i am an student who is working on a nodejs + nginx project taht i didn't start,  so im not sure what is going on.... when i try accessing to my website,  i am recibing a 502 Bad Gateway nginx/1.12.2 error.  i have been trying to solve it with the answers of other similar question but the problem is still there, i think there is something wrong with the configuration, but im not sure what it is.  the nginx.conf file is as follow   #!/usr/bin/env node 'use strict'; /** * Module dependencies. */  //var http = require('http'); var app = require('../app/app'); var config = require('../config/config');  /**  * Get port from environment and store in Express. */ process.env.PORT = config.port; var port = normalizePort(process.env.PORT); //app.set('port', port); app.listen(port , function () { console.log('App listening on port ' + process.env.PORT); }); /**  * Create HTTP server.  */ //var server = http.createServer(app);  /**  * Listen on provided port, on all network interfaces.  */  //server.listen(port); //server.on('error', onError); //server.on('listening', onListening);  /**  * Normalize a port into a number, string, or false.  */ function normalizePort(val) {     var port = parseInt(val, 10);     if (isNaN(port)) {         // named pipe         return val;     }     if (port >= 0) {         // port number         return port;     }     return false; }  /**  * Event listener for HTTP server "error" event.  */ /* function onError(error) {     if (error.syscall !== 'listen') {         throw error;     }     var bind = typeof port === 'string'         ? 'Pipe ' + port         : 'Port ' + port;     // handle specific listen errors with friendly messages     switch (error.code) {         case 'EACCES':             console.error(bind + ' requires elevated privileges');             process.exit(1);             break;         case 'EADDRINUSE':             console.error(bind + ' is already in use');             process.exit(1);             break;         default:             throw error;     } } */  /**  * Event listener for HTTP server "listening" event.  */ /* function onListening() {     var addr = server.address();     var bind = typeof addr === 'string'         ? 'pipe ' + addr         : 'port ' + addr.port;     console.log('Express server listening on port: %d, in %s mode',  app.get('port'), app.get('env')); } */   also i have already checked the logs  2018/11/26 09:32:14 [error] 974#0: *7094 connect() failed (111: Connection  refused) while connecting to upstream, client: 189.183.151.200, server:  mexcx, request: "GET / HTTP/1.1", upstream: "http://127.0.0.1:5001/", host:  "67.227.198.57"   hope you can help me on understanding what is going on, cause at the beginig it was working just fine, i was doing some changes on the code, i restart the server and i got the problem


$(function(){   $('.slider').mobilyslider({     content: '.sliderContent',     children: 'div',     transition: 'horizontal',     animationSpeed: 500,     autoplay: true,     autoplaySpeed: 9000,     pauseOnHover: true,     bullets: true,     arrows: true,     arrowsHide: true,     prev: 'prev',     next: 'next',     animationStart: function(){},     animationComplete: function(){}   });    });   I am integrating the above JavaScript file in a Drupal theme, but it is giving me the "$ is not function" error. I googled it, and changed the code bro the below, but it doesn't work either.  (function($) {   $('.slider').mobilyslider({     content: '.sliderContent',     children: 'div',     transition: 'horizontal',     animationSpeed: 500,     autoplay: true,     autoplaySpeed: 9000,     pauseOnHover: true,     bullets: true,     arrows: true,     arrowsHide: true,     prev: 'prev',     next: 'next',     animationStart: function(){},     animationComplete: function(){}   });    })(jQuery);   The above code gives me following error:     $('.slider').mobilyslider is not a function


Divide a algorithm with small sub parts in more than one page

I want to write down a algorithm using TeXStudio. The algorithm is very huge so it cannot fit in one page. I use \usepackage{algorithm} ,\usepackage[noend]{algpseudocode} to write down this algorithm. I have a demo code here   \documentclass{article} \usepackage{amsmath} \usepackage{xcolor} \usepackage{algorithm} \usepackage[noend]{algpseudocode}   \begin{document} \begin{algorithmic} \State $i\gets 10$ \If {$i\geq 5$}      \State $i\gets i-1$  \Else   \If {$i\leq 3$}         \State $i\gets i+2$      \EndIf \EndIf  \end{algorithmic} \end{document}   Now I want to write down   \begin{document} \begin{algorithmic} \State $i\gets 10$ \If {$i\geq 5$}      \State $i\gets i-1$  \Else   Upto this portion in one page and rest of the portion into another page.      \If {$i\leq 3$}         \State $i\gets i+2$      \EndIf \EndIf  \end{algorithmic} \end{document}   This portion is in another page.  I saw various example in stack exchange which define this problem but I cannot understand how this works. So if anyone help me to divide my example into two pages it is good for me.  Thank you in advance.


Is the following formula right if I want to measure the standard error of the median in case of a small sample with non normal distribution (I'm using python)?    sigma=np.std(data)  n=len(data)  sigma_median=1.253*sigma/np.sqrt(n)


Duplicated objects created in Blender Render are invisible in Cycles

I cannot figure it out. Perhaps you guys can help me out. I have created several objects in blender render, I forgot to switch to cycles at start. Anyways, the first object that I crearted shows up in cycles render, no problem. Any other objects (they were all duplicated meshes from the first object) are gone. I checked the visibility in outliner, all are listed as none under object->duplication. None has any textures applied, not even materials. Any help would he appreciated.   Blender file:   I tried to consult this thread, but no luck:


Intel Wireless-AC 9560 WiFi not working in Ubuntu 16.04

I recently finished my PC build using a motherboard with a built in Intel Dual Band Wireless-AC 9560. While Bluetooth is working in Ubuntu 16.04, WiFi is still not working.   I tried installing the firmware provided on Intel's website  by copying iwlwifi-9000-pu-b0-jf-b0-34.618819.0.tgz to lib/firmware/ but this does not seem to help.  Below is some more information that might be useful:  $ dmesg | grep iwl [    5.535335] iwlwifi 0000:00:14.3: enabling device (0000 -> 0002) [    5.562102] iwlwifi 0000:00:14.3: loaded firmware version 33.610294.0 op_mode iwlmvm [    5.575320] iwlwifi 0000:00:14.3: Detected Intel(R) Dual Band Wireless AC 9560, REV=0x318 [    5.620228] iwlwifi 0000:00:14.3: Microcode SW error detected. Restarting 0x0. [    5.620233] iwlwifi 0000:00:14.3: Not valid error log pointer 0x00000000 for Init uCode [    5.620273] iwlwifi 0000:00:14.3: SecBoot CPU1 Status: 0x3, CPU2 Status: 0x2339 [    5.620274] iwlwifi 0000:00:14.3: Failed to start INIT ucode: -5 [    5.632149] iwlwifi 0000:00:14.3: Failed to run INIT ucode: -5   sudo modprobe iwlwifi returns no output.  $rfkill list all 0: hci0: Bluetooth     Soft blocked: no     Hard blocked: no  $ uname -a Linux xx 4.13.0-43-generic #48~16.04.1-Ubuntu SMP Thu May 17 12:56:46 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux


How can I determine if a .NET assembly was built for x86 or x64?

I've got an arbitrary list of .NET assemblies.  I need to programmatically check if each DLL was built for x86 (as opposed to x64 or Any CPU). Is this possible?


How to decompress a gzipped data in a byte array?

I have a class which has a method that is receiving an object as a parameter.  This method is invoked via RMI.  public RMIClass extends Serializable {     public RMIMethod(MyFile file){         // do stuff     } }   MyFile has a property called "body", which is a byte array.   public final class MyFile implements Serializable {      private byte[] body = new byte[0];     //....       public byte[] getBody() {         return body;     }     //.... }   This property holds the gzipped data of a file that was parsed by another application.  I need to decompress this byte array before performing further actions with it.   All the examples I see of decompressing gzipped data assume that I want to write it to the disk and create a physical file, which I do not.  How do I do this?  Thanks in advance.


Idiomatic way to implement UPSERT in PostgreSQL

I've read about different UPSERT implementations in PostgreSQL, but all of these solutions are relatively old or relatively exotic (using , for example).  And I'm just not a psql expert at all to find out immediately, whether these solutions are old because they are well recommended or they are (well, almost all of them are) just toy examples not appropriate to production use.   What is the most thread-safe way to implement UPSERT in PostgreSQL?


Showing a number $n$ is prime if $(n-2)! \equiv 1 \pmod n$

I need to show that if $(n-2)! \equiv 1 \pmod n$ then $n$ is prime. I think that if $n$ is composite, then we'll have every factor of $n$ in $(n-2)!$, and it would yield that $(n-2)! \equiv 0 \pmod n$. However, I didn't use the fact that it specifically congruent to $1 \bmod n$, so I think I'm getting something fundamental wrong. Is my solution correct? Why do we demand congruence to $1 \bmod n$?


How to diagnose repeated freezing of Windows 7 (comes back alive for a few seconds)

I installed Windows 7 in a 3-year-old machine. It installed successfully, took all drivers and running great, but every 5-6 minutes it freezes for a few seconds... 30 seconds to 1 minute, and then it comes back alive.  I checked Event Viewer, but nothing matched the frozen timeline.  I would appreciate any help on how to detect what is causing it, service or hardware.  After it comes alive, everything runs normal. I did run Task Manager and checked CPU usage, at the time it freezes just before and after that no task took more CPU or memory. It was like an idle machine.  There aren't any external USB drives or devices. It is an on-board Intel desktop board with SATA HDD, and the SATA HDD is running in absolute good mode.


It's common in science to say something doubled (x2) or even quadrupled (x4) or quintupled (x5). However, higher orders of change are less frequently written in this form. The only exceptions are changes of 10x, 100x, 1000x , etc., which are often referred to as changes in "."  This leads to my question: If I have a value that has octupled, is there another way to refer to this increase by avoiding usage of the uncommon word "octuple?"    "Increased 8x (or 8 times) seems more like informal speech being placed into text, but perhaps I'm wrong about that.  Does "increased by an order of eight" work?  Or perhaps, it's more appropriate to say "increased by a factor of 8"?


Here is an example from right-now's hot questions list:   The ServerFault question () actually has 19 votes. The Code Review question ()? Six. Is this number not a vote count, or is this a bug?


This is the code for an opening specific page and after that popup appear which I am unable to handle.  I have used alert, switchTo, etc..  //Open Browser   WebDriver driver = new ChromeDriver();  //Enter the URL   driver.get("https://www.mariatash.com/");    //I Agree PopUp   driver.findElement(By.xpath("//button[contains(text(),'I Agree')]")).click();    driver.findElement(By.xpath("//a[.='Appointments']")).click();    //after this, that popup appears and then its get stop.... u can find it in the image below   Suggest some way to close it.


