Why does Android Studio not deploy my latest changes to my device when I run my project?

Note:This question is not about how to fix a NullPointerException. This question is about why a piece of code that has been updated still generates a stacktrace in the Android Studio application for an older version.   I have a class that checks internet connectivity. This class, however, used to have an invalid piece of code, like this:  public class InternetConnectivityChecker {     private Context context;      public InternetConnectivityChecker(Context context) {         context = context;     }   I fixed this piece of code by changing it to:  public class InternetConnectivityChecker {     private Context context;      public InternetConnectivityChecker(Context context) {         this.context = context;     }   I kept getting a stacktrace, pasted below. To fix that, I decided to remove the invokation of the class altogether.  This class used to be called from SamaWebViewClient, on line 22. However, now it is not being called anymore:  public class SamaWebViewClient extends WebViewClient {     private com.sama7.sama.listeners.OnReceivedErrorListener onReceivedErrorListener;      public SamaWebViewClient(com.sama7.sama.listeners.OnReceivedErrorListener listener) {         this.onReceivedErrorListener = listener;     }      @Override     public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {             onReceivedErrorListener.onReceivedError();     }  }   However, now when I run my code in debug mode, even though I get 0 errors and 0 warnings in the Gradle Build window, this is what I see in logcat:  03-02 08:49:29.240 24373-24373/com.sama7.sama E/AndroidRuntime: FATAL EXCEPTION: main                                                             Process: com.sama7.sama, PID: 24373                                                                 java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference                                                                 at com.sama7.sama.InternetConnectivityChecker.isConnected(InternetConnectivityChecker.java:15)                                                                 at com.sama7.sama.SamaWebViewClient.onReceivedError(SamaWebViewClient.java:22)                                                                 at com.android.webview.chromium.WebViewContentsClientAdapter.onReceivedError(WebViewContentsClientAdapter.java:582)                                                                 at org.chromium.android_webview.AwContentsClient.onReceivedError(AwContentsClient.java:355)                                                                 at org.chromium.android_webview.AwContentsClientCallbackHelper$MyHandler.handleMessage(AwContentsClientCallbackHelper.java:160)                                                                 at android.os.Handler.dispatchMessage(Handler.java:102)                                                                 at android.os.Looper.loop(Looper.java:145)                                                                 at android.app.ActivityThread.main(ActivityThread.java:5832)                                                                 at          java.lang.reflect.Method.invoke(Native Method)                                                                 at     java.lang.reflect.Method.invoke(Method.java:372)                                                                 at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)                                                                 at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194) 03-02 08:49:38.015 24373-24373/com.sama7.sama I/Process: Sending signal. PID: 24373 SIG: 9   Why am I not getting the latest application built and deployed to my Samsung Galaxy S5 device?


How can one install android OS updates even when the manufacturer doesn't provide any? I have an android lollipop phone and wish to update it to marshmallow.


Does the noun "structure" require an article in this case?

Can I write "Structure is key to the clarity of writing" without a determiner before "structure"?


why does the phase change when wave reflects from rigid boundary

when the wave is reflected from open end there is no phase change but when it reflects from the rigid surface its phase changes.  in open surface its phase change is 0 and in rigid surface its phase change is pi. How is it possible. Is is possible to reflect from open end.


"MySQL server has gone away" since update to 3.8

I have a WordPress install on a dedicated server with decent memory (upwards of 8GB).  The WordPress install includes many plugins - 50 active plugins. Most important to note is the  plugin to make WordPress multilingual. The theme is .  The stack is LAMP - CentOS 6.3, Apache 2.4.4, Percona MySQL, PHP-FPM.  I have been quite stupid, and didn't set up a test or staging server.  Everything was running fine till I updated to WordPress 3.8, and also updated several plugins at the same time.  I didn't pay attention at the time, but all my widgets got messed up, and so did any sort of navigation etc.  I enabled error_log for a bit, i.e.  ini_set('log_errors',TRUE); ini_set('error_reporting', E_ALL); ini_set('error_log', dirname(__FILE__) . '/error_log.txt');   This resulted in an immense file - basically the error_log grows by about a GB every 4 minutes or so.  The primary error I found in the error log was database server disconnect, better known as      MySQL server has gone away   The first priority was to patch the problem. So I installed  plugin. This mostly, though not completely solved the issue. Many of the widgets came back.  However, the special (non-English) characters are all messed up (converted to question marks). I tried to fix this by opening wp-mysql-ping.php and commenting out   if ( !DB_CHARSET && version_compare(mysql_get_server_info($this->dbh), '4.1.0', '>='))                                     {                                         $this->query("SET NAMES '" . DB_CHARSET . "'");                                     }   Didn't help.  Besides, the plugin is not a permanent or complete solution. So leaving the site in this messed up state, I started working on other possibilities:  As suggested at , I edited my.cnf to add  wait_timeout = 60   Didn't help.  Also added caching to my.cnf  query_cache_type = 1 query_cache_limit = 8M query_cache_size = 512M   Didn't help.  (and yes, I restarted mysql every time I edited my.cnf)  Also tried the method : In wp-db.php before  $this->select( $this->dbname, $this->dbh );   I added  $this->query("set session wait_timeout=600" );   Didn't help.  I'm at my wit's end. Please help!


\arraystretch both horizontally and vertically

I did an \arraystretch to get taller column vectors, but not the matrices are too small. How can I also stretch them horizontally so that the matrices become square-like again?  Here's the code I used:   \renewcommand*{\arraystretch}{1.8}


Eject button is greyed out for external hard drive on Windows 10

When right clicking my hard drive in This PC, there is no Eject option on the context menu. Also the Eject button on the ribbon toolbar is greyed out so it won't let me click it. It only appears in safely remove hardware. How do I  get it back so it appears?


I want to escape an array in php  I try to escape with addslashes function but it doesn't work   while($row = $res->fetch_assoc())      {         $row['name']=addslashes($row['agente']); //escape ?         $rows[] = $row;     }   I want to escape the name of a person call 'Antonio cinà' but it doesn't work The problem is 'à'


In, at preposition for Room and building?

I want to specify a room in a building. I come up with three optimum sentences -     1-) In room_number at building_name      2-) In room_number in building_name      3-) At room_number in building_name   Though, I prefer to use the third one. But still, I want to know the best sentence in this case.  Though this is the only full phrase I wanna use, you can consider the full sentence as - "The meeting will be held in room_number in building_name."


How prove $E|X|^p<\infty$ and $E|Y|^p<\infty$, if $E|X+Y|^p<\infty$

Let two random variables $X$ and $Y$ be independent of each other, for some $p>0$, we have   $$E|X+Y|^p<\infty$$   Show that   $$E|X|^p<\infty,\quad E|Y|^p<\infty$$   My try: I know Minkowski inequality  $$E|X+Y|^p \leq E|X|^p + E|Y|^p, \tag{$0<p<1$}$$  But this inequality here is not useful, so how prove it? Thank you very much!


If $a\mid b$ then $\phi(a)\mid \phi(b)$ for $a,b\in\mathbb{N}$

Hey I would like to show that     $a\mid b\Rightarrow \varphi(a)\mid\varphi(b)\qquad a,b\in\mathbb{N}$   where $\varphi(n)$ is the the totient function.  My try:  Let $a,b\in\mathbb{N}$ and $a\mid b$. By Eulers formula we have that $$ \varphi(a)=a\cdot \prod_{\substack{p \mid a\\ p\ \text{prime}}} \Big(1-\frac{1}{p}\Big). $$ Now since $a\mid b$ by the Fundamental Theorem of Arithmetic we can factorise $a$ and $b$ into $$ a=\prod_{i=1}^{n} p_i^{\alpha_i} \qquad b=\prod_{i=1}^{m} p_i^{\beta_i} $$ with $p_i$ being primes, $n \le m$, and $\alpha_i \le \beta_i$ for $1 \le i \le n$. Using this we can say  $$ \left.\prod_{i=1}^{n} \Big(1-\frac{1}{p_i}\Big) \middle| \prod_{i=1}^{n}\Big(1-\frac{1}{p_i}\Big)\right. $$ and this concludes the result.   Now my question is that is this correct? If it is is there another way to arrive to this conclusion? My way of describing this felt a bit clucky.  Happy new years eve to all!


Shut down the computer, or shut the computer down?

I'm not sure what they're called, but I notice that 2-word verbs can be arranged around and yet both sound okay.     Have you tried out baseball yet?      Have you tried baseball out yet?   or     Do you want to take out your burger?      Do you want to take your burger out?   or     Remember to shut down the computer.      Remember to shut the computer down.   Which usage is correct?


How do I draw text at an angle using python's PIL?

Using Python I want to be able to draw text at different angles using PIL.  For example, imagine you were drawing the number around the face of a clock.  The number 3 would appear as expected whereas 12 would we drawn rotated counter-clockwise 90 degrees.  Therefore, I need to be able to draw many different strings at many different angles.


How can I achieve effective handdrawn line boil?

I am trying to achieve a  effect in a pose-by-pose animation. Similar, for example, to the effect achieved in  (I know this particular example was done with  rather than by hand).  My process is currently:   hand draw a pose trace second version of pose (with some deliberate tracing badness to achieve line boil) scan both poses repeat for new pose for each pose, display for desired period, looping through two versions   However, the effect is not as I intended. There is often an illusion of movement, rather than a mostly-still pose with vibrant lines, and my intuitions about which lines to boil, and how to boil them, is sometimes just plain wrong. How can I instead achieve an effective line boil? (For example, do I need more than two boiled versions per frame? If so, how many? What line variations generally work, and are there any in particular to avoid? Should I avoid any simulated movement, including gestures and mouth movement?)  (The software I am using happens to be GIMP + Inkscape, but this is mostly for aligning / tweaking images, not the actual drawing or animation. I believe the answer lies in what I'm drawing rather than software, but I'm tentatively open to software related advice.)


After "Oops! Something bad happened" one should be able to try again

Currently I have to manually remove the /error?aspxerrorpath= part from the address to try again. And right now a lot of Oopses happen!


I did already some research but can't find anything in my pc or on the internet about my cause. Some fans in my pc are suddenly getting loud for like 10 sec and than going quite again for like 5 and this keeps going. Or the temperatures on my pc are okay, I have never overclocked my pc and the noise is there even without using the pc.


