I am creating a game in ray lib and have a player header file with a struct of player to keep things organised. I get this error saying that there is multiple definition of the struct 'player'. Error: /usr/bin/ld: main.o:(.bss+0x0): multiple definition of `player'; player.o:(.bss+0x0): first defined here collect2: error: ld returned 1 exit status player.cpp: #include <raylib.h> #include "player.h"  void InitPlayer() {      player.x = 0;     player.y = 0;      player.tint = (Color)RAYWHITE;     player.Frame = 0;     player.FrameWidth = 16;     player.MaxFrames = 3;     player.animation_number = 0;     player.timer = 0.0f;          player.flip = 1;      //Load Texture2D     player.playerTexture = LoadTexture("Sprites/PlayerAll.png");  }  void UpdatePlayer() {  player.timer += GetFrameTime();      if(player.timer >= 0.2f){              player.timer = 0.0f;         player.Frame += 1;   }  if(IsKeyDown(KEY_S)) {         player.animation_number = 16;            player.y += 1;       }else if(IsKeyUp(KEY_S)){         player.animation_number = 0;     }               if(IsKeyDown(KEY_W)){         player.animation_number = 32;         player.y -= 1;     }          if(IsKeyDown(KEY_A)){         player.animation_number = 48;         player.x -= 1;'''     }              if(IsKeyDown(KEY_D)){         player.animation_number = 48;         player.x += 1;         player.flip = -1;     } else {         player.flip = 1;     }          //Clamp frame value     player.Frame = player.Frame % player.MaxFrames;  }  void DrawPlayer() {      DrawTexturePro(player.playerTexture,         Rectangle{player.FrameWidth*player.Frame,(float)player.animation_number,(float)player.flip*16,16},         Rectangle{(float)player.x,(float)player.y,16,16},         Vector2{0,0},0,player.tint); }  void UnloadPlayer() {          UnloadTexture(player.playerTexture); }  Player.cpp: #ifndef PLAYER_H #define PLAYER_H  typedef struct Player{          int x, y;     Color tint;       int Frame;     int FrameWidth;     int MaxFrames;     int animation_number;        float timer;          int flip;        Texture2D playerTexture;          }Player;  Player player;   void UnloadPlayer(); void InitPlayer(); void UpdatePlayer(); void DrawPlayer(); #endif  Main: The main.cpp' file basically calls the functions from the 'player.h' file. And I have included 'player.h' in 'main.cpp' Just for some extra information if needed: I have tried using 'extern' on 'player' but it requires me to compile the cpp files in a strange order. After compiling and linking both object 'player.o' and 'main.o', I change 'player.cpp' to have 'extern' on struct global variable 'player' and compile 'player.cpp' only without compiling 'main.cpp' and link both objects files with the 'main.o' being the old one.

I have a header file  x.h which is included by more than one *.c source files. This header file has some structure variables defined.  I have put multiple inclusion prevention guard at the beginning of the header file as:  #ifndef X_H #define X_H ... .. //header file declarations and definitons.   #endif//X_H   On building I get linker errors related to multiple definitions. I understand the problem.   Won't a multiple inclusion prevention guard at the top of header file as I have, prevent multiple inclusions of the header file x.h and thereby avoid multiple definitions of the variables that are there in x.h? #pragma once does not work on this particular compiler, so what is the solution?  Someone had posted  answer to a similar question. It doesn't seem to work for me. How does this solution work?


A team is to play $n$ games in a row.  In how many ways could they play this series of games without losing two games in a row.  There are $2^n$ total games to be played.  The number of games without consecutive losses would be $2^N$ - (Number of games with at least one consecutive loss).  I'm having a hard time counting the number of games with at least one consecutive loss.  In particular, I can't think of a way to count the number of games with $m$ consecutive losses.  Could someone provide some guidance?

I need to calculate no of possible substrings containing "00" as a substring. I know the length of the binary string.  Eg: for a string of length 4, possible substrings are: 0000 0001 0010 0011 0100 1000 1001 1100  I just need the number of possible combinations, not enumerate all of them.


This question might have been asked before but I have not been able to find it.  How can I find: $$\sum_{i=0}^n 2^{-i}$$ Help?

I've got the following sum which I'm trying to figure out:  $$\sum_{x=0}^n 2^{-x}$$  Wolframalpha tells me that it's equal to $2 - 2^{-n}$ but I am interested in figuring out why, and how to get that result by hand.  Any help is greatly appreciated. Thanks.  Also, as you can tell, I could really use some help with MathJax...


$ cat update-notifier-common  #!/bin/sh  set -e  [ -x /usr/lib/update-notifier/package-data-downloader ] || exit 0  # Try to rerun any package data downloads that failed at package install time. /usr/lib/update-notifier/package-data-downloader   What modifications should I do here to avoid the output being emailed to me every week?  Thanks!

I am facing an issue with Ubuntu server. I am running a PHP script using a cron job which executes every 5 minutes. This folder spool/mqueue is showing 112GB space. The scripts job is to fetch data from MySQL. If there is no data it will show an error. Now there is an error and cron is trying the send the mail to the users where user email is not defined and it is creating log file in mqueue folder.   How to customize cron so that it would not send mails and write logs?


Just finished the final book last night. I understand that (spoilers)     Snape was a double-agent spy for Dumbledore, but what usefulness did he bring? What information did Snape bring to Dumbledore about Voldemort or his Death Eaters?

OK, first of all, my Harry Potter knowledge is a bit rusty so I may be forgetting something.    In The Half-Blood Prince Dumbledore made Snape kill him (I know he was going to die anyway) so he could gain Voldemort's trust. In The Deathly Hallows, his portrait instructs Snape to provide Voldemort with the correct date on which Harry was to be moved, again, to gain Voldemort's trust.   Why did Dumbledore want a spy in Voldemort's inner circle so badly?   Would anything have been different if Snape had not been in Voldemort's inner circle?


If $f$ is uniformly continuous,it's easy to show $f(x+\frac{1}{x})-f(x)=o(1).$  So we have $$\frac{f(x+\frac{1}{x})}{f(x)}=1+o(\frac{1}{f(x)})$$  So I think $\lim_{x\to\infty}\frac{f(x+\frac{1}{x})}{f(x)}=1$ won't necessarily hold.But I cannot find a counterexample.Any help will be thanked.

I am finding difficulties in finding a counterexample to the following statement. If $f\colon (0,\infty) \to(0,\infty) $ is uniformly continuous, then $$\lim_{x\to \infty} \frac{f(x+\frac{1}{x})}{f(x)} =1.$$


Let's suppose to have this simple code:  def my_outer_function():     outer_var = 123     def my_inner_function():         return outer_var + 1     return my_inner_function  get_inner = my_outer_function() get_inner()                         I wonder there isn't any kind of runtime error. outer_var - the variable of the outer function - is available only when that function is running on, i.e. it vanishes when my_outer_function ends. But when I call get_inner(), my_outer_function() is already ended so I would have bet on a runtime error since my_inner_function couldn't find outer_var.  How do you explain all this?

I've been reading a lot about closures and I think I understand them, but without clouding the picture for myself and others, I am hoping someone can explain closures as succinctly and clearly as possible.  I'm looking for a simple explanation that might help me understand where and why I would want to use them.


I have a code written to count the number of times something occurs.... but how do i ( keeping what i have) make another method that counts them based on their occurrences?  like "holy now brown cow"  o 4 w 4 n 2 b 1 c 1 h 1   as well as what it already does  ( The String is: how now brown cow Number of ' ' is 3 Number of 'b' is 1 Number of 'c' is 1 Number of 'h' is 1 Number of 'n' is 2 Number of 'o' is 4 Number of 'r' is 1 Number of 'w' is 4)   my code:  public static void main(String[] args) {      String str = "how now brown cow";      char[] char_array = str.toCharArray();      System.out.println("The String is: " + str);      Map<Character, Integer> charCounter = new TreeMap<Character, Integer>();      for (char i : char_array) {          charCounter.put(i,charCounter.get(i) == null ? 1 : charCounter.get(i) + 1);      }      for (Character key : charCounter.keySet()) {         System.out.println("Number of '" + key + "' is  "+ charCounter.get(key));     }  }

I am relatively new to Java, and often find that I need to sort a Map<Key, Value> on the values.  Since the values are not unique, I find myself converting the keySet into an array, and sorting that array through array sort with a custom comparator that sorts on the value associated with the key.  Is there an easier way?


I don't know why Asp.net MVC developers put the using directives inside System.Web.Mvc namespace as follows.  namespace System.Web.Mvc {     using System;     using System.Collections.ObjectModel;      [Serializable]     public class ModelErrorCollection : Collection<ModelError>     {          public void Add(Exception exception)         {             Add(new ModelError(exception));         }          public void Add(string errorMessage)         {             Add(new ModelError(errorMessage));         }     } }   When do we need to put  using directives inside a namespace scope?

I have been running  over some C# code, and it keeps reporting that my using directives should be inside the namespace.  Is there a technical reason for putting the using directives inside instead of outside the namespace?


I recently gave one answer, and when I edited my  just once, it became community wiki.   I know that if we edit our post many times, that post will become community wiki.  I just want to know why my answer became community wiki in one edit.  I also want to know exactly when a post will become community wiki.  Updated:  Can we earn bounties on community wiki questions?

Some questions and answers are marked Community Wiki and are owned by a community wiki user:  (In fact, this very question is one of them)  Why have Community Wiki posts? How do Community Wiki posts work? How does a post become a Community Wiki post? How can the Community Wiki status be removed from a post? How can I find Community Wiki posts?


