server running the application

I have a third-party application that connects to a SQL Server database via a SQL Server Native Client 10 ODBC data source.  The application requires that each user of the application must have read/write/execute access on the database.  My concern is that this allows each user to connect directly to the database (using Microsoft Excel, SSMS or any other database connection tool) and change or view the data in any way they care to without the controls, restrictions or auditing enforced by the application.  I cannot change the requirement for each user to have access to the database (at least not without paying for the application to be re-written somehow!) but I was wondering if there was a way to restrict access so that those users can only connect to the database via the server where the application is hosted, or via that one specific ODBC data source, or when the connection is set up by that specific application?  I suspect that I know the answer as I haven't been able to find anything, but I wanted to throw the question out there before I gave up on this.  Thanks,  Paul.


How to find out when a disc (DVD) has been written/burned?

Is there a way/tool to determine the date and time when a disc has been written/burned with high certainty? This is about data forensics and should be a solid proof. I already tried IsoBuster, but it didn't show me the date/time at which the track has been written.


Does Find My Mac work if the disk gets erased?

My MacBook Pro was stolen a couple of days ago and Find my Mac had been enabled on it. I have already locked the Mac with a passcode and a message as well as clicked on the play sound feature(on the find my iPhone app), but those actions are pending until the computer comes online. The Mac is on El Capitan and came with Mavericks. The admin user is password protected but I had not enabled FileVault which is the disk encryption feature, so the computer can be wiped by erasing the disk in Recovery. The computer doesn't need to connect to the internet to be erased but it does need an internet connection to reinstall the operating system after the wipe. My question is, if the computer is erased and then goes online, will Find my Mac still work and notify me when it does? Is it still asociated with my Apple ID after the wipe?


Show $\limsup_{n\rightarrow \infty }(-a_{n}) = -\liminf_{n\rightarrow \infty }(a_{n})$ for a sequence $(a_{n})\subset\mathbb{R}$  Attempt: $\limsup_{n\rightarrow \infty }(-a_{n}) = \inf_{n\geq1 }(\sup\begin{Bmatrix} -a_{n},-(a_{n+1}),... \end{Bmatrix} )$  Now using the fact $-\sup(-A) = \inf(A)$ where $A\subset\mathbb{R}$  $= \inf_{n\geq1 }(-\inf\begin{Bmatrix} a_{n},a_{n+1},... \end{Bmatrix} )$ $= -\inf_{n\geq1 }(\inf\begin{Bmatrix} a_{n},a_{n+1},... \end{Bmatrix} )$  I would like to show $-\inf_{n\geq1 }(\inf\begin{Bmatrix} a_{n},a_{n+1},... \end{Bmatrix} )= -\sup_{n\geq1 }(\inf\begin{Bmatrix} a_{n},a_{n+1},... \end{Bmatrix} ) = -\liminf_{n\rightarrow \infty }(a_{n})$ but im not sure the previous inf(-inf) = -inf(inf) step is even correct.  Still trying to wrap my head around this concept!


Why does $K \leadsto K(X)$ preserve the degree of field extensions?

The following is a problem in an algebra textbook, probably a well-known fact, but I just don't know how to Google it.      Let $K/k$ be a finite field extension. Then $K(X)/k(X)$ is also finite with the same degree as $K/k$.    Obviously if $v_1,...,v_n$ is a $k$-Basis of $K$, any polynomial in $K(X)$ can be written as a $k(X)$-linear combination of $v_1,...,v_n$, but I have no idea what to do with a nontrivial denominator.  Is there perhaps a more elegant way of proving this?


Why the existence of the set of reals does not require axiom of choice?

Reals are often introduced as limits of bounded sequences of rationals. But how can we built the set of such sequences, even a single sequence without axiom of choice? Each element of the sequence is chosen from the set of rationals. But we for sure can make such choice infinite times only due to axiom of choice. Where I am wrong?


How can I efficiently query products with many-to-many ingredients and nested products?

I currently have three tables: product, ingredient, and product_ingredient (m2m relationship).  A product has many ingredients and nested products through product_ingredient. The nested products themselves have many ingredients and nested products. How can I efficiently query these relationships so that a single query can select a product's ingredients through multiple levels of nested relationships?  The product ingredients should be ordered by their position int, with respect to its product_id. Each level of nested ingredients need to be grouped and ordered by the product they're related to. The entities are read more frequently than written, so read optimized would be preferred if there are any cache-based approaches (like materialized views). The actual structure has foreign keys on the ingredient table which are aggregated in different ways.  For example: > select * from product;  id | name ----+------------------------   1 | chocolate   2 | chocolate chip cookies  > select * from ingredient;  id | name ----+--------------   1 | cocoa   2 | cocoa butter   3 | flour   4 | eggs   5 | baking soda  > select * from product_ingredient;  id | product_id | ingredient_id | nested_product_id | position ----+------------+---------------+-------------------+----------   1 |          1 |             2 |            (null) |        0   2 |          1 |             1 |            (null) |        1   3 |          2 |             3 |            (null) |        0   4 |          2 |             4 |            (null) |        1   5 |          2 |        (null) |                 1 |        2   6 |          2 |             5 |            (null) |        3  My ideal query would produce the following output: > select ...;  product_id |           product_name | ingredient_id | ingredient_name | position ------------+------------------------+---------------+-----------------+----------           2 | chocolate chip cookies |             3 | flour           |        0           2 | chocolate chip cookies |             4 | eggs            |        1           1 |              chocolate |             2 | cocoa butter    |        0           1 |              chocolate |             1 | cocoa           |        1           2 | chocolate chip cookies |             5 | baking soda     |        3  Note that the sort order is maintained using position through the nested relationships. Additionally, how do I prevent a circular relationships, where a product_ingredient references a nested_product_id that is a parent or grandparent relation? Is there a CONSTRAINT that I can use?


Extra slash added to the chat room URLs in the side bar

There is a extra slash added to the chat room URLs in the side bar. This is not causing any redirection issue or 404 not found error. Just observed it and want to notify to the development team about this. Seems it is not a bug, but that can . Currently the following URLs are binded against the chat rooms in the side bar.  Tavern on the Meta https://chat.meta.stackexchange.com//rooms/89  The Fire Department https://chat.meta.stackexchange.com//rooms/1181   GIF for the reference:


Any way to use the SFMC integrated Bitly link shortner within a Transactional SMS API JSON payload?