A question about Intermediate Value Theorem

Let $f:[0,1] \rightarrow \mathbb{R}$ be a continuous function and $f(0)=f(1)$. Show that for all $n \in \mathbb{N}$ there is $x, 0 \leq x < x+\frac{1}{n} \leq 1,$ such that $f(x)=f(x+\frac{1}{n})$.  I define $g(t)=f(t+\frac{1}{n})-f(t)$ but I couldn't find appropriate $a,b$ such that $g(a)g(b)<0$.


How can I update the BIOS of my Dell laptop from Ubuntu?

I would like to know how I can update my laptop's BIOS from Ubuntu.   My laptop is a Dell E6430.  I see Dell released a version for Windows only, so is there a way to do it from Ubuntu?


I can easily find files with given string in name:  me@comp:/usr/local/hydra/hydra-7.4.2$ find -D stat -name "*hack*" ./hack881663129.txt ./hack881663129_7.txt ./hack881663129_5.txt ./hack881663129_4.txt ./hack881663129_4_7.txt ./hack881663129_6.txt ./hack881663129_1_6.txt ./hack881663129_8.txt   How can I also print file details, like size, date of creation etc.?


How to put a text coming after a div inside the div?

I have the following circle and header. I want the h4 to be centered inside the animating-circle div. I cannot put inside because I will rotate the circle, and I do not want the text to rotate. I have the following CSS. Currently, all circles are stacked into each other. I want them to have their own spacing. Thanks!   .animating-circle {   position: absolute;   min-width: 250px;   min-height: 250px;   box-sizing: border-box;   border: 1px solid black;   border-radius: 50%;   border-top-color: #f1c40f;   border-right-color: skyblue;   border-bottom-color: violet;   border-left-color: lightgray; }  .animating-circle+h4 {   position: relative;   top: 120px; }

Title is here


Is it: The programs will take place at 9 a.m., 11 a.m. and noon  Or: The programs will take place at 9 a.m., 11 a.m., and noon


Which file or directory dose "apt-get update" affect

I have updated my system and I want to do some tests needed to remove the cache. I know the command download the packages list from the repositories,but where is the local database to store this infomation.


I am having a hard time wrapping my head around the way to set up a taxonomy template page.  My goal is to create a taxonomy archive of a custom taxonomy I created. The page would only need to contain a list of all the terms in the taxonomy.  My main problem is not creating the list but more so naming the file correctly. Wouldn't the file be called taxonomy.php. How would I be able to view this page once I created it.


What's the best way to season a cast iron skillet?

I just purchased a new cast iron skillet. What's the best way to season it?   And if I need to re-season an old pan, is the process any different?


Compensate potentiometer wiper resistance with negative resistance

Is it possible to compensate a digital potentiometer's 75 ohm wiper resistance with a negative resistance amplifier?


Continue script if only one instance is running?

now this is embarrassing. I'm writing quick script and I can't figure out why this statement don't work.   if [ $(pidof -x test.sh | wc -w) -eq 1 ]; then echo Passed; fi   I also tried using back-ticks instead of $() but it still wouldn't work.  Can you see what is wrong with it? pidof -x test.sh | wc -w returns 1 if I run it inside of script, so I don't see any reason why basically if [ 1 -eq 1 ] wouldn't pass.  Thanks a lot!


Relay: higher voltage allowed at lower current?

Is it safe to use a 30VDC/1A relay for a voltage of 60V but a current of <100uA? E.g. this one:


Is composition of measurable functions measurable?

We know that if $ f: E \to \mathbb{R} $ is a Lebesgue-measurable function and $ g: \mathbb{R} \to \mathbb{R} $ is a continuous function, then $ g \circ f $ is Lebesgue-measurable. Can one replace the continuous function $ g $ by a Lebesgue-measurable function without affecting the validity of the previous result?


I have lets say 5 individual vertexes objects with the origin all set to the centre of the screen. How could I set each vertex to the geometry of each vertex?


Is it possible to Clone a Dinosaur with a full strand of their DNA?

If you have a full strand of Dinosaur DNA would it be possible to make it living and hatch a dinosaur? Or would it be a failure? Could you use a bird or alligator, for replacein


No Internet connection in Android-x86 4.2 ISO on VirtualBox

I installed Oracle VirtualBox on Windows 8. Then I downloaded android-x86-4.2-20121225.iso from .  After I installed Android x86-4.2 on VirtualBox from the ISO, I could run it, but the Internet is not working.  What can I do to troubleshoot this or get Internet connectivity?  Update:-  (1) I try it In VB, changing NAT connection settings to: AMD PCNet FAST III (Am79C973) but still not working   (2) I use other OS like windows XP with NAT connection settings to: AMD PCNet FAST III (Am79C973) setting that work nice like internet and everything. so plz give me a other option for android-x86-4.2-20121225 to connect internet ??


If electrons can be created and destroyed, then why can't charges be created or destroyed?

I read on Wikipedia that electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. Also, that they can be destroyed using pair annihilation. We also know that charge is a physical property which can be associated with electrons. My question is why can't charges be created or destroyed if electrons can?


Ohm's second law: step by step to obtain this law

Ohm's second law is valid only if the electric current is evenly distributed in the section of the conductor, i.e. in the case of direct electric current and its relation is the following as we all know:  $$R=\rho\,\frac{\ell}{S} \tag 1$$  where $R$ is the resistence knowing that the wire is characterized by a length $\ell$ and a cross-section of area $S$.  I ask you if exist a proof of the $(1)$ starting from Ohm's microscopic law:  $$\mathbf{J}=\sigma \mathbf{E}$$  Note: My question is not a duplicate or How can one derive Ohm's Law or affine questions. Every times that I ask a question there is always a problem (or downvote, or duplicate, or unclear, or bad English language).


i want to sorting hashmap (decending) in java

I want to sort this HashMap:  HashMap<Integer,Integer> hp=new HashMap<Integer,Integer>();  TreeMap<Integer,Integer> stm = new TreeMap<Integer,Integer>(); stm.putAll(hp);   In value reverse sorting.  If the values are the same, I will use key as the next condition. Value is reverse but key is not.


“““Quotations nested multiple times in their entirety.”””

Is anyone aware of an authoritative rule on how to use quotation marks for a statement that has been repeated in its entirety from one speaker, to a second, to a third, to a fourth, to a . . . . . .?  I understand basic nesting rules, but my (law) firm follows a convention that results in the following punctuation if a statement has been "passed down" through a series of speakers: "'"'"What goes up must come down."'"'"   This seems insane to me, but I can't find a "rule" that says to stop nesting entire quotes at a certain level.    I'm certainly interested in the group consensus, but even more interested in something authoritative.


How would I create a TikZ picture of the limaçon $r=0.5+\cos(\theta)$?   Would I have to convert it to cartesian coordinates or is there a way to plot the polar form?


Can external resources be cached for 7 days to improve my PageSpeed score?

Google Pagespeed recommends caching resources for at least a week under "". I've done it for internal files but I was wondering if something could malfunction if I did the same to social media files:   http://connect.facebook.net/en_US/all.js (20 minutes) http://platform.twitter.com/widgets.js (30 minutes) https://apis.google.com/js/api.js (30 minutes) https://apis.google.com/js/plusone.js (30 minutes) https://www.gstatic.com/swiffy/v7.1.1/runtime.js (50 minutes) http://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js (60 minutes) http://pagead2.googlesyndication.com/pagead/osd.js (60 minutes) https://oauth.googleusercontent.com/…e:rpc:shindig.random:shindig.sha1.js?c=2 (60 minutes) http://stats.g.doubleclick.net/dc.js (2 hours)   The numbers in parenthesis indicate current expiration time.


How do I use R code to solve for probability of normal distributions?

I don't understand which R code I am supposed to be using to figure these problems out. I brief explanation of what the code is doing would be amazing. The problems below are two different applications I'm expected to understand and I don't get either. Thank you!   Problem 1. Let Z~N(0,1) For each of the following, find c such that the equation is true.   a) P(Z<c) = 0.8413  b) P(0<Z<c) = 0.3051  c) P(-c<Z<c) = 0.8664   Problem 2. X~N(3,4) compute  a) P(X>3)  b) P(1<X<8)  c) P(-1.5<X<1)


How can I fix active quote mark characters on update to TL 2018?

MWE:  \documentclass{article} \usepackage[utf8]{inputenc} \usepackage{csquotes} \MakeAutoQuote{‘}{’} \MakeAutoQuote*{“}{”} \begin{document}   Hylo \end{document}   This code works fine with pdfLaTeX from TL 2017, but causes compilation errors with TL 2018.  ! Package csquotes Error: Invalid argument.  See the csquotes package documentation for explanation. Type  H <return>  for immediate help.  ...                                                l.15 \MakeAutoQuote{‘}{’}  ? h Only single characters with category code 12 or 13 may be allocated as active quotes. Numbers, punctuation marks, and characters which are part of LaTeX's syntax or reserved for a specific purpose are invalid.   How can I fix my csquotes configuration so that my chosen active quote mark characters continue to work? All my documents use these, so simply switching to a character the package now deems acceptable is not a practical option.  csquotes revision history does not list any changes for version 5.2c which would affect the user interface or package behaviour - there is no entry for this update in the list of such changes. So I would assume that what worked with 5.2b should work with 5.2c. Hence, I wonder if something outside the package has changed rather than the bump from b to c itself altering the behaviour.


Why English pronunciation differs so much from written language, compared to German?

Given that English is derived mostly from German, when Anglo-Saxons (German tribes) migrated to Britain, how do you explain that   although German has a strict correspondence between written language and spoken language (the sounds largely follow 1-1 what is written)... English has sooo intricate pronunciation rules, sometimes directly at odds with what is written? (Too bored to give examples, but it should be obvious).   My pet, tongue-in-cheek theory is that those tribes weren't too literate, didn't have a sound knowledge of the written form of words, so it was easy the pronunciation to follow its own independent path.   Anyone with a more informed explanation?


How to delete thousands of files that have names that are too long?

I'm using Windows 8.1 and have several backups that I want to delete, but the file names are too long for thousands of files.  How can I delete them?  All of the solutions I've seen require that I shorten the names of the files or directories which would be very tedious for this number of files.


A word to describe the act to switch between positive and negative?

I am doing some programming with math. I have written a tidy function which turns any positive number to negative or any negative number to a positive.  I would like to name this function in the most informative way so that if someone else were to look at my function; they would understand, straight away, what it does (and expect what it says on the tin).  The best word I can come up with is 'flip' but I feel that it fails at being obvious.  The function belongs to the Math object so it looks like this:  answer = Math.flip(number)   The results might be  -1 = Math.flip(1)   or  1 = Math.flip(-1)   How can I best describe this act?