Ubuntu 16.04 with Cinnamon desktop.  I cannot update. Attempting gives  $ sudo apt-get update Reading package lists... Done E: Could not get lock /var/lib/apt/lists/lock - open (11: Resource temporarily unavailable) E: Unable to lock directory /var/lib/apt/lists/   I can check to see what file has this locked:  $ sudo lsof /var/lib/apt/lists/lock lsof: WARNING: can't stat() fuse.gvfsd-fuse file system /run/user/1000/gvfs   Output information may be incomplete. COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF   NODE NAME aptd    11127 root    9u   REG   0,24        0 181089 /var/lib/apt/lists/lock aptd    11127 root   57u   REG   0,24        0 181089 /var/lib/apt/lists/lock aptd    11127 root   58u   REG   0,24        0 181089 /var/lib/apt/lists/lock $ ps aux | egrep "11127|PID" | egrep -v grep USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND root     11127  0.5  1.4 296068 103516 ?       SNl  08:59   0:06 /usr/bin/python3 /usr/sbin/aptd   I don't know what /usr/sbin/aptd is or if it's safe to kill.  man /usr/sbin/aptd exists, but it didn't tell me much.  I can't find anything about this in particular online, either.  Is /usr/sbin/aptd related to the small orange square with the white star in my system tray that keeps trying to remind me to update?  Is it safe to kill?  Edit: After waiting a while, whatever had the lock released it on its own. No need to kill anything.

I get this error when trying to use apt-get:  E: Could not get lock /var/lib/dpkg/lock - open (11 Resource temporarily unavailable) E: Unable to lock the administration directory (/var/lib/dpkg/) is another process using it?     How can I fix this?


In Harry Potter and the Goblet of Fire, Harry falls into the Pensieve in Dumbledore's office and experiences Dumbledore's memory of Karkaroff's confessions.  During this memory, Karkaroff mentions Snape as a Death Eater, at which point Dumbledore comes to his defence.  Admittedly, I can't remember the books well enough, but does Harry know about Snape being a Death Eater at this point? In the films, I'm sure he doesn't.  If so, why does he not react to this news?


In the below code I am able to get open, high, low, close and volume with regex but unable to get day_date.  day_values = "('2019-05-10', {'1. open': '197.4190', '2. high': '198.8500', '3. low': '192.7700', '4. close': '197.1800', '5. volume': '38764368'})" day_date = re.search('(\'(.+?)\'', day_values).group(1) day_open = re.search('1. open\': \'(.+?)\'', day_values).group(1) day_high = re.search('2. high\': \'(.+?)\'', day_values).group(1) day_low = re.search('3. low\': \'(.+?)\'', day_values).group(1)             day_close = re.search('4. close\': \'(.+?)\'', day_values).group(1) day_volume = re.search('5. volume\': \'(.+?)\'', day_values).group(1)   How do I solve this problem?

I am tired of always trying to guess, if I should escape special characters like '()[]{}|' etc. when using many implementations of regexps.  It is different with, for example, Python, sed, grep, awk, Perl, rename, Apache, find and so on. Is there any rule set which tells when I should, and when I should not, escape special characters? Does it depend on the regexp type, like PCRE, POSIX or extended regexps?


I have read through other questions/answers related to the downvote system and I must say, I feel this system needs revising. Sometimes a downvote is meant with good intentions.  Before I go any further, I would like to preface this suggestion a little bit. I personally try to suggest revisions or pose a question to the author in cases that might warrant a downvote. This gives the author a chance to either revise or defend their post; thus it gives both the author and myself an opportunity to learn something new. Overall, though, I try not to downvote authors unless their question/answer is completely absurd/unrelated; however, even in these situations, I still try to provide the author some feedback, tell them why I downvoted them, and wait to hear back from them. I believe it is only fair that the author knows my thoughts and can hear my reasoning if I am going to downvote them. This is what leads me to my suggestion.  I believe the downvote system should be revised in the following ways:   Downvotes should cost slightly more reputation. (Maybe 5 reputation points to cast a downvote.) If you have downvoted a post, but you leave a comment on it, the cost of the downvote should be refunded. If you have downvoted a post and you did not leave a comment on it, you should not be refunded the cost of the downvote.   To exemplify this, let's I have 100 reputation points. If I go and downvote a post without providing feedback (a comment), my reputation should drop to 95 points. However, if I provide feedback to explain why I downvoted that post, my reputation should be reinstated to 100 points.  This proposal has two main positive benefits to the Stack Exchange community: by offering users the option to explain their downvote without losing reputation, users will be more inclined to offer feedback/advice; and by increasing the cost of a downvote, users are less likely to downvote for reasons such as, "I don't like you," and, "I don't like your post, but I don't care to explain why." Thus this revision would promote educated and healthy comments which could help the author, the voter, and readers; all of this while still preventing downvote abuse.  On the topic of educated and healthy comments, I would love to hear yours.    Update: The following two prior suggestions are strongly related to this suggestion:       Thank you to hichris123 for bringing them to my attention in the comments.

This is an idea I have seen around, but I have not seen a feature request for it, so here it is.  Downvotes that have no comments are frustrating and difficult to manage.  This is a way to help improve that:   Have a downvote initially cost more to cast for the downvoter (5 points for example) When a comment (from the downvoter) on the downvoted question/answer gets an upvote, you get your points back.   All points (ie all 5) could be refunded or just up till the traditional -1 that is in place now (ie 4 points refunded).    This would encourage good comments and downvotes for real reasons.  (Because comments for questions/answers that are bias related will not get the upvotes as readily.)  This could/should be limited to non-subjective tags.  (ie tags where a downvote just because you "don't like it" is not appropriate.)


Suppose $X$ is a normed vector space with norm $||\cdot||$. Suppose $S$ is a linear subspace of $X$ and $S$ is closed. Let $x\in X$. I was wondering whether the set $\{||x+s||: s\in S\}$ is closed in $\mathbb{R}$

I think no. And I am looking for examples. I would like a sequence $y_n$ in $Y$ such that $||y_n-x||\rightarrow d(x,Y)$ while $y_n$ do not converge.   Can anyone give a proof or an counterexample to this question?


Let the two metrics on $X$ be defined as  $$d_2(x,y) = \sqrt{(x_1 - y_1)^2 + \dots + (x_n - y_n)^2}$$ $$d_{\infty}(x,y) = \text{max}\left\{|x_1 - y_1|, \dots, |x_n - y_n|\right\}.$$     In the general case, for some $\alpha, \beta \in \mathbb{N}$ we have that all metrics $d_p$ and metric $d_{\infty}$ are strongly/lipschitz equivalent since we can find some $\alpha$, $\beta$ such that      $$\alpha d_{\infty}(x,y) \leq d_p(x,y) \leq \beta d_{\infty}(x,y).$$   However, in my particular case,  $$\alpha d_{\infty}(x,y) \leq d_2(x,y) \leq \beta d_{\infty}(x,y).$$  Obviously, $\alpha = 1$, works. What would be a suitable $\beta$. Could we also simply say $\beta = \text{sup}~d_2(x,y)$?

I need to show that the Euclidean metric and maximum metric (or square metric??) are strongly equivalent. I have no idea how to start this proof. Any help?  $d_1, d_2$ are called strongly equivalent if there exist positive constants $K, M$ such that for all $x, y\in X$: $Md_1(x,y)\leq d_2(x,y)\leq Kd_1(x,y)$


When I try to render an animation i made using a tutorial all the frames are blank. I've tried everything I can find on this website and others and nothing is working. Any help?  File:

I have a model which you can see here (camera perspective).    In the second image, you can see how the render turned out.    I'm at my wit's end trying to figure our why it's not showing up in the render. If anyone needs more information, just ask and I'll get it to you. I've already checked the normals and they're not the cause.


I have been using Overleaf combined with a Mendeley web importer to create a References.bib file.  I didn't pay much attention because I thought it did what I wanted.  Now I need to make some corrections to my Bibliography.  I can sort out all the missing Journal names and such like but I decided that I'd like to change the lay out of the names.  I have a piece in my Reference.bib file which looks like this.    \parencite(McDonald2015Mass-lossClusters) generates      (McDonald and Zijlstra, 2015)    in my text but my Bibliography output comes out like this:  [  I think that the main thing is that my Bibliography is consistent, but I see from other papers that the most common Bibliography author name convention would give      McDonald I., Zijlstra A.A., 2015...   Up until now I just relied on the Mendeley wizard to sort my Reference.bib file out for me but I am thinking about downloading it and changing the author field to in notepad, and then re-uploading it, but I don't know what format the author field should like.  I want \parencite() to generate     (surname and surname, year)    in the text and     surname initial., surname initial. initial., year   in the bibliography.    Is it just a case of changing the layout of the author field, if so to what?   Thank you!  Edit:  If I amended the author field to this, would \parencite{} generate     (McDonald and Zijlstra, year)    in the text and     Mcdonald I., Zijlstra A.A., Year   in the bibliography?     author = {McDonald, I and Zijlstra, A. A.},

Suppose I've just made the switch to . I have chosen one of the built-in styles (numeric, alphabetic, authoryear, authortitle, verbose) or of the custom styles available at CTAN, and I've figured out how to sort/compress citations. The bibliography and the in-text-citations look approximately like I want, but need to be tweaked. I've taken a look at the biblatex documentation for advice, but it is somewhat daunting. How do I get started? To add some focus, customization in the following areas would come in handy:   Suppressing of specific BibTeX fields (e.g., publisher); Formatting of fields for specific entry types (e.g., titles of articles not inside quotation marks); Formatting of citation postnotes (i.e., getting rid of "p."/"pp."); Spacing and punctuation in the bibliography (e.g., commas instead of periods as unit separators); Order of first names and last names of authors/editors in the bibliography; Order of certain fields in the bibliography (e.g., swapping location and publisher); Language-specific terms (e.g., replacing "References" with "Works Cited").   Finally, assuming that I'll want to use my style adjustments in a multitude of documents: Where do I put the relevant macro stuff?