I created a Transactional SMS Send Definition via REST API (Transactional API), and am able to send SMS via API just fine.  Is there any way to shorten a dynamic link that is passed in to the API via an attribute?  Example: see below - you'll see an attribute called URL that is being passed in to the API call.  What I would like to do is shorten this URL.  We can do this via the UI using the typical, non-transactional way of sending SMS, but I can't figure out how to do this in real time using the Transactional API. Edit: The end to end process looks like this:  Salesforce CRM makes an API call via an Apex class to SFMC's Transactional Messaging API. SFMC receives the API call (JSON payload) and simply executes it (sending the SMS).  There's no AMPScript involved, although, a viable workaround would be for SFDC to make a POST call to a CloudPage instead, and have that CloudPage make the call out to shorten the URL via AMPScript, THEN, pass that into the Transactional Messaging API, but we are trying to keep this as out of the box as possible with no customizations (out of scope). Host: https://YOUR_SUBDOMAIN.rest.marketingcloudapis.com POST /messaging/v1/sms/messages/f4fe74b7-c3c0-4e5a-9f49-b63a641109a2 Content-Type: application/json Authorization: Bearer YOUR_ACCESS_TOKEN  {   "definitionKey": "account-reset",   "recipient": {     "to": "15555551234",     "contactKey": "Astro25",     "attributes": {       "URL": "https://www.asuperlongurl.com/"     }   },   "subscriptions": {     "resubscribe": true   } }


Bulgarian residency card expiring. Can I use my visa-free passport to re-enter the country?

I’m a Canadian citizen currently studying in Bulgaria. I’ve been here for the past few years and I renew my residency card each year. My card is expiring soon and I’m graduating.  However the process to actually get my diploma takes a few weeks and my card will be expired by then. I don’t want to go through the hassle of renewing my card for just a few weeks if I don’t have to. I want to leave before my residency card expires and then return to pick up my diploma in a few weeks using just my Canadian passport and the 90 days it gives me.  But does this rule apply to me since I’ve been living here for the past few years? Do I have to wait for another 90 days before I can use my passport to enter? Thanks in advance!


The boundary of union is the union of boundaries when the sets have disjoint closures

Assume $\bar A\cap\bar B=\emptyset$. Is $\partial (A \cup B)=\partial A\cup\partial B$, where $\partial A$ and $\bar A$ mean the boundary set and closure of set $A$?   I can prove that $\partial (A \cup B)\subset \partial A\cup\partial B$ but for proving $\partial A\cup\partial B\subset \partial (A \cup B)$ it seems not trivial. I tried to show that for $x\in \partial A\cup\partial B$ WLOG, $x\in \partial A$ so $B(x)\cap A$ and $B(x)\cap A^c$ not equal to $\emptyset$ but it seems not enough to show the result.


Is it offensive to refer to women as "a female"?

It was claimed in  on this  on The Workplace SE (referring to ) that it is insulting to refer to women as "a female", instead of "a woman".      She's female. She's a woman. She's not a female. Google "" for further details.   The poster then later posted an answer to the question, which ended with this comment:     All this in mind, I've reverted JakeGould's edit. And please remember   that the OP is a woman or female but she's not "a female"   However, there appeared to be significant disagreement with the poster in the threads on the offensiveness of the phrase.   Is it considered insulting in general to refer to women as "a female", and if so, under which circumstances is it so?   Additionally, would the degree of offensiveness change if the implicit noun was added, making the phrase "a female person"? Would any offensive implications be changed, if the masculine versions were used instead (e.g. a male or a male person)?


I want to Change ubuntu 14.04 from 64 bit to 32 bit

How can I Change Ubuntu 14.04 from 64 bit to 32 bit ?


Physical interpretation of $\iiint (∇\cdot\vec E)\mbox{d} V$

Can anybody explain the physical interpretation of  $$\iiint (\nabla\cdot \vec E)~\mbox{d}V~=~\frac{Q}{\epsilon_0}?  $$   Also, how is the differential form of Gauss's law obtained from the integral form?           How can volume multiplied by a gradient equals flux through a closed surface?


Discouraging 'minimal correct answers' for fast points

One of the odd patterns I've noticed on SO goes something like this:   Person A asks a question. Person B very quickly delivers the minimum viable answer, with minimal explanation. B's answer starts to receive votes for being 'correct' even though it may not actually help the poster due to its sparseness. Person C started composing their answer at the same time as B, but instead delivers a detailed, well thought out reply with examples and explanations. They receive fewer points due to the time difference since they took longer to compose their answer. Person B then later edits their answer to include more detail to a similar quality as C's. People tend to be more generous with points to the earlier answer so the effect continues.   This strikes me as a cheap way of gaming the system for points by just making sure you have a 'correct' answer as soon as humanly possible to be available for votes.  My question is whether or not this is a behavior that should be discouraged or not, and if so - what could be done about it.  If there is a consensus that this is to be discouraged, I'd like to suggest that for very new question, for the first 15 minutes or so - answers given appear in a random order, and the number of points for each are not shown (except to moderators) and only the voting arrows appear - this would eliminate this kind of pattern I've identified and encourage higher quality answers out of the gate by eliminating order effects and the first poster advantage.


At what height should I drop my kids from to prevent getting splashed?

Today as I was performing my morning biological ritual, "dropping the kids off at the pool" and what not, the cold kiss of Poseidon on my behind inspired an idea for an experiment. What is the ideal height to poop in a toilet bowl to prevent splashing? There and then, I set up a scientific experiment. Trial # 1: I lowered the "factory's" height-above-water by a few inches. I thought "surely the lowered height will cause the falling logs to gain less total kinetic energy during their shorter journey to the bottom, thereby reducing the splash height". Unfortunately, while the splash height may have been lower, the factory was also lower, so Poseidon got me. Trial # 2: Then I raised the factory height, thinking "if I raise the height, the bog water won't reach!". Unfortunately, my hypothesis was wrong again. Poseidon got me once more. I quickly deduced that a higher drop height meant more kinetic energy, which led to a taller splash. But this trail might have been flawed; I think the log had slightly more mass that time. Therefore, I realized that this is more complex than I originally imagined, and it probably requires multivariable calculus to solve - something I was never good at. So instead, I wanted to continue through the trial-and-error route. I sat on the can for another 10 minutes, but alas, I'd run out of artillery, so the experiment will continue tomorrow. However, I figured that by asking here, I can increase the sample size by encouraging more trials among all of you. Or perhaps there is a physicist who can help deduce the ideal height (AKA, at what drop height above the water will there be the largest gap between the drop height and the splash?).


What does it mean when iMessage suddenly stops saying "Delivered"?

I was texting my friend and everything was okay until I took a few minutes to reply to her message and my text suddenly does not say "Delivered" under it. I'm under Wi-Fi and she possibly was too so what could've happened? Was it me or her?


jQuery click only works once even though I use on("click")

.glyphicon-refresh   is a button that refreshes a section of the page dynamically. After refresh, I want it to click refresh after 5 seconds, but it only works once.   Why?  click  $("#btnRefresh").on("click", ".glyphicon-refresh", function (e) {   console.log("clicked"); });   setInterval  setInterval(function () {    $(".glyphicon-refresh").click();   console.log("ok");    if ($("#waitingOrders").length) {     console.log("there are new orders");   } else {     console.log("the page is empty");   } }, 5000);


Prevent Windows 7 from sleep + power button hook

I'm used to not shutdown Windows but to sleeping it. I set up power button (PB) action to do it. When I want to shutdown I must go to start -> Shutdown. That's OK.  Now I think of a mechanism that will be hooked up to a PB. Should be started after I press PB but before OS will go to sleep. Something that will check few conditions (i.e. running backup, running AV scan, ...) and if true (something is running) prevent go to sleep.  Optionally: It would be nice to start the same "mechanism" before restart and shutdown (invoked not only from Start menu, but also by other software (i.e. installers) but with option to allow some sources (i.e. UPS software)  Generally: How to run something after PowerButton but before Sleeping. How to code (C#.NET, vbs, batch (preferred)) sleep prevention (cancellation).