Let (X, d) be a metric space. Show that the metric d is continuous. A metric space is a pair (X, d), formed by a nonempty set X and a function d: X × X → R≥0, called the distance or metric function of X, such that  d (x, y) = 0 if and only if x = y, d (x, y) = d (y, x) for all x, y ∈ X d (x, y) ≤ d (x, z) + d (z, y) for all x, y, z ∈ X please help


An efficent way to draw this graph on overleaf

I can't find an efficent way to draw this graph on overleaf. Any suggestions would be great!


How to restore a system after accidentally removing all kernels?

I was trying to delete old kernels, but I must have deleted all of the kernels on my Ubuntu 11.04 laptop. Is there any way to fix this via USB boot or mounting hard drive on another system?


How do those event registrations differ?

I've now found both ways of registring eventhandlers several times.  What's the difference?  public delegate void SomeEventHandler();  public class SomeClass {     public event SomeEventHandler SomeEvent; }  static void Main(string[] args) {     var sc1 = new SomeClass();     sc1.SomeEvent += new SomeEventHandler(a_SomeEventHandler);      var sc2 = new SomeClass();     sc2.SomeEvent += a_SomeEventHandler; }


How to see that an application (e.g. notepad) is launched at a certain point in time on Event Viewer in Windows 10?

I looked at "Windows log > Application" and "Windows log > Security". In both cases, I can not find any processes that indicating that the notepad was just launched by me. Does Event Viewer not log the event of launching the application such as notepad?


Reverse function has only one argument but recursive function is passing 2 parameters

#include <stdio.h> void reverse(int i); int main() {     reverse(1); } void reverse(int i) {     if (i > 5)         return ;     printf("%d ", i);     return reverse((i++, i)); }   please help me understand this code output of this code is 12345


How to split bibliography into "works cited" and "works not cited"?

I need two bib-like sections: a "References" giving works explicitly cited in my text, and a "Bibliography" (or "Further reading" if you prefer) giving everything from my bibfile that didn't already appear in "References". The first is of course completely standard, but the second... I'm stumped.  Further loose constraints: I'm somewhat committed to biblatex and the biblatex-apa style. But I'll happily accept an answer not related to them if there's any chance I can adapt it.


I'm trying to figure out how tunnel, both horizontally and vertically, through large bodies of water — preferably a method which can be used early in the game and which can be done with on-hand materials rather than a lot of setup.  In earlier versions of the game, water was permanently destroyed by blocks placed in it, allowing tunnels to be easily created by placing blocks, then hollowing them out.  As of Terraria 1.1, however, blocks seem to "store" the water they were placed in, which is then released when they are mined.  The  doesn't yet describe any techniques for dealing with this change.


Koma-Script (scrbook): twocolumn formatting and wide equation problem

I use scrbook class (see bellow) in my book and sometimes I need typeset wide equation.  \documentclass[%     ,fontsize=12pt    %      ,a3paper         % pagesize     ,twocolumn  ]{scrbook} \areaset[5mm]{250mm}{350mm} \unsettoc{toc}{twocolumn}   Is it possible to partially switch between one and two column formatting?  I tried to use the library widetext, but I'm afraid that it is not a part of the MiKTeX distribution. I would like to typeset wide equation in the text, not only at a bottom or top side. Is it possible?  MNWE: (added wide equation; for \setchaptertoc see )  \documentclass[twocolumn]{scrbook} \usepackage[nohints]{minitoc} \usepackage{amsmath, amsthm, amssymb, amsfonts, amsbsy} \usepackage{bigints} \usepackage{mathtools} \mtcsetrules{minitoc}{off} \usepackage{lipsum}  \newcommand*{\setchaptertoc}{%   \setchapterpreamble{   \vspace{1.85\baselineskip} % workaround for removed rule   \smash{\makebox[\linewidth]{\hrulefill}} % workaround for removed rule   \vspace{-1.85\baselineskip} % workaround for removed rule   \minitoc   \vspace{-1.15\baselineskip} % workaround for removed rule   \smash{\makebox[\linewidth]{\hrulefill}} % workaround for removed rule   \vspace{1.15\baselineskip} % workaround for removed rule }} \newcommand{\dd}[1]{\hspace{2pt}d#1}  \begin{document} \dominitoc \tableofcontents  \setchaptertoc \chapter{One} \lipsum[1]     \begin{equation}\label{fyz:fey_eq_elstat18}       E_x(x_1, y_1, z_1) =          \int\limits_{\substack{\text{all}\\\text{area}}}\varrho(x_2, y_2, z_2)         \frac{x_1-x_2}{[(x_1-x_2)^2+(y_1-y_2)^2+(z_1-z_2)^2]^{\frac{3}{2}}}\dd{x_2}\dd{y_2}\dd{z_2}     \end{equation}  \lipsum[1]     \section{One, one} \lipsum[2] \subsection{One, one, one} \lipsum[3] \section{One, two} \lipsum[4]  \setchaptertoc \chapter{Two} \lipsum[5] \section{Two, one} \lipsum[6] \section{Two, two} \subsection{two, two, one} \lipsum[7]  \setchaptertoc \chapter{Three} \section{Three, one} \lipsum[8] \section{Three, two} \lipsum[9] \end{document}


regarding the correct/incorrect use of the comma

There is a building which is taller than all others known as the Burj Khalifa.   Is a comma necessary after "others", which makes the sentence:     There is a building which is taller than all others, known as the Burj   Khalifa.   Should a comma be there or is it unnecessary?


What does why would I do it mean in this context?

I've often heard people saying this. And even I say it when someone accuses me of doing something that I didn't do.  I'd say:  Why would I do that?  But what's the grammar behind it?  Is it future from the past tense or something or what? It's obviously not a conditional construction 😒  Context from SE01 EP02 Austin & Ally  Austin: what does the jacket have to do with the music video?  Trish: It's a line in Ally's song, "my jacket's in the lost and found."  Ally: "my jacket"? It says "I like it." The line is "I like it when you hang around."  Dez: "hang around"? I thought it said "kangaroo." ♪ I like it when you kangaroo. ♪.  Ally: Why would I write "I like it when you kangaroo"?


$P(x)$ is a polynomial with leading coefficient $1$ and degree 2009 such that $P(0)=2008,~P(1)=2007,\cdots,P(2008)=0$

$P(x)$ is a polynomial with leading coefficient $1$ and degree 2009 such that $P(0)=2008,~P(1)=2007,~P(2)=2006,\cdots,P(2008)=0$. Find $P(x)$.   Using remainder theorem, If $P(x)$ is divided by $x-0$, the remainder is $P(0)=2008$. $$P(x)=xQ(x)+2008$$  How should I proceed?


If Eren Jaeger dies without transfering his titan powers, will both powers transfer to the same child?

It's told in the story that if a titan shifter dies without transferring his power, this power will go to an eldian person who just was born. If Eren Jaeger dies without transferring his titan powers, will the attack titan and the founding titan go to different persons?  Note that his is not a duplicate of  as this is not about what happens when a titan shifter dies. But what happens if a titan shifter with 2 powers dies, which is not answered in the answer.


Why enum's size is not optimized to 2 bytes?

We know that C store enum types internally as int, which means that the size of the enum is 4 bytes in 32/64 bit machine. But considering int is signed and range from −2,147,483,648 to 2,147,483,647, we certainly don't need that many available values. We can use unsigned short (max 65,535) or even unsigned char (max 255) suffices. So my questions are: Q1-why C don't make enum type store unsigned short/char internally? Q2-Why we need to use typedef to declare an enum e.g typedef enum { N_LEAF, N_INTERNAL } nodetype_t;  but we don't need to use typedef in struct declaration e.g struct node_s {    char c;    int i[2]; };  Why we can't make enum declaration the same as struct as: enum { N_LEAF, N_INTERNAL } nodetype_t;


I have the Yoga 2 pro (touchscreen convertible). In tent or stand mode, with no access to the keyboard, what is the quickest way to switch between open tabs in Internet Explorer (running in Modern UI)?


Maclaurin expansion of $(1+x)^{82}$ and its accuracy

Sorry for the title it may be a very bad one. The whole question is as following:  How many terms of the Maclaurin expansion of $(1+x)^{82}$ are needed to guarantee finding a value of $1.1^{82}$ accurate to within $10^{-6}$?


How do I install tor on my ubuntu system?

I have Ubuntu 10.04 LTS 64 bit OS. How do I install tor so that it works and doesn't give me an error message? I got tor as an archive file (tar.gz) and I have an amdx64 architecture. I am new to linux as I am coming from a windows background. Please help.


How to tell if the Windows Installer boots in EFI or BIOS?

I have a Windows 7 x64 install USB and want to know if the installer has booted into EFI or BIOS mode.  I found a solution , but it doesn't work since notepad couldn't find: \Windows\Panther\setupact.log


which functions can be obtained as a composition of a continuous function with itself?

let $f(x)=x^2$, then $f(f(x))=x^4$, so $x^4$ is a continuous function from $\Bbb R$ to $\Bbb R$ which can be obtained as $f\circ f$ for a continuous $f\colon \Bbb R\to \Bbb R$. general example: for $f(x)=|x|^{\sqrt{d}}$, $d>0$, we have $(f\circ f)(x)=|x|^d$.  I wonder if it is possible to find for example continuous functions $f\colon \Bbb R\to \Bbb R$ such that  $f(f(x))=x^2+1$  $f(f(x))=x^3$  $f(f(x))=\sin x$  $f(f(x))=\arcsin x$  $f(f(x))=\ln x$  $f(f(x))=e^x$  Is it known?   I don't know which theory can be applied to such problem, I formulated these questions while walking with my dog :-)  Are there any general results or counterexamples?


Is there a word or a phrase that could be used instead of the cringy "and/or" thing? It looks rather bad in an english paper and I can't come up with a short version of expressing it.   Ex: There was always a car and/or a motorcycle in the parking lot.  Thanks for all the answers in advance,  Thomas


What's the term in music, where the singer uses words without meaning?

I've been searching for the word, which is used for describing parts of lyrics, where the singer sings for example the whole refrain only using words of syllables without any meaning. Maybe you could help? (here's one song with that type of refrain: )


What is $\mathbb E[X\mid \sin(X)]$ when $X$ is uniform on $[0,\pi]$?