In a integral domain every prime element is irreducible

I'm trying to understand a proof of  which says that in a integral domain every prime element is irreducible:    I didn't understand why this implication $p=ab\implies p|a$ or $p|b$, is not the contrary $p=ab\implies a|p$ and $b|p$ ?  I'm a little confused  Thanks in advance


Is it possible for a user to have many badges, lots of voted questions and answer and have reputation 1?

User  has plenty of badges on Stack Overflow (57 gold, 298 silver & 650 bronze). He has 740 questions and 1.752 answers, some having lots of votes and reputation 1. I can see he has: 47 Offered bounties for 4,600 reputation. Can that be enough to get such low reputation?


What is the basis of the vector space of polynomials of any degree?

Could we say that the set $\{1,x,x^2,x^3,x^4,\cdots\}$ is a basis of the vector space of polynomials ? Note that, for example the set $\{e_1,e_2,e_3,\cdots\}$ such that $e_n=(\delta_{n,k})_{k \in \mathbb{N^*}} $ is not a basis for the vector space $\mathbb{R}^\infty$, even though the set $\{e_1,e_2,e_3,\cdots,e_n\}$ is a basis of $\mathbb{R}^n$ for any $n \in \mathbb{N}^*$.


Why am I prompted for a CAPTCHA even though I didn't trip any of the rate limits?

Why am I prompted for a CAPTCHA when posting even though I didn't trip any of the rate limits for CAPTCHAs documented in ?


I'm running Ubuntu 20.04, and noticed that I'm running Gnome 3.36.2 - when the latest stable release is 3.36.3. How can I upgrade? Is it safe to do so?


Why won't my Soligor lens work on my Nikon D5000?

I have a Nikon D5000 and got a Soligor 55-200 lens. It seems to go on but the screen says Lens Not Attached. Why?


Prove that for any nonnegative integer $n$ $\exists x,y,z \in \mathbb{N}$ and $0\leq x<y<z$ so $$n=\binom{x}{1}+\binom{y}{2}+\binom{z}{3}$$  Please give me a hint, I don't have any idea.


I looked through the previous questions, and couldn't find one that quite addresses my question. If I start with $1000, and through investing it goes to $1200(100 shares at $10 go to $12), I can say I have a 20% return. I receive a "$0.5" per share imaginary dividend, a $2.50 total gain, I can say I am at 25%. My problem arises when I deposit money, how do I normalize/not count/account for this extra increase? I don't want it to be included in the ROI, as I added the money, it wasn't a gain. Hope the question makes sense.  $1000 Initial $1200 (100 shares increase to $12) ROI 20% $1250 ($0.50 dividend per share) ROI 25%    $1350 (Deposited $100) ROI ??% //Edit correct amount How to track ROI going forward?


I know there are some command-line applications like pdflatex that can help me to compile a LaTex document from C#.Net (using the System.Diagnostics.Process class) .   I wanna know that what's the best command-line tool for compiling a TeX document ?


Possible to turn on Airplane mode with WiFi on only?

I know the definition of Airplane mode is all communications and radio signals are blocked. But is it possible to turn off the "calling/receiving" part of the phone so your phone is not connecting to a cell tower and only allow Wifi? I've looked into a couple of apps in Google Play but they're either not working or out of date with newer versions of Android.   I know there is strong opinions on both sides of the issue but I'm worried about radiation from my phone since i use it a lot in bed and I hold the phone close to my head and face. At night I'm not worried about receiving calls, so I just want to turn off the phone part and  use WiFi. Is there a way? Or am i just crazy and paranoid?


Should the bias value be added after convolution operation in CNNs?

Should we add bias to each entry of the convolution then sum, or add bias once at end of calculating the convolution in CNNs?


Scene is being rendered instead of animation?

I created an animation in blender, exported it as a series of png files, used the blender video editor to merge them as frames in a clip, and continued to add sounds, transitions, etc. to complete the scene.  When I attempted to export the final product to a video file, all of the frames were re-rendered, but instead of the correct color view they rendered as greyscale scene view (essentially not even rendering anything). All of the images were overwritten instantly, and the previous hours spent rendering were wasted.  Now, I'm trying my hardest to re-render the entire scene, but every time I try to render the animation (or even just a still image), it keeps rendering the greyscale image scene as opposed to the actual product. How can I fix this? Also, once this is fixed, what is the proper way to render the final video?


When should we use "Got it?" and "Get it?"

I started learning english.   Often we hear "Got it?" sentence.   So I'm confusing following two sentences. When should we use one over the other?      1) Got it?      2) Get it?   Thank you.


Since childhood we are all familiar with the task of predicting the next number in a sequence. From something simple like, $2,4,6,...$ and $4,9,25,...$ to something more complex like, $0,1,2^2,4^2+1,(4^2+2)^2,(4^2+2)^2+1,((4^2+2)^2+2)^2$ which would look like this if it was asked as a question $0,1,4,5,36,37,1444$.  There (probably) is an infinite number of different possible patterns.  My question is, does an algorithm exist that can predict any type of pattern? And considering that I think that the answer is no, my other question is, are there any algorithms that can predict any pattern to a certain level of complexity?  EDIT  @Thomas Andrews Thank you for pointing out the flaw with my question. In light of that, I would like to change my question to this:  Is there an algorithm to determine a finite (or infinite) list of possible functions that match the given sequence?


Can we search a string value in all tables of oracle db

I have a string value that i need to search in my oracle db with inside all table's columns. Is there any way to search the value in all tables?


I have a form with three fields, "start_date", "days", "end_date". I would like to get the end date by adding days to the start date.   My jQuery code is:  $("#days").change(function(){   var start_date = new Date($("#start_date").attr('value'));   var days = parseInt($("#days").attr('value'))-1;   var end_date = new Date(start_date);   end_date.setDate(start_date.getDate() + days);                               $("#end_date").val(end_date.getFullYear() + '-' + ("0" + (end_date.getMonth() + 1)).slice(-2) + '-' + ("0" + end_date.getDate()).slice(-2)); });   In the "end_date" field I get "NaN-aN-aN".   What am I doing wrong?


Start one function repeatedly while another function is executed

I have a function that takes a long time to finish. How do I execute another function every X seconds while the long function is executed?  The script is using Python 3.4


'fncychap' accidentally converts ToC bibliography entry from chapter to section

I formatted my heading using the fncychap package. However, once applied it changes the format of my bibliography ToC entry from chapter to section (check the outline of the left image).  Compiling the file without the package shows the bibliography formatted as a chapter.   (My original preamble contains a lot more packages but I assume that these ones are the important ones.)  Is there a simple solution to this?    Minimal Code:   \documentclass{scrreprt}  \usepackage[titles]{tocloft} \usepackage{apacite}  \usepackage[Glenn]{fncychap}  \usepackage{hyperref}         \begin{document}  \tableofcontents \begingroup \let\clearpage\relax \chapter{chapter 1}  This is a test reference \cite{R_mgcv}  \phantomsection \bibliographystyle{apacite}  \renewcommand\bibname{Bibliography}  \bibliography{Biblio} \endgroup \end{document}


Should questions be retroactively tagged based on answers?

Sorry if this has already been brought up before. The closest question I could find was  but that question is asking about a case where an editor deletes tags unrelated to the answer. I'm asking if new tags should be added based on the answer. Here is an imaginary scenario: Someone asks the question "What is the 4-legged enemy of dogs". The available tags are ,  and . The question is tagged with  and . My question is: should an editor add the  tag even though  is the answer? One one hand, I feel that it would be weird for a question to have that tag when it is what the OP is asking for. On the other hand,  would be so obvious that an editor may not hesitate to add it. Plus someone searching for that tag might find useful information in the question or answer. A related question is: Are questions only tagged based on the knowledge of the OP (surmised by the question)?


Which interpolation technique is suitable for a bathymetry of a small lake?

This is a lake of approximately 13 ha with 81 sampled depth points in about 10 transect lines:    Previously in ARCgis with a 50 ha lake and about a 100 depth sampling points, I got decent output with the TopotoRaster tool. However, no such exact equivalent seems to exist with QGIS or open source software.  In QGIS, I got the interpolated raster below, using the TIN method in the Raster Interpolation plugin. However, this seemed to be a lucky outcome, when I tried to repeat, I got different results (unsatisfactory) in spite of not really varying any parameter.    These are more urban (constructed) tanks than lakes, therefore, they are fairly regular in their bed profile, hence the low point sampling density. Some articles seemed to suggest Inverse Distance Weighting (IDW) as the most suitable technique, yet I seemed to get the worst results with that (possibly owing to low point density).  Are there any heuristics which can be employed here considering the size of the lake, its regular profile and the point sampling density to arrive at which interpolation method is apt? (between Kriging, IDW, Bilinear, Cubic convolution, TIN or spline)  Or is it always a bit of trial and error?


What characters are allowed to use as delimiters for BibTeX keys?

Surprisingly, I wasn't able to find the list of symbols which can be used for separating fields in BibTeX keys. Many programming languages have their own lists of exceptions, but it seems there is none, neither for BibLaTeX, nor for Biber.  Consider the following example:  @article{Doe1970,   author = {Doe, John},   title = {Lorem ipsum},   volume = {42},   date = {1970-01-01},   pages = {123--456}, }   Common and widely used pattern is [auth][year] (e.g. Doe1970), but what if I would like to include a sequence of homogeneous descriptors (text or numerical fields following one another)? For example, [auth][year][volume][firstpage] would result in Doe197042123, which looks clunky and hard to read; or [auth][shorttitle][year] DoeLoremipsum1970, which also doesn't look great. Can I use something like Doe+1970-42:123 or Doe_Loremipsum;1970 instead?   From what I understand, non-ASCII symbols, white spaces and commas are not allowed, and even though Biber can handle non-ASCII characters, those are usually omitted for better compatibility. However, it would be nice to have a list of characters which are not permitted at all, and a list of recommended symbols which are safe to use and won't cause any troubles upon compilation.


How to insert a blank page depending on current page number?

I postprocess my PDF produced from my LaTeX-document through pdfbook and want to have the last page appear on the back cover. Thus, I need to have as many pages inserted before the last page so it gets onto a page number divisible by 4.  I looked to  question but    that seems complicated, and I do not want to add additional packages if I can do without them.   Therefore my idea would be to add blank pages before the last page, until it becomes 3 modulo 4.  Pseudocode:   regular document text if {current-page} % 4 != 3: \newpage if {current-page} % 4 != 3: \newpage if {current-page} % 4 != 3: \newpage content of last page   Is that feasible? How to code this in LaTeX?