I am looking for a solution/technology which allows remote screencast display and control from desktop. My goal is to provided remote mobile device display through a browser. I found some existing solutions:   AndroidScreenCast: Based on ADB interface. this is just screenshots using a simple primitive provided by ADB. low display. VNC client & server. works for both rooted android and jailbroken iphone. low display. iDemo + ScreenSplitR: Better, jailbroken iphone only. HDMI/TV output: No remote control.   I've heard about "direct-to-device" technology which is used by DeviceAnyWhere. Are there any other solutions?


Need a section "Questions that were edited after they were closed" in review screen

I think we could really do with a section in the review page which shows all questions that were edited by the owners after they were closed (put on hold), in an attempt to improve them.  You know, candidates for reopening.  Would this be feasible?


Quantum mechanical explanation of electrostatic force

Feynman diagram explains repulsion of electrons by means of photon exchange. Similarly can we explain repulsion of protons and attractions between protons and electrons?


What's the natural way to ask about the current degrees of the weather?

What's the natural way to ask about degrees of the weather?  Can I ask: "What's the temperature?" or "What's the weather like now?" and people will understand I'm asking the degrees?  Asking "How many degrees of Celsius are now?" or "How many degrees are now?" are natural? Or maybe another way to ask appropriately what I want.


How to test if a number is a primitive root?

How to test if a number is a primitive root, assuming the $\text{mod}\enspace m$ where $m$ is a prime? And if not?  Is it not enough if the number is relatively prime to the modulus or prime?  I'll write down what I've done and would like to know if I'm right:  I tested if the modulus is prime with the Rabin-miller test. It was prime, so I used python program to factor $m-1$ since $\phi(m) = m - 1$. It printed out $2$ and another prime. So then I calculated $g ^ q \bmod (m-1)$ for all factors where $q$ is the factor and they were $\neq 1$. So $g$ should be a generator, right?


Retrieving start and end point coordinates with ArcPy?

How do I retrieve start and end point coordinates with ArcPy for a polyline feature class?   I expect to pass a segment identifier to a subroutine and have it pass back start and end coordinates. The Field Calculator method doesn't work for me, because I need the value for other calculations that can't be performed within it. (I also prefer not to change the data to store these coordinates as attributes.) I am attempting to calculate address ranging for a "center out" addressing scheme. The address value depends on the distance to the "county center".


Keyboard shortcuts such as Ctrl-C, Ctrl-V and Ctrl-Z not working in Word 2010 on Windows 7

It seems like the shortcuts I've been using for years in previous versions of Word are not working anymore. For example Ctrl-Z, Ctrl-C, Ctrl-V are not working (there is Alt-Backspace, etc) and I have to learn new shortcuts. This is the thing I really don't want to do.  I'm facing this problem only in Windows 7, I've got Windows XP with the same version of Office 2010 and these shortcuts are working just fine. Is there any way to change Word shortcuts to an old version?


PHP code to convert a MySQL query to CSV

What is the most efficient way to convert a MySQL query to CSV in PHP please?  It would be best to avoid temp files as this reduces portability (dir paths and setting file-system permissions required).  The CSV should also include one top line of field names.


Generics are used to decouple logic from data type.   public class Calc<T> {    public T Add(T a, T b)    {        return (a+b);    } }   But this is throwing the below compile time error  Operator + cannot be applied on type T.  I am not understanding why so. because if it allows from main.cs  main() {      Calc<int> obj = new Calc<int>();      int c = obj.Add(10,20); }   Can somebody please explain why I am getting Build errors??


I'm getting a console screen when shutting down my Pop OS

When I shut down my Pop OS, for a fraction of a second the screen turns into a console and prints some statements before shutting down. This happens very fast, and it's impossible to read or capture and I can't find anything referring to this. All I'm able to notice is the word "Failed". This kind of worries me. Any one knows what this is about? I'm not dual booting and I only have one drive, entirely dedicated to the OS. Is there a way to read this message properly? Like, is there a log file somewhere?


Can you install Ubuntu on a Windows 8 laptop without CD/DVD or USB drive?

I have an Acer Aspire laptop running Windows 8.1. I do not have a CD/DVD drive nor a USB stick. What I would like to know is how to install Ubuntu on a partition of your main hard drive without a CD/DVD or USB drive. I've looked all over the web and haven't found anything.


How to nested method in static method PHP

i want make a static method like this:  Class MYClass{     public static $text = 'apple';     public static $text2 = ' & banana';      public static function get($var){          return static::$var;      }     public static function with($var){          return static::$var;      }  }   if i call :  $var = MYClass::get('text');   $var will be returned 'apple'  and if i call:  $var = MYClass::get('text')->with('text2');   $var will be returned 'apple & banana'  how to make that works?


Delay judgment on close votes review audits until "Vote To Close" is clicked in lightbox

Regarding Potential Duplicates: I saw , which got closed as a duplicate of , which in turn has an "accepted" answer, but doesn't answer the question (or, the answer was revoked). So, there still seems to be no thread keeping this issue open for continued discussion or waiting for a viable resolution. There may be other potential duplicates I may have missed, however.  Today wasn't the first time I failed an audit, wanting to learn more about why a question got VTC'ed. I've failed audits by accident before too, so I'm not too torn up about having failed(—although, as the person running the SO Close Votes Reviewers chat room, it'd be pretty ironic if I got banned from those reviews :-)—but I am uncomfortable that the current system fails an auditee who clicks a button which normally functions to display more information (not cast a vote). It's as if normally, it's a Close... button, and during an audit, it's a Close button—and that makes a difference.    Preempting those who'd say that one shouldn't need information about what others are doing to make their own judgment, . But, between (1) the bias that the lightbox might cause (which, we're supposed to trust users about, as answered in the linked question) and (2) penalizing the thoughtful and the curious for wanting to know more, I feel the greater evil is the latter. (Besides, why not just show no votes, as if it were a freshly flagged question? Or, if these are pulled from real examples, just show one of the votes that was originally cast.)  Precisely because I'm always skeptical of what I presently know, when I see something that doesn't make sense, I want to find out more. When I see a question that seems just fine, I instinctively click Close, hoping the subsequent lightbox might shed some light on things, or teach me something new:   Is there a more specialized site for this question that I haven't heard of? Is there some other, subtle reason I'm not yet aware of that this question should be closed? Was a code sample missing previously, but filled in later? If yes, then I want to see how many off-topic votes this question received, because if it has, say, 3 such votes, and the question seems useful, I'd comment, "This question has been improved and should no longer be closed for its initial reason," to fend off its impending doom. (It only takes one more user—tired and on autopilot—or predisposed to bandwagoning—out of all exposed to the question until the votes expire.) I think this is one of those questions asking about objective differences (not opinion-based) between the internal workings of two comparable "software tools commonly used by programmers," which is a valid question. But with the popularity nowadays of closing such questions as being about "a tool, library, or favorite off-site resource," I want to leave a comment explaining the difference to future reviewers. So let's see, how many people voted to close for that reason? (Or, was this question voted to close for something else entirely that I've missed?) I think there might be valid grounds for closing this question. But with the advent of so many new, long-descript close vote reasons, I need to go over them again to know for sure whether I'm doing the right thing.   And so on.  tl;dr  I use the lightbox to make many judgments about how to review a close vote, and especially whether to leave a comment and what if so. I think it's healthy that a user should attempt to investigate the context in which a question was VTC'ed. Alas the current system discourages that curiosity. I think it's inconsistent that the Close button should mean different things in practice, and during an audit.


