QUESTION:   Prove that for all positive integers  $k\leq n$:  $\sum_{i=0}^{k}{n \choose i} (-1)^i = {n-1 \choose k}(-1)^k$  MY THOUGHTS:  INDUCTION : (assuming k even) - We assume:  ${n \choose 0} - {n \choose 1} + ... + {n \choose k-2} - {n \choose k-1} = {n-1 \choose k-1}$  We need to show:  ${n \choose 0} - {n \choose 1} + ...-{n \choose k-1} + {n \choose k} = {n-1 \choose k-1}$  My issue here is that we can say LHS equals ${n-1 \choose k-1} + {n \choose k}$, which is close, but not quite Pascal's Rule.   Another way: I thought looking to find some bijection that can be applied.   Let's assume n is even. Writing out the left and sum and moving all the odd (negative) terms to the RHS gives (note that the last term on the RHS is simply the original RHS:  ${n \choose 0} + {n \choose 2} + ... + {n \choose k} = {n \choose 1} + {n \choose 3} + ... + {n \choose k-1} + {n-1 \choose k}$    I am stuck here, but how I worked out in my mind was that:  $\bigg\{$set of even sized groups of  $\leq$ n people$\bigg\}$ -->  $\bigg\{$set of odd sized groups of  $\leq$ n-1 people$\bigg\}$ + ${n-1 \choose k}$  Then possibly, it would have something to do with adding or removing person n. Let me know your thoughts or suggestions.


Uninstall extra Zoom Meeting application?

Recently I seem to have "acquired" a second copy of Zoom. I cannot find it under the Software application and I cannot remove it via snap or apt. I have no idea where it came from, but it's a different Zoom UI than the version I installed, and doesn't work with my mic correctly. I can still uninstall "my" copy of the app (left in picture below). This may have happened when I upgraded to Ubuntu 20.04. How can I uninstall this unwanted application?  $ snap list | grep zoom zoom-client           5.3.472687.1012             106    latest/stable    ogra           -  $ apt list | grep zoom libnet-z3950-simple2zoom-perl/focal,focal 1.04-1build2 all libnet-z3950-zoom-perl/focal 1.30-2build1 amd64 node-d3-zoom/focal,focal 1.8.3-1 all ruby-zoom/focal 0.5.0-2 amd64 xzoom/focal 0.3-25 amd64 zoom-player/focal 1.1.5~dfsg-5 amd64 zoom/now 5.0.413237.0524 amd64 [residual-config]  $ grep -R Zoom /usr/share/applications ~/.local/share/applications /usr/share/applications/mimeinfo.cache:application/x-zoom=Zoom.desktop; /usr/share/applications/mimeinfo.cache:x-scheme-handler/callto=Zoom.desktop; /usr/share/applications/mimeinfo.cache:x-scheme-handler/tel=Zoom.desktop; /usr/share/applications/mimeinfo.cache:x-scheme-handler/zoommtg=Zoom.desktop; /usr/share/applications/mimeinfo.cache:x-scheme-handler/zoomphonecall=Zoom.desktop; /usr/share/applications/mimeinfo.cache:x-scheme-handler/zoomus=Zoom.desktop; /usr/share/applications/gnome-universal-access-panel.desktop:Keywords=Keyboard;Mouse;a11y;Accessibility;Contrast;Cursor;Sound;Zoom;Screen;Reader;big;high;large;text;font;size;AccessX;Sticky;Keys;Slow;Bounce;Mouse;Double;click;Delay;Speed;Assist;Repeat;Blink;visual;hearing;audio;typing; /usr/share/applications/gnome-keyboard-panel.desktop:Keywords=Shortcut;Workspace;Window;Resize;Zoom;Contrast;Input;Source;Lock;Volume; /usr/share/applications/Zoom.desktop:Name=Zoom /usr/share/applications/Zoom.desktop:Comment=Zoom Video Conference /usr/share/applications/Zoom.desktop:Icon=Zoom.png /usr/share/applications/Zoom.desktop:StartupWMClass=Zoom /usr/share/applications/Zoom.desktop:Name[en_US]=Zoom /home/adsteel/.local/share/applications/chrome-hmbjbjdpkobdjplfobhljndfdfdipjhg-Profile_2.desktop:Name=Zoom


How to say "short, sweet, to the point" in one word?

Is there a single ᴀᴅᴊᴇᴄᴛɪᴠᴇ to denote short, sweet, to the point?    I am thinking of  but I'm not sure that it connotes elegance/brevity, which is an important aspect of the meaning I would like to convey.


Changing ordering of numeric-style citation call-outs

I have 4 entries in my .bib file. The first time I use \cite in my article it generates [2] as the citation call-out. How can I make the first cite I use show [1] in the article?  My code is as follows:  \documentclass[a4paper, 10pt]{article} \usepackage{biblatex} \addbibresource{refbib.bib} ..... The equation is taken from \cite{A2005} and the graph from \cite{B2006}.   and in the numbering I get [1] for B2006 and [2] for A2005.


How can I recover from a `chmod -x chmod`?

Assuming that you can't reach the internet nor reboot the machine, how can I recover from  chmod -x chmod   ?


Can someone tell me where can I find detailed text about mechanisms of evolution of dominance? Or, if it is possible, I would be grateful if someone will tell me about them here.


The number of transpositions between two permutations

Suppose it is possible, through many steps, to move from the permutation $\pi$ to the permutation $\sigma$ by multiplying, at each step, by a transposition.  Knowing that they are not necessarily conjugates, I want to find:   In how many ways (The maximum number) I can move from $\pi$ to $\sigma$.  bound the maximum number of steps needed to switch from $\pi$ to $\sigma$ (is there a reference).   EDIT 2 In other words, as  proposed:  Let $d(\pi,\sigma)$ be the length of the smallest sequence of transpositions we need to multiply by the permutation $\pi$ to take it to $\sigma$.    How can I bound or even calculate the number of sequences of length $d(\pi,\sigma)$ which take $\pi$ to $\sigma$? (I am looking for any idea) How can I bound or even calculate $d(\pi,\sigma)$ (This one is answered as explained above)?    It is known that the number of transpositions in the symmetric group $S_n$ is $\frac{n(n-1)}{2}$ and also it is possible to decompose a certain permutation into disjoint cycles, but I don't how to collect these results to answer my question!  Any kind of help is appreciated.  EDIT 1: I don't think my question is a duplicate! it consists of two parts and the marked question answers only one question! The linked question is not talking about the first part of my question!


$M$ and $N$ are matrices that satisfy $MNMN=0$,what can we say about $NMNM$.

From my personal point of view, we cannot deduce that $NMNM=0$,but I can't find a counterexample.


Circled number on regular polygon with nodes

Which is the best way in order to reproduce something like that?


I try to create proceedings with a uniform title page for individual pdfs that I get from the authors. I use pdfpages for this. The individual pdfs are included and I add title information (not shown in the example below). I have one paper that looks fine, but when I include it, the result does not contain the small caps letters in the attribute value matrices (see figures on page 7 and 8).  \documentclass{article} \usepackage{pdfpages} \usepackage[utf8]{inputenc}         \usepackage{hyperref}         \setcounter{page}{335}         \begin{document} \includepdf[pages=-,pagecommand=\thispagestyle{plain}]{Includes/yatabe.pdf}         \end{document}   This is the paper:    What I get from including is


Deleting files from Remote FTP-Server older than x days

i've got a remote FTP server where i store some backups via cronjob.  The Problem is that i only got a little amount of space so im doing incremental backups. I want to keep the backups about 14 days.  I don't have any other access to the server except FTP and i don't now how to delete files older than x days. Every file got a name with a date in it  yxzNamezxy-date-y-m-d.tar.bz2 (datev-20100111.tar.bz2(   Hope to get some help here.  Cheers and thanks for the hopefully coming answeres,  Dennis  /Edit  I'm trying to use the curl thing which is mantioned in an answere with this part of code  curl ftp://$FTP_SERVER --user $FTP_USER:$FTP_PASS --list-only > files.tmp declare -a aFiles let iCount=0 exec < files.tmp while read sLine do         aFiles[$iCount]=$sLine         ((iCount++)) done  echo -e "\n Files: \n\n\n" echo ${aFiles[@]}  echo -e "\nfor ...\n\n\n" for sFile in $aFiles do         echo -e "\nFile:" $sFile done   but the secound loop doesn't give me more than 1 filename  Cheers,  Dennis


Years ago (35 or so) I read a series of books about kids who met a Mr. Bass. They travel in space and it involved spores or mushrooms. I'd like to find them again. I think my kid would like them.  Can you help find these books?


In Linear regression, we have $\textbf{$\theta$} = \textbf{$\left (X^TX\right )^{-1} X^T y$}$.   In Ridge regression, we have $\textbf{$\theta$} = \textbf{$\left ( \lambda I+ X^TX\right )^{-1} X^T y$}$.  I learnt somewhere that while $\textbf{$X^TX$}$ is not guaranteed to be invertible, $\textbf{$\lambda I + X^TX$}$ is guaranteed to be invertible.  Is this true? If so, why?


Is there a substantial difference between $\leq$ and $\leqslant$? My textbook uses both, but I could not tell why the authors selected one or the other. I asked my teacher, and she said that there was no difference between the two, but if there is no difference, why were both used? When I am writing solutions and proofs, is there any time when it would be considered better practice to use one than the other?


Java error message array in other method

My code isn't compiling the error that is given to me is "non-static method sumArray(double[]) cannot be referenced from a static context". I have tried to figure this out but I'm not sure what I need to change. Please help and let me know what the error is.  import java.util.*; public class Homework5 {  public static void main( String[] args ) {      Scanner key = new Scanner(System.in);     System.out.println("How many numbers would you like in the array?");     int arrayLength = key.nextInt();      Homework5 inst1 = new Homework5();      double[] numbers = new double[arrayLength];     System.out.println("Enter " + arrayLength + " numbers:");      for( int i=0; i < arrayLength; i++ )     {         numbers[i] = key.nextDouble();     }     System.out.println( "The sum is "+sumArray(numbers)); }  public double sumArray( double[] newArray ) {     double total=0;      for( int index = 0; index < newArray.length ; index++ )     {         total = total+newArray[index];     }      return total;   }   }


What is the best way to connect two cylinders at a 90 degree angle?

I can't seem to find any method to fill this one model. Does anyone know?


Is it possible for this puzzle to be solved without the use of computational software?

was found from the Hot Network Questions on the right. A repost of a question in a way (from Mathematica SE), but I was wondering if the following puzzle could be done:  A quick translation:  Can anyone solve this? It's so hard! Fill in the numbers $1–9$ in the boxes, the numbers cannot repeat.  It has already been solved in the given link, the answers being (hidden for those who wish to try and solve it):   $17\times4=68+25=93$  The answer to the Mathematica question stated there's a way to solve it without brute-forcing, but I didn't understand it too well. How would one—if possible—solve this without using too complex softwares?


Prove that if $\mathcal P(A) \cup \mathcal P(B)= \mathcal P(A\cup B)$ then either $A \subseteq B$ or $B \subseteq A$.