Suppose that $X$ is uniformly distributed on $[0,\pi]$. Find $\mathbb{E}[X \mid\sin (X)]$.   My attempt:   $$\mathbb{E}[X\mid \sin (X)] = \int_{0}^{\pi} \dfrac{1}{\pi} f_{X\mid \sin (X)}(x) \,  \mathrm{d}x$$  How would I calculate $f(X\mid \sin (X))$?


Port 25 won't open on Digital Ocean droplet

I’m trying to set up an email server. I can’t seem to get port 25 to open for me. I literally just did: ufw disable  ufw reset  ufw default deny incoming  ufw default allow outgoing  sudo ufw allow 22/tcp  sudo ufw allow 25  sudo ufw enable  And then sudo ufw status verbose… Status: active Logging: on (low) Default: deny (incoming), allow (outgoing), disabled (routed) New profiles: skip  To                         Action      From --                         ------      ---- 22/tcp                     ALLOW IN    Anywhere                   25                         ALLOW IN    Anywhere                   22/tcp (v6)                ALLOW IN    Anywhere (v6)              25 (v6)                    ALLOW IN    Anywhere (v6)     However, one cursory glance of sudo netstat -tulpn | grep LISTEN and.. tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      512/systemd-resolve  tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      664/sshd: /usr/sbin  tcp6       0      0 :::22                   :::*                    LISTEN      664/sshd: /usr/sbin   and telnet [my server IP] 25: telnet: Unable to connect to remote host: Connection refused  What gives? How can I open up my ports? UPDATE At the advice of the users here, I decided to install Postfix now and check again if the ports are now being acknowledged.. sudo netstat -tulpn | grep LISTEN tcp        0      0 127.0.0.53:53           0.0.0.0:*               LISTEN      512/systemd-resolve  tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      664/sshd: /usr/sbin  tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN      43246/master         tcp6       0      0 :::22                   :::*                    LISTEN      664/sshd: /usr/sbin  tcp6       0      0 :::25                   :::*                    LISTEN      43246/master       and telnet [my server IP] 25 Trying [my server IP]... Connected to [my server IP] Escape character is '^]'. 220 ubuntu-s-1vcpu-1gb-lon1-01 ESMTP Postfix (Ubuntu)  It seems it's connected, but does that mean the port is open?


Just this - How do you add a timer to a C# console application? It would be great if you could supply some example coding.


Exhibit an integral domain $R$ and a non-zero non-unit element of $R$ that is not a product of irreducibles.   My thoughts so far: I don't really have a clue. Could anyone direct me on how to think about this? I'm struggling to get my head round irreducibles.  Thanks.


Configuring Hibernate logging using Log4j XML config file?

I haven't been able to find any documentation on how to configure Hibernate's logging using the XML style configuration file for Log4j.  Is this even possible or do I have use a properties style configuration file to control Hibernate's logging?  If anyone has any information or links to documentation it would appreciated.  EDIT: Just to clarify, I am looking for an example of the actual XML syntax to control Hibernate.  EDIT2: Here is what I have in my XML config file.  <?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">  <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">     <appender name="console" class="org.apache.log4j.ConsoleAppender">         <param name="Threshold" value="info"/>         <param name="Target" value="System.out"/>         <layout class="org.apache.log4j.PatternLayout">             <param name="ConversionPattern" value="%d{ABSOLUTE} [%t] %-5p %c{1} - %m%n"/>         </layout>     </appender>     <appender name="rolling-file" class="org.apache.log4j.RollingFileAppender">         <param name="file" value="Program-Name.log"/>         <param name="MaxFileSize" value="1000KB"/>     <!-- Keep one backup file -->         <param name="MaxBackupIndex" value="4"/>         <layout class="org.apache.log4j.PatternLayout">             <param name="ConversionPattern" value="%d [%t] %-5p %l - %m%n"/>         </layout>     </appender>      <root>         <priority value ="debug" />         <appender-ref ref="console" />         <appender-ref ref="rolling-file" />     </root> </log4j:configuration>   Logging works fine but I am looking for a way to step down and control the hibernate logging in way that separate from my application level logging, as it currently is flooding my logs. I have found examples of using the preference file to do this, I was just wondering how I can do this in a XML file.


I just observed related questions  contained a post that has a score higher than 999, causing it to look different from the others:        I think it should be consistent.  As per , either it should show 1k or it should look something like:        The post is marked as status-completed but it still appearing not fixed to me:


Folders Completely Hidden Except via Save As

I'm using an audio program called Supercollider on Windows 10. I have saved some files in a folder called "tunes" from SC via Save As, but Windows Explorer and CMD both seem unable to recognise access or recognise the "tunes" folder.  C:\Users\HP>cd "C:\Program Files (x86)\SuperCollider-3.7.2\supercollider-robin\tunes" The system cannot find the path specified.  C:\Program Files (x86)\SuperCollider-3.7.2\supercollider-robin>dir/a doesn't show it either.  However, when saving from SC with Save As, it's there clear as day. I can even shift+right-click to get the path: "C:\Program Files (x86)\SuperCollider-3.7.2\supercollider-robin\tunes"  This makes no sense to me. Can anyone explain and tell me how to access my folder tunes folder please?


Prove the identity $\sum_{{{\underset{k-even}{k=0}}}}^{n}{n \choose k}2^{k}=\frac{3^{n}+(-1)^{n}}{2}$

I need to prove the following identity:  $\sum_{{{\underset{k-even}{k=0}}}}^{n}{n \choose k}2^{k}=\frac{3^{n}+(-1)^{n}}{2}$  I know that -   $\sum_{k=0}^{n}{n \choose k}2^{k}=3^{n}$  but don't know how to continue.


Why are checks preferred to wire transfers in the US?

When moving to the US from Switzerland, I have been surprised by the difference in banking systems. One point that interests me particularly is the use of checks vs wire transfers.  In Switzerland, the default way of paying somebody is to transfer money to their account. This is free, can be done online, and the money arrives the next day. It's a bit like PayPal, except that payments cannot be undone.  In the US, from what I've learned so far, to pay somebody I write a check on their name. The payee then brings the check to a bank to receive the money. Wire transfers in the US seem to incur high fees.  From a newcomer's perspective, the US system seems more complicated, more expensive, and more prone to fraud. What are its advantages? Why are things the way they are?


Automatically make user local administrator on their computer through GPO?

In our AD 2003 domain each user gets local admin permissions on their computer.  Everyone else can login with their domain account as normal user.  Right now this means going to the desktop and manually adding the user as a local administrator.  Is there any way to automate this process through logon scripts or GPOs?  I have found ways to use a gpo to make everyone who logs in to a computer a local admin, but really only want to give it to the primary user (or in some cases users) of the computer.  I've also seen methods that required adding a group for each computer...but really dont want to clutter AD like that.  I do have a list mapping each user to each computer name.  If it matters the desktops are a mix of xp and win7.


How to use the iPhone microphone when connected with Bluetooth to a speaker?

I would like to ask you how to use the iPhone microphone when connected to a speaker? The speaker don't have its own microphone and I should disconnect the speaker every time when I have to talk  for example. Any ideas is this possible?


Can anyone help me prove that in the most simple way possible?


It seems to me that my costlier (Tamron 90 f/2.8 macro) lens gives better colors than my cheap Canon 18-55 IS kit lens.  So does lens matter for color quality? What physical processes are involved in that?


My 12 year old computer finally gave up the ghost. I just bought a new computer a month earlier, but that's a different story. Just say procrastination. The problem with the old computer was not the hard drive. After a recent power outage [dozens over the years] the BIOS system fizzled out. Basically 12 years of accumulated research and downloads is still intact on my old hard drive. I believe that I can add the old hard drive to my new computer. Haven't tried it yet. I'm not sure if I can read the Ubuntu ISO of my old hard drive or what to do. As far as locating files or even my old desktop. Yes, I have Ubuntu 18.04 on my new computer. Any help would be appreciated.


How do I determine reflection matrix over a line through the origin with direction vector $\vec{v}=\left(a,b\right) ^{T}$?

I don't understand this really good and couldnt find anything helpful on internet. I only found in book the following: A is the matrix with reflection over line through the origin with direction vector $\left(\cos(\frac{\alpha }{2} ) , \sin(\frac{\alpha }{2} ) \right) ^{T}$ $A=\begin{pmatrix} \cos(\alpha ) & \sin(\alpha ) \\ \sin(\alpha )  & -\cos(\alpha )    \end{pmatrix}$ I'm not sure how to connect this from book to solve it, because there is another direction vector.


UTF-8 encoding problems in MySQL DB (php)

I have problems with UTF-8 encoding in MySQL DB. I use HTML form to insert data in MySQL DB and PHP code to represent the data from DB. When I insert string "ąčęėįšųū" using HTML form, I see such “Ä…ÄÄ™Ä—Ä¯Å¡Å³Å«” symbols in DB in PHPMyAdmin. I don’t have problem with data representation on the WEB, the string “Ä…ÄÄ™Ä—Ä¯Å¡Å³Å«” is represented trough select function as "ąčęėįšųū".  My goal is to store data "ąčęėįšųū" not “Ä…ÄÄ™Ä—Ä¯Å¡Å³Å«”. Do you know how to solve this problem?   MySQL setting > my.ini   init-connect=SET NAMES  utf8 collation_server=utf8_unicode_ci  character_set_server=utf8  DB settings:  Database Collation > utf8_general_ci  Table Collation > utf8_general_ci  Field “Title” collation > utf8_general_ci  Apache > php.ini:   default_charset="UTF-8"  HTML form to submit data:    <!doctype html> <html>  <head>   <meta charset="utf-8">   <title>Untitled Document</title> </head>  <body>   <form id="form1" name="form1" method="post" action="tournaments-action.php" accept-charset="utf-8">     <p>       <label for="textfield">Text Field:</label>       <input type="text" name="title" id="textfield">     </p>     <p>       <input type="submit" name="submit" id="submit" value="Submit">     </p>   </form> </body>  </html>     PHP form for submiting data:    <?php include("../config.php");  $title = mysqli_real_escape_string($db, $_REQUEST['title']);  // attempt insert query execution $sql = "INSERT INTO tournaments (title) VALUES ('$title')";  if(mysqli_query($db, $sql)){    $msg="Records added successfully.";    echo "Loading"; } else{  $msg="ERROR: Could not able to execute $sql. ";     echo "Loading"; } // close connection mysqli_close($db); ?>


What are the differences between executing shell scripts using "source file.sh", "./file.sh", "sh file.sh", ". ./file.sh"?