If $G$ is a group with $xy=yx$ for $x,y\in G$, and  $x^m=y^n=e$, then: (1) $o(xy)|mn$, where $o(xy)$ is the order of $xy$, and (2) if $(m,n)=1$ then $o(xy)=mn$.   Well, I've already proved (1), but I'm having trouble with (2), I was thinking that maybe, if we already know (1), $o(xy)|mn$ then we just have to show that $mn|o(xy)$, that way we get equality. So we get: $mn|o(xy)$ iff $o(xy)=mn*l$ for some $l\in\Bbb Z$. On the other hand, we know that $(xy)^{mn}=e$ then it's obvious that for any $l\in\Bbb Z$, $(xy)^{mn*l}=e^l=e$, we get what we wanted, but if there's an infinite number of $l's$, what does this means? I feel that what I'm doing is wrong since I didn't used the principal hypothesis: $(m,n)=1$, but this is the only way so far I've been able to do something.

Another homework problem from my Group Theory class.  Let $a,b$ be elements of a group, $G$.  Let $\operatorname{ord}(a)=m$ and $\operatorname{ord}(b)=n$. Let $a$ and $b$ commute. Prove: If $m$ and $n$ are relatively prime, then the $\operatorname{ord}(ab)=mn$.  So I am having trouble starting off on this problem.  Here is what I believe I know:  $a^m=e$ and $b^n=e$ [as defined by the order of the elements] which leads $a^m=b^n$  $\operatorname{ord}(ab)=mn=\operatorname{ord}(ba)=nm$ as defined by commuting.  $\gcd(m,n)=1$ as defined by $m,n$ being relatively prime.    I don't know how to start this proof. Do I want to to go the route of $a^mb^n=e$?  Then $(ab)^{mn}=e$?   Any tips to start this would be greatly appreciated!!!


Sorry for this stupid question, but I spent a time to figure out!!  #! /bin/bash a=/etc cd $a  Normally, if I assign value for $a variable and then cd $a, it works. But when I create a separate file - it doesn't!  Why does it happen like this?

I just want to write a script which changes my directory.  I put the below commands in the file /home/alex/pathABC  #!/bin/sh cd /home/alex/Documents/A/B/C echo HelloWorld   I did   chmod +x pathABC   In the Terminal, while in /home/alex, I ran ./pathABC, but the output is just HelloWorld and the current directory is not changed.  So what is wrong?


I'm very new to blender and am trying to export a model from blender for use in three.js. From what I've read, the best way to do this is to export it as a glb/gltf file. I can get the file to export, but it loses most of the color and all of the texture I've added. I added the color and texture via the shading tab and I made sure that I have enabled it to export with materials. Am I missing something or is this just not possible? Color and texture added via shading tab:  What the model looks like in blender:  What the model looks like in three.js:

I used node textures in a mesh I exported to .FBX.  I then imported it into Unreal Engine 4 and it didn't import any textures; I clicked the Upload Textures option in Unreal Engine.  Is there something I'm doing wrong or is it Blender?


What is the difference (if any) between "I should go," and "I ought to go"?

It's essential that the documents (should)/(ought to) be destroyed immediately.   Which one is more suitable one as I know "ought to" and "should" are synonyms.


I have pgAdmin 4 and PostgreSQL 10.   I can't execute a query without quote marks i.e. I want to excute this   select * from table   but it only works if I use   select * from databasename."table"   How can I remove this restriction?  The name of the table is Complexitie. I was using postgresql the last year and I remember I could write queries in a simple way without mandatory syntax things like case senstive, mandatory quotes.   I read something about to setup arbitrary SQL queries en Postgres, but I can not find steps to configure it. thanks

I used pg_restore to load my postgres db with a dump file. I connected to my db with my user :  sudo -u arajguru psql dump  select current_user;  current_user  --------------  arajguru   Now I was able to see all the newly created tables:  dump=> \dt                List of relations  Schema |       Name        | Type  |  Owner    --------+-------------------+-------+----------  public | Approvals         | table | arajguru  public | Approvers         | table | arajguru  public | Conditions        | table | arajguru  public | Entities          | table | arajguru  public | EntityDefinitions | table | arajguru  public | Projects          | table | arajguru  public | Rules             | table | arajguru  public | run_history       | table | arajguru (8 rows)   But when I try to fire a select * query, it gave me this error:  dump=> select * from Approvals; ERROR:  relation "approvals" does not exist LINE 1: select * from Approvals;   What can be the reason for this error? Please help.


To take the newton limit of the geodesic equation:  $$\frac{\mathrm{d}^2x^\mu}{\mathrm{d}\tau^2}+\Gamma^\mu_{\nu\rho}\frac{\mathrm{d}x^\nu}{\mathrm{d}\tau}\frac{\mathrm{d}x^\rho}{\mathrm{d}\tau}=0 $$   We assume obeject is moving slowly so :  $$\frac{\mathrm{d}x^i}{\mathrm{d}\tau}\ll \frac{\mathrm{d}x^0}{\mathrm{d}\tau} \tag{1} \text{   }i = 1,2,3$$  Therefore, we only take the first component of the second term in the geodesic equation.  My question is, does equation (1) necessarily mean that $\Gamma^\mu_{00}\frac{\mathrm{d}x^0}{\mathrm{d}\tau}\frac{\mathrm{d}x^0}{\mathrm{d}\tau}$ is the dominant term of all possible combinations? Because in the affine connection:  \begin{equation} \Gamma^\mu_{\nu\rho} = \frac{\partial{x^{\mu}}}{\partial{\xi^{\alpha}}} \frac{\partial^2{\xi^\alpha}}{\partial{x^\rho}\partial{x^\nu}} \end{equation}  the c terms in $x^0$ which is considered to dominate will be cancelled in the dominator of the affine connection. What makes us still take $\Gamma^\mu_{00}\frac{\mathrm{d}x^0}{\mathrm{d}\tau}\frac{\mathrm{d}x^0}{\mathrm{d}\tau}$ to be the dominate term?

The Newtonian description of gravity can be formulated in terms of a potential function $\phi$ whose partial derivatives give the acceleration:  $$\frac{d^2\vec{x}}{dt^2}=\vec{g}=-\vec{\nabla}\phi(x)=\left(\frac{\partial\phi}{\partial x}\hat{x}+\frac{\partial\phi}{\partial y}\hat{y}+\frac{\partial\phi}{\partial z}\hat{z}\right)$$  However, in general relativity, we describe gravity by means of the metric. This description is radically different from the Newtonian one, and I don't see how we can recover the latter from the former. Could someone explain how we can obtain the Newtonian potential from general relativity, starting from the metric $g_{\mu\nu}$?


Instead of From: listing { "Name"  }  and showing up on recipients email as such,   I would like to only have the email address shoe up so the above would be  -  { ,xxx@yyyy.zz }.  I have three domains I send and receive from I would like to keep one of them private, without my name showing.  Thanks iciarch

Instead of "from" showing (Name,Name)blablabla@hjgy.xxx  -  just show   blablabla@hjgy.xxx.  Only want my email address to show on certain outgoing emails from certain servives, ex. show Name and email address from Verizon service but (no name) email address only when sent from Gmail service.  Thanks


Some journal submission systems are very transparent to the author to let the authors know the submitted manuscript at what stage. Recently I noticed that in the manuscript submission system of a journal number of days is written next to submission to first decision. I have been waiting for an editorial decision about the manuscript. But still, no editorial decision is not showing, or I have not received the decision email.

What steps does a manuscript typically go through from submission to publication (or rejection) in a typical journal? How are these steps referred to, in particular by editorial systems, and how long do they each typically take?  Note that this question is about the typical situation and hence not about:   Journals with an atypical workflow, e.g. those that allow for an instantaneous reviewer–author interaction. Exceptional steps or rare occurrences such as withdrawal or .   This is a canonical question on this topic as per . Due to its nature, it is rather broad and not exemplary for a regular question on this site. Please feel free to improve this question.


Can anyone please let me know which is the best software in ubuntu to plot graph against data??

I am looking here for the best simple and intuitive application that is designed to produce neat looking graphs, for example "number of Ubuntu users in the last 10 years" or "average amounts paid by windows, mac and linux users for each Humble Indie Bundle edition".  I just want it to be easy to produce (not too many functions), and nice looking (no ugly business charts)!  Thanks for your help!


Example:  Turn 1: Cast haste. Do things.  Turn 2: Cast invisibility (end haste). Be invisible. No movement, no actions.  Turn 3: Be invisible. No movement, no actions. (Resolve haste)    The section on "" states:     [...] You lose Concentration on a spell if you cast another spell that requires Concentration. You can’t concentrate on two Spells at once. [...]   The  spell states:     Casting Time: 1 action [...]      Duration: Up to 1 minute [...]      When the spell ends, the target can’t move or take actions until after its next turn, as a wave of lethargy sweeps over it.   The  spell states:       Casting Time: 1 action [...]      Duration: Up to 1 hour [...]      The spell ends for a target that attacks or casts a spell. [...]

Say a spellcaster has previously cast haste on themselves and is currently concentrating on it. However, they see a situation unfolding that desperately requires them to concentrate on another spell (e.g. hypnotic pattern).  They move and take their action to start casting the new spell. However, concentration on a spell begins , which would immediately end , causing "a wave of lethargy" that makes the spellcaster unable to move or take actions until after their next turn.  The spellcaster has already finished moving, and has already chosen an action to take (casting a new concentration spell), and has actually started taking that action.  Does haste's lethargy effect interrupt the casting of the new spell, or does the new spell go off and then the caster becomes lethargic immediately afterwards?