Prove that for any sets $A$ or $B$, if $\mathcal P(A) \cup \mathcal P(B)= \mathcal P(A\cup B)$ then either $A \subseteq B$ or $B \subseteq A$. ($\mathcal P$ is the power set.)  I'm having trouble making any progress with this proof at all. I've assumed that $\mathcal P(A) \cup \mathcal P(B)= \mathcal P(A\cup B)$, and am trying to figure out some cases I can use to help me prove that either $A \subseteq B$ or $B \subseteq A$.   The statement that $\mathcal P(A) \cup \mathcal P(B)= \mathcal P(A\cup B)$ seems to be somewhat useless though. I can't seem to make any inferences with it that yield any new information about any of the sets it applies to or elements therein. The only "progress" I seem to be able to make is that I can conclude that $A \subseteq A \cup B$, or that $B \subseteq A \cup B$, but I don't think this gives me anything I don't already know. I've tried going down the contradiction path as well but I haven't been able to find anything there either.  I feel like I am missing something obvious here though...


I ran the Mann-Whitney in SPSS.  In addition to the U, the output generated the Wilcoxon W and the Z score. Why would the W and Z be present in the output? I cannot explain them being present. Also, the U and W are very large and different. Why is that?   Edit: I understand now why the U and W are large. My sample is large. However, they are different!


Does Ubuntu install on Windows 8.1 with dual boot options

I want to install Ubuntu on an HP Laptop with Windows 8.1 installed. Does the Ubuntu installer allow the dual boot setup?


Is work a form of energy or means of transfer of energy?

What actually is energy? Is it a property associated with matter or just a number? By doing work are we changing the energy of the body or converting one form of energy into other which is already present.


Is it possible to create a partition that is usable by both Linux and Windows and supports the features of both?

I recently received a new computer that I would like to dual boot both Windows 10 and some flavor of Linux on. I am planning on creating a separate partition for Windows and a separate partition for Linux "/".  However, I would like to create a data partition that would be accessible by both. Ideally, this partition would also keep "/var" and "/home".  Is there a particular FS type that would be ideal for use like this?  I understand that there is a similar question on here recommending either ext3 or NTFS, but the answers are from 2010 so I'm pretty sure the state-of-the-art has changed since then.   (from 2010)


Prove that the order of the cyclic subgroup $\langle g^k\rangle $ is $n/{\operatorname{gcd}(n,k)}$

Let $G$ be a cyclic group of finite order $n$. Then, the order of the cyclic subgroup $\langle g^k\rangle$ is $\frac {n}{\operatorname{gcd}(n,k)}$  Proof:  $G$ cyclic $\Rightarrow \exists g \in G: G = \langle g\rangle$ $\Rightarrow \operatorname{ord}(g) = \lvert G\rvert = n $  We know, because every subgroup of a cyclic group is cyclic, that $\lvert\langle g^k\rangle\rvert =  \operatorname{ord}(g^k)$. Therefore, we only need to find the order of $g^k$.  Let $l$ be the order of $g^k$. Then:  $(g^k)^l = e \iff g^{kl} = e \iff n|(kl)$  I'm now trying to show that $l = n/{\operatorname{gcd}(n,k)}$, but this seems difficult for me. I tried to assume that there was an element $l' < n/{\operatorname{gcd}(n,k)}$ that satisfied the conditions, in the hope of reaching a contradiction, but this did not work out. Can anyone help?


Which is correct?     None of us are getting out of here alive.   or     None of us is getting out of here alive.


I have been struggling to preload database in the android app.  I am making a dictionary app in which i have a database containing word and meaning.  I need to preload this database with the app and make the user directly start using it.  The only successful way i have been able to implement is making a db file externally and putting it in the assets folder and on app startup copy that file to the internal memory of android phone. But this way reduces the efficiency of the app. Copying such a huge database reduces the speed of the app and during the first time use the app becomes useless. i need a way to include the database right from the start of the app  I have seen so many android offline dictionary apps which come with a complete preloaded database which start working right from the first time with high speed.  Please help


How to run cgi scripts in tomcat in Windows system

I installed tomcat and removed the comments of cgi script in web.xml in conf folder Now iam not able to understand where to place my cgi script  I have read many resources and i placed it in a Webapps/Myfolder/WEB-INF/cgi/hello.cgi here hello.cgi is my sample cgi script I also typed the following in Webapps/Myfolder/WEB-INF/web.xml  `    <web-app>    <servlet>     <servlet-name>cgi</servlet-name>     <servlet-class>org.apache.catalina.servlets.CGIServlet</servlet-class>     <init-param>       <param-name>debug</param-name>       <param-value>0</param-value>     </init-param>     <init-param>       <param-name>cgiPathPrefix</param-name>       <param-value>WEB-INF/cgi</param-value>     </init-param>      <load-on-startup>5</load-on-startup> </servlet>   `  Now iam not understanding where should i map my cgi script here I am not getting any idea what exactly this web.xml does Can any one provide a solution how can i do this.


How long after the use by date can I safely cook and consume chicken drumsticks?

I discovered that the use by date of the chicken that I bought recently was two days ago. It is still sealed and looks fine. I have yet to conduct the sniff test as I'm unsure whether there is any point. Is it generally still safe to cook with?


I just started the LOL client and there's this 0% bar on the top left.  I hover over it and it says like 13562 MB left... I don't really know what that is.  Could anyone please clarify that?  Thanks...


After formating my computer, some folders and files turned to green and now I cannot open certain files. From the properties of the disk, I am not able uncheck "Encrypt content to secure data".   How can I unencrypt my disk and make my data available?


Why can't quantum mechanics and general relativity be unified?

Excuse me for my little knowledge in physics, but it seems very bizarre for two theories, relativity and quantum mechanics (which describe phenomena very accurately in their regions) to be unable to be unified into a single model of the universe. Aren't they describe the same universe but different aspects of it. Why can't this be done?


We're using Samsung with Android 4.1.2 as a scrabble timer - via the default Clock application. It would be much more comfortable if I could force the phone screen to be always on so that we can see the time remaining. I found no setting or downloadable program to achieve that.  I need some workaround tip - any ideas?


How to prove that for every finite field its cardinality is $p^n$?

How to prove that for every finite field its cardinality is $p^n$ where $p$ is prime and $n\in\mathbb{N}$?  Thanks in advance!


The following problem:  The Fibonacci number is denoted by  $f_{n}$, show that the following holds when $n$ is a positive integer:  $f_{0}f_{1}+f_{1}f_{2}+...+f_{2n-1}f_{2n} = f^{2}_{2n}$  My idea was to do an induction proof, which holds for $n$ = 1  $f_{0}f_{1} + f_{1}f_{2} = f^{2}_{2}$  So we assume it holds for $n$ and show for $n+1$  $f_{0}f_{1}+f_{1}f_{2}+...+f_{2n-1}f_{2n} + f_{2n}f_{2n+1} = f^{2}_{2n} + f_{2n}f_{2n+1}$  I fail to get  $f^{2}_{2n+1}$ out of the term  $f^{2}_{2n} + f_{2n}f_{2n+1}$  Is there a difference between "show that" and "prove that". So might be induction the wrong tool here?  Many thanks for your hints in advance :-)


Intuition for Conditional Expectation of $\sigma$-algebra

Let $(\Omega,\mathscr{F},\mu)$ be a probability space, given a random variable $\xi:\Omega \to \mathbb{R}$ and a $\sigma$-algebra $\mathscr{G}\subseteq \mathscr{F}$ we can construct a new random variable $E[\xi|\mathscr{G}]$, which is the conditional expectation.     What exactly is the intuition for thinking about $E[\xi|\mathscr{G}]$?  I understand the intuition for the following:   (i) $E[\xi|A]$ where $A$ is an event (with positive probability).  (ii) $E[\xi|\eta]$ where $\eta$ is a discrete random variable.   But I cannot visualize $E[\xi|\mathscr{G}]$. I understand the mathematics of it, and I understand that it is defined in such a way to generalize the simpler cases that we can visualize. But nonetheless I do not find this way of thinking to be useful. It remains a mysterious object to me.     For example, let $A$ be an event with $\mu(A)>0$. Form the $\sigma$-algebra $\mathscr{G} = \{ \emptyset, A, A^c, \Omega\}$, the one generated by $A$. Then $E[\xi|\mathscr{G}](\omega)$ would be equal to $\frac{1}{\mu(A)} \int_A \xi$ if $\omega \in A$, and equal to $\frac{1}{\mu(A^c)} \int_{A^c} \xi$ if $\omega \not \in A$. In other words, $E[\xi|\mathscr{G}](\omega) = E[\xi|A]$ if $\omega\in A$, and $E[\xi|\mathscr{G}](\omega) = E[\xi|A^c]$ if $\omega \in A^c$.   The part which is confusing is that $\omega \in \Omega$, so why do we not just write $E[\xi|\mathscr{G}](\omega) = E[\xi|\Omega] = E[\xi]$? Why do we replace $E[\xi|\mathscr{G}]$ by $E[\xi| A\text{ or } A^c]$ depending on whether or not $\omega\in A$, but not permitted to replace $E[\xi|\mathscr{G}]$ by $E[\xi]$?     Note. In responding to this question do not explain this by using the rigorous definition of conditional expectation. I understand that. What I want to understand is what the conditional expectation is supposed to be calculating and why we reject one in place of another.


I am using a script to connect to multiple servers. At the moment, I am using something like:  for SERVER in server1 server2 server3 ; do ssh $SERVER "my-command" ; done   I have to specify the (many) servers every time. I was wondering if there is a better way, for example if ssh has any possibility to define "groups of servers", so that I could refer to it as   for SERVER in $SERVERLIST ; do ssh $SERVER "my-command" ; done   or is this a bad idea, and should be done in bash instead?


Why does searching "0.693" bring me to "0.0.2.181"?

While working on math, I encountered a number and wondered if it had any significance. So, in the browser search bar I entered it ("0.693"). I got redirected to the IP address 0.0.2.181, which resulted in an "unreachable" error message.  Why did I get redirected to this IP address?


About a polynomial with a root $\sqrt[3]{2} + \sqrt{5}$.

How to find a polynomial with integer coefficients and a root $\sqrt[3]{2} + \sqrt{5}$? The degree of this polynomial can't be more than 7.


How do I stop stacktraces truncating in logs

Lots of times in Java logs I'll get something like:  Caused by: java.sql.BatchUpdateException: failed batch     at org.hsqldb.jdbc.jdbcStatement.executeBatch(jdbcStatement.java:1102)     at org.hsqldb.jdbc.jdbcPreparedStatement.executeBatch(jdbcPreparedStatement.java:514)     at org.hibernate.jdbc.BatchingBatcher.doExecuteBatch(BatchingBatcher.java:48)     at org.hibernate.jdbc.AbstractBatcher.executeBatch(AbstractBatcher.java:242)     ... 113 more   Does anyone know how to get the full stacktrace showing (i.e. show the other 113 lines)?    The  for Throwable have a pretty detailed explanation of what's going on.


The Diophantine equation $x^2 + 2 = y^3$

How to solve the Diophantine equation $x^2 + 2 = y^3$ with $x,y>0$ ? ($x,y$ are integers.)


What are the Path components of $\mathbb{R^w}$ in product topology.

$\mathbb{R^w}$ is connected in product topology but what about the path components of $\mathbb{R^w}$ in product topology?


How to stop constantly blinking Wifi LED?