I am new to electronics and ohms law is confusing.  When I power the led with analogWrite and give it only 3 volts do I have to still use a resistor? When I power the led with 5 volts does it matter if I put a resistor before or after the led?


states that you cannot know the position and the momentum of a particle at the same time (I believe this is the main idea behind it). And I have read in various places an example of that which goes something like this:  If you were to look at an electron under a microscope, you have to have a photon bouncing off of it and then travelling to your eye in order to see it. But this mere act of a photon hitting the electron changes its momentum so by the time you know about its position, the momentum is changed so you can't know them both at the same time.   But this seems like a physical problem to me. What if we could find out the position of an electron without ever interacting with it physically? Would the momentum then be unknown to us too?


I have a residency of Ukraine and two valid passports. One is an old non-biometric, and the new one biometric. In a few months I have a flight from Ukraine to Germany and from Germany to Morocco with Ryanair. Both flights booked using my new passport data. I am allowed to enter Germany (and other Schengen countries) without visa using my new biometric passport (and so I will). However I need a visa for Morocco and let's assume I have it in my other passport. I assume there will be no problems with the border authorities, but what about Ryanair visa check before my Germany - Morocco flight? Is it ok to have a plane ticket booked using one passport and having my visa in another?  UPD:  My question is rather will there be any problems on Ryanair visa check with two passports (one with the visa in it and another used for ticket booking), than just about travelling with two passports.


I am trying to set margin top to the inside div ("main") but it's not working, and sometimes it pushed the outside div ("news_wrapper") instead.  Here is the fiddle link:   This is the div that need to get the margin top:  #main {   margin-top:30px;   background-color: #FFF;   padding: 0 30px 0 28px;   border-radius: 4px;   text-align: left;    color: #494949;   border: 1px solid #d0d1d3;   background-position: center center;   background-repeat: no-repeat;   margin: 0px auto;   width: 150px;   padding: 23px;   min-height: 350px;   height: auto; }


How do I get the file extension from bash? Here's what I tried:  filename=`basename $filepath` fileext=${filename##*.}   By doing that I can get extension of bz2 from the path /dir/subdir/file.bz2, but I have a problem with the path /dir/subdir/file-1.0.tar.bz2.  I would prefer a solution using only bash without external programs if it is possible.  To make my question clear, I was creating a bash script to extract any given archive just by a single command of extract path_to_file. How to extract the file is determined by the script by seeing its compression or archiving type, that could be .tar.gz, .gz, .bz2 etc. I think this should involve string manipulation, for example if I get the extension .gz then I should check whether it has the string .tar before .gz — if so, the extension should be .tar.gz.


bounded operator $T$ is not compact then there exists an orthonormal sequence $e_n$ and $d>0$ such that $\|T(e_n)\|>d$ for all $n\in\Bbb{N}$?

I want to prove that if a bounded operator $T$ is not compact then there exists an orthonormal sequence $e_n$ and $d>0$ such that $\|T(e_n)\|>d$ for all $n\in\Bbb{N}$. Could someone helps me?    I think that the fact that T is not compact implies that there exists an arbitrary sequence in H that doesn't contain convergent subsequence, not for a orthonormal sequence. Moreover, we know that if T is a compact operator and en an orthonormal sequence then ||T(en)|| converges strongly to 0 but not the inverse. We want to show this.


How to search for and launch an exe automatically in C#?

I am coding an app in C# Visual Studio 2019, where the app will launch Microsoft Word for the user. However, I am struggling to have the app search for word. I know word installs in different locations based on 64 or 32 bit Windows, the exact version of word etc. So I am handling this by attempting to seach Program files for winword.exe then launch it if found. If  it can't find it it launches notepad.               string rootDirectory = System.IO.DriveInfo.GetDrives()[0].RootDirectory.FullName;              string [] files = System.IO.Directory.GetFiles(         Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles),         "WINWORD.EXE", System.IO.SearchOption.AllDirectories);               Process.Start(files);           }         catch (Exception e)         {             Console.WriteLine("I could not find word, so launching notepad.");             Process.Start("C:\\WINDOWS\\system32\\notepad.exe");  It is using string files to search for word and then process.start(stringname) launches word when found, but it returns this error. Any thoughts would be appreciated, thanks very much.


I'm learning to use the game engine and I don't know why a mesh change its shape when I press P key.  This happened when I subdivided the red mesh. I subdivided it because I want the ball collide the red wall but I don't want a rigid wall, I want a soft wall.      Here is the file:  (The ball moves with left and right arrows)  Thank you!


I got two cube objects I want two align their bottom to be on one surface , like they are buildings on the ground. i dont want to change objects center


Is the reputation system the same across all Stack Exchange sites?

As the title says, I'm wondering if some sites have customised their pointing system.   I've just come across Troy Hunt's profile on Information Security:   Currently he has 2,785 points. But he also an answer that has 381 upvotes. He has other highly upvoted answers but this answer alone should give him 3,810 points assuming upvoted answer gets 10 points. I couldn't make sense of the numbers so decided to ask here.  Sorry if it's a silly question :-)


How do I add a custom script to ubiquity source code that will create a few new folders on desktop when the installer finishes?

edit: I need to do this manually by tampering with the ubiquity source code, not with the help of some tool like Ubuntu builder  I need to have a few new folders and files be automatically created once ubiquity installation is complete.  Where do I add a custom script that can do this in the ubiquity source code?  Any sort of help will be much appreciated. Thanks.


proving $ \sqrt 2 + \sqrt 3 $ is irrational

I need to proof that $\sqrt{3} + \sqrt{2}$ is irrational, without using the fact that an irrational number plus a rational number equals irrational. also, i can't use the rational root theorem. that's why i posted a new question..  thanks for help!


A way to determine type of derived class with minimum code in c++

I have a class (Say A) with many subclasses and 4 level inheritance. I have wrote function type in Base class to determine the type of class as below:     const string A::type() const {     int status;     const char *  realName;     string name;     const std::type_info &ti = typeid(*this);     realName = abi::__cxa_demangle(ti.name(), 0, 0, &status);      name= realName;     int index =name.find_last_of(':');     name = name.substr(index+1, name.length()-index-1);     free((void *) realName);     return name; }   This is working with this code:   B tmp("temp");     cout<<tmp.type() // Prints "B"   But not with this code:   A  tmp = B("temp");     cout<<tmp.type() // Prints "A"   I have a vector<A> which can take any subclass. Is there a way to force A to return back the type of the derived class?


Why can I not assign publicip.get() to a variable?

Update If I do print(publicip.get()) then I get the correct ip addressed printed. If I do myip = publicip.get() and then do print(myip), then the value None gets printed Original Question When I ran the site on localhost, the value of myip would be 127.0.0.1. But publicip.get() would give me my public IP address. Unfortunately if myip = "127.0.0.1": and if myip = 127.0.0.1: give me syntax errors. What is the correct way of checking the value in the variable myip.      myip, is_routable = get_client_ip(request)      if myip = "127.0.0.1":         myip = publicip.get()       print("myip")      print(myip)


I have played Dungeons & Dragons 4th edition for a long time now, and I am sorry to see it go. I liked the complexity of it, where as 5e is really based on quickly getting through encounters.  Is it possible to play a completely solo D&D 4e game, on a budget? In the Red Box, in the player's book, there is a little bit of a solo game at the end, but I cannot find another solo adventure anywhere. I know there is , but I'd like to play it on the tabletop.


Can mathematical definitions of the form "P if Q" be interpreted as "P if and only if Q"?

Possible Duplicate:          So when I come across mathematical definitions like "A function is continuous if...."A space is compact if....","Two continuous functions are homotopic if.....", etc when is it okay to assume that the definition includes the converse as well?


Randomly take $51$ numbers from the set 1, 2, ..., 159. Find variance of their sum.

We randomly take $51$ numbers from 159 natural numbers $1,...,159$ without replacement. Let $\alpha$ be a random variable equal to the sum of the selected numbers. Find the variance of $\alpha$. Firstly I need to understand something about $\alpha$ destribution. There are totally $$C^{51}_{159} = \frac{159!}{51!108!}$$ kinds of sums. A lot of them are equal, because $$\sum_{i=1}^{51}i = 1326\leq\alpha\leq\sum_{i=109}^{159}i=6834$$ Consequenlty, I want to know how many subsets of $51$ numbers have the sum equal to $N$, where  $1362\leq N\leq6834$. I'm stuck here because I don't know how to do it.


Unfortunately i did replace windows7 with ubuntu os . my hard drive is formatted please help me any one to recovery my files


Constructive proof that algebraic numbers form a field

We know that the set $\mathbb{A}$ of algebraic numbers is a field. But there is a constructive proof of this statement? I.e. : given a sum (or a product) of numbers of the form $\sqrt[n]{q}$ with $ q \in \mathbb{Q}$ we can find a polynomial in $x$, with rational coefficients, that has as solution this sum (or product)? I've find that such a proof can be given using the resultant of the polynomials that have as roots the given numbers, but, as far as I know, the resultant is a number, so how can we find a polynomial?  I would appreciate an example: e.g. how to find the rational polynomial that has root $ \sqrt{2}+\sqrt[3]{3}$.


Disable direct login for normal users but allow scp and sftp?

Is it possible to disable direct login for normal users (like oracle) in Linux but allow scp and sftp for that use?


Need help in proving an inequality in lecture notes

While studying class notes in number theory I am unable to deduce this inequality. ( It is used in chapter gauss sums).  Assume ( q, m) be gcd of q and m and all s, q, m be positive integers .      It is to be proved that $\sum_{s| (q, m) } 1/s \leq \sum_{s\leq q} 1/s \leq (1+log  q)  $ .    I am unable to deduce how inequality in the middle leads to rightmost inequality.   Please help.


How can I change the default runlevel in Lubuntu 14.04? Some say by changing the inittab file but, I can't find any /etc/inittab file in my computer.


Question: Can you provide an example of a claim where the base case holds but there is a subtle flaw in the inductive step that leads to a fake proof of a clearly erroneous result? [Note: Please do not answer with the very common  example.]  Comment: Sometimes inductive arguments can lead to controversial conclusions, such as the ,  and a host of other paradoxes. However, I am interested in examples of a more mathematical nature (as opposed to linguistic) where the inductive argument is subtly flawed and leads to erroneous conclusions.   Note: If you provide an answer, please do so in a way similar to how current answers are displayed (gray out the flaw so people can be challenged to discover it).


I Installed the 1.8.0v on Win7 profesional SP1 system (as administrator) and I take this message: "The procedure entry point sqlite3_open_v2 could not be lovated in the dynamic library sqlite3.dll". QGIS 1.7 was working. Help


Why can't I list a directory with read permissions?