I need to solve the following problem.  Let $X_{1},X_{2},\dots$   be random variables on $(\Omega, \mathcal{F}, P)$. Show that the set $A = \{\omega \in \Omega :X_n(\omega) \hspace{1mm}converges\}$ is in F and that there exists a F-measurable random variable X such that $X_{n}(\omega) \to X(\omega)$ for $\omega \in A$.  Thanks in advance.

Let $E$ be a measurable subset of $\mathbb{R}$ and let $F_n :E \to \mathbb{ R} $ be a sequence of measurable functions. Let $$E^*= \{ x\in E : F_n  \text{ is convergent } \}$$ Is the set $E^*$ measurable?    To solve this, I need to understand the relation between the set $E^*$ and the functions $F_n$. They are strongly related, but how can I express this relation in terms of sets and measure?


I was watching a relativity video, and although I am not sure, I felt that it was trying to tell that the effect of gravitation of a body is instantaneous, in the sense that a sudden change in the mass of a body will instantaneously be felt by any object at a distance, even before light can be exchanged between them. So I want to make sure if its true. You don’t have to explain me why this is so if you don’t wish to. Also, please tell me if this has been experimentally established, or it is just a theory.

A thought experiment: Imagine the Sun is suddenly removed. We wouldn't notice a difference for 8 minutes, because that's how long light takes to get from the Sun's surface to Earth.   However, what about the Sun's gravitational effect? If gravity propagates at the speed of light, for 8 minutes the Earth will continue to follow an orbit around nothing. If however, gravity is due to a distortion of spacetime, this distortion will cease to exist as soon as the mass is removed, thus the Earth will leave through the orbit tangent, so we could observe the Sun's disappearance more quickly.  What is the state of the research around such a thought experiment? Can this be inferred from observation?


Is it East Coast, East coast, or east coast when used in a sentence such as, "The airline flies to both the East Coast and the West Coast?" I've seen it all ways. I can't find a definitive answer as to if or where capital letters are needed in this phrase. Thanks for your help.

I am trying to capitalize Western Canada or western Canada properly and am wanting a definition for when the "ern" is added as a suffix to a locational distinction of a proper noun.  I believe the capitalization is related to the suffix and am grouping two questions.  After researching on the internet I have found a trend that areas of discrete area become capitalized along with their proper noun   East New York West Hollywood East London (Britain) East Los Angeles   Some locations have "ern" added to their locational modifier.    Web Examples (from government sites):   eastern Canada ( Western Canada ()   All the examples listed contain discrete areas.  The "ern" suffix is used for larger areas, but I am unable to determine when an area becomes large enough.


How do I prove that there is no other polynomial $p$ which is normed and of less or equal degree than $4$ which satisfies the equation $p(\sqrt[4]{2})=0$ ? Is there some sort of algorithm one can use to solve those kind of questions? I did not cover any galois theory. We just heared what algebraic and trancendent is

I'm trying to show that the polynomial $X^n -2$ ($n \in \mathbb{N}$) is irreducible in $\mathbb{Q}[X]$ but am a bit stuck. Methods I know to show irreducibility:   Gauss' lemma - which says that if I can show it is irreducible in $\mathbb{Z}[X]$ then it will be irreducible in $\mathbb{Q}[X]$. This would allow me to check reduction modulo a prime.    However this doesn't work in this case, because if I reduce mod 2, then the polynomial is just $X^n$ which is reducible.  I'm also aware of Eisensteins criterion where I can check that if a prime divides all the coefficients but its square doesn't divide the constant coefficient, then it is irreducible.  None of these methods are working for this polynomial so help would be much appreciated! Also are there any general methods to look out for when trying to show polynomials are irreducible?  Thanks


I want to find the line number of a code dynamically. How can this be done?  public static void main(String[] args) {          System.out.println("This Line Number is : ????");  }

How to print line numbers to the log. Say when outputting some information to the log, I also want to print the line number where that output is in the source code. As we can see in the stack trace, it displays the line number where the exception has occurred. Stack trace is available on the exception object.  Other alternative could be like manually including the line number when printing to the log. Is there any other way?


If a user has a link to a website such as www.enlarge-your-brest.com (no kidding, I've encountered some) in their About Me Section or the user card, should the moderation be alerted?

There are many inactive user profiles on SO that were clearly registered by spammers. The spam posts (if there were any) are already removed but the profiles remain. Some of them put their spam text into the "about me" field, see for example  and . If you google this text, it has been spammed all over the web. I guess that the purpose is manipulating search engines - when searching for particular keywords a website with a link to the spammer's site will likely come up as a result. Is that something that we need to worry about? I can see why the answer would be "no": unlike spam in questions, this isn't a problem for SO - nobody sees these profiles. So this isn't really worth investing effort into. Then again, I hate spam and don't like making spammer's life easy. If the answer to the previous question is "yes", what can be done about it? Obviously, anything requiring much effort from the community or the devs isn't going to work. One solution I can think of: stop displaying "about me" text for profiles that have neither answers nor questions and that have been inactive for at least a month. Maybe stop displaying the webpage link as well. Edit: I found many dozens of user profiles (now all deleted) when searching the user database by the keywords "sms", "market", "website", "free", "cheap", "gift", "flower" and "florist". If you then sort by all time reputation score and concentrate on accounts with reputation 1 to 11 it isn't hard to find lots of spammer accounts. (Some of them have the necessary keywords in their user name, they don't use the "about me" text then.) Still, combing through the user database like this requires far too much effort and I definitely don't think that it is a viable solution. As staticbeast notes in the comments, the Data Explorer is great for .


If I remember correctly, one could share multiple recordings at the same time with a share extension using the old version. This doesn't seem to be true with the post iOS 12 version.

iOS seems to refuse to allow me to email "long" voice memos, and I'm unaware of any way to extract them from iTunes backups of my phone. How can I retrieve entire voice memos that aren't really short?


i recently bought a power Mac but it recognizes my dedicated wifi but when I got to open a window no connection. And that's when it connects on wifi after many attempts.  My iPhone and iPad are working online fine.  I am using xfinity as my internet provider.  Any help?  Henry

I bought a new MacBook Air and was able to connect to the internet at first but now it won't connect.  I have other devices as well as other computers on wifi but my Mac won't connect.  When I try and click on the wifi, it tells me that it can't be joined.  How can I troubleshoot?


I have the following script named export.sh:  #!/bin/bash  SOURCE="${BASH_SOURCE[0]}" while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink   DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"   SOURCE="$(readlink "$SOURCE")"   [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located done  SOURCE=$(dirname ${SOURCE})  export $(cat "${SOURCE}/../params.env" | xargs)   In some words what it does it to export enviromental variables from a file named params.env that is located by convention on the prarent folder and exports the contents as enviromental variables.  Sample contents of params.env file are:  SOMEVAR="val1" SOMEVAR2="val2"   And a successfull run will provide me SOMEVAR with value val1 and SOMEVAR2 with value val2 enviromental variables.    But if I run:  ./export.sh   And afterwards  printenv | grep SOMEVAR   It does not show that the enviromental variable is set.

I have multiple Amazon EC2 accounts and want to quickly be able to switch variables, such as $EC2_HOME, using a script.  I have have a shell script set up like this:  #!/bin/sh export EC2_HOME=/home/me/.ec2 echo $EC2_HOME   When I run the script I know that EC2_HOME is set, but I thought that using export would make the variable stick around after the script completed. It does not, as running echo $EC_HOME does not show anything.  I know this must be very rudimentary Linux scripting knowledge, but I don't know it. I tried looking for related questions without luck - so my apologies if this is a duplicate.


I'm wondering if there's any addons or online libraries of materials I can download. I've found one called , but then discovered it was from 2008 and thought by now something like that might already be integrated into Blender.

Since asking for tutorials, videos, resources, links to other content or downloads is considered off topic here, this is a specifically created Community Wiki which gathers resources for Blender and it has been approved by the .  Just write in the appropriate answer/section. If you have concerns, questions, post a  question, so we don't clutter the comments, but you can link your meta question from the comments.  Questions regarding such resources are not allowed anymore, except for very specific and on topic requests (ask on  if you're unsure about your question). Follow the instructions made in the question about how to post, what can be posted, etc.  Learning             Assets    (also see: )   Reference Images/Blueprints (also see: )    Tools    (also see: )      Other   Special Interest ()     Also see the .


Let $A$ be an algebra. For $a, b \in  A $ we define maps $L_{a}, R_{b} : A \longrightarrow A$, called the left multiplication map and right multiplication map, by  $L_{a} (x) := ax, R_{b} (x) := xb$.  Note that for all $a, b \in  A, \lambda , \mu \in F ( field)  $ we have  $L_{a}b = L_{a}Lb, R_{ab} = R_{b}R_{a} $,  $L_{a}R_{b} = R_{b}L_{a}$,  $L_{\lambda a+\mu b} = \lambda L_{a} + \mu L_{b}, \quad  R_{\lambda a+\mu b} = \lambda R_{a} + \mu R_{b}$  so , is there an element in $M ( \mathbb{H} ) $  (  $ \mathbb{H}$ is  division algebra of quaternions )  that cannot be written as $ L_{a} R_{b}$,  $  a, b \in  \mathbb{H} $?

Let $ \mathbb{H}$ be a division algebra of quaternions.  Is there an element in $M ( \mathbb{H} ) $    that cannot be written as  the left multiplication map and right multiplication map?   Let $D$ be an algebra. For $a, b \in  D $,  maps $L_{a}, R_{b} : D \longrightarrow D$ are the left multiplication map and right multiplication map, by  $L_{a} (x) := ax$  $ R_{b} (x) := xb$.