I have a Dell E6510 and after installing Ubuntu and connecting to a wireless network, my Wifi LED keeps blinking all the time, probably in response to traffic.   This is really annoying because it keeps drawing my attention away from the screen. Is there any way to turn this functionality off and just let the wifi light stay on all the time as long as it has a wifi connection?   Here is my lspci for the wifi:  Network controller: Intel Corporation Centrino Advanced-N 6200 (rev 35)


Is every real monic polynomial the characteristic polynomial of a real matrix?

Is every monic real polynomial the characteristic polynomial of some real square matrix? I strongly suspect so, but I couldn't find a proof.


I'd always assumed that if you start with safe fish (appropriately stored/frozen), stay with "normal" fish (i.e. don't try to prepare poisonous puffer fish at home), and follow normal food hygiene practices, it was "safe".  And indeed, for years I've been going to the local Japanese market fish counter, and asking for "fish for sushi". The gentleman behind the counter then recommends some fish, optionally slices it for me,  wraps it up and I take it home and make various types of sushi.   Is this correct, or am I missing something? Is there some special technique that I need to follow at home to make safe-sushi?  To be clear, I'm not asking about the safety of the fish itself, I trust the Japanese market fish counter to sell me sushi-safe fish.


Is it possible to do infrared photography with digital cameras?

I remember taking infrared pictures with a simple filter and black and white film. How can I do something like this with digital cameras? Or is this even possible?


run php file from cron and start browser through exec on ubuntu

I am trying to start FireFox from php script using exec("firefox"). This works fine if i run php file from the terminal but does not work when run by the cron. User for cron & terminal is root. Please suggest some solutions.


Installing Ubuntu 14 from bootable USB with updated packages

I want to install Ubuntu 14 Desktop on PC which doesn't have internet. So I created a bootable USB of Ubuntu, installed all updates including KDevelop. Then I installed Ubuntu from it on my PC, but the KDevelop and other updates are not refelecting in the installation. When I boot from USB, KDevelop is running, but not from hard disk.  What could be solution? Please let me have your suggestions.


Checking my understanding: $1 - 1 + 1 - 1 + 1 - ... = \frac{1}{2}$

I've recently run into a proof that claims that $1 - 1 + 1 - 1 + 1 - 1 ... = \frac{1}{2}$ that proceeds as follows:     Let $S = 1 - 1 + 1 - 1 + 1 - 1 + ...$. Then $$S = 1 - (1 - 1 + 1 - 1 + 1 - 1 ...) = 1 - S$$ Therefore, $2S = 1$, so $S = \frac{1}{2}$. QED   I was under the impression that this sum doesn't converge, and therefore this step of the proof is invalid:     Let $S = 1 - 1 + 1 - 1 + 1 - 1 + ...$   That is, it's not even valid to suppose that the sum is equal to some (implicitly real or complex) number $S$, and therefore the reasoning that follows is meaningless because $S$ doesn't exist and therefore has any properties we want it to have.  Is the reasoning I've given above correct? That is, is it correct for me to claim that the proof fails because $S$ doesn't exist?  (I've heard that there are techniques for evaluating divergent integrals by using complex analysis and Taylor series, so perhaps there's another way to prove that the summation is $\frac{1}{2}$; I just wanted to see whether my reasoning is sufficient to explain why this particular proof is incorrect. If the proof actually is correct, then I stand corrected!)  Thanks!


I am currently slowly mapping field boundaries of old agriculture map areas using QGIS. Has anyone designed a magic plugin or method so that the black outlines of the boundaries are automatically detected. A bit like finding edges in photoshop. I realise that some manual editing would be required, but I thought I would ask.


How to make an object emit light in Cycles?


What are the existing collaborative webmapping systems/platforms?  I am looking for some information like on , but specific to out-of-the-box on-line geographical data capture systems.  These systems should not necessarily be open-source but should remain highly customisable for specific purposes. I am specifically interested in systems that could be made private, with a capture tool usable on mobile devices.  So far, I am aware of the systems  and . I am sure you know others!  Precision: I am not looking for existing collaborative cartography projects like in  but rather in the background systems for these projects. Wikipedia's system for example has been released as the MediWiki system - maybe there are comparable initiatives in collaborative webmapping.


Can white walkers be killed by Valyrian steel weapons, too? (latest television episode on HBO indicated obsidian weapons stabbing a white walker will destroy them)


If $A$ and $B$ are closed subsets of the set of real numbers, then is $A+B$ closed?

Let $A$ and $B$ be two closed subsets of the set of real numbers.  Define $A+B=\{a+b\in\mathbb{R}:a\in A ,b\in B\}$.  Is it true that $A+B$ is closed in $\mathbb{R}$?  If not, could you give a counter-example?


When I run single-core computations on my 10-core iMac Pro, the CPU does not reach the advertised Turbo Boost of 4.5GHz but rather 3.8-3.9GHz. See plot:    I am running a Mathematica code using only one kernel (note that there are 20 kernels as the CPU supports Hyper-threading). The room temperature is 24ºC and the fans are going at the minimum speed. Anyone knows why? Note that I am not asking what Turbo Boost is but rather why it is not performing as advertised by .   it is said that the Turbo Ratios can be found using Console.app. Is this still possible in Mojave? I could not find AppleIntelCPUPowerManagement.


Why don't intelligent animals like primates use plastic bags?

I'll be honest here. Although this is a serious question, what made me wonder about it is this comic from Wumo:   This question is not specific to monkeys. It applies to animals that live with or sufficiently close to human dwellings and would be able to observe our habits daily. I'm not referring to training animals. Even among animals that have an opposable thumb like ours but different , the use of . Chimps have been known to re-use tools and even  is documented. Whales have been hypothesized to have high intelligence (although ) due to  containing . But I couldn't find any info on whether whales use tools (Dolphins are said to  though).    On considering if mirror neurons were helping chimps copy each other and use tools, I found that the very existence of .    So if a chimp can use simple tools, what prevents them from looking at us and imitating our use of something as simple as using a plastic bag or a crude tray to carry a bunch of fruits? Is there a gradation of complexity of tool use that various brains can process? A reason that no matter what happens, a chimp would not be able to imitate our use of tools? Could this be compared to how aged people are unable to learn how to use a smartphone or computer no matter how many times it is explained to them (or even how young people )? Perhaps the ability is related to an animal's capability to form new neural connections of a certain type?  Training an animal like  is different from what I'm asking.  Some examples of primates trying to carry many fruits.


I'm Using ASP .NET core with git repository command is not working

As you can see Git command to check status untrack file in my repository. git status  i want to remove/ reset those untrack file but git command is not working  even i try clean untrack file still hard luck  even i try to pull from remote repository still no luck. can anyone tell me how to remove those file from untrack status? Thanks in advance.


debian testing / stretch resetting /etc/resolf.conf

i know there is already a post about this topic here:     but i already checked that network-manager dhclient resolvconf    are not installed on this server system.  could dnsmasq be responsible for changing the resolf.conf file? but that wouldnt make much sense since it reads its "upstream" dns servers from it...or does it not?  my /etc/network/interfaces looks like this:    source /etc/network/interfaces.d/*  auto lo iface lo inet loopback  auto eth0     iface eth0 inet static     address 192.168.178.215     netmask 255.255.255.0     gateway 192.168.178.1   what else would change that file...and why?


How Many Harry Potter Chocolate Frogs Must I Buy?

Each Chocolate Frog comes with one collectable illustrated wizard card (very cool and not dorky at all, honest). There are equal odds of each card being in a pack (i.e., they have all been produced and distributed evenly). How many packs must we buy in order to have an 80% chance of having obtained all 12 cards? How about 90%? Thanks.


Suppose that $f$ is a function defined in $[a;b]$ to $[a;b]$ and continuous on $[a;b]$. The problem is I haven't the definition of the function, this is more abstract, but even if how can I prove that $f$ would have a fixed point?


Is the set of matrices with rank at most $r$ closed?

The question is as follows: $\DeclareMathOperator{\rank}{rank}$     Is the set $S_r = \{A \in \Bbb R^{n \times n}: \rank(A) \leq r\}$ closed in $\Bbb R^{n \times n}$ in the Euclidean topology?   I have a feeling that this is true, but I got stuck looking for a convincing argument.  Certainly this is true for $r = n-1$.  Perhaps it can be shown that $S_{r-1}$ is a closed subset of $S_r$?  No neat tricks are coming to mind, but I would think that there must be one. This seems like the kind of thing that has a canonical answer, so links are welcome.


I created a little macro in TeXstudio for online math mode. I want to change the typical $$ for ${}$ and I did it:  `  When I execute the standard macro for online math I get $ | $ (the | represents the cursor), but when I execute my own macro I get ${}$|. Someone knows if there is a way for executing my own macro and obtain ${|}$?. Remember: | represents the cursor


How can I match a Pandas Dataframe with invalid characters (accents) to an array?

I have been trying to use a Pandas Dataframe  in Python 3 to find a specific id matching a name from a CSV file. The API I am reading from gives me the name António, along with other names, the way I need it to with the accent in a column called "first". I have an array of names that won't necessarily have all of the accents I need to match. This program seems to work for every name I try except for the ones that have different values for accented characters.  import pandas as pd  nameArray=[Antonio,Matt,Mark,Raul] playersUrl = 'https://www.FakeSite.com/players' playerData = pd.read_csv(playersUrl, names=["PLAYERID", "FIRSTNAME"]  for first, playerid in zip(playerData["FIRSTNAME"],playerData["PLAYERID"]):     for i in len(nameArray):         testName = nameArray[i]             if first == testName:             return playerid


Java String formatting question about taking 3 instance variables and formatting them as HH:MM:SS + more

as the description say's i have 3 instance variables  private int Hours; private int Minutes; private int Seconds;   i have already completed the part of setting and getting said values, but i am rather stuck on the part where i need to format this into the HH:MM:SS format with leading zeros for the values that are less than 0, we are assuming that we are using a scanner to allow a user to input whatever we want.  thanks!  heres the method its being done under  public String toString() { //dont know what to do to format it as wanted //return "the formatted output" }


Adding (partial) support for a non-SVO language in biblatex-apa

I'm trying to add some partial support for Japanese in a document I'm making, which uses APA style (mostly English references, plus some in Japanese (the main text is in Japanese, I'm also using lualatexja and ployglossia plus csquotes if that matters), unfortunately I don't have any minimal working examples since I don't have any lbx files yet).  Although  covers a lot, my main question is that whether it's possible to add support for a SOV language which mostly tends to use postpositions rather than prepositions. For example an entry in Japanese should look like URL [from] rather than [from] URL, so merely translating the "from" key in biblatex-apa's lbx file would result in a wrong sentence order. Same goes with a lot of biblatex's Action keys (for example, bytranslator), since there doesn't seem to be a 〈name〉 command to set the location of the main name before a suffix.  And what should one do in order to localize the APA style? Create 2 lbx files for japanese-apa and and japanese and put them in the main directory of the project?  Edit: This is how far I've come so far:   One issue is the date, it should be ２０１９年９月11日, polyglossia actually does support Japanese dates, but for some reason it's not being used. The other issue is から which should be after the URL (It's a postposition equivalent to "from").  is a zip file containing a working sample, not that lbx files are mostly copies from English. You will need lualatexja.  Edit2: The sample exceeds the limits, but  it is in a single text file on github. (also my account has been messed up so I can't even comment on/edit my own question, so...)


Please stop asking me a captcha with over 500 reputation. I am human

I wonder how it is possible that Stack Overflow is still asking me to solve an unreadable  before I can post a question when I have more than five accounts on Stack Exchange, and I have more than 500 reputation on Stack Overflow.