I created a directory d and a file f inside it. I then gave myself only read permissions on that directory. I understand this should mean I can list the files (e.g. ), but I can't.  will@wrmpb /p/t/permissions> ls -al total 0 drwxr-xr-x   3 will  wheel  102  4 Oct 08:30 . drwxrwxrwt  16 root  wheel  544  4 Oct 08:30 .. dr--------   3 will  wheel  102  4 Oct 08:42 d will@wrmpb /p/t/permissions> ls d will@wrmpb /p/t/permissions>   If I change the permissions to write and execute, I can see the file.  will@wrmpb /p/t/permissions> chmod 500 d will@wrmpb /p/t/permissions> ls d f will@wrmpb /p/t/permissions>    Why is this? I am using MacOS.  Edit: with reference to @ccorn's answer, it's relevant that I'm using fish and type ls gives the following:  will@wrmpb /p/t/permissions> type ls ls is a function with definition function ls --description 'List contents of directory'     command ls -G $argv end


Updating one table row from another separate table row

I am moving 2 rows from a table called allCooks to one row in a table called recipeChallenge (cookAAA against cookBBB in a pizza challenge) Each match already has an ID, and this is the row I want to UPDATE  I am doing the update twice, once for cookAAA and then for cookBBB To update the matchID with cook A...(i-ve left the php variables in)  "UPDATE `recipeChallenge` AS v1,          `allCooks` AS v2      SET v1.`cookAAAID` = v2.`cookID`,          v1.`cookAAAName` = v2.`cookName`    WHERE     v1.`matchID`='" .$matchID."'          AND v2.`cookID`= '" .$cookAID."'";   and then for cook B  "UPDATE `recipeChallenge` AS v1,          `allCooks` AS v2      SET v1.`cookBBBID` = v2.`cookID`,          v1.`cookBBBName` = v2.`cookName`    WHERE     v1.`matchID`='" .$matchID."'          AND v2.`cookID`= '" .$cookBID."'";   The table recipeChallenge is updating, but the second update is ALSO creating a new matchID and row in the recipeChallenge table. Why?


How to tell if a public SSH key has a passphrase

This is probably a noob question, but how can I determine if the public SSH key someone gives me has a passphrase or not?  We have a situation where I am not generating the SSH keys for users, but I want to make sure every SSH key I put on a server has a passphrase, but I get the feeling the passphrase is only part of the private key.  Thanks!


Senator Mike Pencil announced today that the Florida State Senate passed legislation...  *Edit: It's a specific example that I don't see an answer for in another post.


Equivalent definitions for simple connectivity

For a path connected space $X$, it is simply connected iff any two paths sharing endpoints are homotopically equivalent. Here simple connectivity means it has trivial fundamental group.    I'm doing the if part, so let's suppose $X$ is path connected with equivalence property. Now given $a\in X$, I wish to show $\pi_1(X,a)=1$. Let $f\in\Omega(X,a)$, now if $f$ consists solely of a single point we are happy, if it contains another point say $b\ne a$, then we can split $f$ into two consecutive paths $g,h$ such that $h$ follows $g$ and $f=g*h$ (note: path multiplications are to be read from left to right, unlike ordinary map composites). Now, I have $h=g^-$, so, up to path homotopy, we have  $$[f]=[g][h]=[g*g^-]. $$ Now I can't figure out how to show $g*g^-$ is equivalent to the constant path at $a$, although it is intuitively evident. Also for the converse question: if $[g*h]=[c]$ ($c$ means constant path) then how to prove $h\sim g^-$, I completely have no clue either. Intuition doesn't get me anywhere.   Silly as the two questions may look, could anyone enlighten me on them? Best regards to you!


How to print strings in column-like in java

Lets say i want to print 3 lines and a number next to each separated with 3 tabs and the output seems like this:   this is a line          3 this is a medium line           3 this is a very long line            3   ok all these lines are separated with the "3" number with 3 tabs. Is there any way to make all the "3" numbers appear the one below the other like this? :   this is a line                  3 this is a medium line           3 this is a very long line        3


Ban JSBin, Codepen, etc. links without code too

A user may not post a  link if the user doesn't also post some code with it.  I recently learned that .  Why isn't this ban in place with all the other sites similar to JS/PHPFiddle, like , , , ,  etc.?


Buying used Macbook Pro, checking if it's linked to previous owner

If I buy a used Macbook Pro from 2015, how do I check if it is registered to the seller, i.e. linked to his AppleID? I checked through the "Check coverage" Apple support site (), and the first point is a green check mark, the remaining two are yellow exclamation marks saying that it has expired. How is this to be understood?  Also, what other things do I need to check to make sure that I do not end up with a Macbook linked to someone else? I want to be able to link it to my own ID as if it were new. I've read that one of these things is that "Find my mac" is deactivated, how can this be verified?


If I have declared a double *positions[2] array, is there a way of finding the actual size of the double *positions[2] array?  Is there like a sizeof function to find the size?  I have tried an example, and it does not return the size as 4


Is it possible for an x86 processor to match an ARM processor in terms of performance per watt?

From my personal experience with my tablet, and from the benchmarks and articles I've read, it always seems ARM processors, as seen in virtually all mobile devices, deliver incredible performance for the amount of power they consume.  It really seems like ARM is inherently more power-efficient than x86.  To me, it looks like that this is because x86 is a  while ARM is a . However, Intel Atom processors deliver very good performance relative to their power consumption as well.  In addition, having studied computer architecture, it is my understanding that in modern processors, the complex x86  is internally translated into simpler  that use an internal instruction set that is closer to the simpler ARM or MIPS ISAs than x86 proper.  As such, the ISA as presented to the programmer is little more than an interface to issue commands to the processor, rather than a representation of the actual low-level operations the chip performs.  Then again, implementing this translation layer requires additional silicon space on the chip...  That said, assuming that they are implemented using the same semiconductor process, is ARM inherently more efficient than x86? With a properly designed , is it possible for an x86 processor to deliver the same performance per watt as an ARM processor?  Remember, I'm looking for a well-written technical answer in the spirit of Stack Exchange and not mere speculation.


Why do some elements burn different colors?

I have a torch lighter and it makes a green color when the flame passes over the metal in the center. What on the molecular level would a flame change color although there is no difference in temperature? Do some elements produce a different color when exited?


Displaying the same title search results from "Ask Question"

When I search for a question I'd like to be shown the same results as when I type in a title in "n" I often use the "Ask Question" as a search tool, like this: Some results!  Better results?  Update: I have updated the screen shot to a version without quote marks, the two search results are still inconsistent. But are they better?


In my statistics notes , they used the following result in an exercise $E[X|X]=X$ , where $X$ is a normal random variable. They simply stated that if I know $X$, the expected value is $X$. How can I prove that more rigorously?


Last year in Pre-Algebra we learned about square roots. I was taught then that $\sqrt{64}=8$ and $\sqrt{100}=10$, which I understood and accepted. I was also taught that $\pm\sqrt{64} = 8,-8$ because both of those numbers squared is 64, which I also get. But this year, with a new school and teacher in a different state, our teacher is telling us that: $\sqrt{64}=8,-8$ and $\pm\sqrt{64}$ also is $8,-8$. The way to get the positive root of something is: $+\sqrt{64}=8$ And these seem to contradict each other. I was always taught that a regular square root returned a positive number and only a positive number, but now my teacher is saying a regular square root gives two numbers, and considering the square root of a number $n$ is defined as $y^2=n$ I see where he is coming from. Upon researching this Wikipedia says:  For example, $4$ and $−4$ are square roots of $16$ because $4^{2} = (−4)^{2} = 16$  And Wolfram MathWorld says:  Note that any positive real number has two square roots, one positive and one negative. For example, the square roots of $9$ are $-3$ and $+3$  But on the other side, Wolfram Alpha, when given "The square root of 9" gives only 3.  So, which is right? Is $\sqrt{64}$ considered $8$? or is it $8,-8$?


Sound indicator for when a script temporarily stops? For example, to fill in data or passwords?

I have a quite long Bash script I use to install Apache server environments including PHPmyadmin and several other utilities, after logging to the remote machine via SSH. I run the script via the Ubuntu server 16.04 CLI terminal.  When the script runs, it stops sometimes, about 5-6 times to ask for password (whether in Unix itself or in some installation programs it starts).  Is there a way to make sure a sound notification will be played in each such stop whether in Unix itself or when a new installation program is initiated?    Update for SYN:  I did:      82  sudo apt install alsa-utils    83  speaker-test -t sine -f 1000 -l 1   And got:  speaker-test 1.1.0  Playback device is default Stream parameters are 48000Hz, S16_LE, 1 channels Sine wave rate is 1000.0000Hz ALSA lib confmisc.c:768:(parse_card) cannot find card '0' ALSA lib conf.c:4292:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings ALSA lib conf.c:4292:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name ALSA lib conf.c:4292:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory ALSA lib conf.c:4771:(snd_config_expand) Evaluate error: No such file or directory ALSA lib pcm.c:2266:(snd_pcm_open_noupdate) Unknown PCM default Playback open error: -2,No such file or directory


In fluid mechanics, the drag force is determined by the product between the drag coefficient, the dynamic pressure, and the reference area.  My question is how can I know what geometric area to use as the reference area?  (I had read the post regarding the reference area of a parachute but it doesn't give me a clear answer, should I look up the drag coefficient, then calculate back to find the reference area?)


Please help me. I tried everything that I found online but still in the grub menu appears only Ubuntu option. But I installed Linux alongside with Windows. Any idea? And also after the command sudo os-prober in the terminal I take the output only for Linux. I tried another command (that I don't remember now), too, and everything showed up in the terminal, but no in Windows. Do you think I may lost my Windows?


I am new with Ubuntu, so please give detailed answers. I want to fix this error: Could not connect to in.archive.ubuntu.com  Each time I try to update, it shows up. I have included the following additional packages:  packages.microsoft.com/repos/vscode packages.microsoft.com/repos/ms-teams  Screenshot of my terminal:


How can I get my jQuery function to output total to each row in a table?

I have a simple invoice table I am trying to create.  I want the values inputed to update on a keyup function I am running, which it does for any fields created in the html.  I have an add row button and a delete row button.  Once I add a row the function does not work on keyup of the row added, but if I go back to the original row the function will added the totals for each row and look like it should.  I'm not sure where I am going wrong or how I can get it to work properly.  I thought it might be in the .map or .each but that didn't work and I made sure to be using classes instead of ids.  Im pretty new to javascript and even less experienced in jQuery.