Have a look at the code:  #!/bin/bash read -p "Eneter 1 for UID and 2 for LOGNAME" choice if [ $choice -eq 1 ] then         read -p "Enter UID:  " uid         logname=`cat /etc/passwd | grep $uid | cut -f1 -d:` else         read -p "Enter Logname:  " logname fi not=`ps -au$logname | grep -c bash` echo  "The number of terminals opened by $logname are $not"   This code is used to find out the number of terminals opened by a user on the same PC. Now there are two users logged on, say x and y. I am currently logged in as y and there are 3 terminals open in user x. If I execute this code in y using different ways as mentioned above the results are :  $ ./file.sh The number of terminals opened by x are 3  $ bash file.sh The number of terminals opened by x are 5  $ sh file.sh The number of terminals opened by x are 3  $ source file.sh The number of terminals opened by x are 4  $ . ./file.sh The number of terminals opened by x are 4   Note: I passed 1 and uid 1000 to all these executables.  Now can you please explain the differences among all these?


I have VMware Player running in Windows 7 and I need the Ubuntu 12.04.3 LTS Precise Pangolin  for a project. Could anyone help me where can I download the Ubuntu 12.04.3 LTS to run it in VMware Player, please?


After beating the game, I still have several empty inventory spots.  I most likely missed several items in my addicted frenzy to finish the game.  What are all the items that can be found in the game? And where can they found?


Analytic solution of: ${u}''+\frac{1}{x}{u}'=-\delta e^{u}$

I am trying to find the analytic solution of  $${u}''+\frac{1}{x}{u}'=-\delta e^{u}$$ given the homogeneous mixed boundary conditions  $${u'(0)}=0$$ $$u(1)=0$$  How would one attack such a problem? I have been given that the analytic solution is  $$u=ln\left ( \frac{8a/\delta }{(ax^2+1)^2} \right )$$  where $a$ solves $8a=\delta (a+1)^2$.    My approach (EDITED):  I was given a hint: use the relation $x=e^{-y}$. I proceeded with that and used the chain-rule as follows $$(u\circ y)'(x)=\frac{d}{dx}u(y(x))=u'(y(x))y'(x)=u'x=-u'e^{y}$$ $$(u\circ y)''(x)=\frac{d}{dx}[u'(y(x))y'(x)]=u''(y(x))[y'(x)]^2+u'(y(x))y''(x)=u''e^{2y}+u'e^{2y}$$ substituting these relations into the ODE yields $$e^{2y}u''=-\delta e^{u}$$ or in an alternative form $$u''=-\delta e^{-2y} e^{u}$$  which is separable (thanks for the help).


How do I get all the values of a Dictionary as an IList?

I have a the following dictionary:  IDictionary<int, IList<MyClass>> myDictionary    and I am wanting to get all the values in the dictionary as an IList....    Just to add a bit of a background as to how I've gotten into this situation....  I have a method that gets me a list of MyClass. I then have another method that converts that list into a dictionary where they key is the id for MyClass. Later on...and without access to that original list...I'm needing to obtain the original ungrouped list of MyClass.    When I pass myDictionary.Values.ToList() to a method that takes an IList I get a compile error that says that it can't convert from   System.Collections.Generic.List<System.Collections.Generic.IList<MyClass>>    to:  System.Collections.Generic.IList<MyClass>   Now, I can understand that its gone and added each of the groups of IList to the new list as separate elements of the list....but in this instance its not really what I'm after. I just want a list of all the values in the entire dictionary.  How then can I get what I'm after without looping through each of the key values in the dictionary and creating the list I want?


BibTeX: found no \citation \bibdata \bibstyle

I know there are some rather similar questions. I have read an tried most of them, but it doesn't work in my code. simplified i use this code in my latex document:  \documentclass{article} \usepackage{biblatex} \addbibresource{bibtex.bib}   \begin{document} test test\cite{Buch1}   \printbibliography \end{document}   If I compile the code (using bibtex) in Texmaker I get folowing messages:   Process started  This is BibTeX, Version 0.99d (MiKTeX 2.9.7250 64-bit) The top-level auxiliary file: TEst.aux I found no \citation commands---while reading file TEst.aux I found no \bibdata command---while reading file TEst.aux I found no \bibstyle command---while reading file TEst.aux (There were 3 error messages)  Process exited with error(s)    I have already made sure, that the editor uses biber and not bibtex. I also tried TexWorks but got same messages. What else could be the problem?


suppose that $u$ is differentiable function and verifies: $$\lim_{x\to +\infty}u(x)=1$$ do we have $\lim_{x\to +\infty}u'(x)=0$?  My idea: we inserve limits   $$\lim_{x\to +\infty}u'(x)=lim_{x\to +\infty}\lim_{h\to 0}\frac{u(x+h)-u(x)}{h}=\lim_{h\to 0}lim_{x\to +\infty}\frac{u(x+h)-u(x)}{h}=\lim_{h\to 0}\frac{1-1}{h}=0$$


I don't really understand the meaning of the term: "Industry sources" in this text. please aware me. "Details of the agreement have yet to be made public, but industry sources have said Noble and Delek will be allowed to keep control of Leviathan, the world's largest offshore gas discovery of the past decade. "


I've tried alt+0198but it doesn't work. I guess that only works in Windows. How do I type it in Ubuntu?


Simplest way to calculate the intersect area of two rectangles

I have a problem where I have TWO NON-rotated rectangles (given as two point tuples {x1 x2 y1 y2}) and I like to calculate their intersect area. I have seen  more general  to this question, e.g. more rectangles or even rotated ones, and I was wondering whether there is a much simpler solution as I only have two non-rotated rectangles.   What I imagine should be achievable is an algorithm that only uses addition, subtraction and multiplication, possibly abs() as well. What certainly should not be used are min/max, equal, greater/smaller and so on, which would make the question obsolete.  Thank you!  EDIT 2: okay, it's become too easy using min/max or abs(). Can somebody show or disprove the case only using add/sub/mul?  EDIT: let's relax it a little bit, only conditional expressions (e.g. if, case) are prohibited!  PS: I have been thinking about it for a half hour, without success, maybe I am now too old for this :)


How can I reinstall Windows 7 if I lost my installation DVD?

Possible Duplicate:          I have lost my Windows 7 installation DVD, but I do have the license key. How can I get a Windows 7 DVD? Can I download an ISO image somewhere? While installing can I use my original Windows 7 Key?


I have received a shapefile with measurement points to be analyzed, but no matter how I try, I can't find how to convert to lat lon. I suppose it would be good to know the projection but when I look into the file (with R and summary()) it says "Is projected: NA" and "proj4string : [NA]".  One measurement-point I know is close to the border Peru-Chile has x,y = 354521, 7997417.8.  How can I find out how to convert this point (and many others) to lat lon?   I tried to follow the instructions of similar questions here, but to no avail.


I have an AMD Raedon 6770 graphics card in my computer, and for some reason I'm unable to get Ubuntu 13.10 to read it. I had another copy of 13.10 on my desktop, but when I tried to install the .run file for the card from the terminal, it corrupted something within my operating system and I could no longer get Ubuntu to boot. I'm fairly new to this operating system, but am beginning to grasp the concept pretty fast. Is there anyway to add a library of screen resolutions? I really need something with a 16:9 ratio for my Emerson TV screen which I'm using as my monitor, and currently only 4:3 is available (linked tv to computer through a monitor cable).  I've also tried to run a few xrandr commands without any success. Any suggestions would be greatly appreciated!


Why is possible for some answered questions to be deleted on some SE sites but not on others?

It didn't fit in the title, but I'm talking about questions answered by others, i.e. not self-answered . On some SE sites (e.g. politics, if I recall correctly) one cannot delete his own question that has been answered by others, while on other SE sites (e.g. on psychology) such an action is possible. Why this difference? Is there a site-wide flag controlling this behavior?


Resample random forest OOB to choose number of trees?

My post was inspired by this one ()  Although random forest models do not overfit$^{1,2}$, it can be good to know how many trees are needed for a stable solution.  My question is about the best way to calculate OOB to know when additional trees no longer provide benefit (i.e. the OOB error is stable). As I understand it we have $B$ trees fit to $B$ many bagged datasets of size $N$, trying $\sqrt{p}$ predictors at each split. After fitting all of the trees we predict the class for every observation using only the trees for which it was withheld and then comparing it to the known class. This gives a misclassification rate for each tree and each observation (these become the predicted probabilities).  In R you can plot the sequential cumulative average of the OOB errors:    You can also do this in Python but requires a little more work since the trees are created sequentially$^{3,4}$.  It seems to me that when the number of trees in small (e.g. 1) there should be high variance in the OOB error. In other words if I fit 100 random forest models with 5 trees the average OOB error will have greater variance than if I fit 100 random forest models with 50 trees. Of course since we can fit the trees in parallel it is easy to grow many trees at once for a single model.  Does it make sense to calculate some sort of boosted OOB where the OOB score for $n$ trees is the average of $b$ samples of trees? For example take 10 samples of 5 trees out of the 500 trees and calculate the average OOB score from that. Then when the variance at number of trees $n$ is small stop growing trees (perhaps calculate something similar to the Gelman-Rubin statistic for MCMC convergence).  Since trees should be grown randomly rather than sequentially I'm not sure how much value there is to this, especially since I think the OOB error converges fairly quickly in most cases. However with larger datasets this may save some computational time when the number of trees needed is unknown.   Breiman states random forest models do not overfit:  but Mark R. Segal (April 14 2004. "Machine Learning Benchmarks and Random Forest Regression." Center for Bioinformatics & Molecular Biostatistics) says it can for noisy datasets ()


I believe I have solved a famous open problem. How do I convince people in the field that I am not a crank?

I am interested in the situation where you have a very interesting result. For instance, you have solved a very important open problem. However, you are not known in the field and do not have any remarkable publications. Your supervisor thinks the work is good and you submit the work to a high profile journal, but you get rejected.  The thing is that the contribution is very strong. It breaks what most people believe or what they have already proven: e.g., you solve the P vs. NP problem or any other well known open problem.   The reviewers strongly reject your work with no justification and they do not state why the result is wrong. Examples of reviewer comments include:   "The proof must be wrong."  "You cannot achieve such a result."  "You do not understand well the notion of ..."   My question is what to do in this situation? Where to go? If your advisor accepts the work, but the reviewers from the top journal reject the work without even explaining the mistakes,  what should you do?