I want to follow the interface segregation principle but the class is closed. Is a wrapper the right way?

More than a few times I've found my self working with a class that is closed (I can't modify it) that I wish implemented a nice .  My client code is supposed to own the interface but I know of no mechanism to announce that this closed class is a implementation of my narrowed interface.    I'm trying to allow this class to be passed in (dependency injected) to my code (composition) but also anything else that can support the narrowed interface. In other languages duck typing makes this trivial.  I'm in java though, so I'm expecting to have to write a whole other class just to wrap the closed class to make this happen.  Is there a way I'm missing?  Thanks    EDIT to address dupe:   offers no mention of the closed class issue which is the point of this question.  Please reconsider marking as dupe of this particular question.    This question:  , has a good example of the interface segregation principle:  class A {    method1()    method2()    // more methods    method10() } class B {     A a = new A()  }   will become   interface C {       method1()       method2() }    class A implements C{       method1()       method2()       // more methods       method10()   }   class B {        C c = new A()   }      But note how it requires a change to class A.  If A is closed to modification how do I accomplish the same thing cleanly?


Help Solving Integration $\int_{-\infty}^{\infty} {(\text{Standard Normal} \times \text{Sigmoid}) }$

Does anyone know how to analytically solve the below expression?  $$\int_{-\infty}^\infty p(x) \times \sigma(ax + b) \, dx $$   where $ p(x) = N(0, 1) = \frac{1}{\sqrt{2\pi}}e^{\frac{-x^2}{2}}$ and $\sigma(z) = \frac{1}{1+e^{-z}}$.  I know that the  is $\pi$. Moreover, the integration of sigmoid alone is,  $$\int \sigma(x) \, df = \int \frac{e^x}{1+e^x} \, dx = x + c$$  But I cant figure out how to integrate the first equation), when they are multiplied together.  Can we use integration by part and solve above equation?  Any help will be appreciated.  Thanks  Edit 1:  Sorry about the complicated notations.  If we simplify the above expression, then we get following equation.  $$ \frac{1}{\sqrt{2\pi}} \int_{-\infty}^\infty \frac{e^{-\frac{x^2}{2}}}{1+e^{-x}} dx $$


How to size div to fill available height in parent

I am trying to create a web page that will fill the screen on a mobile phone.  However I haven't found a clean way to do this yet (without fixing sizes of things)  especially when scrollable areas are involved.  I have a fixed sized body (in the example set to 200px to test although would be 100% normally) with a
 within it. There is a scrollable
 who's height I would like to be that which is available. This is within the
. Now with the #page there is a #top, #main, and #footer-div.  The verical size of
 is set to the size of body.
 and
 end up being whatever size they need to be for their contents. Now I need #main to be #page.height - #top.height - #footer.height.  How do I do this ?  I have looked at various methods including the flex system, but this does not seem to do the job. The questions that could be duplicates don't cover the issue (see comments).  Consider the simplified following code. this has a fixed size for #main to make it work(ish).    html {   height:  100%;   margin:  0px; }  body {   height:  200px;   margin:  0px;   font:   100% Verdana, Helvetica, Arial, sans-serif;   background: #999999;       color:   Black; }  #page {   height:  100%;   margin:  0px; }  #top {   background-color: #CCDDDD; }  #main {   /* height: 100%; */   height:  calc(100% - 40px);   background: white; }  #footer {   font:   80% Verdana, Helvetica, Arial, sans-serif;   font-weight: bold;   background:  #7AB5E5;   border-top:  1px solid #436976;   border-bottom:  1px solid #436976;   clear:   both;   float:   none;   padding:  0.1em 0.1em 0.1em 0.1em;   text-align:  left; }  div.MessageScroll {   height:  100%;   margin:  0px;   overflow-y: auto; } <!DOCTYPE html>         <title>Test</title>     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />     <meta name="viewport" content="width=device-width, initial-scale=1.0">

         Header

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

             Some Text.1
             Some Test 2
             Some Test 3
             Some Test 4

         Footer


How come PK/Alien realizes that Sarfaraz did not write the letter?

In the movie PK, Tapasvi predicts that Sarfaraz will betray the Jaggu. And then Jaggu believes that Sarfaraz has betrayed her and left her at the altar with just a letter. Later, when Tapasvi refers this fact that he predicted this already to Jaggu. Then PK (alien) reveals that Sarfaraz has not betrayed her. But how come he came to know this? He never knew Sarfaraz, he just read the Jaggu's mind. But she believes otherwise. Does PK sees something in her memory that she herself doesn't know?


Integrate $\displaystyle \int \frac{(1+x^2)dx}{(1−x^2)\sqrt{1+x^4}}$  I don't know how to do this one. I need some suggestions. Thank you!


How do you hide the dot after the bullet number in an ordered list?

Initially, I thought I could use :first-letter in CSS, legacy browser support aside, but I don't think the bullet numbers technically exist in the DOM. Assume I'm not going to use bullet list images or background images.  So something like:   Apples Bananas Oranges   would become    1 Apples   2 Bananas   3 Oranges


Looking for a short story about a man walking on an alien road at night, stalked by some unseen alien animal

I think this is probably a golden age short story by a notable author that I read in the 1970's in an anthology.  Set on an alien planet colonized by earth men.  A man is walking alone on a road at dusk or night.  I can't remember if he set out on foot or his vehicle broke down.  The road winds through mountains or hills or valleys.  He knows it is unsafe to walk this road at night (others have disappeared here?), and he is angry at himself for getting a late start.  About midway, he senses that he is being stealthily stalked by something.  Some dangerous alien animal in the brush?  Can he keep his wits about him, not panic, and make it to safety?  He may or may not have a weapon.  I don't remember how the story ends.  I want to read it again so bad.  It was very suspenseful, just one character, detailing his thoughts throughout the journey.  Reminiscent of Bradbury's The Ravine.


Do I really have to create a boot disc? I downloaded Ubuntu. unpacked the 7zip file and installed. Then it said I must restart for the installation to complete. When I restarted it showed an error. Is this because I didn't create a boot disc? I'm not technical but I would really like to use Ubuntu for safety. I'm finding it very hard to create a boot disc. I guess I'm too stupid. I don't know how to change the boot area. Can't one just install and let it run?


Save button missing on User Account Edit form

I have months old problem of missing "Save" button on the user account edit form. Which is annoying to the point that now I have to find the solution.   I don't usually use account edit form since there is only one user. I have updated many modules and different cores but problem always remained there. Right now I am running latest core which is 7.23. And all modules are updated. This is a multilingual website.    Since this problem has appeared I am unable to save any change in any user account. Please have a look on the image attached. Please help.  Thanks.


How do I know the device path to an USB-stick?

I have a USB-stick (used as an installation medium). Now I need to install a driver from a restricted folder on that device). But how do I get the device path to my USB-stick (e.g. /dev/sda3 so I can mount it using the mount command?  I have read the answer to  but fdisk -l shows nothing to me.


Has Stack Exchange made anything approaching a clear or detailed statement on the current crisis?

Over the past few days, a great many Meta sites for various sites in the Stack Exchange network have been lit up by publicized moderator resignations and some dismissals.  Most of these have blamed a vaguely-defined trend of unilateral bureaucratic action by SE staff. Some others have had other motivations -- for example,  and  cited a demand for strict, affirmative adherence to a particular standard for discussing gender and use of pronouns with no room for discussion or alternatives,  by contrast complained that they felt variously unwelcomed and put-upon by what they characterized as a steady stream of individually low-intensity anti-queer bigotry. (However, almost none of the high-profile moderator resignation or dismissal posts have been very detailed.)  As a result of this, Stack Exchange is clearly in crisis with some major sites having few or no active moderators.  It often appears that all of these questions, reports, complaints, etc. on various meta sites are linked to each other; following these links  provides much background, though a few bureaucratic non-responses from SE staff (often downvoted into negative hundreds) have shown up.  I am a very casual user of Stack Exchange and rarely have insight into internal politics that many power users seem to consider obvious. Indeed, I believe this is the first time that I have made any action at all on any SE Meta site. I wish it were under happier circumstances.  Has Stack Exchange made any statement about this crisis which has crippled their moderator corps and probably driven away many of the strongest contributors? Either on Stack Exchange or by any other channel? Has anybody publicly discussed internal politics of Stack Exchange's response to the crisis?


I have been working on my probability. I have "possibly" memorized how to solve but, I really like to understand it with my heart. But.. I am kinda stuck.   I am trying to find out the possible outcomes of four of kind (unordered)  Here is my intuition:  $$\frac{52 \cdot 3 \cdot 2 \cdot 1 \cdot 48}{5!}$$   I do not see why this is wrong.   Please help me out!


Error_log file size from Var/Log/Cups/ is increasing so much (70GB+) and wont stop until i get the error saying i don't have enough space left.  ***Error_log***    W [08/Jun/2017:18:59:48 +0530] Notifier for subscription 3 (dbus://) went away, retrying!  E [08/Jun/2017:18:59:48 +0530] File \"/usr/lib/cups/notifier/dbus\" has insecure permissions   These 2 errors are written constantly to the Error_Log. I think about 50 Megabytes/sec. Making system lag


For Candy box two, after throwing away 3,000 pieces of candy does it just KEEP saying "NUM"? Cause if it does, would it be wasting your candies?


Error : java.lang.NullPointerexception: attempt to invoke virtual method void android.widget.TableLayout.addView

I am getting this NULL POINTER EXCEPTION ERROR. Need to fix this.  Trying to display the data in Table, In logs the data seems to be fetched, but its not displaying it in table format.   try {                         jsonArray = new JSONArray(respString);                         Log.d("jsonArray",jsonArray.toString());                         TableRow[] tr_head = new TableRow[jsonArray.length()];                         JSONObject jobj = null;                         for(int i=0;i<jsonArray.length();i++){                             jobj = jsonArray.getJSONObject(i);                             tr_head[i] = new TableRow(getApplicationContext());                             tr_head[i].setBackgroundColor(Color.GRAY);                             tr_head[i].setLayoutParams(new TableRow.LayoutParams(                                     ViewGroup.LayoutParams.MATCH_PARENT,                                     ViewGroup.LayoutParams.WRAP_CONTENT));                             TextView tv_item1 = new TextView(getApplicationContext());                             TextView tv_item2 = new TextView(getApplicationContext());                             TextView tv_item3 = new TextView(getApplicationContext());                             TextView tv_item4 = new TextView(getApplicationContext());                             Log.d("Table Name",jobj.getString("tb_name"));                             tv_item1.setText(jobj.getString("tb_name"));                             tv_item1.setGravity(Gravity.CENTER);                             tv_item2.setText(jobj.getString("cust_name"));                             tv_item2.setGravity(Gravity.CENTER);                             tv_item3.setText(jobj.getString("ord_date"));                             tv_item3.setGravity(Gravity.CENTER);                             tv_item4.setText(jobj.getString("ord_time"));                             tv_item4.setGravity(Gravity.CENTER);                             tr_head[i].addView(tv_item1);                             tr_head[i].addView(tv_item2);                             tr_head[i].addView(tv_item3);                             tr_head[i].addView(tv_item4);                             t1.addView(tr_head[i], new TableLayout.LayoutParams(                                     ViewGroup.LayoutParams.MATCH_PARENT,                                     ViewGroup.LayoutParams.WRAP_CONTENT));                          }


Coordinates of corners of camera view border

How to get coordinates of corners of camera border in camera view relative to the viewport area?  After checking  import bpy print('-----') print() print() for a in bpy.context.screen.areas:     if a.type == 'VIEW_3D':         for s in a.spaces:             print(s)             for d in dir(s):                 print(d) print('-----')   I have no idea how to find out where I can get this


Why hasn't Anakin Skywalker's Force Ghost advised Kylo Ren?