NullPointerException for similar of System.out.println

I was checking System.out.println to understand composition of Java and i tried to make a similar of it like this;  FakeSystem class  public class FakeSystem { public final static Print out = null; }   Print class  public class Print { public void print(String text){     System.out.println(text);  } }   Main class  public class Main { public static void main(String[] args) {     FakeSystem.out.print("my text");  } }   It gives NullPointerException when i do this but it has null when i check "out" variable of original System class at java.lang package. It gives "my text" output when i change "out" variable to this;  public final static Print out = new Print();   I wanna understand why doesn't it work when i make it null.


Why is here working and here not working?

public class Main {    public static final PrintStream x = null;     public static void main(String[] args) {        /*Line 8*/ System.out.println("Da");       /*Line 9*/ x.println("Da");     } }  Why is line 8 working, even if the "out" reference is null, and on line 9, where I made another reference same as the reference "out" (static final of type "PrintStream" with a value of null) is not working and I get "NullPointerException"?


Proving that if $G$ has a Hamiltonian circuit, then the line graph $L(G)$ also has a Hamiltonian Circuit

I have a graph G = (V, E). I know that the line graph L(G) of G is defined as follows: each vertex in L(G) corresponds to an edge in G, and two vertices are connected by an edge in L(G) if and only if the corresponding edges in G are adjacent.  Now I am trying to (a) prove that if G has a Hamiltonian circuit, then L(G) also has a Hamiltonian circuit, and (b) give an example of a graph G such that G does not have a Hamiltonian circuit but L(G) does.  However, I'm extremely stuck on how to do this, and any help would be greatly appreciated. Thanks so much!


Eigenvalues of $AB$ and $BA$ ${}\qquad{}$

Are the eigenvalues of the matrices $AB$ and $BA$ identical? If yes, why?  From the examples that I have tried I think they are identical but I just can't come up with a formal proof for this.


Why is the moment of inertia (wrt. the center) for a hollow sphere higher than a solid sphere (with same radius and mass)? I have completely no idea and I am inquiring about this as it is an interesting question that popped in my head while doing physics homework.


What exactly is ? My book confuses me:     a force can lift an object to a height h, or it can accelerate an object through gravity. In all these cases, a force displaces an object and change the object's total energy.   The examples it gives confuse me. On one hand, there is lifting and on, accelerating through gravity.   I can imagine how lifting will change total energy (kinetic + potential). It essentially gives it more potential energy, and does not take from it any kinetic energy. But just dropping an object and let gravity do the work does not seem to me to increase total energy. Because the total amounts of kinetic and potential energy should be equal.  If just let drop, the object will gain kinetic and lose some potential. Not really anything added to the total energy.


How do rich people guarantee the safety of their money, when savings exceed the FDIC limit?

I am curious how a millionaire would guarantee the safety of his money, given that the FDIC only insures up to $250K of an individual's deposits at a bank.  If someone had $3 million that they wanted to put into the bank, would they have to open up 12 different bank accounts and deposit $250K into each one, so that all of his money is insured by the FDIC?  Or is there an easier way to guarantee the safety of all his money?


Error caused by tabular environment suddenly started happening on a previously working file

I'm working on a pretty big document with a lot of \usepackage and custom commands. I'm using texlive 2018 on both my laptop with Linux Mint 17 and my desktop with Windows 10. After updating texlive on Linux, the file does not compile anymore, and I get many errors for most of the tables and a  tree in the document. I completely reinstalled it, but compilation still fails. The file still compiles on my Windows pc, whose texlive installation has been updated a few days ago.  Here is a not-quite-minimal example:  \documentclass{book}  \usepackage[utf8]{inputenc} \usepackage[T1]{fontenc} \usepackage[english]{babel} \usepackage[dvipsnames,table]{xcolor}  \begin{document}  \frontmatter \tableofcontents  \mainmatter  \begin{table}[h]     \begin{tabular}{lp{8.8cm}}         x & y \\         x & y \\     \end{tabular} \end{table}  \backmatter \end{document}   And here is the error log:  Use of \@startpbox doesn't match its definition. \begin{tabular}{lp{8.8cm}} Extra }, or forgotten \endgroup. \begin{tabular}{lp{8.8cm}} Use of \@startpbox doesn't match its definition. \begin{tabular}{lp{8.8cm}} Extra }, or forgotten \endgroup. \begin{tabular}{lp{8.8cm}} Extra }, or forgotten \endgroup. \begin{tabular}{lp{8.8cm}} Extra }, or forgotten \endgroup. \begin{tabular}{lp{8.8cm}} Missing # inserted in alignment preamble. \begin{tabular}{lp{8.8cm}} Missing { inserted. x & y Missing } inserted. x Missing } inserted. x Missing } inserted. x Missing { inserted. x & y Missing } inserted. \end Missing } inserted. \end Missing } inserted. \end   I'm using this command to compile:  pdflatex -synctex=1 -interaction=nonstopmode %.tex  I noticed that by replacing the column specification with {ll} I don't get any error. Also, removing the xcolor package solves the problem, at least on this MWE, but it can be it's fault as it is still an old 2016 version. Does anyone know which package may cause this problem?    Finally, here's a truly minimal MWE:  \documentclass{book} \usepackage[table]{xcolor} \begin{document} \begin{tabular}{p{1cm}}         x \end{tabular} \end{document}


Extra character from StringStream to String in C++

I was writing a code in C++ 11 that would read some lines and print the first word of each line. I decided to use getline and stringstream.  string line, word;  stringstream ss;  while(somecondition){     getline(cin, line);     ss << line;     ss >> word;      cout << word << endl; }   I tried testing this piece of code with the following input:  a x b y c z   The expected output would be:  a b c   But the actual output is:  a xb yc   Could someone please explain why this is happening?  Things I have tried:   ss.clear(); inside the while loop initializing the strings to empty inside the while loop: word = "";   Nothing seems to work, and all produce the same output.   However, when I declared the stringstream ss; inside the while loop, it worked perfectly.   I would be very glad if someone could explain why putting the stringstream declaration outside the while loop may cause the occurance of extra character.  Also I used g++ compiler with --std=c++11.