Child document embedding in lyx creates a redundant blank in the end

Child document created by lyx is this. %% LyX 2.3.3 created this file.  For more info, see http://www.lyx.org/. %% Do not edit unless you really know what you are doing. \documentclass[english]{article} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage{babel} \begin{document} Hello \end{document}  The parent document has this child document. %% LyX 2.3.3 created this file.  For more info, see http://www.lyx.org/. %% Do not edit unless you really know what you are doing. \documentclass[english]{article} \usepackage[T1]{fontenc} \usepackage[latin9]{inputenc} \usepackage{setspace} \usepackage{babel} \begin{document} \begin{onehalfspace} \input{Hello.tex}. \end{onehalfspace} \end{document}  Then, if I convert using pdflatex, I don't get "Hello." I get a redundant blank so I get "Hello ." How can I fix this?


Can we get some consensus on what flag to use for link only answers?

Related:  (not a dupe, that's a feature request and was closed as a dupe of another one)        (old) post does indeed say that Link-only answers can be flagged as NAA, but there are a lot of posts like  which define Not An Answer is a way that it doesn't apply to link-only answers.  Can we get some up-to-date consensus on this? That link only answers are not allowed is .


Command Block should only activate if someone logs on

How would I run a command block that only runs if someone logs on? By the way, it should somehow activate another command block that has the command in it as it needs a whole command block to work


How to avoid cutting labels along the map border?

I am labeling areas on a map (for example, forest (coniferous, deciduous trees), swampland, and so on).  A cartographer has criticized it because labels which extend beyond the boundaries of the specific areas are cut off.  Therefore, I would like to show only those labels that are completely contained within the area.  (I tried to work around the problem by masking the area with an internal buffer of the area's border, but that only cuts the labels along the buffer boundary.)  I would appreciate any ideas about how this could be accomplished with QGIS 1.80.   Thank you, whuber,  for your assistance*


Selecting a string with funny character from mysqli using php

So I'm trying to find "Wrocław" in my Mysql table with collation utf8_general_ci.  In PHP, I'm using this code  $query = $mysqli->query(" SELECT *    FROM locations  WHERE location    LIKE 'Wrocław' ") or die(mysqli_error($mysqli)); while($row = mysqli_fetch_array($query)) { echo'found it'; exit; }   However, I'm not getting any results. I will get a result when searching for "Barcelona". So I'm guessing that the problem is due to the funny character "ł".   When entering the above Query in PhpMyAdmin, I am in fact finding the row containing "Wrocław" which is the expect result.  Any idea why it's not working on the PHP side? I've also tried to previously use mysqli_real_escape_string on Wrocław  Thanks!


So is there no way for me to move a file from internal memory to the external SD card in Android KitKat version? I used to use Wifi Transfer style apps to move stuff from my laptop to the internal memory, and then move them to the SD Card using one of the many explorer apps for Android. Is this not possible at all anymore??  Seems like an uncalled for restriction!


How to change the Start Menu icon for a Windows Application?

How do you change the icon for a Windows Application on the Start Menu? My specific target is Skype.


Could someone give an example of a ‘very’ discontinuous derivative? I myself can only come up with examples where the derivative is discontinuous at only one point. I am assuming the function is real-valued and defined on a bounded interval.


Canonical vs. non-canonical terminal input

I am studying for an exam and I am confused as to how canonical vs. non-canonical input/output works in Unix (e.g., curses).  I understand that there is a buffer to which "line disciplines" are applied for canonical input.  Does this mean that the buffer is bypassed for non-canonical input, or does it simply mean that no line disciplines are applied?  How does this process differ for input and output operations?  In the curses programs I have worked with that demonstrate canonical input, the input typed by a user is automatically entered either after a certain number of characters have been typed or a certain amount of time has passed.  Are either of these things considered "line disciplines" or is this something else entirely?


Reinstalling windows 10 free upgrade, which key should i use

Hello my parents updated their laptop with Windows 7 to Windows 10, apparently by mistake. Since they do it themselves, I did not see the terms of conditions nor any information displayed before the upgrade. Since then they get used to the new appearance of windows so I did not do the rollback to windows 7 for them.   Now I start wondering if in the future I will do the disk format and fresh install of windows (which I usually do for them every 3 - 4 years), how will I be able to activate their copy of Windows 10 after fresh installation? Will I be able to use their Win7 key?  Please note that my parents do not have the hotmail account, and I don't want to force them to make one.


Resistance to electric current in conductors

Why does the resistance to electric current increases in a conductor when the temperature is increased?


Trying to remember the name of a series I saw around 15 years ago

I sadly cannot remember much about it except that the magic system was based on a spectrum of color.  There were two main characters (one male, one female), and the second book started with them offering a 'blood sacrifice' to bind storm spirits to them on a hill.


Why does Nikon SB-910 flash fire three times on Nikon D850?

I have a new Nikon D850, and I'm using the Nikon SB-910 flash. When I take a shot, the flash pops 3 short flashes. Then the shutter engages, and the full flash goes off. The batteries are OK.  Does anybody have any ideas what the issue could be?


What happens when I change a variable in a factory function? (javascript)

the following factory function has on = false. function Radio(mode) {   let on = false;    return {     mode: mode,     turnOn: function () {       on = true;     },     isOn: function () {       return on;     }   }; }  If I created an object using this factory function and used the function fmRadio.turnOn(); inside it to change the value of on to be true like in the following lines.. let fmRadio = Radio('fm');  fmRadio.turnOn();  The output of fmRadio.isOn(); will be on = true So, Where does on variable change? I mean it's not part of the fmRadio object created..if we tried to call it it will return undefined fmRadio.on; //undefined  Does it change the value of on in the original factory function?


Running a computer without Integrated Graphics or Dedicated GPU

Is it possible to run a computer without integrated graphics and no dedicated gpu?  If so would it be able to perform basic functions such as browsing the web.  If not then why wouldn't it work?


Why is bias term not included in Regularization (Regression/Classification)?

I read different articles including .   Why is bias term not included in regularization, in general? I see some of the algorithms such as LinearSVC includes bias term in regularization. Also, is bias term used for only predicting minimum value possible when all weights are zero? What is its significance exactly?


I have a JAR file named helloworld.jar. In order to run it, I'm executing the following command in a command-line window:  java -jar helloworld.jar   This works fine, but how do I execute it with double-click instead? Do I need to install any software?


So my mom claimed me for 2018 Taxes when she shouldn’t have. For 2019 taxes I filed my taxes on April 3rd this year. I am a college student currently part time but my parents do not provide for me financially so they shouldn’t be able to claim me which they didn’t. I support myself with two jobs making over 40k a year My parents didn’t claim me this year. Would I still be eligible for the check?


I'm trying to round a number the 100.  Example:  1340 should become 1400 1301 should become 1400   and  298 should become 300 200 should stay   200   I know about Math.round but it doesn't round to the 100.  How can I do that ?


Help understanding this sentence structure: "many a congressman was"

Jawaharlal Nehru was the first prime minister of India. Below is a quote from his autobiography.     Many a Congressman was a communalist under his national cloak   I am sure this sentence is grammatically correct but somehow I find it quite unnatural, particularly the "many a congressman was" part. Shouldn't this sentence be simply written as:     Many congressmen were communalist under their national cloak   Can someone please explain the above quote and maybe give some common examples of similar usage?


What is the best way to replace all '&lt' with &lt; in a given database column? Basically perform s/&lt[^;]/&lt;/gi  Notes:   must work in  2000 Must be repeatable (and not end up with &lt;;;;;;;;;;)


how many isomorphism are there from $Z_{12}$ to $Z_4\oplus Z_3$??

Isommorphism that maps identity elements of each group. But how to find the number of such isomorphism.


How to typeset mathematical set with conditions in multiple rows

With the TeX code  \begin{equation}   \max\left\{ \sum_{i=1}^{n}|\langle x^{(i)},b\rangle|^2\;\mid\vbox{   \hbox{Condition 1}   \hbox{Condition 2}   \hbox{Condition 3} }\right\} \end{equation}   I get the output    How can I achieve the following two things?   The separator produced by \mid shall have the same height as the curly brackets. The three conditions shall be centered vertically.


After a refusal (V4.2(a)(c)) proving I have sufficient funds when applying for a UK Standard visit visa

I applied for a standard visitor visa to the UK for seven days. I earn £278/month and have been working at the same organization for more than a year. I have saved up enough funds for the trip and I attached bank statements to prove it. The ECO refused my visa stating:      I note that you stated that your trip to the UK will cost you £1100, this is approximately 4 times your monthly income. I do not find it credible that you spend this amount on a trip.   I am a single woman, with no financial responsibilities and I saved up for this trip because I really wanted to visit the UK.  How do I prove to the ECO and the authorities that spending £1,100 for my trip wouldn't have caused me any financial harm neither would I have had to access UK government funds?    Another concern of mine is that if I reapply without the partial funding of my father or get sponsored by a different person, does the amount given by my father previously cause hindrance in my visa application?  Won't they still reject it on the basis of my pay being too insignificant?


passing a variable as a parameter and not effecting it

some times in typescript when i pass a variable as a parameter in a function and modify it in the function the original variable also modify can any one explain to me what's happening let mybrew :any[] = [     {         id:5,         materials:[-1,-1,-1,-1],         price:16         },  ] console.log(mybrew); function bestBrew(abrow:any[]){     abrow.forEach(         e=>{             for (let i = 0; i < e.materials.length; i++) {             e.materials[0] += e.materials[i];             }         }     ) } bestBrew(mybrew); console.log(mybrew);  output [ { id: 5, materials: [ -1, -1, -1, -1 ], price: 16 } ] [ { id: 5, materials: [ -5, -1, -1, -1 ], price: 16 } ]


Python: strange list behaviour when initialising empty nested list


Is there a menu bar tool which will let me eject external drives easily?

I usually have a lot of external drives connected to my MacBook, such as flash drives, hard drives, and SD cards. It so happens that I need to eject them quite often.  The usual way I eject these is by either showing the desktop using a shortcut and dragging the drives I want to eject to the trash, or navigating to the finder and ejecting the drives from there, or by using a script which ejects all my external drives at once. However, when I want to do something simple like ejecting a flash drive or SD card (which I do quite often) I'd prefer not to break my workflow and simply be able to, say, click on a menu bar icon and select which volume I want to eject.  I haven't yet seen a utility which can achieve this. Does anyone know of one?