For my dissertation I am preparing a list of symbols used in the text, which basically is a table that consists of the symbol, a short explanation and the dimension it has as indicated below:  Symbol    Description                                     unit x         way travelled by the thing                      km z         fraction of the x and the total possible way    ?   My problem lies in the second symbol "z" which is a dimensionless quantity. I could of course just leave the unit column empty for such quantities, however that would look a bit like there was something forgotten and therefore I would like to indicate somehow that this symbol denotes a dimensionless quantity. Is there a convention to indicate that a unit is dimensionless?

I'm making a table where columns are labelled with the property and the units it's measured in:  Length (m)  ||||  Force (N) |||| Safety Factor (unitless)  ||| etc...  I'd like not to write "unitless" on several columns...and I'm quite surprised I can't seem to find a symbol for it. Any suggestions?


Hello Mathematics Community, currently I am trying to prove:  $(\sum_{i=1}^{n+1}i)^2 = \sum_{i=1}^{n}i^3$  by Induction.  My Progress:  Assumption: $(\sum_{i=1}^{n+1}i)^2 = \sum_{i=1}^{n}i^3$  Induction Hypothesis: $=(\sum_{i=1}^{n+1}i)^2 = \sum_{i=1}^{n+1}i^3$  Induction Step:  $(\sum_{i=1}^{n}i)^2 = \sum_{i=1}^{n}i^3$  $=(\sum_{i=1}^{n+1}i)^2 = \sum_{i=1}^{n+1}i^3$  $=(\sum_{i=1}^{n} i + \sum_{i=n+1}^{n+1} i)^2$  But how can I use my Assumption here ?  It is important that I want to prove this with the summation symbol and not with the closed-form equations.  sincerely, M.Hisoka

How can I prove that     $$1^3+ 2^3 + \cdots + n^3 = \left(\frac{n(n+1)}{2}\right)^2$$    for all $n \in \mathbb{N}$? I am looking for a proof using mathematical induction.  Thanks


I defined a Table with lable the following way:  \begin{table}[t]    \centering    \begin{tabular}{|c|c|}       \hline Transaktionsnummer & Enthaltene Items \\        \hline 1 & f,a,c,d,g,i,m,p \\        \hline 2 & a,b,c,f,l,m,o \\        \hline 3 & b,f,h,j,o \\        \hline 4 & b,c,k,s,p \\        \hline 5 & a,f,c,e,l,p,m,n \\        \hline     \end{tabular}     \label{tab:transaktionsdatenbank}    \caption{Transaktionsdatenbank nach \cite{han2000mining}} \end{table}   The caption shows:  Tabelle 5.1: Transaktionsdatenbank nach [HPY00]  When using the reference:  \begin{figure}[t]     \centering     \includegraphics[width=0.5\textwidth]{img/FrequentPatternTree58.png}     \caption{Frequent Pattern Tree aus Transaktionsdatenbank in Tabelle \ref{tab:transaktionsdatenbank}}     \label{fig:frequentPatternTree} \end{figure}   I get: Abbildung 5.1: Frequent Pattern Tree aus Transaktionsdatenbank in Tabelle 5.2.2 where 5.2.2 is the subsection the table was defined in instead of 5.1.  What could I have done wrong?

\documentclass{article} \usepackage{algorithm}  \begin{document} \setcounter{section}{54} \section{A section with no label} \begin{algorithm} \label{myalg} \caption{An algorithm with the label `myalg'.} \end{algorithm} Reference to myalg: \ref{myalg}. \end{document}   With this code, the reference givens 55 (the section number); if I move the label after the caption command, I get the correct reference (1).  Why should this be the case? I find it confusing: when thinking about an algorithm as an environment, you expect to be able to label it right after you began it. At the very least I would expect some kind of error or "??" to appear, rather than the previous environment or reference-able entity being used.


This question had a sequel to the question just below.   Thanks to WS2's reply and link I draw my conclusion for the phrase 'blow me down.' But to my surprise I think I have reached a different answer than you.  Here are examples that you presented in your link.        I'm absolutely blowed if I know what to do.         I think this sentence means that I would be shocked if I know what to   do. That is, I think I have no chance of knowing what to do.          Blow me tight if ever I saw such a thing in my life before.         I would be shocked if I saw such a thing in my life before. There's no   chance of my seeing such a thing in my life before. That is, that's my   first time that I saw such a thing in my life.         Blow me if I do!         I would be shocked if I do.  That is, there's no chance that I do   (it).   Am I right in my description of the three sentences above?  And on the sentence in question, I draw my comprehension based on your explanation.        "Blow me down if she didn’t just run off!"         I would be shocked if she didn’t just run off! There's no chance that   she didn’t just run off. That is, she must have just run off. If not,   I would be shocked.   The last line is my conclusion that I drew on your explanation.  Here is your sentences. "When she just ran off, you could have knocked me over with a feather!" "She's run off ? - well blow me down!"  These two sentences implies that I am shocked because she runs off. That means the speaker didn't expect she would run off.  If that is your thought, that's just the opposite of mine.

What's the meaning of this sentence below from Longman Dictionary of Contemporary English?     ▪ Blow me down if she didn’t just run off!     The Longman Dictionary says you use 'blow me' to show annoyance or surprise and is usually used in British English. But I still cannot figure out what it means and in what situation it can be used.


I am using Lubuntu 14.04.1. and my notebook is Lenovo ThinkPad e531-6885 ERG, I am connected to the internet through wire (eth0), and i guess it must work because under Windows 7 with MyPublicWifi it just flows amazingly.  So what do I need to do?  btw: the device which should I be able connect is Nexus 7 (2013)  Thanks in advance

How to setup an Access Point (AP) mode Wi-Fi Hotspot?  Point to be noted: Wireless access points aren't the same as ad hoc networks. They differ significantly. In short, ad hoc networks aren't supported on newer devices and most Android, Windows Phone and Blackberry devices (and maybe iOS devices too), whereas AP mode Wi-Fi hotspots are. To get an idea about AP mode hotspots, ad hoc networks and their difference, refer to .


Let $\Pi_{n\in \mathbb{N}}\mathbb{Z}:= M$ Is $ M \otimes_{\mathbb{Z}} \mathbb{Q} \cong \Pi_{n\in \mathbb{N}}\mathbb{Q}$ ? I believe this is true but I don't know how to prove this. Kindly help me with an idea/ hint. Thanks in advance.

It is well known that the tensor product of $R$-modules over some ring $R$ does not, in general, distribute over infinite direct products, an obvious example being $\mathbb Z_p \otimes_\mathbb Z \mathbb Q \neq 0$. I also know that a sufficient condition for the tensor product to distribute is .  What other sufficient conditions are there? For instance, it would seem intuitive that $\mathbb Q \otimes_\mathbb Z \prod_\mathbb N \mathbb Z \cong \prod_\mathbb N \mathbb Q$. But is it?


I made some  and used it once. There were some left overs, so I added more flour and a bit of water. There is now a layer of water on top of it, after I left it for a few days.  How do I know if it is off?    Update: I think I'm making alcohol. I opened it and it smells like alcohol. I've mixed in the "water" layer on top and added more flour.   Lets see what happens?

Why does my sourdough starter have in the top the liquid separated from the flour? 2 days after beginning a new one, a liquid (water) appeared on top of it, it appeared after I fed it the first time. To feed it I discarded half of the starter and then I added 5 tbsp of flour and 5 tbsp of tap water to feed it. Then, on the next day the liquid appeared like that. I don't think it's OK, so I discarded that liquid, and then waited a full 24 hours to feed it again like that.


I'd like to render a neural network in Python to make sure it is set up properly.  I'd like to verify that it has the correct # of nodes, correct edge configuration, and perhaps even correct edge weights after training.  I'd like to visually debug simple examples by printing them to a PNG/JPG but do not know any libraries that do this.  Is there a library for drawing a neural network for visual debugging?  (Such a library would of course make assumptions on the data types/structures - e.g., assuming the neural network comes from Theano, TensorFlow, or some other library.  I'm flexible on the assumptions made.)

When writing a paper / making a presentation about a topic which is about neural networks, one usually visualizes the networks architecture.  What are good / simple ways to visualize common architectures automatically?


I am trying to create clickable divs that will set a variable once they are clicked.  For example,  If my program had to do with playing with balls.  When a user inputs a name, and what kind of ball they want (lets say name= Johnny and Ball=BasketBall) and then clicks "Create a Ball", My program will create a div called "Ball0". The "Ball0" div will display Johnny's name. When a user Clicks on his name it will say "Johnny has a BasketBall.  Here is how I am trying to do this code  var ballRefrence = -1;  function createBall() {     ballRefrence +=1;     var myElement = document.createElement('div');     myElement.id = 'individualBall'+ballRefrence;     ballArea.appendChild(myElement);//ball area is where I want to list the divs     myElement.style.width = "550px";     myElement.innerHTML= userName+" has bought a ball!";      createEventListner(); }   function createEventListner() {     var iBall = document.getElementById("individualBall"+ballRefrence);     iball.addEventListener("click",showBall,false); }   function playCaption() {     //I am not sure how to pull the individual up here.      //Since I am using the "BallRefrence"variable     //it will always be the last person clicked..     //(Basically I cannot say      //alert.(ballRefrence); }   I guess what I am trying to say is this,  I have my "BallRefrence" that goes up by 1 each time. I store all the items in an array. (so first person will go to index 0, second will go to index 1...ect) I am having problems refrencing the element, because I am not sure how to pull the corrisponding numbe from the div.  Example: After 3 clicks of "create ball" my html will look something like this.