Polygons overlapping points (not points within the polygon)

I use QGIS 2.14. I have one layer for the points and one layer with many polygons. I'm having trouble finding the polygons that overlapped with the points. Is there a way to do this? I'm not asking for how many points are within the polygon, but the vice versa. How many polygons overlapped a certain point. Hopefully, I could have an attribute table with the points that has the overlapping corresponding polygon/s.  Here's a screenshot of what I'm working on.


2x2 matrix and convergence under iteration connected to eigenvectors and eigenvalues.

When working with a general matrix $A=$ \begin{bmatrix}a & b\\c & d\end{bmatrix},  I find that the eigenvalues are:  $\lambda = \frac{d+a \pm \sqrt{(d-a)^2+4bc}}{2}$  I then find that eigenvectors, $e=$ \begin{bmatrix}-b\\a-\lambda\end{bmatrix}.  I also know that under iteration with initial vector $x_n$ = \begin{bmatrix}x_0\\y_0\end{bmatrix},  we have $x_{n+1} = Ax_n$.  The matrix $A$ converges to a line with a slope $m$.   I am told that the slope of this line is in the same direction as the eigenvector associated with the largest eigenvalue.   How do I prove this?


What's the time limit for turns in Words With Friends?

When I accidentally clicked "resign" while the game was on my opponent's turn, I got this message:     You can only resign when it is your turn.  But fear not!  If your opponent does not make a move in a reasonable amount of time they will be resigned automatically.   What is the "reasonable amount of time" referred to, here?


parsing xml string and getting the value out

I need to write the code in C#.  I get the following string containing xml elements.   **"\n                        <iqn:CDFID xmlns:iqn=\"ns:iqn:cwm:1.0\">Clearance Type</iqn:CDFID>\n                        <iqn:CDFName xmlns:iqn=\"ns:iqn:cwm:1.0\">Clearance Type</iqn:CDFName>\n                        <iqn:CDFValue xmlns:iqn=\"ns:iqn:cwm:1.0\">THE ACTUAL VALUE</iqn:CDFValue>\n                     "**   The elements are  CDFID CDFName CDFValue  The above 3 elements could be in any order inside the string. How do I identify the CDFValue xml element and extract the value "THE ACTUAL VALUE" out.   How can I treat the string in an xml manner and get the value of the desired element out.


How to avoid numbering the first page of the document?

I have two sections before the table of contents.  \documentclass{article} \usepackage{lipsum} \begin{document} \thispagestyle{empty} \section*{First random title} \lipsum[1] \section*{Second random title} \lipsum[2] \clearpage \tableofcontents \section{First section} \lipsum[3] \section{Second section} \lipsum[4] \section{Last section} Wombat \lipsum[5] \end{document}   The problem is, that LaTeX starts the page numbering on the first page and I don't want that. I want the page numbering to start after the table of contents. How can I do this?


How to access static property of child class in php?

<?php class A{     static $var;      function test(){       var_dump(self::$var);     } }  class B extends A{     static $var = 'something'; }  $b = new B(); $b->test(); ?>   why does this print out null and how do I fix this? It works if I do not set $var as static but i need it to be accesible without creating an instance.


Issues with detecting a string within a string

On a site called Codingbat.com I have been presented with the challenge of detecting whether a string ends in "ly" or not. I have thoroughly checked my code, but it doesn't seem to be working. When I input "ly" it detects perfectly fine, however, words such as "oddly" or "exactly" don't issue the true Boolean response as they should. Here is my code so far:  if (str.length() > 1) {   String lastTwo = str.substring(str.length()-2, str.length());   if (lastTwo == "ly") {     return true;   } else {     return false;   } } else {   return false; }


Does xbox live gold membership stack when I purchase a new one?

I currently have an Xbox Live Gold membership that will expire in March 2011. However the price of membership is increasing to $59.99 starting November 1, 2010.   If I buy a 12 month membership now at the current price of $49.99, will the additional 12 months be added on to my existing membership or will I start a new membership which will expire 12 months after I buy it?


How to convert line of text into meaningful words

I have a line of strings:   "specificationsinaccordancewithqualityaccreditedstandards"   Which needs to be split into tokenized words such as:   "specifications in accordance with quality accredited standards"   I have tried nltk's word_tokenize but it was not able to convert,  Context: I am parsing a PDF document into text file, and this is the text which I am getting back from the pdf converter, to convert pdf into text I am using PDFminer in Python


Let $f(x)=1/3$ if $-1<x<2$ and zero elsewhere, be the PDF of X. Find the CDF and PDF of $Y=X^2$.

This is problem 1.7.24 Hogg, McKean, and Craig. I understand the process for finding such a CDF and PDF. Here is what I have,  $$F_Y(y)=P(Y\leq y)$$ $$=P(X^2\leq y)$$ $$=P(-\sqrt{y}\leq X\leq \sqrt{y}).$$  So I would think the answer would be  $$F_Y(y)=\int_{-\sqrt{y}}^\sqrt{y}\frac{1}{3}dx$$ on $0\leq y<4$. But the solutions manual says   $$F_Y(y)=\int_{-\sqrt{y}}^\sqrt{y}\frac{1}{3}dx$$ on $0\leq y<1$ and   $$F_Y(y)=\int_{-1}^\sqrt{y}\frac{1}{3}dx$$ on $1\leq y<4$.   I don't understand how the reasoning behind using these bounds. Any  explanation would be much appreciated.


I have this query   $query = "SELECT * FROM customers WHERE customer_name = '{$orders}'";   but when the value of the $orders have a single quote(') for example:  $orders = "Carlo's shop";   the query return an error.  is there any good way to handle this situation?


Qualitative variable coding in regression leads to "singularities"

I have an independent variable called "quality"; this variable has 3 modalities of response (bad quality; medium quality; high quality). I want to introduce this independent variable into my multiple linear regression. When I have a binary independent variable (dummy variable, I can code 0 / 1) it is easy to introduce it into a multiple linear regression model.  But with 3 modalities of response, I have tried to code this variable like this :  Bad quality      Medium quality      High quality       0                1                  0      1                0                  0      0                0                  1      0                1                  0   But there is a problem when I try to do my multiple linear regression: the modality Medium quality gives me NA:    Coefficients: (1 not defined because of singularities)    How can I code this variable "quality" with 3 modalities? Do I have to create a variable as a factor (factor in R) but then can I introduce this factor in a multiple linear regression?


Expected area of the intersection of of triangles made up random points inside a circle, all the triangles must contain the origin

How to find the expected area of the intersection of a set of triangles made up $N$ random points that are picked uniformly inside a circle? The triangles must contain the origin of the circle. If none of the trinagles contain the rigin we pick again $N$ random points until at least one triangle contain the origin and calculate the expected intersection area of all the triangles that contain the origin.