We know that Anakin Skywalker has become a Force Ghost — at the end of Episode VI, Anakin's Ghost is a wallflower at the ewok party on the Forest Moon of Endor.  We also know that it doesn't necessarily take special training in order to commune with Force Ghosts — while Yoda mentions in Episode III that he can teach Obi-Wan to speak to Qui-Gon's Ghost, Luke can speak to Obi-Wan's with no special training.    In The Force Awakens, Kylo Ren meditates in the presence of the helmet of Darth Vader and pleads to Vader,     "Show me again the power of the darkness..."   I assume that Anakin has not actually appeared to Kylo, for if he did, he would have surely advised Kylo to return to the Light and to give up his obsession with the dark period of Anakin's life.  Given that Kylo is Force sensitive, given the stakes involved, and given the familial connection between Anakin and Kylo, why hasn't Anakin's Ghost appeared to Kylo Ren?


Is $\lim_{n\rightarrow\infty}\sum_{k=1}^{n}\frac{1}{\sqrt{n^2+k}}$ konvergent or divergent?

Is $$\lim_{n\rightarrow\infty}\sum_{k=1}^{n}\frac{1}{\sqrt{n^2+k}}$$      konvergent or divergent?   I'm trying to use the squeeze theorem here but I can't find a suiting lower bound. For the upper bound I have that  $$\sum_{k=1}^{n}\frac{1}{\sqrt{n^2+k}}\leq n\cdot \frac{1}{n}=1.$$  Is $\frac{n}{\sqrt{n^2+n}}$ suitable for a lower bound? If so, please explain how. I can't see that this will always be less than or equal to my sum.


I unblocked an old friend on Facebook and right after I tried to add them back. However, the "Add Friend" button is not available on their page anymore.    I can send a message and we have over 15 mutual friends. Why is this happening and how can I fix it?


How exactly does a generator comprehension work?

What does generator comprehension do? How does it work? I couldn't find a tutorial about it.


Are PPAs safe to add to my system and what are some "red flags" to watch out for?

I see a lot of interesting programs out there that can only be obtained by adding a "PPA" to the system but, if I'm understanding correctly, we should stay within the official "repositories" for adding software to our system.   Is there any way for a novice to know if a "PPA" is safe or if it should be avoided? What tips should the user know about when dealing with a PPA?.


I want to develop a webportal that will show the QGIS generated images on dynamic website. For this reason I need to run gdal_translate command inside php page. but I don't know is it possible or not. If possible than please let me know how to do this and if not possible than please give any alternative solution in this regard.


Determine which of $N$ points is not on $\sin(ax + b)$, where $a$ and $b$ are unknown.

Suppose $N$ points ($(x_1,y_1), (x_2,y_2), ... (x_N,y_N)$) are given from a curve $y=\sin(ax+b)$ where $a, b$ values are unknown. Before giving these $N$ points to you, $y$ coordinate of one point is randomly tampered so that it does not lie on the curve.  Write a program to determine which point among $N$ points is NOT on the sinusoidal curve, whose $a$, $b$ values are unknown.  Any logic on how to approach this question, would be highly appreciate would be very thankful!


Switch from Fedora to Ubuntu and Evolution to Thunderbird

Presently I have the system with Fedora 15 and Evolution 3.0.3 for emails. I'm planning to switch my OS to Ubuntu and and Thunderbird for emails. Is there any way I can do this keeping all my earlier email data imported into Thunderbird with new OS?


Since I've started electronics I'm using this kind of board for permanent projects:     But sometimes it's a bit annoying, especially when I need a line going from the top to bottom of the board.  I've seen this kind of board:     My question is, how can I cut the strips?  By cutting the strip I don't mean cutting the board itself, just the copper strip. I've tried with a precision knife but I'm not sure about the method, the blade gets damaged really quickly and it's really hard to cut the copper.


Summing a list and specifying number of elements on list

How would I create something like either of the following on LaTeX?


Unable to change resolution back to normal

After fixing the "System runs in low graphic mode"-error, the resolution of my screen changed to 640x480. Obviously, this is not my native resolution.  I cannot set it to the native resolution (1366 x 768) for some reason, since there is no other resolution shown in the Monitor Settings. Arandr also does not show 1366x768 as a possible resolution.  My laptop is a Samsung R519 with standard resolution 1366x768, with an Intel graphic card.  Does anyone have an idea how to solve my problem? I hope I explained it clear enough (if there is some missing info, please let me know)


New comment notification should be skipped if I'm known to have seen it

Someone commented on an answer I've written, and I noticed there was a "1 more comment" message. I clicked on it, and saw the comment. I even replied.  A couple of minutes later I'm seeing a red [1] over my "inbox", and the comment is what I'm notified about.  Comments with which I've known to have interacted - e.g. by clicking "more comments" or by replying below them - should be considered as not requiring notification.


What harm can be done with a copy of one's passport?

In one of the questions on this site, it was suggested the use of  to save a backup copy of your passport, in case you need to proof who you are if your original document is lost.   I like the idea, but what if someone gets access to your Dropbox folders and is able to acquire the copy of your passport.  The same goes for when you leave a copy of your passport at a hotel receptions desk. Once someone has the info printed on that copy, would that make it easier to steal your identity?


For example, "Tables sizes" as far as I know, is wrong. Correct is "Table sizes". But it may mean either "sizes of the one table" or "sizes of many tables". How to specify that I want to say about many tables? What rule is used there? Where can I read more about it?


Can we change the color of comments or questions' text?

Is it possible to change the colour of comments text or of the text while asking questions. I know that we can make the text bold, italics etc.   But don't know how to change the text colour from black(default)to red,green etc.


Which one is better - more cross-type sensor or better sensitiveness of cross-type sensors?

What makes better sense for situations like: low light, sports/action, wild life?   More cross-type sensor on AF (like Canon does) Or more sensitive cross-type sensors (like Nikon does)


Find the limit $ \lim_{n\to \infty} 2^{\frac{1}{n}}$

$$\lim_{n\to \infty}2^{\frac{1}{n}}$$   Basically looking at $$\lim_{n\to \infty}2^{\frac{1}{n}}=2^{\lim_{n\to \infty}{\frac{1}{n}}}=2^0=1$$  But if I use $$\lim_{n\to \infty}2^{\frac{1}{n}}=\lim_{n\to \infty}e^{\ln\left(2^{\frac{1}{n}}\right)}=\lim_{n\to \infty}e^{{\frac{1}{n}}\cdot{\ln(2)}}=\lim_{n\to \infty}e^{\frac{1}{n}}\cdot\lim_{n\to \infty}e^{\ln(2)}=1\cdot2=2$$  Where did I got it wrong?


I am traveling from the US to the UK and then to Portugal. Round trip. I have a laptop without a battery, so I am hesitant to bring it as carry-on in the plane because I had troubles already with a laptop not turning on through security.   Is there any problem with sending the laptop in the checked-in luggage? If they open my luggage and they find it, would that be a problem? Could they take it away?


I know that crystal oscillator is a type of oscillator. But why in colloquial terms crystal is different from oscillator and how they are physically different?


How to migrate the SQL Server instance and system databases to a different drive (mapped to a different letter) on the same server?

I'm tasked with moving our SQL Server instance and system databases from the existing drive it's on to a new drive on the same server. I know I can stop the SQL Server service, literally move the instance and database files to the new drive and start the service again, but the drive is going to be mapped to a different letter.  I'm guessing I'll need to update the database file paths for the system databases to point to the new drive letter.  What else do I need to do to reconfigure the instance so that's pointing to the correct drive, to ensure it works properly when I start the service again?  Edit: It sounds like this Microsoft doc is pretty encompassing of what to do, especially from the system database perspective, but are there any other steps or gotchas I should be aware of from the instance perspective:   Note: I am unable to re-use the same drive letter for business reasons.


The following is part of the conversation between a detective and Nick in the movie "Gone Girl":       Detective: “What do you do now for work?”      Nick: “My sister and I own The Bar downtown.”      Detective: “Oh, The Bar? Love the name. Very meta.”       Nick: “Thanks.”     What does "very meta" mean?


Featured question appears twice on mobile iOS app

The featured meta question appears twice on the iOS app, pictured here:    It seems as if one link is showing the question at a previous time (and is not updated), given the mismatch in answer counts.   App Version: 1.6.2.5 Device: iPhone 6s OS Version: Version 10.2.1 (Build 14D27)


Simple probability problem of placing balls in 5 boxes

There are five empty boxes. Balls are placed independently one after another in randomly selected boxes. Find the probability that the fourth ball is the first to be placed in an occupied box.   We only need to consider the first 5 balls. The total possibilities are $5^5$. I have been trying various cases but cant seem to pinpoint the crux of the strategy any help?


Minecraft Repeating Command Block constantly /tp me

So I am in this minecraft world and I was messing around with a command block right next to my build and accidently /tp myself to a random location and it was a repeating block so I am stuck, HELP!


Is it legal to upload a paper to arXiv when it is under double blind review for one of the IEEE journals? I am suspicious that it may violate the double blind review requirements and I couldn't find any thing in the journal's homepage specific to this issue. In general IEEE allows preprint versions to be uploaded to arXiv.


A reference to primitive type in Java (How to force a primitive data to remain boxed)

I would like to pass a reference to a primitive type to a method, which may change it.  Consider the following sample:  public class Main {      Integer x = new Integer(42);     Integer y = new Integer(42);      public static void main(String[] args) {         Main main = new Main();         System.out.println("x Before increment: " + main.x);          // based on some logic, call increment either on x or y         increment(main.x);          System.out.println("x after increment: " + main.x);     }      private static void increment(Integer int_ref) {         ++int_ref;     } }   The output running the sample is:  x Before increment: 42 x after increment: 42   Which means int_ref was past to the function by value, and not by reference, despite my optimistic name.  Obviously there are ways to work around this particular example, but my real application is way more complex, and in general one would imagine that a "pointer" or reference to integer would be useful in many scenarios.  I've tried to pass Object to the function (then casting to int), and various other methods, with no luck. One workaround that seems to be working would be to define my own version of Integer class:  private static class IntegerWrapper {     private int value;      IntegerWrapper(int value) { this.value = value; }     void plusplus() { ++value; }     int getValue() { return value; } }   Doing this, and passing a reference to IntegerWrapper does work as expected, but to my taste it seems very lame. Coming from C#, where boxed variable just remain boxed, I hope I just miss something.  EDIT:  I would argue my question isn't a duplicate of , as my question isn't theoretical, as I simply seek a solution. Philosophically, all method calls in all languages are pass-by-value: They either pass the actual value, or a reference to the value - by value.  So, I would rephrase my question: What is the common paradigm to workaround the issue that in java I'm unable to pass a reference to an Integer. Is the IntegerWrapper suggested above a known paradigm? Does a similar class (maybe MutableInt) already exist in the library? Maybe an array of length 1 a common practice and has some performance advantage? Am I the only person annoyed by the fact he can store a reference to any kind of object, but the basic types?