   Since each individual div will match up to the element in the array I want, How will tell my program  "When you click individualBall0, I want ball[0].." or "when you click indivdualBall2, I want ball[2]"  I hope this makes more sense.

I have a bit of code where I am looping through all the select boxes on a page and binding a .hover event to them to do a bit of twiddling with their width on mouse on/off.  This happens on page ready and works just fine.  The problem I have is that any select boxes I add via Ajax or DOM after the initial loop won't have the event bound.  I have found this plugin (), but before I add another 5k to my pages with a plugin, I want to see if anyone knows a way to do this, either with jQuery directly or by another option.


Just as the title says, I am looking for beginner's book for blender. Specifically I want to learn special effects and 3D models. Anyone got any suggestions?

Since asking for tutorials, videos, resources, links to other content or downloads is considered off topic here, this is a specifically created Community Wiki which gathers resources for Blender and it has been approved by the .  Just write in the appropriate answer/section. If you have concerns, questions, post a  question, so we don't clutter the comments, but you can link your meta question from the comments.  Questions regarding such resources are not allowed anymore, except for very specific and on topic requests (ask on  if you're unsure about your question). Follow the instructions made in the question about how to post, what can be posted, etc.  Learning             Assets    (also see: )   Reference Images/Blueprints (also see: )    Tools    (also see: )      Other   Special Interest ()     Also see the .


I have a Nikon D3300. RAW images are usually 25-28 MB at a resolution of 6000 x 4000. I exported from Lightroom at Quality: 100; DPI: 240. The exported JPEG turns out to be around 12 MB. I took the same RAW file and this time bumped up the DPI to 600. It turns out, both images are exactly the same file size.   I was anticipating that a higher DPI setting would mean larger files. Higher DPI = more dots per inch = more information = bigger files. Why is this not the case?

I often see statements in discussions about web displayed image quality that go something like this: "I only upload pictures at 72 dpi and 1200 pixels on the long edge, so if someone copies and prints the image it won't look as good as if it were 300 dpi."  What? Have I missed something here?  Does an image edited and saved/exported with 1200x800 pixels at 300 ppi look any different online than the same image saved/exported with 1200x800 pixels at 72 ppi? Other than the metadata regarding ppi, is there any difference in the two images at all? If so, what is the difference? If I tell my printer to print the images at 4R (4X6 inches) will there be any difference at all in how the printer creates a print from the 1200x800 @ 300 dpi image versus the 1200x800 @ 72 dpi image?


In PHP, when accessing MySQL database with PDO with parametrized query, how can you check the final query (after having replaced all tokens)?  Is there a way to check what gets really executed by the database?

Is there a way to get the raw SQL string executed when calling PDOStatement::execute() on a prepared statement? For debugging purposes this would be extremely useful.


When Morpheus offers the pill choice to Neo, they are still in the Matrix. That leads me to belive that none of the pills are real thus having no particular effect in the real world. Was it some sort of placebo effect that freed Neo from the Matrix or do the pills have an actual effect?

During the first meeting between Neo and Morpheus in The Matrix, Morpheus states that if Neo takes the blue pill,  Does this mean that the blue pill acts as a selective amnesiac? A program to make Neo feel as though he dreamed the meeting, similar to his experience of having a bug implanted by the Agents? Would it include something that makes him no longer of interest to the Agents? Since, technically, all that Neo has to do, if he refuses Morpheus' offer, is get up and leave the room, why have a blue pill at all?


I've been working through a proof for why the determinant can be calculated from any row in a square matrix. In this proof we first develop the determinant from row 1, and then (in the sub-determinants) from the arbitrary row k. We then develop the determinant from the arbitrary row k, and then from row 1 in the sub-determinants, the idea is to prove that these expressions are equal. I've arrived at the following expressions (please forgive me för just using copy/paste).  I don't quite agree with the annotation, but i is supposed to represent the number of the element in the first row, while s is supposed to represent the number of the element in the kth row. The expressions $|(A_{1i} )_{ks} |$ and $|(A_{ks} )_{1i}|$ refer to the sub-determinants of their respective expression. In the next step, we are supposed to realize that the expressoin on the upper left and the lower right are the same. If we start with the expression on the upper left and chech which pairs of i and s are possible, we arrive at the following types of pairs:           (2,1)    (3.2), (3,1)  (4,3), (4,2), (4,1) (......and so forth) If we look at the colums we will find that the only i that are possible for a certain s are those with a minimum value of s+1. The next step is a bit...hazy, but I think I'm supposed to realize that this means I can somehow switch places of the summation signs and change the indecies, so that: $$\sum^n_{i=1}\sum_{s=1}^{i-1}=\sum_{s=1}^n\sum_{i=s+1}^n$$ ...And I'm way to tired but I think that would make those expressions equal, after which the same procedure can be performed on the expressions to the upper right and lower left. But is it really possible to swap the summation signs in this manner and in that case why? I would appreciate some kind of intuitive explanation.

I'd like to see a proof of this identity I discovered:  $$ \sum_{i=1}^{n}\sum_{j=1}^{i}a_j = \sum_{i=1}^{n}a_i(n-i+1) $$  Probably there's something I forgot because I couldn't manage it.  [edit]Possibly with just identities, not examples please!  [edit2]No induction procedure, either.


If I want to know the meaning of wget -b, I see the manual by man wget, then search the -b option.     -b    --background        Go to background immediately after startup.  If no output file is specified via the -o, output is redirected to wget-log.   I want to get the result by a command like man wget -b. (Of course this doesn't work.)  Is there a similar way to make it possible?

I want to get output of any desired description or option from a man page.  Example: I want to get the description for the autoclean option from the apt-get man page:  Please suggest a command, something like man apt-get | <somecommands> autoclean to get this output:   autoclean            Like clean, autoclean clears out the local repository of retrieved package files. The difference is that it only removes package files that can no longer be downloaded, and are            largely useless. This allows a cache to be maintained over a long period without it growing out of control. The configuration option APT::Clean-Installed will prevent installed            packages from being erased if it is set to off.   I've tried man apt-get | grep autoclean but it is limited to out-put matching lines for word autoclean so I can't get full description and seems it is not that what I want!  Hence, Help me to filter part from man-page for expected output mentioned above.   (Here apt-get and autoclean is only used as example I am asking this question because when man-page is too long then filtering by such way is very helpful for getting exact thing)


I have a Schengen Visa that I issued from the German embassy back in 2011 (it's still valid till mid-2014). I never actually went to Germany though.  It says visa type: C, multiple entries, 90 days duration.  I want to go soon to France and from there to Italy. My understanding is that I will have to first enter from Germany though, is that correct? Also, at the top, it says valid for: "Schengener Staaten" which I take is Schengen states, but it also has a "D" for  Deutschland on the far right. What does this "D" mean. Only valid for Germany? Or that entry must be via Germany?

In case, if I get a multiple-entry Schengen visa in one of the embassies in Ukraine, Kyiv - should my first trip be to the country which issued the visa?  Any there any requirements of this sort? Does this condition vary depending on embassy which issued the visa?  What are the possible consequences on not visiting that country first? Does it somehow depend on country where the embassy is (i.e. non-Schengen and not EU members)?


I am running ubuntu 18.04.1 LTS and I need to run node v6. I am following    curl -sL https://deb.nodesource.com/setup_6.x | bash -  # Install Node.js and npm apt-get install -y nodejs    I can see in the apt-get output  Hit:4 https://deb.nodesource.com/node_6.x bionic InRelease   before installing:  node -v -su: /usr/bin/node: No such file or directory   after apt-get install -y nodejs  $ node -v v8.10.0   but for some reason it installs node v8  How can I install v6?

I ran into a problem today when I decided to use npm update -g in a nodejs app directory. This was a bad decision, because it caused me to run into a .   The solution is to reinstall nodejs and npm. Unfortunately when I go to install npm using sudo apt-get install npm it doesn't work.  The full error in the terminal is here:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that  some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies:  npm : Depends: nodejs but it is not going to be installed    Depends: node-abbrev (>= 1.0.4) but it is not going to be installed    Depends: node-ansi but it is not going to be installed    Depends: node-archy but it is not going to be installed    Depends: node-block-stream but it is not going to be installed    Depends: node-fstream (>= 0.1.22) but it is not going to be installed    Depends: node-fstream-ignore but it is not going to be installed    Depends: node-github-url-from-git but it is not going to be installed    Depends: node-glob (>= 3.1.21) but it is not going to be installed    Depends: node-graceful-fs (>= 2.0.0) but it is not going to be installed    Depends: node-inherits but it is not going to be installed    Depends: node-ini (>= 1.1.0) but it is not going to be installed    Depends: node-lockfile but it is not going to be installed    Depends: node-lru-cache (>= 2.3.0) but it is not going to be installed    Depends: node-minimatch (>= 0.2.11) but it is not going to be installed    Depends: node-mkdirp (>= 0.3.3) but it is not going to be installed    Depends: node-gyp (>= 0.10.9) but it is not going to be installed    Depends: node-nopt (>= 2.1.1) but it is not going to be installed    Depends: node-npmlog but it is not going to be installed    Depends: node-once but it is not going to be installed    Depends: node-osenv but it is not going to be installed    Depends: node-read but it is not going to be installed    Depends: node-read-package-json (>= 1.1.0) but it is not going to be installed    Depends: node-request (>= 2.25.0) but it is not going to be installed    Depends: node-retry but it is not going to be installed    Depends: node-rimraf (>= 2.2.2) but it is not going to be installed    Depends: node-semver (>= 2.1.0) but it is not going to be installed    Depends: node-sha but it is not going to be installed    Depends: node-slide but it is not going to be installed    Depends: node-tar (>= 0.1.18) but it is not going to be installed    Depends: node-which but it is not going to be installed E: Unable to correct problems, you have held broken packages.   What can I do to get npm properly installed and running again?  Thanks.