In Python we can get the index of a value in an array by using .index(). But with a NumPy array, when I try to do: decoding.index(i)  I get:  AttributeError: 'numpy.ndarray' object has no attribute 'index'  How could I do this on a NumPy array?


Is the age of the universe different for different people located at different points in the Universe?

From Earth we say that the age of the universe is 14.5 billion years ago because that is how far we are able to see. But since we are probably not the center of the universe, wouldn't some one many billion light years away from us feel that the age of the universe is different ?  If so, how is it possible that the age of the universe varies by distance ?   This question came to my mind whilst watching tis video  [about the 8:30 mark till 12 mins]


Is it safe to use a power supply with a different laptop?

Possible Duplicate:        I have a Dell Vostro 1500 laptop, but unfortunately I lost the power supply in Indianapolis last month. I have a power supply for an old Sony laptop lying around, that looks like it fits in the same port.  Is it safe to use the old power supply in the new laptop? If they're not compatible will it simply not work, or will it reverse the polarity and open a gate to Zuul or something similar?  (A new PSU is on order, but UPS failed to deliver it yesterday and I need it today, hence this stopgap solution.)  Thanks!


Why is it correct to say "fewer calories" when calories are continuous?

This question, , asks whether units of a continuous quantity should be spoken of as discrete or continuous. The top answer states  The rule is simple, and you obviously know it: discrete quantities require the use of "fewer" and continuous quantities require the use of "less". Calorie, as a unit, requires the use of "fewer". Energy, as a continuum, requires the use of "less". "Fewer calories means less energy."  I do not understand the logic here though.  Calorie is a unit, yes, but it is a continuous unit (it is possible to have half a calorie, or 4.582394 calories).  Since a calorie is such a small unit of energy compared to what it is usually used for (food energy and human metabolism), it is very seldom expressed in a fractional form and instead is rounded (usually to the nearest 10 or higher). Why then should "fewer" be used with calorie instead of "less"?  Is there another relevant rule than just "continuous quantities use "less" and discrete quantities use "fewer"?


How can I continue playing with my demo character?

After reaching level 9 on the Diablo III demo for PS3 I installed the full version. However, my character from the demo does not appear on the full version. Do I need to have an online membership to transfer my demo character?


How to create the matrix attached that has 2x2 blocks in its diagonal and a square outlining them?

I am struggling to create the matrix in the picture attached using Latex. I have tried using commands like \hline but the matrix ends up looking messy as the line goes all the way across.    Edit: To clarify, I am looking for each block to have a square outline.


I am getting the following error.  E: The package ros-indigo-librealsense needs to be reinstalled, but I can't find an archive for it.   It blocks every package installation with apt-get. What should I do?  EDIT: I can't really do anything with apt-get now. How to remove package by hand?


Expected Number of coin flips for 2 consecutive heads for first time.

I was working on problems on expectation and found this one as a question from a well-known exam  Assume that you are flipping a fair coin, i.e. probability of heads or tails is equal. Then the expected number of coin flips required to obtain two consecutive heads for the first time is.  (A)4  (B)3  (C)6  (D)10  (E)5  I worked up like Let N be the number of tosses required untill 2 consecutive heads are obtained for the first time.  Let the probability of obtaining heads be p and tails be q and for a coin p=q=1-p=1-q.  For N=2, the probability will be $p^2$  For N=3, the probability will be $p^2.q$  For N=4, the probability will be $q^2.p^2$  For N=5, the probability will be $q^3.p^2$  and so on...  Now, $E[N]=2(p^2)+3(p^2.q)+4(q^2.p^2)+5(q^3.p^2)+......$  and this comes out to be $\frac{3}{2}$ but it matches with none of the options.  Please tell me where I am wrong and what should I do to reach the correct solution?


Could someone please explain the difference between these two?  data=[] for row in csv_file_object:      data.append(row[1:])    and  data=[] for row in csv_file_object:     data.append(row)


I have 2 databases, they both share many of the same tables, I want to identify which tables do not exist one database but not the other. Is there any simple way of doing this?


Does light have mass as it is attracted through gravitational force?

I have heard that no one escape from the intense gravitational field of a black hole (obviously that's why it is black). And gravitational force is due to the mass having the body, no mass no gravity, as  $$F=GMm/r^2$$ Putting $0$ in one of the two bodies' masses, gives no gravitational force.  But light cannot escape from black hole due to its strong gravity, does that mean that light has mass? please correct me.


Should I not receive Strunk & White badge?

When I saw my edits statistics there was written that I have 111 edits approved.     Why I didn't receive "Strunk & White" badge if required value is 80 edited post and I have 111 edits?


How to improve the system verilog testbench for JK flip flop

I have a system verilog module as shown in (a) which passes the testbench in (b) but this should be the case as this is not the correct implementation. Correct implementation shown in (c). I am missing anything or any suggestions. Also, in my testbench I will like to get rid of the correct JK flip flop code block as the current testbench is dependent on it.  a)  module jk_ff (input j, input k, input clk, output logic q);   always @(posedge clk)   case ({j,k})   2'b01 : q <= 0 ;  2'b10 : q <= 1 ;  2'b11 : q <= ~ q ;  endcase   endmodule   b)  `include "jk.sv"  module tb_jk();      // open fitness file     int passedFile;     reg j;    reg k;    reg clk;    wire q;     logic q2;     always #5 clk = ~clk;     jk_ff    jk0 ( .j(j),                   .k(k),                   .clk(clk),                   .q(q));     initial begin      $dumpfile("test.vcd");      $dumpvars;      // open file     passedFile = $fopen("passed.txt", "w");     //if(!passedFile) $display("error");     //if(passedFile)     //  $display("file opened");     //else     //   $display("couldn't open the file");        clk = 0;       j = 0;       k = 1;        #10 if(clk == 1 && j == 0 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);          else $fdisplay(passedFile, "%d", 0);       #10 j = 0; k = 0;        #10 if(clk == 1 && j == 0 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 0;         #10;  if(clk == 1 && j == 1 && k == 0 && q === q2) $fdisplay(passedFile, "%d", 1);              else $fdisplay(passedFile, "%d", 0);       #10 j = 1; k = 1;        #10 if(clk == 1 && j == 1 && k == 1 && q === q2) $fdisplay(passedFile, "%d", 1);             else $fdisplay(passedFile, "%d", 0);         #10 $finish;           // close file       $fclose(passedFile);    end      always @(posedge clk) begin : good        case ({j,k})            2'b00 :  q2 <= q2;            2'b01 :  q2 <= 0;            2'b10 :  q2 <= 1;            2'b11 :  q2 <= ~q2;        endcase    end     always @(negedge clk) begin        if (q === q2) begin            $display($time, " pass q=%b", q);            //$fdisplay(passedFile, "%d", 1);        end else begin            $display($time, " fail q=%b q2=%b", q, q2);            //$fdisplay(passedFile, "%d", 0);        end    end endmodule   c)  module jk_ff ( input j,                input k,                input clk,                output q);     reg q;     always @ (posedge clk)       case ({j,k})          2'b00 :  q <= q;          2'b01 :  q <= 0;          2'b10 :  q <= 1;          2'b11 :  q <= ~q;       endcase endmodule   Earlier post


In German the verb fragen takes 2 direct objects. Is it the same in English?     I ask you something.   Or is the person being asked considered an indirect object?   If so, can I reformulate it using  to?     I ask a question to you.   Also, are there examples for verbs that take two direct objects?


How to download playlist to mp3 format with youtube-dl?

I'm trying to download some videos in mp3 format. It's a playlist. How do I download the whole playlist using one command?


Mission Control isn't working on my Mac. I've tried killing the Dock through Terminal and Activity Monitor multiple times, but nothing seems to be working. Even shortcuts or Hot Corners don't work anymore.  What do I do?


How to get Steam to recognize existing game files from a different source?

Let's say I have a game bought on retail/other digital download and installed on my hard drive. I buy the same game (or a minor variant of it, say the GOTY edition) on Steam. It should be possible to use the existing installation to avoid the generally big downloads. This is very useful as it saves both bandwidth and time.   Previously, as far as I understood, Steam downloaded the game files directly to steam\steamapps\common\<game_name>. Since this folder would be created on starting the download, pausing and closing steam, copying the game files to this folder and then validating game files would make Steam absorb as much as possible and just download the missing files.  Currently, Steam downloads the files to steam\steamapps\downloading\<game_id> and then moves them over to the aforementioned folder once the download finishes. So first of all, what the final folder would be is not clear. So what would be the correct way of doing the same thing, that is, make steam use as much of the existing files as possible? Should the files be copied to downloading\*\, or should I figure out the actual folder (say via googling) and copy the files to steamapps\common\*\?  More specifically, I had a retail copy of Arkham City installed and I just bought the GOTY version on Steam. Now I tried both of the above things, in either case, the validating does not seem to do anything. Assuming I have the correct folder name steamapps\common\Batman Arkham City GOTY, according to , if I copy the files there, Steam seems to just continue with its 17GB download. If I copy it to steamapps\downloading\200260 then the download keeps stopping every few seconds with "Disk Write Error" after modifying 1 or 2 files, and I have to keep hitting resume.


I have table named ITEMS where there should be 2 auto increment columns.  So the table structure would be:  ID   |   ITEM_ID --------------------------------- 1    |   ITEM201521080225-001 2    |   ITEM201521080301-002 3    |   ITEM201521080345-003   The column.ITEM_ID structure is ITEMYearDayMonthHourMinute-Increment Value  I managed to Generate the ITEMYearDayMonthHourMinute value thru POST(PHP POST/ PHP Generated).  I am using MySQL and PHPMyAdmin at the moment, and I'm seeing errors if I set column.ITEM_ID to AUTO_INCREMENT    How can I make column.ITEM_ID to AUTO_INCREMENT? Is it Possible?