                 Item	                 Price	                 Quantity	                 Cost

                                <input id="item" type="text" value="Food"/>               	               $                 <input class="price" type="num" value="0"/>               	                                <input class="quantity" type="num" value="0" />               	               $$0.00

         <button id="btnAdd">Add Row</button>         <button id="btnDel">Delete Row</button>

        Grand Total:$

     Javascript  //calculate rows on input   $(".item input").keyup(calcSub);    function calcSub() {    var mult = 0;    // for each row:    $("tr.item").map(function () {        // get the values from this row:        var $val1 = $('.price', this).val();        var $val2 = $('.quantity', this).val();        var $total = ($val1 * 1) * ($val2 * 1)        $('.cost',this).text(formatCurrency($total));        mult += $total;    });    $(".grandTotal").text(formatCurrency(mult));    }    //formatting currency and fixing to two decimals   function formatCurrency(n) {       return n.toFixed(2).replace(/(\d)(?=(\d{3})+\.)/g, '$1,');   }   //add rows to my invoice  $('#btnAdd').on('click', () => {   const $lastRow = $('.item:last');   const $newRow = $lastRow.clone();     $newRow.find('input').val('');    $newRow.find('td:last').text('$0.00');    $newRow.insertAfter($lastRow);     $newRow.find('input:first').focus(); });    var table = document.getElementById('tableInfo');   var delBtn = document.getElementById('btnDel');    delBtn.addEventListener("click", deleteRow);    function deleteRow() {     table.deleteRow(1);   }


Entering Belgium with a visa for Germany

I am going to apply for visa to go Germany, but I have an idea to go Belgium too. Is it possible to enter Belgium if I have visa for Germany.


Health effect of electromagnetic and acoustic waves on brain function

What if any effects are there on brain function from prolonged exposure to electromagnetic or acoustic stimulation?


Remove the restricton of attaching images with low reputation

I think preventing newbies to attach image to the question is unnecessary. I could add links  to the images I want to attach, so the first reader with high reputation will edit my post and add it as a image. So why this restriction? It just force Stack Overflow users to double work (bit work, but double)


Install a .NET windows service without InstallUtil.exe

I have a standard .NET windows service written in C#.  Can it install itself without using InstallUtil? Should I use the service installer class? How should I use it?  I want to be able to call the following:  MyService.exe -install   And it will have the same effect as calling:  InstallUtil MyService.exe


I want to delete the records from Data Extension based on Date Field in my DE i.e. I want to delete record which were created date before 30 days.But I didn't find date manipulation function in SSJS like dateadd() in ampscript


Stack Overflow interesting questions implementation

According to the tooltip of the 'interesting' tab, interesting questions are     "questions that may be of interest to you based on your history and tag preferences"   Does Stack Overflow use a recommendation engine or just some sql sort/filter?


Is this search system vulnerable to SQL injection?

I have created a PHP and SQLi based search system. It is very basic and works how all of the ones I have found have. I just have one question. Can a very mean and angry person SQL inject my search system. The search is submitted through an HTML form in POST. Search System Code ...  require 'includes/dbh.inc.php';  $search = $_POST['search'];  $mysqli = $conn;  $query = "SELECT * FROM listings WHERE listing_name LIKE '%".$search."%'"; echo ' Listings

';   if ($result = $mysqli->query($query) and mysqli_num_rows($result) > 0) {      while ($row = $result->fetch_assoc()) {         $price = $row["listing_price"];         $name = $row["listing_name"];         $seller = $row["listing_seller"];         $picture = $row["listing_picture"];  ...


How to get saved WiFi password from my android 5.1.1  without rooting?  I checked the path /data/misc/wifi/ using adb pull from terminal, but it's empty


I don't know agile software development. Where do I ask questions about it?

What's the best Stack Exchange site to ask questions about  on?


As defined by  the “dummy it” is  The use of ‘it’ as a subject (or dummy subject) in sentences about times, dates, and the weather (such as, It's raining) and in certain idioms (It's OK). Also known as ambient "it" or empty "it." Unlike the ordinary pronoun it, ‘dummy it’ refers to nothing at all; it simply serves a grammatical function. In other words, ‘dummy it’ has a grammatical meaning but no lexical meaning.  Wikipedia's “” has nothing about the term's origin. The following page, , provides examples of “Pronoun it”, “Dummy it”, and “Anticipatory it” but no mention as to who the author might be.  has only one mention of “dummy it”. And Etymonline has the following for :  1590s, "mute person," from dumb (adj.) + -y (3). Extended by 1845 to "figure representing a person." Used in card games (originally whist) since 1736. Meaning "dolt, blockhead" is from 1796.   says that the term ‘dummy’ is an object designed to resemble and serve as a substitute for the real or usual one, which is where I imagine the grammar term is derived. Someone must have coined this handy expression. A grammarian, a linguist, a professor of English. If one looks back to the 19th century, there were grammarians who recognized that it did not always refer back to a subject, e.g.;   (1830)  (1838)  (1841)  (1853)  (1860),  and  (1874).  Not one of these authors mentions "dummy it" and yet that is exactly what they are all referring to.   Who coined the grammatical term “dummy it”? What is its origin?


I have a hard disk which is in NTFS. I want to make it writable without formatting.  I have gone through some solution for it but its working in previous version not in el captian.  I tried this  but when doing this step   sudo mv /sbin/mount_ntfs /sbin/mount_ntfs.original  sudo ln -s /usr/local/sbin/mount_ntfs /sbin/mount_ntfs   its says its not permitted.


ASUS RT-N56U router Linux create mount point issue

On my RT-N56U router I'm trying to create a ext3 partition on an attached usb drive to store my media center data. The problem is I am unable to create to a mount point after creating the partition. When I run this command: mkdir /media/AiDisk_a1, it says it can't do it because file system is read only. This is probably because it's the in memory router OS. How can I mount my ext3 partition to /media/AiDisk_a1?  Also, is there a way in Linux to create a mount point without having write access to the main OS volume?


Depending on how a user places his hat it may become hard to impossible to click e.g. the "Activity" button on a users profile-page - like e.g. here:  When trying to click the visible part of "Activity" I always end up on that users hat-list.


i have this problem when i open phpmyadmin

I have a problem when I open phpmyadmin,  When I write myip.com/phpmyadmin  shows up instead of phpmyadmin login screen, please help.  I have tried reinstalling everything using   apt-get purge   then  apt-get install   But nothing worked. I think its Apache2 that is causing the problem. I really need this so please help thanks.


How many $n\times m$ binary matrices are there, up to row and column permutations?

I'm interested in the number of binary matrices of a given size that are distinct with regard to row and column permutations.  If $\sim$ is the equivalence relation on $n\times m$ binary matrices such that $A \sim B$ iff one can obtain B from applying a permutation matrix to A, I'm interested in the number of $\sim$-equivalence classes over all $n\times m$ binary matrices.  I know there are $2^{nm}$ binary matrices of size $n\times m$, and $n!m!$ possible permutations, but somehow I fail to get an intuition on what this implies for the equivalence classes.


Proof that $\partial(A\times B) = ((\partial A)\times B)\cup (A\times(\partial B))$

I need to prove that:   $$\partial(A\times B) = ((\partial A)\times B)\cup (A\times(\partial B))$$  In other terms, the boundary of the cartesian product is the union of the things in the RHS.  I've found  but it does not even provide an intuition.  If $x\in ((\partial A)\times B)\cup (A\times(\partial B))$, then certainly $x \in \partial(A\times B)$ because:  $$((\partial A)\times B)\cup (A\times(\partial B))$$  is the union of $$(\partial A, something)$$  with  $$(something, \partial B)$$ Any ideads on how to say it rigorously?  What about the other side of the proof? What does this result means?


Unlocking and locking mac screen via ssh

Is there a way to unlock and lock screen from command line, via ssh? I know /System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend command, but it doesn't seem to work via ssh. The perfect solution would be a command, that I could type logged via ssh and it would unlock the screen or lock it back again, so I don't need to tell anybody my password, if he wants to use it. Is there any builtin tool, that would provide such functionality?


how can I calculate the sum of $i*2^i$ from $i=0$ to $\log n$?

What is $$\sum_{i=0}^{\log n}i\cdot 2^i\:?$$ I know it's $O(n\cdot\log n)$ but how do you calculate this sum?


I got a text that is written in German. I'm using \usepackage[utf8]{inputenc} since the text comes with the correct umlauts like ö, ä, ü and not "o, "a, "u. The output is pretty fine.   \documentclass[12pt,a4paper,ngerman]{article} \usepackage[utf8]{inputenc} \usepackage[ngerman]{babel}    %\input{glyphtounicode} %\pdfgentounicode=1  \parindent0pt  \begin{document} Viele Menschen sollten denken können, aber möchten es nicht. Dies ist ein Text den ich im PDF sehen möchte. \end{document}   But when I'm trying to copy text from the output (PDF) to Word, then I get the following:     Viele Menschen sollten denken k¨onnen, aber m¨ochten es nicht. Dies   ist ein Text den ich im PDF sehen m¨ochte.   Question: Any workaround here? The PDF text must support Copy&Paste. The glyphtounicode didn't help. Any idea?


I was told that another alternative for 'a few minutes ago' is 'a short while ago'.  Let's say I am a student of a 20- minute English phone class and my teacher asks me questions which I answer during the first 10 minutes of our class.  On the second 10 minutes she corrects my sentences.  She says, "A while ago you answered, 'I go to work yesterday'.  It should be 'went'.  Past tense."  Is it correct to use 'a while ago' and not 'a short while ago'?  The situation is very clear.  We never talked before the 20-minute class.  It means that she refers to the period of time within the 20-minute class.  Thank you.


Is $\mathbb{R}$ a finite field extension?

Is there a field $K \subseteq \mathbb{R}$ with $[\mathbb{R} : K] < \infty$?  My intuition tells me no: I would imagine that $K(\alpha)$ would be missing some $n$th root of $\alpha$ for all $x \in \mathbb{R} \setminus K$. But I'm not sure how to approach this: it's certainly not true of all finite field extensions (e.g. $\mathbb{R} \subseteq \mathbb{C}$), and there are irrationals $\beta$ s.t. $\beta$ has arbitrarily (but finitely) many roots in $\mathbb{Q}(\beta)$: e.g. $n$th powers of numbers satisfying $x^n - x - 1$.


Why does substitution work in antiderivatives?