Find the limit, interpreting this as as the limit of the integral sum of a suitably chosen function.  $$\lim_{n\to\infty} \frac{1}{n} \sqrt[n]{(n+1)(n+2)... (n+n)}.$$    A hint that has been given: find the logarithm of equation and then find a limit of logarithm.

In my homework I have to find limit (by interpreting it as an appropriately chosen function as the limit of integral sums):  $\lim_\limits{n\to \infty} \frac{1}{n}\sqrt[n]{(n+1)(n+2)(n+3)...(n+n)} (1)$. $$ $$ Solution:   $\lim_\limits{n\to \infty} \frac{1}{n}\sqrt[n]{(n+1)(n+2)(n+3)...(n+n)} = \lim_\limits{n\to \infty} ln(\frac{1}{n}\sqrt[n]{(n+1)(n+2)(n+3)...(n+n)}) = \lim_\limits{n\to \infty} ln(\frac{1}{n}\sqrt[n]{n^n(1+\frac{1}{n})(1+\frac{2}{n})(1+\frac{3}{n})...(1+\frac{n}{n})}) = \lim_\limits{n\to \infty} ln(\frac{1}{n} n\sqrt[n]{(1+\frac{1}{n})(1+\frac{2}{n})(1+\frac{3}{n})...(1+\frac{n}{n})}) = \lim_\limits{n\to \infty} ln((1+\frac{1}{n})(1+\frac{2}{n})(1+\frac{3}{n})...(1+\frac{n}{n}))^{1/n} = \lim_\limits{n\to \infty} \frac{1}{n} ln((1+\frac{1}{n})(1+\frac{2}{n})(1+\frac{3}{n})...(1+\frac{n}{n})) = \lim_\limits{n\to \infty} \frac{1}{n} \sum_{k=1}^{n} ln(1+\frac{k}{n}) = \lim_\limits{n\to \infty}  \sum_{k=1}^{n} \frac{1}{n} ln(1+\frac{k}{n})$ $$ $$ Note that function $f(x)=ln(1+x)$ is continuous in $[-1,1]$. Find integral $\int ln(1+x) dx = (x+1) ln(1+x)-x+C$.  Then $\int_{-1}^{1} ln(1+x)dx = ln(4)-2$. $$ $$ Assume that that limit $(1)$ is A. We show that $\forall \epsilon>0$ $\exists N\in \mathbb{N}$: $\forall n\in \mathbb{N}$ $n\geq N \Longrightarrow $ $|\sum_{k=1}^{n} \frac{1}{n} ln(1+\frac{k}{n})-A|<\epsilon$.  Suppose that $\mathfrak{T}$ is $[-1,1]$ set of subdivisions. Fix. $\epsilon > 0$. That $f$ is integrative $[-1,1]$, then exist $\delta >0$:   $\forall$ $T = T[x_0,...,x_n]\in \mathfrak{T}$ $\forall \xi=(\xi_1,...,\xi_n)\in[x_0,x_1]\times...\times[x_{n-1},x_n]$  $\lambda(T)<\delta \Longrightarrow |\sum_{k=1}^{n} ln(1+\xi_k) (x_k-x_{k-1})-A|<\epsilon$.  Which $N$ to choose? Is this right solution so far?


I need to write a backslach but LaTeX always wants a command after . Any ideas?

I know what my symbol or character looks like, but I don't know what the command is or which math alphabet it came from. How do I go about finding this out?


Is there a way for the Python print statement containing a bash command to run in the terminal directly from the Python script?  In the example below, the awk command is printed on the terminal.   #!/usr/bin/python import sys  print "awk 'END{print NF}' file"   I can of course think of writing the print statement in a separate file and run that file as a bash script but is there a way to run the awk command directly from the python script rather than just printing it?

How do you call an external command (as if I'd typed it at the Unix shell or Windows command prompt) from within a Python script?


Is there a Stack Exchange site where I can ask programming-related questions which may have answers based on user's personal preference?   For example:     What is the best IDE to use for building PHP based websites?

Stuff like polls, recommendations based on subjective constraints, puzzles, webcomics etc. do not belong on the serious main SE sites, where professionals should be considered at work and having just a few spare minutes ("code's compiling") to answer questions, so they should not be distracted by such things. However, I'd also like to have a home for these things still using the SE engine. For the reason I mentioned before, this needs to be a separate place though. Let's call it four.[sitename-here].com.


Sometimes users down-vote if they don't understand the issue, but others did, also vote to close. There are many different minds over the world. What I said, maybe you don't realize it but maybe and maybe not others know what I meant.   If the programmers had the same minds, there'd be no Google, no Yahoo!, no Microsoft, no Facebook, even Stack Overflow would never exist. The people are not on the same mind. Up-vote means I have the same issue, I agree with you. But down-vote seems like I don't like your question, I don't realize your mind. If you don't agree, just leave. Maybe someone else knows what the question means.   I think Stack Overflow needs to help programmers, but down-vote the helpless. Tt is help for the others, but not for the one who has the question.       Why is Stack Overflow still using down-votes? Is it help to the one who has questions? Even on meta, which was supposedly founded to discuss Stack Overflow issues. I think I will receive an answer saying "For person like you".

Note: If you're looking for a simple explanation as to why comments aren't required on downvotes, see .   I used to get "upset" (though that is too strong a term) when I got downvoted without comment. If my answer isn't good enough then I'd like to know why. Not only does it improve the answer for the OP but it improves my knowledge too.  Where the down-vote has been explained I've found it useful & it has improved my answer, or forced me to delete the answer if it was totally wrong.  So is there any way we can encourage people to leave a comment? Perhaps they don't lose rep if they explain their down-vote?  I must admit though that I haven't always explained my down-vote either so you could call me a hypocrite. I've also grown a thicker skin over the months of using SO (it seems to have come with the higher rep score ;-)), so I'm less bothered about this now.


I am a recent graduate working as a Data Scientist and I often get lost in 'choosing' which model/models to use for a predictive task. Just recently I was trying to build a prediction on time-series and the number of different models/methods available such as ARIMA, SARIMA, ARIMAX etc is pretty large. Not only that, but even though I can read more about them and have an 'educated guess' at which one to use; I still do not know the assumptions behind the models and whether they are suitable for a task at all. It is like a try and see if it works method. So I am looking for some books/reference mostly concerned with traditional statistical inference models I can dive deep into and learn as much as I can about it. (I have a background in Mathematics and Statistics) Thank you

I started by Time Series Analysis by Hamilton, but I am lost hopelessly. This book is really too theoretical for me to learn by myself.   Does anybody have a recommendation for a textbook on time series analysis that's suitable for self-study?


If the total energy of the particle is less than the height of potential well. What could be interpretation that the particle can be found outside the well.

I understand that if a particle approaches a finite potential barrier of height $V_0$ with energy $E < V_0$, there is still a finite probability of finding the particle on the other side of the barrier due to quantum tunneling.  My question is, since the wavefunction is nonzero inside the barrier region, is it possible to actually make a position measurement and locate a particle inside the barrier?  I mean, if we can say that "there is a nonzero probability that the particle is inside the barrier", surely this would suggest we can do so?  If not, why not? Am I understanding the whole wavefunction/probability distribution thing right?


Noob Java question: Why won't this Do While loop accept the user input? When I use a different variation (such as int for the answer), it works. But when I look for a string, it never accepts the string and escapes the loop.  This works:  int value = 0; do {     System.out.println("Enter a number: ");     value = scanner.nextInt(); } while(value != 5); System.out.println("Do while loop has ended.");   This doesn't work:  String pass; String word = "word"; do {     System.out.println("Enter password: ");     pass = scanner.nextLine(); } while(pass != word); System.out.println("Password accepted.");   Thanks

I've been using the == operator in my program to compare all my strings so far. However, I ran into a bug, changed one of them into .equals() instead, and it fixed the bug.  Is == bad? When should it and should it not be used? What's the difference?


I'm looking for a way to open an image in tty*  I have this Memory about hearing w3m can render images.  If I use w3m to open an image in a GUI it spawns a child window. This was the only way with my current settings to get it to show an image.  Is there a supported file list for w3m? I might have been trying to open an unsupported file type.  Is there some configuration in Ubuntu where I can permit or add the ability to draw images in terminal?  Is there a different command that can render an image in terminal?  I know this question has been asked a few times before but at least one had no solution and it was closed for being unclear; there were answers on other questions but they suggested using commands to spawn x-windows or they would use colored spaces to render the image.  The solution I'm looking for is something that can get pixel level access on a character block or that this is not possible [in Ubuntu 17.10 but it is possible in ...].  If the only available answer is to convert the image to colored ANSII/Unicode I would be super interested but it isn't the answer to this question.

This is a quick mockup I copy and pasted together. I imagine this being super cool and useful.  Does something like this exist already?


From book Real Analysis by Royden & Fitzpatrick,      Let $f$ be a continuous function defined on $E$. is it true that   $f^{-1}(A)$ is always measurable if $A$ is measurable?