Chrome 29.0.1547.57:  0.0095 .toFixed(3) // "0.009" 0.1095 .toFixed(3) // "0.110" 1.1095 .toFixed(3) // "1.109"   What's wrong with this function? I know that I can write my own function, the question here is why stock function is so buggy? According to MDN it was implemented in JS 1.5 so it's not new. Or maybe I don't understand this function right?


ubuntu 15 on hp pavillion 15 with realtek rtl8723be, weak wifi signal

I suppose you will assume this question as a duplicate and probably will ban it, but believe me I tried almost everything I could find on this forum and beyond but nothing helped. Please help me with this weird problem, laptop is brand new. WiFi signal is very weak, even when I put it next to adapter, it disconnects after logout/sleep and needs reboot to reconnect.  Tried following solutions: lfwinger/rtlwifi_new, rtl8723be.conf in /etc/modprobe.d/...but none of this solutions has any effect.  wlan0 IEEE 802.11bgn ESSID:"one13"  Mode:Managed Frequency:2.467 GHz Access Point: 50:2E:5C:EE:D0:E1  Bit Rate=72.2 Mb/s Tx-Power=20 dBm  Retry short limit:7 RTS thr=2347 B Fragment thr:off Encryption key:off  Power Management:off  Link Quality=40/70 Signal level=-70 dBm  Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0  Tx excessive retries:0 Invalid misc:1088 Missed beacon:0


To prove $\sum_{n=0}^\infty \binom{r}{x}\binom{N-r}{n-x}=\binom{N}{n}.$

To prove $$\sum_{x=0}^n \binom{r}{x}\cdot \binom{N-r}{n-x}=\binom{N}{n}.$$  I tried comparing the coefficients of $(1+x)^{(n+k)} = (1+x)^n(1+x)^k$ but couldn't reach the answer.


I am currently stuck in the problem below, which is somehow a converse to a  I asked.     Suppose that the following commutative diagram in an abelian category $$\require{AMScd} \begin{CD} 0 @>>> X'@>>>X@>{g}>>X''@>>>0\\ @.@V{f'}VV @VV{f}V @VV{f''}V\\ 0@>>> Y'@>>>Y@>{h}>>Y''@>>>0 \end{CD}$$ has exact rows and $f'$ is an isomorphism. Then the rightmost square $\require{AMScd} \begin{CD} X@>>>X''\\ @VVV @VVV\\ Y@>>>Y'' \end{CD}$ is a pullback.   I think the snake lemma could help in this case, which yields that $f$ and $f''$ are monic and thus it also suffices to show the square is a pushout (it seems easier to check...) What I actually have so far is no more than this and I would like to ask for some hints about what to do next.  Any help is appreciated.


Why are home networks prefixed with 192.168?

Why are home networks prefixed with 192.168 ?  Why those numbers?  For some historical reasons?


Are the "Lord of the Rings" and "The Hobbit" movies connected someway?

Are those two movies connected, if yes, what should be the order in which I shall watch these movies?


Why are people downvoting my question on Meta?

On all of the other SOFU sites a downvote means The question is unclear or not useful.  However, here on meta, a downvote has become a sign of I don't agree with the question, suggestion, feature request, bug, etc. being described in the question.   What does a downvote on Meta really mean? What other reasons do people downvote on Meta? Why is it okay for meta to redefine the meaning of the downvote?  The tooltips and instructions are all the same here on meta.   Note: I'm not saying I disagree with the practice, just curious.


How to permanently set an environment variable

I am completely new to Ubuntu, and I would permanently set an environment variable. I have read  that I have to set ~/.profile, but I don't know how to apply it. In my case I would permanently set export PATH="/home/name/anaconda/bin:$PATH", how could I do?


How to have straight single quotes in lstlistings

All single quotes in code samples are displayed as backticks and the copy-pasted code can't be compiled without fixing the quotation. Is it possible to prevent this?  for example:  \documentclass{beamer} \usepackage{listings} \begin{document}  \lstset{language=Python} \begin{frame}[fragile]{Code} \begin{lstlisting} print 'hi'  \end{lstlisting} \end{frame} \end{document}   Compiled with latexmk -pdf file.tex, which creates a log starting like: This is pdfTeX, Version 3.1415926-2.5-1.40.14 (TeX Live 2013).  Output:


How to show that $f_n(x) \to f$ pointwise?

I have that $(r_n)$ is a strictly decreasing sequence s.t. $lim_{n \to \infty}r_n=0$ and let $f:R \to R$ be continuous and define $f_n(x)=f(x+r_n).$  I have to show two things:  i) Show that $f_n \to f$ pointwise.  ii)Show that if $f$ is uniformly continuous, then $f_n \to f$ uniformly  my attempt:  $lim_{n \to \infty}f(x+r_n)=/lim_{n \to \infty}r_n =0/=f(x+0) = f(x) \quad$ but this seems to bee way to easy. Is this even a complete/correct proof?  for the second part I thought that it if $f$ is uniformly continuous then we MUST have that each $f_n$ is continuous and if each of $f_n$ is continuous then $f:n \to f$ uniformly, i.e. $f_n$ converges uniformly to $f$. Is my proof correct? Do I miss something?


I am being asked to prove that $$\sum\limits_{k=0}^{n}\cos(kx)=\frac{1}{2}+\frac{\sin(\frac{2n+1}{2}x)}{2\sin(x/2)}$$ I have some progress made, but I am stuck and could use some help. What I did: It holds that $$\sum\limits_{k=0}^{n}\cos(kx)=\sum\limits_{k=0}^{n}Re(\cos(kx))=\sum\limits_{k=0}^{n}Re(\cos(x)^{k})=Re(\sum\limits_{k=0}^{n}\cos(x)^{k})=Re\left(\cos(0)\cdot\frac{\cos(x)^{n}-1}{\cos(x)-1}\right)=Re\left(\frac{\cos(x)^{n}-1}{\cos(x)-1}\right) $$ For any $z_{1},z_{2}\in\mathbb{C}$ we have it that if $z_{1}=a+bi,z_{2}=c+di$ then $$\frac{z_{1}}{z_{2}}=\frac{z_{1}\overline{z2}}{|z_{2}|^{2}}=\frac{(a+bi)(c-di)}{|z_{2}|^{2}}=\frac{ac-bd+i(bc-ad)}{|z_{2}|^{2}}$$ hence $$Re\left(\frac{z_{1}}{z_{2}}\right)=\frac{Re(z_{1})Re(z_{2})-Im(z_{1})Im(z_{2})}{|z_{2}|^{2}}$$ Thus, $$Re\left(\frac{\cos(x)^{n}-1}{\cos(x)-1}\right)=\frac{(\cos(nx)-1)(\cos(x)-1)-\sin(nx)\sin(x)}{(\cos(x)-1)^{2}+\sin^{2}(x)}=\frac{\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{\cos^{2}(x)-2\cos(x)+1+\sin^{2}(x)}=\frac{\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{-2\cos(x)+2}=\frac{\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{-2(\cos(x)-1)}= \frac{=\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{-2(-2\cdot\sin^{2}(x/2))}=\frac{\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{4\sin^{2}(x/2)}=\frac{\cos(nx)\cos(x)-\cos(nx)-\cos(x)+1-\sin(nx)\sin(x)}{4\sin^{2}(x/2)}=\frac{\cos(x(n+1))-\cos(nx)-\cos(x)+1}{4\sin^{2}(x/2)} $$ This is the part where I am stuck, I would appriciate any help or hint on how to continue. Edit: Given the corrections by André I get: $$(\cos(nx+x)-1)(\cos(x)-1)+\sin(nx+x)\sin(x)=\cos(nx+x)\cos(x)-\cos(nx)-\cos(x)+1+\sin(nx+x)\sin(x)$$ so $$\cos(nx+x)\cos(x)+\sin(nx+x)\sin(x)=\cos(xn+x-x)-\cos(nx)=0$$ Edit 2: I found anoter mistake in the above, I will try to correct Edit 3: When multiplying correctly the above it works out :-)


I can't seem to pass arguments with spaces in bash script

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Create unique sequence per set of rows sharing the same foreign key value


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Singular covariance matrix in Mahalanobis distance in Matlab

I am using the Mahalanobis distance to classify an unknown 64-dimensional vector into one of 75 classes. There are n samples of 64-dimensional vectors for each class, arranged into an Nx64 matrix format. Reading this into Matlab with no problem.  However when the 64x64 covariance matrix is calculated using the cov() function it is not being positive-definite or non-singular. Hence the inverse of the covariance matrix required to calculate the Mahal. dist. is undefined.  Now the data that is used to get the feature vector is basically co-ordinates of points taken from handwriting samples. In such a case it seems that the distribution is naturally giving rise to a singular covariance matrix. Is there any way to apply the Mahalanobis distance, or some way of modifying the vectors to yeild a non-singular covar. matrix?


Is there any way to preview a bibliography inline?

Take a look at the article at : you will notice that mousing over hyperlinked citations generates a popup that previews the bibliographic entry corresponding to that citation. Is there a way to implement this in a tex-generated pdf?


I am a grade 12 student from India and my physics textbook does not delve deep in the bohrs quantisation condition but has given us a paragraph to figure out what it is:     “Consider Motion of an electron in a circular orbit of radius r around the nucleus of the atom. According to De Broglie hypothesis, the electron is also associated with wave character. Hence the circular orbit can be taken to be a stationary energy state only if it contains an integral number of De Broglie wavelengths.”   I can’t comprehend or understand this explanation. I know what wavelength and de Broglie’s hypothesis is, but why should their be an integral number of wavelengths in a particular orbit? What is a stationery energy state?


I don't know if you've ever experienced such a behavior from your mouse pointer but it's happened to me several times.    The thing is, when I buy a brand new mouse, everything is fine for some time (a year or two) but after that, the mouse pointer starts twitching sometimes.    I first thought it's because of those old ball mice and due to their mechanical nature that this happens. But it keeps happening to the optical mouses too. I wonder what might cause this problem and how to avoid it?    This happens when the mouse is idle. I mean I'm not touching it at all and I use a standard mouse pad.


Is there a documentclass that produces 'endless' pages?

Does anybody know of a documentclass that produces a page that has a fixed width and a variable length, depending on the actual content that needs to fit on the sheet? I'm trying to get something like a kind of scroll if possible.


How can I make Outlook close to the system tray?

When I close a window in Outlook, I want the program to minimize to the taskbar so I can continue receiving email notifications as I work.  I know it's possible to have Outlook , but programs like Skype, Steam, and Discord have gotten me used to programs continuing to run in the background when closed.  How can I make Outlook close to to the taskbar, so it can continue running in the background?


Is it bad to start a sentence with a citation

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Is this site supposed to be copying all of Stackexchanges info?

I hope this is the right place to post this.  If you go to the rather lengthy link below you'll see that it is one of my questions, with comments, and answers here on Scifi Stackexchange. I'm not sure if this is a copyright violation or if it's just a companion site. I wanted to bring it to everyone's attention just in case.    I hope I posted this in the right place and did the right thing. Thanks