I'm not entirely sure what I want to ask here, so please bear with me!  I think the explanation they give us in school for how finding the antiderivative by substitution works is: $$\int f(g(t))g'(t)dt=(Fg)(t)=F(g(t))=F(u)=\int f(u)du$$  But I never really understood the equality $F(u)=\int f(u)du$. Why can we behave as if the identity $u=g(t)$ doesn't exist, compute the integral $\int f(u)du$, and then 'substitute' $u$ in the result yielding the correct answer? In a sense, it feels like the variable $u$ switches from being 'meaningful' in $F(u)$ (where it stands for $g(t)$) and being insignificant in $\int f(u)du$, since as I perceive it the "variable name" here is meaningless and we could say $ \int f(u)du = \int f(k)dk = \int f(x)dx = ... $ all the same. Another way to ask the same thing: why $(Fg)(t)=\int f(u)du$ and not, say, $(Fg)(t)=\int f(x)dx$? Where am I getting confused?  Maybe someone can explain this better than my high school teacher? Is there a 'formal' explanation for this? Thank you a lot!


I am the author of an add-on for Blender 2.8.  I have one user that is experiencing an error. I understand what is causing it, but I don't understand why.  My add-on is selecting the "Standard" option from this list:    The user, however, does not have that option. Hist list looks like this (note also the different Display Device):    We are both using clean installs of the latest Blender 2.8 beta (11 July 2019 build).  What exactly is "sRGB / BT.709"? Why does he have this option, whereas I do not?


Show that a group with $|G| = 33$ contains an element of order $3$.   Using Lagrange's theorem, the possible orders are $1$,$3$,$11$, and $33$ (from the factors of $33$).  If there is a subgroup containing an element with an order of $33$, then we are done.   There is only one identity element with an order of $1$.   I am currently left with elements of orders $3$ or $11$. What is the best way to show that any element of order $11$ is a contradiction?


Please make it possible to view the question when answering using the Android app

Often, I need to copy an identificator or variable name or another fragment from original question and paste to my answer. But if I push back button, I will have to write my answer anew. Thus, it may be useful to see an original question post when answer is being writing using Stack Exchange mobile application.


I am trying to connect 2 separate paths somewhere along its centre, see picture:    Is there a way to do this?


Decomposing a concave mesh into a set of convex meshes

I'd like to be able to decompose a concave mesh into a set of convex meshes for 2 reasons:   Transparent rendering Physics shapes   Is there an algorithm that takes a set of triangles (concave) as input and outputs a number of sets of triangles (convex)?  I'd like it to not fill in the holes between parts of the original mesh.  I've already come across a small idea: find all the concave edges, and split the meshes along the edge loops.  Am I on the right track?  How could I implement this?


Vertically aligning cells in tabu environment

I'm not sure if there's been a change to the tabu package, but in recompiling docs I've written before, vertical alignment of tabu cells no longer places content in the middle. For example,  \begin{tabu} to\textwidth {|X[c m]|X[m,c]|X[m,c]|}     Hello & World & Long sentence that wraps around... \end{tabu}   simply places all of the cell content at the very top. I've been able to hack around it by placing the cell content in a varwidth environment but it's incredibly taxing. I don't see any mention of a change to the package that would lead to this; have I always been doing this wrong?


What temperature is achieved in focus point by 5000 flat 1x1cm mirrors onto a satellite dish?

There is this  ("R5800 Solar Death Ray") where teenager built a 5000 mirror device which concetrates the solar rays which is showing the potency of the mosaic method of concentrating sunlight using elliptical dish. It can fire the wood, boil the water in seconds, melt an aluminum, glass or even burn the whole in concrere or rock.  What is the approximate maximum temperature (could be a range) is achieved by this mirror device in its focus point on sunny day?       The R5800 solar concentrator, replaced by the new R23k, is made from   an ordinary fiberglass satellite dish. It is covered in about 5800   3/8" (~1cm) mirror tiles. When properly aligned, it can generate a   spot the size of a dime with an intensity of 5000 times normal   daylight. This intensity of light is more than enough to melt steel,   vaporize aluminum, boil concrete, turn dirt into lava, and obliterate   any organic material in an instant. It stands at 5'9" and is 42"   across.   Technical details & calculations:     Calculations: Area of dish aperture (elliptical)= (pi x 102cm x   73cm)/4 = 5848 sq cm       Area of focal point (circular)= pi(0.6cm)^2 = 1.14 sq cm      Dish Type= 0.7m x 1m offset focus elliptical.      Concentration Power= 5000x      Output Power Estimate = 560 watts


Is there a performance difference between i++ and ++i in C++?

We have the question   What's the answer for C++?


Is there a law for the anti- derivative of $sin^n(x)$？

I have calculated the antiderivative of $sin^n(x)$ from $n=1$ to $n=20$ by software. Now I want to know if there are some laws about them？


Overloaded child class function cannot call parent of similar name

I am assuming this is one of those "just not how it works" issues, but I fail to see why. Why do I need to qualify B's call to As Start with A::. If I change B::Start() to B::DoSomethingElse() I could call a parameter less Start() without A::. So what is happening? #include <iostream> #include <string>  class A {   public:     void Start(){              } };  class B : public A {     public:         void Start(int x){             Start();     // cannot call this               A::Start();  // can call this           } };


I am an Egyptian travelling to Bulgaria. I only have a Bulgarian visa. Can I fly to Bucharest (Romania) for 2 days with my Bulgarian visa and then travel to Bulgaria?   If it's possible, will I have any problem at the airport here in egypt or in Bucharest? I will have a hotel reservation and a Bulgarian ticket.


Using the Possessive with Gerunds: appreciate their thinking or appreciate them thinking?

In formal writing, which sentence would be a better choice to imply "I appreciated that they had thought of me"?   I appreciated their thinking of me. I appreciated them thinking of me.    Is there a subtle difference in the two constructions? To mean that sentence number 1 stresses on the act of thinking and sentence number 2 stresses on the people who are thinking? Or can both be used to mean the same thing?


How to get Analytic s licenses for my developer edition?

I am the beginner to "Wave Analytic's" in sales force. I need to learn what is "Wave Analytic's" in salesforce, where we will use "Wave Analytic's" and why we use "Wave Analytic's" in salesforce. Is it possible to use wave analytics in my edition. How to get Analytic s licenses for my developer edition.. can any one tell me solutions for these questions..


How to split one list in a list of x list with python?

How to split a list in a list of x lists in python ?  Exemple with list splited in 2 lists:  elements = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -> ([0, 1, 2, 3, 4], [5, 6, 7, 8, 9])   Exemple with list splited in 3 lists (note the third list of tuple, containing "division rest"):  elements = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] -> ([0, 1, 2], [3, 4, 5], [6, 7, 8, 9])   etc ...


Latex IEEE template: Use single column table in multicolumn latex content

I am trying to use this IEEE  to write a report. I don't see any package named \usepackage{multicol} which is used for multi-column. So I can not change it from two column to single column. Problem is, I have a big table which need whole page without two column. That is, my table should be in single column with whole page. You can see the example image. Sorry for bad image. Also, I have to use this template to write my report.


When and why should I use % !TEX TS-program and % !TEX encoding?

Occasionally, I see other people's documents starting with two lines like that:  % !TEX TS-program = xelatex % !TEX encoding = UTF-8 Unicode   It's clear to me that the first line declares the engine that should be used for compilation, and the second lines states the text encoding of the input file. It's not clear to me, however, when and why I should use such expressions.  More detailed questions on this subject matter would be:   How can I compile without determining which engine I want to use so that I would even need that comment? Which editors/programs pick up on these directives? Who introduced them? Is there any "documentation" of possible values etc.? Are there more such expressions? Are they standardized in any way? Can I add options to the compilation engine, e.g. pdflatex -enable-write18 or xelatex -interaction=nonstopmode? What does the "TS" in TS-program stand for? What additional value does the encoding line provide if I'm already using inputenc? Are there any downsides to using them or reasons not to use them?   Meta: Even though it technically contains multiple questions, I'm pretty sure this question conforms with our standards as a catch-all question on a narrow topic. I guess I know some partial answers to some of my questions, but I'll leave that up for people who have experience with these expressions. I just wanted to provide a question that allows for a maximal amount of information on this subject matter.


How can a string be inserted as code at runtime?

Suppose I have this method:  1. public int sum(int a, int b){ 2.     int x = 0; 3.  4.     return x; 5. }   Is it possible to get a string x = a + b; and place in line 3 (during runtime), so that after this string is inserted, the code now does the sum of a and b?  I wanna write some code in a text input field, so when I press a button, all that code (that is a string) should be able to go inside some part of some existing code. The sum above is just an example but it can be anything.


We all know that $\frac{1}{3} = 0.\overline{3}$, and that when we multiply it by $3$, we get $1$. But, $3\times \frac{1}{3} = 0.\overline{9}$.   Are there any ideas on how to prove that $0.\overline{9}= 1$?  I have no ideas, I only wrote down that $0.\overline{9}+x= 1$ for $x\neq 0$, but I don't know how to proceed.


Upgrade from Windows 7 to Win10, what happens?

If I will accept the Windows 10 upgrade from Windows 7, will all my games and programs stop working? How does it work?   Do they just give you a link to download it and then you do the rest (one) or they somehow replace your Windows 7 with Windows 10 (two)?  If number one, then no problems.  If number two, then will that keep all your games and programs currently installed and will they all work ok?


Is "who" used correctly in the sentence "Or he's a supernatural demon designed to torture people, who got offered his dream job"?

I was watching the TV series The Good Place when I came across this line:  Or he's a supernatural demon designed to torture people, who got offered his dream job and has flipped on us like a ten-stone griddle-chip.  I have been taught "who" as a relative pronoun should be used right the person it's referring to. However in this case, the word ahead is "people", which confuses me. I have looked into many online sources and could not find the explanation on this.


Parse a list Of wrapper class in javascript don't want apex:repeat

I have a list of wrapper class list tempList  public class employeeBookedClass{     public string locationName;     public string locationDate;     public string trainerName;     public string uniqueId;      public employeeBookedClass(string locationName, string locationDate,                                 string trainerName){         this.locationName = locationName;         this.locationDate = locationDate;         this.trainerName = trainerName;         this.uniqueId = locationDate + '~' + locationName;      } }   Now I want to loop over the list in javascript.  for(var ids in listEmplyee){ console.log(ids + '>>>' + listEmplyee[ids]); }   This is what I get in javascript and want to loop over that.  [employeeBookedClass:[locationDate=19/02/2018, locationName=London, trainerName=Nayank, uniqueId=19/02/2018~London], employeeBookedClass:[locationDate=12/03/2018, locationName=Rajasthan, trainerName=Chris, uniqueId=12/03/2018~Rajasthan]]


How can I delete my question when it is very simple?