There is currently no way to delete questions or answers in the iOS app, even with the required Trusted User privilege. We can edit and vote, but not delete.  Can this option please be added to the app?


Why does my washing machine trip the GFCI breaker?

My Samsung washer WA52M7750AV/A4 occasionally pops the GFCI breaker. This a new home not quite a year old. The only item on the breaker is the washer.It always completes the wash cycle and the breaker pops maybe twice a month when I push power on to start another load. I think the breaker is to sensitive.. I have had this washer for about 5 months. The old washer never had this issue.. Thoughts and recommendations please..


Why do people use real values for the Wick-rotated time $\tau$?

In doing instanton problems or when connecting quantum field theory to statistical mechanics, I often see people trying the Wick rotation trick by defining an imaginary time $\tau\equiv it$. So, in this case, we should make sure that $\tau$ is imaginary, right? However, I often see places where people seem to handle $\tau$ as a real number, for example setting $\tau$ to $\pm\infty$. Moreover, I remember in one of my quantum mechanics classes, the professor said the Euclidean time $\tau$ was real. I am so confused and need some good explanations.


Show that each point of closed submanifold $\mathbb R^{n+2}$ have “tangent line” in $\mathbb R^{n+2}$

Let $n \geq 1$ be an integer and $M \subset \mathbb { R } ^ { n + 2 }$ a smooth $n -$ dimensional submanifold   which is a closed subset of $\mathbb { R } ^ { n + 2 } .$ Prove that for any $x _ { 0 } \in M ,$ there exists a   line $L$ in $\mathbb { R } ^ { n + 2 }$ satisfying the condition:   $$\quad L \cap M = \left\{ x _ { 0 } \right\}$$   How can I use the property of smooth submanifold and closed subset to reveal that each point correspond to a line which have one intersection and the intersection is itself?


/etc/sysctl.conf doesn't persist after reboot

In a mission to reduce frequent memory flushes to filesystem, I added the following two lines to /etc/syctl.conf.  vm.dirty_background_ratio = 50 vm.dirty_ratio = 80   I then ran, sudo sysctl -p and the changes were in effect right way. Upon a system reboot, however, I still see old values for dirty_ratio and dirty_background_ratio.  new-sys-admin@ThinkPad:~$ sysctl -n vm.dirty_background_ratio  10 new-sys-admin@ThinkPad:~$ sysctl -n vm.dirty_ratio  5   I'm running Ubuntu 12.04.3 LTS 3.2.0-52-generic-pae. After looking at a couple of posts:         it looks like the upstart job, /etc/init.d/procps is supposed to run on system boot and reload /etc/sysctl.d/* and /etc/sysctl.conf contents via /etc/init/procup.conf but it doesn't seem like it does.  On the next reboot, I ran service procps start and the changes were in effect. I'm wondering how to make procps run consistently on boot time and if I am missing an additional step in making these changes persistent.  EDIT 1  Also tried having these values in /etc/sysctl.d/10-local.conf as per Bill's suggestion.  new-sys-admin@ThinkPad:~$ cat /etc/sysctl.d/10-local.conf  vm.dirty_background_ratio = 50 vm.dirty_ratio = 80   Upon restart, the values are reverted back.


How do I view JRE's source code in Eclipse?

Using Eclipse I want to view the source code for a core Java class (E.g. java.util.concurrent.ConcurrentHashMap) but when I navigate to the source using 'Open Declaration' it says 'Source not found' and gives me the option to attach the source.  My question is; how do i attach the source? Where do i get the source .jar from for the java.util.concurrent library?


I've got a button on my page that allows a user to add a form. When a button within the new form is clicked, a jquery function should run. Unfortunately, the jquery function doesn't seem to run on the newly appended divs (it does run divs  that existed on initial page load).

         Remove

     Add Another Form
        When the user clicks the deletebox within the newly appended form, nothing happens. I.e. jquery doesn't register that it was clicked and no message is printed to the console. Do you know how this issue can be addressed?  Thanks!


What is the best way to put an array pattern onto a flat surface?

For the past couple of weeks I've bene trying to place a repeating hexagon pattern onto the top of a cylinder.  I've watch multiple tutorials on using boolean modifiers, but I always get a few tiles missing along with artifacts. I've used the boolean modifier with success to cut out the cylinder's surface first (no tiles hanging off into space), but that's as far as my success has gone.  I've joined vertices on opposite sides of the cylinder to create equal density mesh, but I oddly enough seem to lose more tiles doing that successfully add to the cylinder. My goal is to 3D print the final image so my little hut will have a tiled floor.  Any suggestions or even tutorials to watch would be greatly appreciated.


I have two polygon layers:  one indicating countries, and other on top indicating lakes. I want to create a new layer that keeps the countries but have the lakes cut out of them. What tool do I use?


Cannot enroll in Apple Developer program

I have been meaning to finish my developer account and sign up for the iOS program, and since WWDC2015 just happened, I thought no better time than now.   Unfortunately, when I go to enroll, I am told     "Sorry, you can’t enroll at this time."   I figured this might have to do with me being under 18, however, I have set up a corporation so I can bypass this roadblock. Furthermore, when I started to sign up previously, I had no issues up until this point.  Is this a side-effect of WWDC? What can I do?


Redirect HTTP to HTTPS /etc/apache2/sites-available/default not working

I know this question has been posted ad-nauseam; however, I still cannot manage to get a working solution.  OS being used is Debian 7 Wheezy.  vHosts file (/etc/apache2/sites-available/default):  <VirtualHost *:80>   ServerName www.example.com   ServerAlias *.example.com   RedirectPermanent / https://www.example.com/ </VirtualHost>  <VirtualHost *:443>         ServerAdmin domains@example.com         SSLEngine on         ServerName www.example.com         SSLCertificateFile /etc/apache2/ssl/ev-cert.crt         SSLCertificateKeyFile /etc/apache2/ssl/private.key         SSLCertificateChainFile /etc/apache2/ssl/intermediate.crt         SSLProtocol all         SSLCipherSuite HIGH:MEDIUM         DocumentRoot /var/www      <Directory /var/www/>             Options -Indexes FollowSymLinks MultiViews             AllowOverride All             Order allow,deny             allow from all     </Directory>          ErrorLog /var/log/apache2/error.log         LogLevel info         CustomLog /var/log/apache2/access.log combined </VirtualHost>   EDIT (Added description of the problem):  Upon restarting apache2, I get no errors; however, when I visit  it goes no where and get a server connection error (cannot connect to server), though when I visit  I get through just fine.  There are no logs in apache to indicate a failure.


How can I prove $\neg \exists x.\phi \vdash \forall x . \neg \phi$?

I have checked some post in this web but in this particular situation I am finding trouble with the negation. I have tried supossing by hypothesis that $\forall x. \phi$ but the contradictions of this does not mean $\forall x . \neg \phi$. I am also not sure at all of some notation. Once I have supposed something by hypothesis and got a contradiction, how should I justify what I have proved by contradiction in next line?  Thank you for your attention.