Punctuation for multiple questions in one sentence

I have multiple questions that I want to put in one sentence. Is this punctuation correct?  Is there anyone who can read it? Understand it? Translate it?  or  Is there anyone who can read it? understand it? translate it?  Alternate would be:  Is there anyone who can read it? Is there anyone who can understand it? Is there anyone who can translate it?


I want my private IP address 192.168.xxx.xxx to be fixed and do not change, Is it possible? I am using Ubuntu 14.04.  I need it to work even when I change the network? Thank's


Why is variable called "variable" in mathematics if in fact it's immutable?

I've never thought of this issue until recently when I've been using Haskell to build a substantial project. In Haskell (and functional programming languages in general), most so-called "variables" are actually mathematical variables, which seem to be immutable by definition.  This made me quite confused. "Variables" in imperative programming languages make perfect sense because they indeed are mutated often. However, such a denomination seems very weird when the thing it represents is actually invariable.  Since the word "variable" originated from mathematics and has been in use for several decades, I'm curious how such an apparent self-contradiction came into existence in the beginning. Did people have a different idea in mind when they first invented the word, and it evolved over time to its current meaning? Was immutability not an important concern at that time such that it was overlooked? Or did I just get it wrong and "variables" in mathematics are actually not totally immutable after all?


Create a book cover with spine, rear page and flaps

I have just finished my thesis, and I want to ask if there is a way to create a front-title page with spine (I don't know if this is the right term for the area between front page and rear page)? I would also like to include a back page.  Some preliminary ideas are shown bellow    I found a package called zwpagelayout which allows somehow to create a spine and flaps as well. I tried to use it by  \documentclass[11pt]{book} \usepackage[english,greek]{babel} \usepackage[iso-8859-7]{inputenc} \usepackage{kerkis} \usepackage[pdftex]{graphicx} \usepackage{colortbl} \usepackage{xcolor} \usepackage[papersize={,293mm}, topmargin=2mm, botmargin, strictheight, leftmargin=0mm, flap=50mm, textwidth=209mm, spine=13mm, cropmarks, cropframe, croptitle=Πρότυπο Εξωφύλλου]{zwpagelayout} \linespread{1}  \begin{document}  Εξώφυλλο \end{document}   Using this code produces an error that spine is not defined... Any ideas?  I edited the previous code and the result is     Now I have to find a way to "move" around pages... Any ideas will over-welcomed!!!  I also used this  \documentclass[12pt,a4paper]{article} \usepackage[T1]{fontenc} \usepackage[latin1]{inputenc} \usepackage{pstricks} \pagestyle{empty}  \makeatletter  \def\La{%   L\kern-.36em{%   \setbox0\hbox{T}%   \vbox to\ht0{%     \hbox{$\m@th$%       \csname S@\f@size\endcsname       \fontsize\sf@size\z@       \math@fontsfalse\selectfont A}%       \vss%     }%   }% } \def\AllTeX{(\La\kern-.075em)\kern-.075em\TeX} \makeatother  \begin{document} \begin{titlepage} \psset{unit=1in,linewidth=2pt}% \psline(-0.75,2)(-0.75,-\paperheight)% \psline(-0.25,2)(-0.25,-\paperheight)% \rput[lb]{90}(-0.3,-0.75\paperheight){\red\Huge\textbf{Study}}% \rput[lb]{90}(-0.4,-0.1\paperheight){\red\Huge\textbf{MicroMEGAS}}%  \vspace*{3cm} \centerline{\Huge \textbf{P}ost\textbf{S}cript \textbf{T}ricks}  \vspace{2cm} \centerline{\Large Athanasios Stamatopoulos} \end{titlepage}  \end{document}   but my compiler cannot recognise commands like the following  \psline(-0.75,2)(-0.75,-\paperheight)%   The output from this code is     As you see no spine is produced. Instead spine is inserted in frontpage...  I have found a way to move around pads... The complete and correct code is  \documentclass[11pt]{book} \usepackage[english,greek]{babel} \usepackage[iso-8859-7]{inputenc} \usepackage{kerkis} \usepackage[pdftex]{graphicx} \usepackage{colortbl} \usepackage{xcolor} \usepackage[papersize={,293mm}, topmargin=2mm, botmargin, strictheight, leftmargin=0mm, flap=50mm, textwidth=209mm, spine=13mm, cropmarks, cropframe, croptitle=Πρότυπο Εξωφύλλου]{zwpagelayout} \linespread{1}  \begin{document}  \hbox to \textwidth{% \vbox to \textheight{\hsize \CropFlap \centering Back flap\vfill}\hss \vbox to \textheight{\hsize \UserWidth \centering \begin{tikzpicture}\draw (0,0) --(5,5);\end{tikzpicture}\vfill \leavevmode     ISBN+EAN}\hss \vbox to \textheight{\hsize \CropSpine \centering \vfill \begin{sideways}Name Title\end{sideways}\vfill}\hss \vbox to \textheight{\hsize \UserWidth \centering Front cover\vfill \LaTeX}\hss \vbox to \textheight{\hsize \CropFlap \centering Front flap\vfill}} \end{document}


"User memory limit exceeded" using Random Forest classification

I am trying to classify using randomForest classification in GEE . However, I always get the error User memory limit exceeded, so I assume the number  of the feature are too large. Nevertheless, I saw many developers can classify even bigger dataset, so I am wondering if there is a better option there? The code can be accessed via  var fire= ee.FeatureCollection('users/spatola/recovery_rf_1712').map(function(feature){     var num = ee.Number.parse(feature.get('CLC_311'));     return feature.set('CLC_311', num);   }) var indices= ['EVI_mean','Dnbr','NBR2_mean','NBR2_min','NBR2_max','EVI_min','EVI_max']; var fire1=  fire.filter(ee.Filter.notNull(indices)); var fire2= fire1.select('Class_R','Dnbr','EVI_max','NBR2_max','imageId') var bands= ['NBR2_max', 'EVI_max']; var classProperty= 'Class_R'; var random= fire2.randomColumn('random'); var split_train= 0.8; var split_test= 0.2; var trainPartition= random.filter(ee.Filter.lt('random',split_train)); var testPartition= random.filter(ee.Filter.gte('random',split_test));  var RFtrained_c= ee.Classifier.smileRandomForest({  numberOfTrees: 100,  minLeafPopulation:2,  seed: 123,  }) .setOutputMode('CLASSIFICATION') .train({     features: trainPartition,     inputProperties: bands,     classProperty: classProperty,     }) print(RFtrained_c); var dict =  RFtrained_c.explain(); var test = testPartition.classify(RFtrained_c) print(test.first())


I am unable to install or update anything because of malformed error .  Error :   E: Malformed entry 1 in list file /etc/apt/sources.list.d/realsense-public.list (Component) E: The list of sources could not be read.  can anyone help


How did Vader beat the Millennium Falcon to Bespin?

I understand that Boba Fett could have worked out the Falcon's destination from it's bearing/trajectory, but if the Falcon is "the fastest hunk of junk in the galaxy", how did Vader manage to "Arrive just before [they] did"?  This implies Vader beat the Falcon to Bespin, doesn't it? how would he have been able to negotiate  with Boba, and then still beat the ship to Bespin?  Unless by "they" (as in "they arrived just before you did"), Lando is referring to the Empire as an entity, and not to they physical presence of the Empire as Manifest by Vader?  Anyone have any canon answer?


How to draw line between intersecting meshes in Freestyle?

Is it possible to draw a line between intersecting objects? With my current setup, it won't draw anything between them.


Suppose I have applied for a 6-month J-1 internship Visa and suppose it is successfully granted. Suppose that, due to force majeure or other circumstances beyond my control, I am forced to cancel my travel to the US and that, therefore, I never validate and use my Visa. Will this have negative consequences on my status/record for possible future Visa applications?  Thanks for your support.


Trouble in proving that a continuous function vanishing at $\pm\infty$ attains at least its maximum or minimum.

Let $f:R\to R$ be a function continuous on $R$. Let $\lim_{x\to \pm\infty}f(x)=0$  Then I have to show that $f$ :$\;$   $1)$ is bounded on $R$ and   $2)$ attains at least its maximum or minimum on $R$.  I tried to prove the above as follows:  For $1)$: Since $\lim_{x\to \pm \infty}f(x)=0$. Let $\alpha\gt 0$ be such that $\forall x\gt \alpha: |f(x)|\lt1$. Similarly, let $\beta\lt 0$ be such that $\forall x\lt \beta: |f(x)|\lt 1$. By Boundedness theorem on $[\alpha,\beta]$,$\;\exists M\gt 0$: $|f(x)|\le M$  $\;\;\forall x\in [\alpha,\beta]$ ,$\;$therefore $\;$$ |f(x)|\le sup(M,1)$ $\forall x \in R$. Hence $f$ is bounded on $R$.  For $2)$: By maximum-minimum theorem of continuous functions on $[\alpha, \beta]$, $f$ attains its maximum and minimum values on $[\alpha, \beta]$. How do I extend the concept of maximum-minimum theorem  from $[\alpha, \beta]$ to $R$? Please help. Thanks in advance.


Is COT (cost of transfer) exsists in bank from a certain country to another? (Eg. Uk to philippines or othe country to philippines)

Heres the scenario: I have invested through bitcoin to a certain company but the thing is endless payments were being asked and i have complied with them. A few days i received from a certain bank named hpsbank(i dont even know where it is located) asking me for a COT (cost of transfer) of $3500. The account was on my name and they gave me my account name and my password. I was a bit hesitant because their website seemed to be legit but the cons was they dont have a contact number and ive googled about it they are not registered with BBB and FDIC. Now here are my questions i hope you can help me shed light on this. Questions:  Is there really what they called a cost of tranfer between international banks? If ever these are not legit, where can i possible file a complaint to get my money back?  Thank you.


Let $f: \Bbb R \to \Bbb R$ be a differentiable function such that $\sup_{x \in \Bbb R}|f'(x)| \lt \infty$. Then

(UGC CSIR-2015, DECEMEMBER, MATHEMATICAL SCIENCES)        $f$ maps a bounded sequence to a bounded sequence.   $f$ maps a Cauchy sequence to a Cauchy sequence.   $f$ maps a convergent sequence to a convergent sequence.   $f$ is uniformly continuous.      I choose all of the options as possible answers because the condition $\sup_{x\in \Bbb R}|f'(x)| \lt \infty$ forces $f$ to be uniformly continuous.(Because $f$ becomes Lipschitz and Lipschitz condition implies uniform continuity)  i.e. $\frac {|f(x)-f(y)|}{|x-y|} \le \sup_{x\in \Bbb R}|f'(x)|$ $ \forall x,y$.  Hence all other options are bound to be true.  Am I correct?


Basic geometry question and proof that $dT/d\Theta = 1 + T^2$

I started to flick through Needham's Visual Complex Analysis and pretty much fell on my face in the first exercise.  On page ix, he shows a proof that $dT/d\Theta = 1 + T^2$ if $T = tan(\Theta)$.  He does so by comparing the black triangle with the initial triangle (grey). What I don't understand is why the length of the one segment is $L*d\Theta$. I'm sure I'm lacking some basic math here.....   Shouldn't the length be $L*tan(d\Theta)$ (which obviously would be less helpful)?