I have come to the conclusion that Stack Exchange websites are for really highly trained professionals dealing with really high tech questions and most of the time, I have the feeling, that simple and primitive questions for new learners are not welcome. Now I have asked this question:    And since no answer is given, I think I better remove and come back when I have higher knowledge of neural networks. How can I do that?


Regex not working to get string between 2 strings. Python 27

From this URL view-source: I want to get string between var iframeContent = and obj.onloadCallback = onloadCallback;  I have this regex iframeContent(.*?)obj.onloadCallback = onloadCallback;  But it does not work. I am not good at regex so please pardon my lack of knowledge.  I even tried iframeContent(.*?)obj.onloadCallback but  it does not work.


I am looking into buying a LENOVO RD330 SERVER with a ThinkServer RAID 500 Adapter II RAID controller. I am having problems finding out if all of the hardware that I am wanting will be compatible with Ubuntu. I have check the "Certified Hardware" list but the list is very limited. Both the computer and the RAID controller say they support RedHat and Suse but obviously Ubuntu isn't mentioned. I have talked with my vendor and they also not certain if this hardware will work. I have also Google around and the RAID controller appears to be an LSI chipset. But again I haven't been able to find any definitive information saying that this will work.  Any suggestions on how I can find out if the hardware will work?


Finding counterexamples in elementary set theory.

I had the following two problems:     Find a counterexample for $f_*(A \cap B) \supseteq f_*(A) \cap f_*(B)$ and $ f_*(A-B) \subseteq f_*(A) -f_*(B).$ Where $f_*(X)$ is the image of $X$ under $f$ for some function $f:A \rightarrow B $ and some subset $X \subseteq A$.   I came with the following answer:  Let $ f: \mathbb{Z} \rightarrow \mathbb{Z} $, where $f: x\mapsto 0$; let $A=\{1,2\}$, and $B=\{3,4\}$.     For $f_*(A \cap B) \supseteq f_*(A) \cap f_*(B)$, $$ f_*(A \cap B) = f_*\{ \varnothing\} = \varnothing \hspace{1cm} \text{and} \hspace{1cm} f_*(A) \cap f_*(B)=\{0\} \cap \{0\} = \{0\}. $$ It follows that $ \varnothing \nsupseteq \{0\} $. For $ f_*(A-B) \subseteq f_*(A) -f_*(B)$, $$f_*(A-B)=f_*(\{1,2\})=\{0\} \hspace{1cm} \text{and} \hspace{1cm} f_*(A) - f_*(B) = \{0\} - \{0\} = \varnothing$$ It follows that $ \{0\}  \nsubseteq \varnothing $.   Now (assuming my answer is correct), let's say I want to find more counterexamples or maybe a more general answer (e.g. all the conditions under which the inclusion fails). Other than by trial and error or just intuition, how would I do that?   I know this is a broad question, so I'm specifically asking for methods or advice on how to build counterexamples in elementary set theory (for example, tips on where to begin or rules that apply in general that may be unobvious).


I have seen people say  'I am your age' instead of saying 'I am of your age'. Similarly, a sentence like 'you have done this your whole life' instead of 'you have done this for your whole life'. My question is: why for/of is omitted? Any gramatical reason?  Thanks in anticipation


After a power failure, unable to mount the drive "Get a newer version of e2fsck"

I have a desktop computer with Ubuntu Desktop 14.04.4 LTS 64-bit with an attached HDD USB 3.0 4TB Intenso 1 partition ext4 data drive only (no OS or Apps). After a sudden power failure, I am unable to mount the drive (checked different host Linux machines with no result).  error message:  sudo mount /dev/sdd1 /mnt mount: wrong fs type, bad option, bad superblock on /dev/sdd1,        missing codepage or helper program, or other error        In some cases useful info is found in syslog - try        dmesg | tail  or so   Tried with fsck, e2fsck with no result. The error message says "Get a newer version of e2fsck".  Tried with all available superblocks backups with no result.  Tried offline file/drive Linux checkers on the offline and UNmounted volume with no result.  Finally, I received the following error message for which I couldn't find any help online:   "has unsupported feature(s): metadata_csum". e2fsck 1.42.9 (4-Feb-2014) /dev/sdd1 has unsupported feature(s): metadata_csum e2fsck: Get a newer version of e2fsck!   Can anyone help me take my data back?


Bibiliography included in ToC but wrong hyperref linking

I included my bibliography in the tableofcontents as follows (documentclass report):  \clearpage \addcontentsline{toc}{chapter}{References} \phantomsection \bibliographystyle{IEEEtran} \bibliography{report}   This generates the correct output, with the correct page number (41) in the toc. However, clicking References will take me to the page preceding (40) the page with the references (41). How can I modify this to take me straight to page 41? Thanks!


I want to loop over list with indexes, while looping I want for loop to consider both start index and last index, although it respect start index it does not respect last index. The code I am trying is this:  arr = [0,1,2,3,4,5,6,7,8,9]  for i in arr[4:8]:         print(i)   Actual Result:  4 5 6 7   Desired Result:  4 5 6 7 8


finding all combinations of a list of any count

I am looking for a way to generate all combinations of items in a given list with an output of a given count. The inputs will be the list and the number of items in each returned combination. For example:  list = [a, b, c, d] number of items in output: 2   returns:  [(a, b), (a, c), (a, d), (b, c), (b, d), (c, d)]   The same list with number of items in output: 3  returns:  [(a, b, c), (a, b, d), (a, c, d), (b, c, d)]   note that (a, b) == (b, a) etc.  Thanks!


Convergence of a sequence of $n\text{th}$-roots.

I am trying to solve the following problem in real analysis: Let $(a_{n})$ be a non-negative sequence in which $a_{n+m} \leq a_{n}a_{m} \; \forall n,m \in \mathbb{N}$.  Show that the sequence $(\sqrt[n]{a_{n}})$ converges and that $\displaystyle \lim_{n \to \infty}\sqrt[n]{a_{n}}=\inf\{\sqrt[n]{a_{n}}|n \in \mathbb{N}\}$.   So far, I have deduced from the assumption $\displaystyle a_{n+m} \leq a_{n}a_{m} \; \forall n,m \in \mathbb{N}$ that $\displaystyle a_{n} \leq a_{1}^{n} \; \forall n \in \mathbb{N}$. So $(a_{n})$ grows at most exponentially. Also, since $\displaystyle \sqrt[n]{a_{n}}=e^{\frac{\log(a_{n})}{n}}$, I'm trying to show that the sequence $\displaystyle \frac{\log(a_{n})}{n}$ either converges or diverges to $-\infty$ instead, but I haven't been able to do so.   Any help would be greatly appreciated. Thank you.


Found an annual pass - America the beautiful

I recently found an annual "America the beautiful" pass with no signatures in the back.  I seems to be new, as it is still valid for a eleven months.   I was wondering if there is any way to return it... is it registered to someone? If not, does anything speak against using it? Will I get in trouble if I just put my signature on it?   Would appreciate your feedback!


How to publish two different bib files in CV

I have two separate bib files. One for journals and other for conference publications. Now I want to publish both of them in the CV. Any idea how to do it? \renewcommand{\refname}{Journal Publications} \nocite{*} \bibliographystyle{IEEEtran} \bibliography{MMjournals}  \renewcommand{\refname}{Conference Publications} \nocite{*} \bibliographystyle{IEEEtran} \bibliography{MMconference}   The problem with above code is, it is publishing the MMjournals twice. It did not publish the conference proceedgins. How to fix it?


How do you show $\lim\limits_{h \to 0} \frac{a^h-1}{h} = 1$ when a = e?

This limit appears using the definition of a derivative applied to an exponential function. I understand the implications but I don't know how to show the basic result.


How to remove the default title in minipage?

I am currently using overleaf online generating side by side plots.  This is my code:  \begin{figure} \begin{minipage}[b]{0.33\linewidth} \centering \includegraphics[width=1.5in]{FC SVM for Ctl-AD.png} \caption{fig1} \end{minipage}% \begin{minipage}[b]{0.33\linewidth} \centering \includegraphics[width=1.5in]{FC SVM for Ctl-PD.png} \caption{fig2} \end{minipage}% \begin{minipage}[b]{0.33\linewidth} \centering \includegraphics[width=1.5in]{FC SVM for Ctl-ADPD.png} \caption{fig3} \end{minipage} \end{figure}   It proves that everything is perfect except for the three default titles(like: "FC SVM for Ctl-AD.png") on each of the three subplots.  This is the effect of minipage.    Are there any ways to remove the three titles?


How to see featured (bounty) questions from all Stack Exchange sites?

I am aware of below links which shows the questions from all Stack Exchange site:   on Stack Exchange network ! '' on Stack Exchange network All Stack Exchange Meta link -   Is there any way to check all featured questions from a single URL ?


Converting String to Double for calculation cause me problem with decimal numbers, how to round it?

I found many answer speaking about converting String to Double (with two decimals) but I'm facing a weird case. When printing the value no problem, it is right. But when I do calculations the program acts weird.  I have this code:  String str = "21.90";   I want to convert this string into a double. I tried many solution but none works properly.   double amount = Double.valueOf(str);   or  double amount = Double.parseDouble(str);   or  try {     amount = DecimalFormat.getNumberInstance().parse(str).doubleValue(); } catch (ParseException e){     // error }   I've tried also with rounding methods like:  double roundOff = Math.round(amount * 100.0) / 100.0;   Number is converted in "21.9" but when I do, for example:     System.out.println(number - 21.8) = 0.09999999999999787   I don't understand why it's doing this.  Thanks in advance for your help.


Should I use t-test on highly skewed data ? Scientific proof, please?

I have samples from a highly skewed (looking like an exponential distribution) dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using two-sample unpaired t-tests(and t-tests with the Welch’s factor, when the samples had different variances). As I have heard that, for really large samples, it doesn't matter that the sample are not normal distributed.  Someone, reviewing what I've done, said that the tests I am using were not suitable for my data. They suggested to log-transform my samples before using the t-tests.  I am a beginner, so it sounds really confusing to me to answer my research questions with "log of participation metric".  Are they wrong? Am I wrong? If they are wrong, is there a book or scientific paper which I could cite/show them? If I am wrong, which test should I use?