We found a new iPhone 8 in a foreigner country, the owner of the phone is also a tourist in that country. The sim card in this phone is a new local sim card that this owner bought at that same day( I know by an sms on the lock screen he received about it).  It’s locked with touch ID.  We really really wanted to find this man, but we couldn’t.   We waited for him to call but we suspect that he doesn’t know his own phone number because it’s a new number he bought probably for data only. He didn’t use Find my iPhone(i think) or got any message from a friend on the lock screen( because this sim is a new number/data only probably)   Now, i am not sure i can find him or return it to him because we left that city, and soon the country anyway.  I left with a locked new iPhone 8 that i feel guilty to use anyway.  What are my options to give it back? I feel bad to ask - but if I can’t find him- can i use this device? Unlock it and remove all data?  Thanks.


Is there a way to make  invoke makeglossaries (part of the  package)?  Specifically I want to use latexmk to compile a LaTeX document that uses the glossaries package to produce a glossary.  Currently I'm using this rather clumsy sequence of commands:  makeglossaries document latexmk -pdf document.tex makeglossaries document latexmk -pdf document.tex   The first run of makeglossaries is required to produce files that the glossaries package needs, or otherwise causes latexmk to fail, but there's still no data in the (non-existant) .aux file, so that first makeglossaries invocation produces nothing (except for an empty file).  So, how to do this using latexmk alone (and let that deal with invoking makeglossaries at the right time)?


Dual-boot Ubuntu/Windows 7 upgrade to Ubuntu 16

I installed Ubuntu 3 years ago and an upgrade attempt failed. The disk was configured dual-boot with Ubuntu + Windows.   I tried to install an ISO file for Ubuntu 16.  How can upgrade my previous Ubuntu installation to Ubuntu 16 without losing the dual-boot or Windows!?


Why is my minecraft skin is not showing up?

Just like a normal Minecraft player, I go onto servers and play with friends. But wait. When I join, my skin does not show up.  I am on a 1.8 server and nobody can see my skins. Please help someone.


Error: connection failed in Ubuntu 18.04 app (Windows 10)

So I installed Ubuntu 18.04 app using  website, and this . All seems cool. But after installation and assigning username and password, I try to use this code as described:  sudo apt update && sudo apt upgrade   and then I am getting this error:   Previously, I tried to do sudo apt autoremove but nothing happened. Please, someone, help me with it.  P.S. Sorry for my kind of poor description. I am a newbie to ubuntu.


How to add gksudo or what to use instead in Ubuntu 13.04?

I used to use gksudo gedit /etc/something.conf to edit system configuration files but this doesn't seem to work any more. Looks like there is no gksudo in 13.04. How can I add it back or what am I intended to use instead?


When I render one of my models in my app, black lines (which I did not draw) are getting rendered which run from various points on my model all to a single point.  Please see image.  As I move my camera around in the app, the single point moves around (and in turn the destination of the lines).  What are these black lines, what are they pointing to, and how do I fix?          Note: Blender newbie here  Thanks  Edit new photo showing mesh issues in blender too.  Removed reference to libgdx to remove confusion.


How to get displacement working on a completed house?

I made a house with blender but how can I apply displacement modifiers only to the walls and not to the whole object?


Expected value of the longest run of heads or tails in N flips of a coin

What is the expected value of the longest run of heads or tails observed in $N$ flips of a fair coin?   I'd like to consider this for any $N$, small or large.


how to remove password authentication in ubuntu software center?

I am new to ubuntu.Frequent password authentication while downloading any software in ubuntu is frustrating.Is there any way to remove it ? thanks in advance.


Rotating each iteration of an Array Modifier

Is there a way to rotate each iteration of an Array Modifier?  For example, I've created the helices of a DNA molecule, and I'm trying to add the base pairs. I've got a cylinder with an array modifier.    Then, I thought I'd apply a simple deform to twist them 360 degrees, corresponding to one twist of the double helix. The problem I'm seeing is that the deform modifiers squishes the cylinders, rather than rotating them independently.


Warning in WordPress for Declaration of SplitMenuWalker::walk($elements, $max_depth)

I started receiving the following error on a WordPress site:      Warning: Declaration of SplitMenuWalker::walk($elements, $max_depth) should be compatible with Walker::walk($elements, $max_depth, ...$args) in /home/relati67/public_html/wp-content/themes/mentis/inc/mega-menu/split-menu.php on line 0   I have no idea what to do here. I found a thread with something similar, but the error pointed to a specific line (not line 0) and wasn't the exact same error.  I'm new to Stack Exchange -- thanks in advance for any help!


If $n^2+1$ people are lined up, there are $n+1$ whose heights are increasing or decreasing

Suppose $n^2 +1$ people are lined up shoulder to shoulder is a straight line. Then it is always possible to choose $n+1$ of the people to take one step forward so that going from left to right their heights are increasing (or decreasing).  I know my teacher wants us to use the pigeonhole principle on this and so you know its not a difficult proofs class, but please explain the calculus if your using summation as it's my hardest thing to grasp, my teacher forgets to show us the calculus or explain it sometimes.


series $\sum_2^\infty\cos( \log n)/n\log n$ converges or diverges??

I want to know the series $\sum_2^\infty\cos( \log n)/n\log n$ converges or diverges. The log n in the bottom makes every my effort futile....Could anyone please help?


Is there a rule of thumb on how to deal with apostrophies in the following cases?  Group name vs. Group's name Car brand vs. Car's brand  And pretty much anything similar.


Raycast only specific layer and ignore other collider

I am willing to raycast specific layer and ignore other layers no matters its colider is above to my navPoint layer object?   int specificLayerMask = LayerMask.GetMask("NavPoint");//raycast only this layer ignore others          if (Physics.Raycast(raycastObject.transform.position, fwd, out objectHit, specificLayerMask))//50         {}   the above code raycasting to navpoint layer but unable to bypass other layers colliders. is there any way available to ignore all other collider and raycast to desired layer only no matter colliders are behind any other collider


value of $ \sum_{k=1}^{\infty} \frac{1}{k!}$

Is $ \sum_{k=1}^{\infty} \frac{1}{k!}$ diverges?    First I check that  \begin{align} \lim_{k\rightarrow\infty} \frac{1}{k!} =0 \end{align}  It means at some point the above summation add $0$, thus it seems to me the above series sum converges. But how do we get the value of that summation?


Creating a variable in JavaScript means the value doesn't update when it should?

My test involving a mock function (React, Enzyme and Jest) works:  it('should do a thing', () => {   const myButton = wrapper.find('Button');   expect(mockFunction.mock.calls.length).toBe(0);   myButton.simulate('click');   expect(mockFunction.mock.calls.length).toBe(1); });   However when I try to simplify the code with a variable the test fails. numberClicks is 0 both times.  it('should do a thing', () => {   const myButton = wrapper.find('Button');   const numberClicks = mockFunction.mock.calls.length;   expect(numberClicks).toBe(0);   myButton.simulate('click');   expect(numberClicks).toBe(1); });   Is this normal JavaScript behaviour or some weirdness with the testing libraries?