Add local file to IE11 Trusted Zone or Local Intranet

I'd like to add a local file (C:\Users\David\AppData\LocalLow\LastPass\iehome2.html) LastPass needs to open my LastPassVault in IE11.  Scripting is disabled in my Internet zone and the file needs JavaScript in order to work ("JavaScript is required for this page to function.").  However, I am having a hard time adding the file to IE's Trusted Sites or Local Intranet.   The most logical thing to me is to add file://* to the zones, but IE won't except that


Installing windows on Mac won't recognize USB

I am trying to install windows as a boot camp partition on my main hard drive ssd (after spending countless hours trying to get it installed on the optical bay hard drive).  I assumed this would be simple since o am no longer trying to install to an "external" hard drive. But it has turned out to be just as difficult.  The biggest problem I am encountering is that i have a 2010 15" macbook pro which originally came with an optical drive which i have replaced with a Hard disk and the main drive is now an ssd also I am trying to install windows 7. I tried modifying my info.plist so i could create a USB install of my windows iso but when I create a boot camp partition and hit install it restarts into a gray screen and nothing happens. If I attempt to force restart from this It boots into an apple logo that hangs until it goes to a black screen that says "No bootable device found - please insert a bootable device and hit any key." I then force restarted and held down option and when it loaded it didn't show my USB as a device (only my main ssd drive and my optical bay hard disk).  I found a YouTube video of a Czech guy who used virtual box to start the install and then move it to the desired disk and used refit to access it, but when I installed refit it didn't even show up in my boot devices when I held down option...   My question is how I can go about installing windows 7 on my 2010 macbook pro that has an ssd in the main hard drive and a hard disk on the optical bay drive. It can be installed to either disk but I suppose the ssd would be better since its faster to boot. I have a working ISO (showed working from virtual box installs) and a USB drive.


I know it's not NEC and far from the right thing to do.  I need 30 amps at the garage.  I already have two unused 12/2 cables (w/ground) running to the garage. I was thinking to use one 12/2 cable, combine the black and white from one, put it on one phase and use another 12/2 wire, combine the black and white from that one, and put it on the other phase. The grounds of both would be tied to neutral.  In the garage I'd make a breakout box and attach each 12/2 to a wire of a 6/3. Each 12/2 would be a hot, 120VAC of a leg of the 2 double circuit breaker.   I'd be pulling about 30 amps for an electric car charger.  Please give me all the reasons why NOT to do this, and that it's a bad idea.  12/2 - Black & White - Phase 1, 120VAC   > Black wire on 6/3  12/2 - Black & White - Phase 2, 120VAC   > Red wire on 6/3 Ground > White on 6/3  Grounds of each would be tied to neutral/ground.


How to find the equation of a Parabola with given 2 points from which tangents are drawn and point of intersection of these tangents

You are given two points (2,3) and    (3,1) on Parabola from where 2    tangents are drawn intersecting at    (-1,-2) . Find the locus of Parabola   This question is supposed to have some trick or some clever approach I have tried really hard but I am failing to see any gimmicky solution


How to sent .jar app to client but they dont have to install JVM to run

i want to sent my app java to clients but they dont have to install JVM to run. They just click double in app and run.  How do i have to adjust my app ? i hope everybody guide. Thank you!


Selecting 3 non-consecutive days of the week

We need to find how many groups of $3$ days of the week there can be, given that no two days should be consecutive. The answer should be $7$, but I do not know how to get to the answer. Thanks in advance.


Ubuntu 20.10: There was an error creating a child procsess. fix please

This is what happens when I launch the terminal  There was an error creating a child process So I have been using the Ubuntu terminal on my raspberry pi 4 model b 8gb with Ubuntu for a couple moths when Ubuntu 20.10 came out for the pi But now I have a problem where I launch the terminal and it gives that message. I have gone for alternatives and tried to fix it but all the solution where outdated or there where on a different distro and the Ubuntu commands did not fix because it only triggers when they did a certain command.


Packages have unmet dependencies on Ubuntu sdk installation

The following packages have unmet dependencies:  ubuntu-sdk : Depends: qtcreator but it is not going to be installed               Depends: qtcreator-plugin-ubuntu but it is not going to be installed               Depends: qtcreator-plugin-ubuntu-cordova but it is not going to be installed               Recommends: qtdeclarative5-qtaudioengine-plugin but it is not going to be installed E: Unable to correct problems, you have held broken packages.   I am using ubuntu 13.04 x64


can I make Excel always open a delimited text file with "text" translation?

Opening a tab-delimited data file in Excel to view & manipulate the data is a very common operation around here.  However, by default Excel (2003/4 or 2007/8) will read the columns in a "General" format, which occasionally does terrible things like turning "1/2" into "2-Jan".    Is there a way to tell Excel never to do this, but always process the values as Text, without going through the format wizard, selecting all of the columns, and doing it manually?    Extra points if this works in both Mac and Windows versions of Excel.


Is there any difference between ES6 class constructor functions and method?

Is there a difference between a constructor function vs a method like so:  class foo {   constructor() {     // A -> Function inside constructor     this.init = () => {       console.log('test');     }   }    // B -> Method   bar() {     console.log('foo');   } }   I tried this on the babel REPL and tried to grok the code that it compiles but it doesn't make any sense to me ATM:


Where can I find the official document on advanced cp command?

I want to copy all contents in folder A(but not include A itself) to another folder B recursively, and overwrite any existing files or folders with the same name.  Originally I plan to use the following command:  cp -f -r /home/alan/A/* /home/alan/B/   However, after searching online, I find all others recommend the following format:  cp -f -r /home/alan/A/. /home/alan/B/   such as:     The strange thing is that I cannot find any official document on this advanced cp command. I tried to use:  man cp info coreutils 'cp invocation' cp --help   But none of them indicate such usage. How can I find the official document on advanced cp command and usage?  Thank you very much.


$$\lim_{x\to0}\left(\frac{\sin(x)}{x}\right)^{\frac{1}{x^2}} \stackrel{?}{=} 0$$  My calculations (usage of  will be denoted by L under the equal sign =): (Sorry for the small font, but you can zoom in to see better with Firefox) $$ \begin{align} & \lim_{x\to0}\left(\frac{\sin(x)}{x}\right)^{\frac{1}{x^2}} = \\ & \lim_{x\to0}e^{\ln\left(\left(\frac{\sin(x)}{x}\right)^{\frac{1}{x^2}}\right)} = \\ & e^{\lim_{x\to0}\frac{1}{x^2}\ln\left(\left(\frac{\sin(x)}{x}\right)\right)} = \\ & e^{\lim_{x\to0}\frac{\ln\left(\left(\frac{\sin(x)}{x}\right)\right)}{x^2}} \stackrel{\frac{0}{0}}{\stackrel{=}{L}} \\ & e^{\lim_{x\to0}\frac{x}{2x \sin(x)}\cdot\frac{\cos(x)x -1\cdot\sin(x)}{x^2}} = \\ & e^{\lim_{x\to0}\frac{1}{2}\cdot\frac{1}{\sin(x)}\cdot\left(\frac{\cos(x)}{x} - \frac{\sin(x)}{x^2}\right)} = \\ & e^{\lim_{x\to0}\frac{1}{2}\cdot\left(\frac{\tan(x)}{x} - \frac{1}{x^2}\right)} = \\ & e^{\frac{1}{2}\cdot\left(\lim_{x\to0}\frac{\tan(x)}{x} - \lim_{x\to0}\frac{1}{x^2}\right)} \stackrel{\frac{0}{0}}{\stackrel{=}{L}} \quad\quad \text{(LHopital only for the left lim)} \\ & e^{\frac{1}{2}\cdot\left(\lim_{x\to0}\frac{1}{\cos^2(x)} - \lim_{x\to0}\frac{1}{x^2}\right)} = \\ & e^{\frac{1}{2}\cdot\left(1 - \infty\right)} = \\ & e^{-\infty} = 0\\ \end{align} $$    Edit #1:  Continuing after the mistake of the $\tan(x)$:  $$\begin{align}  & e^{\lim_{x\to0}\frac{1}{2}\cdot\frac{1}{\sin(x)}\cdot\left(\frac{\cos(x)}{x} - \frac{\sin(x)}{x^2}\right)} = \\ & e^{\lim_{x\to0}\frac{1}{2}\cdot\left(\frac{\cot(x)}{x} - \frac{1}{x^2}\right)} = \\ & e^{\lim_{x\to0}\frac{1}{2}\cdot\left(\frac{\frac{1}{\tan(x)}}{x} - \frac{1}{x^2}\right)} = \\ & e^{\frac{1}{2}\cdot\left(\lim_{x\to0}\frac{\frac{1}{\tan(x)}}{x} - \lim_{x\to0}\frac{1}{x^2}\right)} \stackrel{\frac{0}{0}}{\stackrel{=}{L}} \quad\quad \text{(LHopital only for the left lim)} \\ & e^{\frac{1}{2}\cdot\left(\lim_{x\to0}\frac{\frac{\frac{-1}{\cos^2(x)}}{\tan^2(x)}}{1} - \lim_{x\to0}\frac{1}{x^2}\right)} = \\ & e^{\frac{1}{2}\cdot\left(\lim_{x\to0}\frac{-1}{\sin^2(x)} - \lim_{x\to0}\frac{1}{x^2}\right)} = \\ & e^{\frac{1}{2}\cdot\left(-\infty - \infty\right)} = 0\\ \end{align} $$


I'm studying the following circuit   The image is explicit but as you can see the input measured in the upper terminal is a square wave with \$E_c\$ and \$-E_c\$ as levels.   Now I also had no trouble understanding that if \$R_B \leq \beta R_C\$ when the square wave is in the positive half-cycle we have saturation and when it is on the negative half-cycle we have cutoff situation.  Now in saturation we will (because the junction voltages are zero) an output voltage of zero. That is correct with the figure. However when we are in cutoff, applying KVL to the output mesh leads us to   $$U_{CE}=-E_c$$  because currents can be neglected.  That however is not concordant with the figure which shows $$U_{CE}=E_c$$ Why is that? What am I missing?


I want to write a reference with the bullet numbering of the form: [] For example,   [] Drucke, D., 1992, Reflection Properties of Curves and Surfaces, Mathematics Magazine, v.65, p.147.  is a reference in my paper. I am currently using the following code:   \begin{enumerate} \item Drucke, D., 1992, Reflection Properties of Curves and Surfaces, Mathematics Magazine, v.65, p.147.  \end{enumerate}   As a consequence, I am getting the following output:    Drucke, D., 1992, Reflection Properties of Curves and Surfaces, Mathematics Magazine, v.65, p.147.   Is it possible to achieve  instead of 1. in a list?   Update 1 The code snippet seems to works partially:   \begin{enumerate} \item [[ 1]] Drucke, D., 1992, Reflection Properties of Curves and Surfaces, Mathematics Magazine, v.65, p.147. \end{document}   Output:   Any improvements, will be extremely helpful...


Quantum teleportation - the alternative to destroying atoms

Can't you just disassemble, not destroy our atoms and transport them to another teleporter via networking or telecoms?  This is my thinking of how to keep the same person, not an exact copy of him/her, alive when teleporting.  Please answer to tell me if it's possible or not.


Is there a database of Linux compatible hardware?