How to make iso image of current logged in system to use it as future installation media

I have just installed Ubuntu 13.04 and due to installation of faulty media and different programs, my ubuntu crashed more than 7 times in last 3 days, Nvidia was the leading cause in 7 failure, and each time i had to install approx 600-700 mb of different application for my suite, like QT creator and Virtual Box, and different other apps.  Now, I don't want to trouble myself to install them again , all i want is to make image of my current Installation, so that all i have to do is burn current iso in bootable pen drive and install them as it is.  Please give me option of verified source list download only..   I recently visited remastersys, and the text written on front page seems like to me, it might have been compromised, and if it is the case, than may be his package is backdoored, so i don't want to risk myself in using such binary.  Are there valid , verified and secured way to make my current installation into ISO image, so that it can be used to burn it into some USB for bootable purpose.  Update I don't want to download again any of already downloaded file, all i want is to use is same downloaded file.  Important Does ubuntu has no such built in verified application which can do some sort of system-restore or create backup of whole system, so that there is no re-installation required whenever system is in trouble  Thanks


Fourier transform of the regular tempered distributions induced by $x^\alpha$, $\sin(\langle a, x \rangle_{\mathbb R^n})$, and $\mathbb 1_{[-1,1]}$

Compute the Fourier transform of the following tempered distributions on $\mathbb R^n$, which, for $\phi \in \mathcal S(\mathbb R^n)$ are given by    $T_1(\phi) := \int_{\mathbb R^n} x^{\alpha} \phi(x) dx$, $\alpha \in \mathbb N_0^n$.     $T_2(\phi) := \int_{\mathbb R^n}\sin(\langle a, x \rangle_{\mathbb R^n}) \phi(x)dx$, $a \in     \mathbb R^n$.     $T_3(\phi) := \int_{\mathbb R} \mathbb 1_{[-1,1]}(x) \phi(x) dx$.   Here's what I know and what I've tried so far $\mathcal F$ denotes the Fourier transform $$ \mathcal{F} f (\xi) := \hat{f}(\xi) := (2 \pi)^{-n/2} \int_{\mathbb R^n} f(x) e^{-i \langle x, \xi \rangle} dx $$ and $\mathcal{S}$ the Schwartz space. We defined $(\mathcal{F} T)(\phi) = T(\mathcal{F}(\phi))$. I am also going to use the following rules for the Fourier transform: $D^{\alpha}(\mathcal{F} \phi)(\xi) = (-i)^{|\alpha|} \mathcal{F}(x^{\alpha} \phi)(\xi)$ and $\xi^{\alpha} (\mathcal{F}\phi)(\xi) = (-i)^{| \alpha |} \mathcal{F}(D^{\alpha} \phi)(\xi)$.  Is the following calculation correct? \begin{align*}             \mathcal{F}(T_1(\phi))             & = T_1(\mathcal{F}(\phi))             = \int_{\mathbb{R}^n} x^{\alpha} \hat{\phi}(x) dx             = (-1)^{| \alpha |} \int_{\mathbb{R}^n} (\hat{\phi}(x))^{(\alpha)} dx \\             & = (-1)^{|\alpha|} \int_{\mathbb{R}^n}  (-i)^{|\alpha|} \mathcal{F}(t^{\alpha} \phi)(x) dx             = i^{|\alpha|} \int_{\mathbb{R}^n} \mathcal{F}(t^{\alpha} \phi)(x) dx \\             & = i^{|\alpha|} \mathcal{F}^{-1}(\mathcal{F}(t^{\alpha} \phi))(0)             = i^{| \alpha |} 0^{\alpha} \cdot \phi(0)             = \begin{cases} i^{| \alpha |} \phi(0), & \alpha = 0, \\             0, & \text{else.} \end{cases}         \end{align*}  I am pretty stuck with this one as I haven't found a way to further reduce this expression. Any hints? \begin{align*}         \mathcal{F}(T_2(\phi))         = T_2(\hat{\phi})         = \int_{\mathbb R^n} \sin(\langle a, x \rangle) \hat{\phi}(x) dx     \end{align*} The next step I will try is to shift the Fourier transform to the sin, as I have done in 3. But I am even struggling to evaluate the integral for $n = 1$, which is $$ \int_{\mathbb R} \sin(a x) e^{-i x \xi} dx = \frac{e^{-i \xi x}(a \cos(ax) + i \xi \sin(ax))}{\sqrt{2 \pi} (a - \xi)(a + \xi)}\bigg|_{x = - \infty}^{\infty} $$  Here I redristribute the Fourier transform inside the integral, which should be valid by Fubini. Is it valid in this case? \begin{align*}         \mathcal{F}(T_3(\phi))         & = T_3(\hat{\phi})         = \int_{\mathbb{R}} \mathbb 1_{[-1,1]}(x) \hat{\phi}(x) dxf         = \int_{\mathbb{R}} \widehat{\mathbb 1_{[-1,1]}}(x) \phi(x) dx \\         & = \int_{\mathbb{R}} \sqrt{\frac{2}{\pi}} \frac{\sin(x)}{x} \phi(x) dx     \end{align*}   Edit With @guy3141's hint I proceeded as follows: With $\Im(x) = \frac{x - \bar{x}}{2i}$ we have \begin{align} \int_{\mathbb R^n} \sin(\langle a, x \rangle) e^{-i \langle x, \xi \rangle} dx & = \frac{1}{2i} \int_{\mathbb R^n} \left(e^{i \langle a, x \rangle} - e^{-i \langle a, x \rangle}\right)e^{-i \langle x, \xi \rangle} dx \\ & = \frac{1}{2i} \int_{\mathbb R^n} e^{-i \langle \xi - a, x \rangle} - e^{-i \langle \xi + a, x \rangle} dx. \end{align} Now we can use Fubini's theorem (F) to evaluate both summands separately: \begin{align} \int_{\mathbb R^n} e^{- i \langle \xi \pm a, x \rangle} dx & = \int_{\mathbb R^n} \prod_{k = 1}^{n} e^{-i x_k (\xi_k \pm a_k)} dx  \overset{\text{(F)}}{=} \prod_{k = 1}^{n} \int_{\mathbb R} e^{-i x_k (\xi_k \pm a_k)} dx_k, \end{align} but I fear that I can't use Fubini's theorem as the integral on the RHS doesn't converge.


Are there other governments in The Hunger Games world?

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I'm making a user plateform on my website with php/mysql, and I want to know if is it good to allow users add photos using the mysql blob file, or adding their photos in a folder with their id, and storing every photo's path with a VARCHAR variable into the database. Thanks


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Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV to 100mV range and are generated by very low power sources that can yield currents in the order of nanoAmps. Often signals of interest fall within 1Hz-10KHz range (most often 10Hz-10KHz). To make the matters worse usually there are lots of noise generating tools that are necessary to be around (in the clinic these are other monitoring, diagnostic and therapeutic devices in the lab these are other monitoring, scientific devices). To reduce the impact of noise and increase the signal to noise ratio, there are a few generally applied rules like:  If possible use a current amplifier (often called head-stage), an amplifier with very high input impedance and rather low voltage amplification or even no voltage amplification. very near to the signal source (body). To connect the source (recording electrodes) to the first stage amplifier (head-stage) use wires that don't have shields (to avoid capacitative distortions of the signal). Avoid ground loops When possible use differential amplifiers (to cancel the induction noise from the electromagnetic sources around). Always use Faraday cages and grounded shields (usually Aluminium foils) to cover the signal source and anything connected to it (body, equipment ...). You can't do this without proper filters (usually a 10KHz high cut and a low cut that depending on the signal may be anywhere from 1Hz to 300Hz ) If you can't get ride of the mains noise (50Hz or 60Hz in different countries) and only if your signal covers that range you can use active filters like Humbug   My question is: Are there any other suggestions that I missed? Is any of these suggestions flowed or wrong? Usually people in this fields (like me) do not have formal education in electrical engineering  and sometimes there are myths passing from a teacher to student generation after generation without proper evidence. This is an attempt to correct this. EDIT:  if possible use batteries or very well regulated power supplies in all your devices, including any pumps, microdrives, monitoring devices, even you can put filters on the mains of your computers (although this usually is not a serious issue).


I was looking around the net and found  and found something I really can't grasp.   int i = 42;  i = 43; // ok, i is an lvalue  int* p = &i; // ok, i is an lvalue  int& foo();  foo() = 42; // ok, foo() is an lvalue  int* p1 = &foo(); // ok, foo() is an lvalue    What's the point of int& foo()? What is foo() = 42 in this example?  EDIT: Since the part that got me confused and doesn't have anything to do with rvalues I'll write the part that solved my problem:  I didn't know you could write function declarations inside scopes so int& foo() became a int reference with empty initializer which also is impossible since references must point to something. But in the heat of the moment I went full .......


Show that  the set of non zero rationals is not a cyclic group under multiplication.I know the set of rationals is  not a cyclic group under addition. In an exercise of my book it is given that  the set of non zero rationals is not a cyclic group under multiplication. I do not know how to prove it. Can someone give me a hint?


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What factors cause males to be more common than females in humans, from an evolutionary perspective?

Fisher's principle states that there should be a 1:1 ratio between males and females born on average for a population.  However, if you look at birth statistics your find that boys are slightly more likely to be born then girls.     If it was truly advantageous for an even sex ratio to exist at birth I imagine we would have evolved to make that happen, by slightly favoring more female sperm or by having the processes that decides which embryos to spontaneously abort be stricter for males embryos then females.  For that matter since it's more important for males to be exceptionally healthy then it is for females, since males have to compete for a mate while females don't, you would think more strict filtering for 'bad' embryos in the case of males then females would make sense anyways.  Thus I'm inclined to think that the increased number of males to females is not random evolutionary fluke, but adaptive.  I'm wondering what would cause there to be a benefit for males to be slightly more common then females.  I know males are more likely to die in childhood, due to risk taking activities to impress the females, so could it be that the increase in males is due to the expectation that more males will die before reaching sexual maturity?  I'm not certain I buy this logic, it doesn't seem you should favor a sex any more because it's likely to take higher risks.  I know that strong/healthy mates would prefer males and weak ones prefer females, since strong males would out compete weak males for mates it's good to have strong males that can achieve multiple mates and weak females since their guaranteed to have at least one mate.  Is it possible that our increased nutrition and health of recent generations simply results in more males because our bodies judge each of us as 'healthy' compared to the standard that existed for 99% of our evolution, ie, evolution hasn't caught up with technology when judging health to decide which sex to favor?  Is there some more obvious explanation for why favoring males slightly would be adaptive in humans?  Edit: I want to stress again, I'm not asking how the bias happens.  The article I linked clearly explains what causes males to occur more in terms of pregnancy.  I'm asking why the bias happens.  This could be evolved away in the past if it was disadvantageous,  Whatever mechanisms cause there to be a bias this bias is presumably adaptive for it not to be evolved away.  Both the possible duplicate and the current answer only address what causes the bias to happen today, not why it would be evolutionarily adaptive to have.