Parity of number of factors up to a bound?

Consider $b,n\in\mathbb{N}$ where $b\leq n$. We want to find the parity (ie. odd or even) of the number of divisors of $n$ that are $\leq b$.  The question is to find a fast algorithm to find that parity.  (ref: this is essentially problem E from ACM-NA regional contest 2013: )  Now the problem is rather easy for $b\geq\frac{n}{2}$, as it boils down to simply checking whether $n$ is a perfect square. However, I can't figure out how to solve for the general case. Obviously, factoring out $n$ is going to be rather slow, but since we are only trying to count the number of divisor, it might not be as hard. The worst case scenario for this problem appeared to be when $b\approx\sqrt{n}$: using the perfect square technique, we can reduce the problem to the case when $b\leq\sqrt{n}$.  I am looking for a polynomial time algorithm, or a proof that it is polynomially reducible from one of the more well-known problem with no known polynomial time solution (or both -  :D). If neither are possible, even any suggestions for a reasonably fast algorithm would be appreciated. Thank you for your help.  (not sure which tag to put, number-theory or elementary-number-theory; while I don't have much background in number theory, I don't mind people answering using advanced number theory as long as they provide references)


New mobile web theme doesn't highlight comments from the OP

On main and in the old mobile site (iirc) the username of the OP is highlighted in the comments.  This is no longer the case after the new design/theme was rolled out yesterday.  Can we get this back?


I have an executable file in my home directory (/home/user/filename/filename.sh). I am a non-root user. How do I make this script launch by typing the name in terminal? Not using the cd command, chmod command, and ./. I also want to launch the script by clicking just the application icon.


Zoom meaning the ability to make something distant appear closer.  Consumer cameras are sold with a maximum zoom which is supposed to define how much closer.  For example a camera might be 40x zoom, 4x optical, 10x digital.  Can someone explain that in simple English?  Is a 2x zoom the same as taking a picture at half the distance?


Java Jersey 2.27 ServletException in basic example

Is something wrong with web.xml?  I am not using maven here I created dynamic web app using eclipse , tomcat 8.5, jersey 2.27  Please first have look on my web.xml ? Am i not using correct servlet class and init-param in web.xml? My problem is not just Exception I am not sure about web.xml  resulting in following errors:  http status: 500  javax.servlet.ServletException: Servlet.init() for servlet [jersey-servlet] threw exception.  java.lang.NoClassDefFoundError: Could not initialize class org.glassfish.jersey.internal.inject.Providers  Below is my web.xml  <?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"     xmlns="http://xmlns.jcp.org/xml/ns/javaee"     xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"     id="WebApp_ID" version="3.1">     <display-name>RestWebService</display-name>     <servlet>         <servlet-name>jersey-servlet</servlet-name>         <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>         <init-param>             <param-name>jersey.config.server.provider.packages</param-name>             <param-value>com.swapnil.webservice</param-value>         </init-param>      </servlet>     <servlet-mapping>         <servlet-name>jersey-servlet</servlet-name>         <url-pattern>/rest/*</url-pattern>     </servlet-mapping> </web-app>   My java class:   package com.swapnil.webservice;  import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.PathParam; import javax.ws.rs.Produces; import javax.ws.rs.core.Context; import javax.ws.rs.core.HttpHeaders; import javax.ws.rs.core.MediaType;  @Path("*/helloWorld") public class HelloRestService {      @GET     @Produces(MediaType.TEXT_PLAIN)     @Path("name")     public String getGreeting(@Context HttpHeaders httpHeaders, @PathParam("name") String name) {         String greeting = "Hello" + name;         return greeting;     } }


AVR: Using ATmega328 Timer1 to create a delay

I am having some trouble wrapping my head around this, and it might just be some small error somewhere, that I keep missing .. but as it stands, I am trying to create a hardware "delay" that can run at the same time some code executes.  For practise purposes, I am simply trying to blink an LED at PD4 at an interval of 1 second.  I have used the following formula to determine the prescaler, and the value of the Output Compare Register A (OCR1A):    Using a prescaler of 256, I get a value for OCR1A of 62499:    Looking at the registers TCCR1A and TCCR1B in the datasheet, I set the Waveform Generation Mode bits (WGM) to use CTC and the Clock Select bits to use the 256 prescaler.  Now, in my main function, I am starting of by turning on the LED, then calling my function that should start the timer. I am then checking to see if the overflow flag has been set in TIFR1, and if it has, I am turning of the LED and writing a logic 1 to TOV1 to reset the overflow flag.  int main(void) {    DDRD = 0xFF;    PORTD = 0x00;     while (1) {        // Turn on LED at PD4       PORTD |= (1 << PD4);        oneSecondDelay();        // Checking to see if the overflow flag has been set       if (TOV1 == 1) {           // Turn off LED at PD4          PORTD &= ~(1 << PD4);           // Set 1 in the Output Compare A Flag to reset the overflow flag          TIFR1 = (1 << TOV1);       }    }     return 0; }   In my function I start off by setting OCR1A to the value that I calculated earlier. I then set the bits in the TCCR1B register that needs to be set for using the specific prescaler and CTC mode, and I then create a loop while waiting for the overflow event to happen; which I envision should take one second.  void oneSecondDelay() {    // Set the target value to 62499    OCR1A = 0xF423;     // Set prescaler to 256 and start the timer    TCCR1B |= (1 << WGM12) | (1 << CS12);     // Waiting for the overflow event    while ((TIFR1 & (1 <<  OCF1A))) {     } }   TLDR: Now the problem is that no matter what I can dream up, the LED is just constantly turned on, and I am not sure if I am setting the the wrong values in the registers, or if I am just having some brain farts?


Was just wondering is it possible to Install apks directly from pc. I am not talking it through Google play . I have a rooted device.


Is it a wise-decision to buy full-frame lenses for use on an APS-C body?

I have a Canon 550D which I've been using for around a year now. I really love it and have learned a great deal with this and the 18 - 135mm kit lens. But now with experience I feel the need to get some better glass. I won't be buying a new body any time soon because I figure investing in some good glass is more important.   As I have looked around, I see quite a few good used L lenses I can get in ebay for good bargain prices. But I know that the EF lenses don't have the same focal length in the cropped sensors. Is it a wise decision to buy these EF lenses or buy the cropped sensor alternatives?  I have the following lenses in mind that I am looking to buy down the line from the canon range over the next several months.  16-35mm f/2.8L, 24-70mm f/2.8L, 70-200 f/4L.  Are these apt choices for cropped sensors? I know most pros with FFs use these but I am a bit skeptic that they will serve the same purpose for me. If so what are the alternatives for this that have almost as good image quality?


Is she adult Rika in the final of Higurashi no Naku Koro ni Kai?

In the final scene of Higurashi no Naku Koro ni Kai, we see how the past of Takano changed when she was a child and eventually her parents don't die, then an adult version of Rika appeared.    What does it mean? Can Rika travel through the ages? Is she another version of Rika?