I want to know if there is a centralised community site where all Hardware is listed in terms of compatability with Linux. Something like AppDB for Wine.


Defining aliases for a certain directory

Is there a way to have an alias set for a particular directory and its subdirectories?  I know I can put it in my .bashrc file, but I would like it only for a certain directory.  Edit: what i mean is i'd like to run commands that are aliased inside of the directory  ~$ foo -bash: foo: command not found ~/project$ foo Bar!


Is it safe to change the lens on my new DSLR?

I recently bought myself a shiny new DSLR camera. Before I can use it, I had to do something kind of terrifying: mount the lens.  Now of course, half the advantage of SLR cameras is that the lenses are interchangeable. But sitting there holding an extremely expensive brand new camera and staring into its bare innards, I'm just terrified that if I make one wrong move, a hair or a piece of dust could fall in there, and then the camera will be irreparably damaged and I'll never be able to use it again.  This might sound like a stupid question, but… is it actually “safe” to change the lens on the camera? Is this likely to destroy it?  (Obviously it goes without saying that you should limit the time spent with no lens attached to the minimum number of seconds possible. But even if you have lightning fingers, the camera will still be lenseless for some number of seconds. And it's not like I'm standing in a class 100 cleanroom here! Besides, you don't want to be too rough with the delicate lens mounting either…)


NumLock ON in logon screen (Lubuntu 14.04)

I just installed a danish version of the Lubuntu 14.04 and I have fought with this problem = NumLock is OFF when the logon dialog comes up AND my users have numbers in their passwords !  I have tried, I would say, ALL of the methods I found in this forum and none of them worked.  I shall say that some methods describes dialogs that I don't have or that looks different and DON*T have the fields mentioned in that method.   Other methods describes adding a line to files that are NON-EXISTENT or have no content at all - and if I that add the line described as the only line in that file, the machine wont start.  I'm very frustrated to be the only one in the world where NumLock can't be set ON in the logon dialog.  I'm NOT that skilled in this LINUX world, so bare with me.  Do you have a bullet proof method that can bee used to set the NumLock ON when the logon dialog is shown on the screen after re-boot ?


I have two RasberryPi running debian wheezy and I would like to mount a folder from computer A on computer B.  What is the best (as in most efficient) way to do this?  I can do it via SMB, but that is for windows, I think there must be a better way to share across linux.


Do black holes attract more in GR than Newtonian gravity beyond their event horizon?

I was once shown that if a black hole with the mass of our Sun replaced our Sun in the solar system (I believe it was in a simulation program), the attraction it has on the planets will be the same because the distance between the planets and centre of mass is the same, regardless of the density. How well does this hold up to more accurate mathematics of physics such as GR, because I was shown this in the context of Newtonian Mechanics?


I am working on a conceptual model for a database. I have the following entities:  Student (id, name, date of birth, department)  Subject (id, name)   This is a many-to-many relationship, one student may be enrolled in many courses, each course has many students. From what I understand, as I should break this many-to-many relationship by introducing a new into a entity, say 'registered' which allows a one-to-one relationship or one-to-many relationship?  Is this correct design decision?


Is a multishot self-timer mode available on mid-range cameras?

I'm looking for a digital camera that has multiple shot self-timer mode.  Is this feature available on mid-range cameras or is just high-end ones?


Comment upon down voting a question on stack-overflow

Apologies if this is not the correct platform for asking this. I recently got my question down voted, now under normal circumstances a developer would not just post a question unless they think they have exhausted all the other resources like asking co-developers(mostly seniors of course). My question was down voted but that person did not bother to maybe add a comment to say why.  I was wondering if is there perhaps a way of forcing someone to at least leave a comment after a down vote, I understand a down vote means the voter thinks a question is not well put or no enough research was done prior to the question being asked so at least a person should be able to leave a comment maybe a link that points to an answer to that very same question(especially the one answered on the very same stack overflow site), that why I can see how lazy or stupid I am for not seeing an answer that is right under my nose.


How to determine quantiles (isolines?) of a multivariate normal distribution

I'm interested in how one can calculate a quantile of a multivariate distribution. In the figures, I have drawn the 5% and 95% quantiles of a given univariate normal distribution (left). For the right multivariate normal distribution, I am imagining that an analog would be an isoline that encircles the base of the density function. Below is an example of my attempt to calculate this using the package mvtnorm - but to no success. I suppose this could be done by calculating a contour of the results of the multivariate density function, but I was wondering if there is another alternative (e.g., analog of qnorm). Thanks for your help.  Example:  mu <- 5 sigma <- 2  vals <- seq(-2,12,,100) ds <- dnorm(vals, mean=mu, sd=sigma)  plot(vals, ds, t="l") qs <- qnorm(c(0.05, 0.95), mean=mu, sd=sigma) abline(v=qs, col=2, lty=2)   #install.packages("mvtnorm") require(mvtnorm) n <- 2 mmu <- rep(mu, n) msigma <- rep(sigma, n) mcov <- diag(msigma^2) mvals <- expand.grid(seq(-2,12,,100), seq(-2,12,,100)) mvds <- dmvnorm(x=mvals, mean=mmu, sigma=mcov)  persp(matrix(mvds,100,100), axes=FALSE) mvqs <- qmvnorm(0.95, mean=mmu, sigma=mcov, tail = "both") #?  #ex. plot    png("tmp.png", width=8, height=4, units="in", res=400) par(mfcol=c(1,2))  #univariate plot(vals, ds, t="l") qs <- qnorm(c(0.05, 0.95), mean=mu, sd=sigma) abline(v=qs, col=2, lty=2)  #multivariate pmat <- persp(seq(-2,12,,100), seq(-2,12,,100), matrix(mvds,100,100), axes=FALSE, shade=TRUE, lty=0) cont <- contourLines(seq(-2,12,,100), seq(-2,12,,100), matrix(mvds,100,100), levels=0.05^2) lines(trans3d(cont[[1]]$x, cont[[1]]$y, cont[[1]]$level, pmat), col=2, lty=2)  dev.off()


Can we say that infinity equals to infinity

In real analysis, we know that the cardinal number of a certain set can be infinite and these infinite can be compared following continuum hypothesis. But for a function, such as $f(x)= x, g(x)=x^{2}$, when x goes infinity, are these infinity equal to each other?


I've heard many people say that if the number of expected elements in the container is relatively small, it is better to use std::vector instead of std::map even if you were to use the container for lookups only and not iterating.  What is the real reason behind this?  Obviously the lookup performance of std::map cannot be worse than std::vector (although it may differ in nanoseconds/microseconds) so does it have something to do with memory usage?  Does std::vector fare any better/worse than std::map in fragmenting the virtual address space?  I am using the STL library that comes along with Visual Studio (i.e. Microsoft's implementation).  Does that make any difference compared to other implementations?


I'd like to join three ideas into one interesting and sometimes useful feature. There was a question about using multiple passwords earlier this year, but it didn't receive much attention. I'd like to ask the question again after showing an interesting and new way to use the feature. The three original posts I found to be interestingly combined were:        Basically I'd like to login to my account with two passwords and depending on the password I use, I would get a different content in my home directory. In a way I would get a cryptographically hidden account into my system. So the question is, is it possible to allow multiple passwords to log on to Ubuntu/Linux for the same user?


Do users with higher reputation get even more reputation?

In Stack Overflow, I noticed (yes, subjectively) that users with higher reputation are more likely to receive upvotes, even if the answer is not the best choice among many.  As an example - users who asked or answered a very generic, fundamental and popular question on Stack Overflow in community's early days get a lot of upvotes which makes his/her reputation tens or hundreds of thousands of points from residual reputation and for most of the visitors or new programmers, they are willing to continue upvoting it if it works or solves their problems (even if it's not a very good solution), which it will hurt the copy/paste users in long run.  I'm just wondering if my assumption is true, or completely wrong, is there any evidence or data to prove or disprove this observation.  PS: Feel free to edit my question since English is not my first language.    Edit  I only mentioned point 0), which is not very complete.  0) will hurt the copy/paste users in long run (previous version)  So I think I need to elaborate more on the things that I concerned with:  1) Some (really small portion from my observation) high-reputation users are not getting reputations from answering questions, instead, it's from asking maybe some popular questions. And at the same time, I think users will tend to believe that higher reputation users most likely provide a correct answer, so users may willing to continue upvotes his/her answer, which this pattern may potentially damage the community.  2) Will users bravely vote up if it works without considering that there may be an even better answer provided by a low-reputation user or a same correct answer by a low-reputation user?  3) Will high-reputation users cause something like 'Academic monopoly' which may discourage some potential good knowledge or truth to be discussed or discovered?    Edit  I got quite a number of downvotes, which makes me feel a bit sad.  If I use any inaccurate words which makes people feel uncomfortable, I apologize for that, because English is not my first language, I have really no intention to offend or hurt anyone in the community.  I just want to clarify that:   1) I'm not jealous of high rep users, a very very large majority of them are brilliant and fantastic, they deserve it for absolutely no doubt.  2) I point it out from the perspective that is there any way to improve the reputation system, or does it need any amendment to help community users more.


Reference unnumbered starred header and titlesec

This is a follow up to this question:   My issue is that, in my document, I use the {titlesec} package. For some reason that package interferes with the code found in the example above. As a result, I'm not getting the name of the referenced starred section, just its page number.  How may I get the name of the starred section and its page number?  Thank you.  \documentclass{book}  %\usepackage{titlesec}  \usepackage{hyperref} % Hyperlinks  \begin{document}  \section{A section}  In \textbf{\nameref*{abus}} we will see a lot of boring stuff and here's a link to it: see \nameref{abus}, \pageref{abus}.  %\blindtext[10]  \section*{A boring unnumbered section} \label{abus}  Very boring stuff  \end{document}


Series composed of arithmetic and geometric mean properties

We have that $0<b\le a$ are two positive real numbers. Their arithmetic mean is defined as  $a_1=(a+b)/2$ and their geometric mean is $b_1=\sqrt{ab}$.  Firstly we have to show an that $b_1\le a_1$ iff $a=b$, so we must show both directions algebraically.  Then we define two sequences by setting $a_{n+1}=(a_n+b_n)/2$ and $b_{n+1} = \sqrt{a_nb_n}$. Using mathematical induction to show : $a\ge a_1\ge\dots \ge a_n\ge b_n\ge\dots\ge b_1\ge b$.  Prove that both series converge and show their limit.  I'm having trouble with the first step in proving the iff statement in the forward and backward direction, as well as showing the proof by induction. Also how would one determine the convergence and limit of this series?


Classnot found. Null Pointer exception when i wanna change .Jar to .exe

I have created a java application to connect to a MySQL database. Once through the program install creator, I created a .exe .  This executable runs, and the first form is login. When he tries to access the database to confirm the details of login gives this error.  java.lang.NullPointerException Someone can help me solve this? The path is correct because if run the .jar the application runs normally.  I apologize for the inconvenience.  enter image description here  Only have this to try to explain better my question :S  I'm so sorry... I'm running an executable version from my java application.


What is this S icon inside white square?

Anybody who knows about this app please reply. Phone is Vivo


I am having trouble finding mod arithmetic questions.  Can you show how to solve these?  $x + 30 \equiv 1 \pmod {12}$  $30x \equiv 1 \pmod {12}$  $x + 3y \equiv 1 \pmod {12}$ and $2x + y \equiv 7 \pmod {12}$