Let $f$ be a continuous function on a set $E$.  Is it always true that $f^{-1}(A)$ is always measurable if $A$ is measurable?  I say no.  We know that $\bar{\psi(x)}:=\frac{\phi(x)+x}{2}$ where $\phi$ is the Cantor (or Cantor-Lebesgue) function and $\bar{\psi}:[0,1] \rightarrow [0,1]$.  We know this function maps a measurable subset of $C$ (the Cantor set) into a non-measurable set $W$.  A few observations about $\bar{\psi(x)}$.  It is strictly increasing and continuous, so it has a continuous inverse $\bar{\psi(x)}^{-1}$.  Thus $\bar{\psi(x)}^{-1}(W)=c \subset C$; that is, $\bar{\psi(x)}^{-1}(W)$ is non-measurable, but c is.  Is this correct?


Let $T : [0, 1]^2 → [0, 1]$. Consider the following properties:  $T_1 : T(x, 1) = x$  $T_2 : T(x, y) = T (y, x) $  $T_3 : T(x, T (y, z)) = T(T (x, y), z) $  $T_4 $: If  $x ≤ u  , y ≤ v \Rightarrow T(x, y) ≤ T(u, v) $  Function $T: [0, 1]^2 → [0, 1]$ that satisfies $T_1 −T_4$ is T-norm.  consider $$T_L(x,y) = max(x+y-1,0) $$ we can show that $T_L(x,y)$ is a T norm.  Conditions 1, 2 and 4 are obviously. Can you help me to prove condition 3?

Let $T : [0, 1]^2 → [0, 1]$. Consider the following properties:  $T_1 : T(x, 1) = x$  $T_2 : T(x, y) = T (y, x) $  $T_3 : T(x, T (y, z)) = T(T (x, y), z) $  $T_4 $: If  $x ≤ u  , y ≤ v \Rightarrow T(x, y) ≤ T(u, v) $  Function $T: [0, 1]^2 → [0, 1]$ that satisfies $T_1 −T_4$ is T-norm . For $T(x) = \begin{cases}min(x,y),&max(x,y)=1,\\0,&o.w.\end{cases} $ conditions 1, 2 and 4 obviously.  Can you help me prove condition 3.


For the first time I am using Ubuntu and I installed Ubuntu MATE 16.04. I wanted to install code block  and heard from a friend that I should look for it on Software Center.  I tried searching for it on the Software Center and got it but I couldn't figure out how to install it, and also Software center icon is missing. Please help me since I am new to it.

I am using 64-bit Ubuntu and I want to install the Code::Blocks IDE. Is there any repository?


I'm attempting to dynamically reference an Equation number in tikzpicture (via \eqref or \ref) using the following:  % Filename:  Test.tex (say) \documentclass{article} \usepackage{latexsym,amsfonts,amsthm,amssymb,amsmath} \usepackage{tikz} \usepackage{pgfplots} \pgfplotsset{compat=newest}  % Due to a large number of Tikz plots \usepgfplotslibrary{external} \tikzexternalize  \begin{document} Here is an equation: \begin{equation}     \label{eqOne}     y = x^2 \end{equation} that I'd like to appear in TikZ.  \begin{figure}[htbp] \centering \begin{tikzpicture} \begin{axis}[% xmajorgrids, ymajorgrids ]  \addplot[const plot,color=red,solid,line width=0.5pt] plot table[row sep=crcr] {% 0  0\\ 1  1\\ 2  4\\ 3  9\\ }; ] \node[right, align=left, inner sep=0mm] at (axis cs:2,4) {Equation \eqref{eqOne}}; \end{axis} \end{tikzpicture} \end{figure}  \end{document}   but this won't work via pdflatex -shell-escape Test.tex.  The output generated shows 'Equation (??)'   By trial and error, dynamic referencing seems to only work without \usepgfplotslibrary{external} and \tikzexternalize, but I need these two lines due to the number of TikZ plots that I have.  Is there a way around this dynamic referencing problem; perhaps I'm going about this the wrong way?  Many thanks!

I was writing on an document with a lot of pgfplots in it. Because of the memory limitation in LaTeX and in order to save some compiling time I tried out the externalize command. With most of the plots it perfectly worked out. But when I use the \ref command, namely \ref{<legendname>} the legend gets lost and instead there is a ??.  I think this question in a way is similar to  and . But no answer to these questions could solve my problem. Even the use of xr and zref packages showed no effect.  Am I just missing something?    MWE of the maindocument:  \documentclass{article} \usepackage{zref-user} \usepackage{xr-hyper} \usepackage{pgfplots} \usetikzlibrary{pgfplots.groupplots} \usepgfplotslibrary{external}  \tikzexternalize \externaldocument{part1}  \begin{document} \input{part1} \end{document}     With part1.tex looking like this:  \begin{tikzpicture}     \begin{groupplot}[       group style= {  columns=3,xlabels at=edge bottom,                 y descriptions at=edge left,                 horizontal sep=2cm,group name=plots},     width=0.4\textwidth,     xtick=data,     legend columns=3]     \nextgroupplot[xlabel=site 1,legend to name=grouplegend]     \addplot coordinates {(1,20)(2,23)(3,24.5)};     \addlegendentry {AaAaA,BbBbB,CcCcC}%     \nextgroupplot[xlabel=site 2]     \addplot coordinates {(1,14)(2,16)(3,17)};     \nextgroupplot[xlabel=site 3]     \addplot coordinates {(1,10)(2,11.5)(3,12.25)};     \end{groupplot}   % Legend     \node at (plots c2r1.north) [anchor=south] {\ref{grouplegend}}; \end{tikzpicture}     I'm writing with MikTeX 2.9 and the latest updates of the packages used. For compiling I used the command pdflatex -enable-write18 <file name>.  I hope the MWE is short enough ;) and some knows how to solve this problem.


Below is my code n = 4 m = 4 figures = [1,2,2]  def almostTetris(n, m, figures):     grid = [[0] * m] * n      def shape1(count):         for i in range(n):             for j in range(m):                 if grid[i][j] == 0:                     print(grid[i][j])                     print(grid[1][0])                     print(grid[2][0])                     print(grid[3][0])                     grid[i][j] = count                     print(grid[i][j])                     print(grid[1][0])                     print(grid[2][0])                     print(grid[3][0])                     return      def shape2(count):         for i in range(n):             for j in range(m - 2):                 if grid[i][j] == 0 and grid[i][j + 1] == 0 and grid[i][j + 2] == 0:                     grid[i][j] = grid[i][j + 1] = grid[i][j + 2] = count                     return      for i in range(len(figures)):         if figures[i] == 1:             shape1(i + 1)         elif figures[i] == 2:             shape2(i + 1)          return grid  print(almostTetris(n, m, figures))  and this is what I got printed out: 0 0 0 0 1 1 1 1 [[1, 2, 2, 2], [1, 2, 2, 2], [1, 2, 2, 2], [1, 2, 2, 2]]  My question is how does grid[i][j] = count convert all numbers in the first column to 1 (the value of count)? I thought that because i and j are all 0, only the first element would change to 1.

I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?


I want to make a file which when executed would install all the packages listed inside it like pip install numpy, pip install pandas and others.  How is this done? please guide me to appropriate resources for learning. Thanks

In Windows I can write a file containing commands for cmd (usually .cmd or .bat files).  When I click on those files it will open cmd.exe and run them commands the file contains.  How would I do this in Ubuntu?         I'm sure this is a duplicate, but I can't find my answer. Its similar to these questions, but they don't answer the question:


As per §4.a of the  that all Stack Exchange posts are under,      upon notice from any Licensor [Stack Exchange] must, to the extent practicable, remove from the Collection any credit as required by Section 4(c), as requested.   The most obvious way for a contributor to do that is to flag their own post. This is what is mentioned by ; I couldn't find any mention in the help center. This transmits the request to moderators, who have no way to honor it and must pass on the request to Stack Exchange staff.  It would be more direct if content disassociation requests went directly to Stack Exchange staff, via the . Please mention content credit removal in the  — possibly under

As a moderator I sometimes1 find myself needing to explain disassociation to a user, usually one who has tried to delete posts that he's belatedly realized are connected to him.  It'd sure be handy if I could link to a page in the Help Center instead of explaining it anew each time.  We have a page on how to delete an account, but not the less-drastic action of disconnecting a single post. I understand that this is not something we want to encourage people to do willy-nilly, as it must be done by an SE employee (we mods can't do it) and that's a hassle.  But I don't think having a page in the Help Center will, by itself, cause a surge of requests. I'll propose some language here in an effort to help out and not just ask for things.  Use it or not as you see fit. While this request comes from the "insider" knowledge of the solution, disassociation, I'm writing the topic from the "outsider" perspective, which is closer to "aiieeeee, I shouldn't've posted that!". (I've belatedly become aware of , but mine is a little more specific so I'm posting it anyway.) 1 Three times this week, though fortunately that's unusually frequent.   I've thought better of my question; can I delete it? You may have had second thoughts about a question you've asked.  Maybe you don't want your coworkers to see that question about job-hunting, or you don't want certain family members to see just how much of an expert you've become on video games when they thought you were focusing on school.  We get it; Stack Exchange makes it easy to get good answers to your questions, so naturally you asked. If your question has answers, though, it's not fair to the people who wrote them for you to delete your question.  They put effort into helping you and even if you no longer want the answers, somebody else might.  This is why the system prevents you from deleting answered questions most of the time, and it's also why if you flag to request deletion the flag will probably be declined. However, you can request that a post you've made (question or answer) be disassociated from your account.  This means it will remain on the site, but it will no longer be attributed to you.  It won't show up on your profile, it won't have your name on it, and you won't get any reputation from it.  (You also won't be able to accept an answer later, because it's no longer your question, so do that now if you want to.)  Disassociation is irreversible, so make sure this is what you want. To request disassociation, use the "contact us" link at the bottom of the page.  In the form, say you want to disassociate a post and include the URL. While disassociation is permitted, this is meant to be an exception, not a routine action.  Please be respectful of people's time and do not abuse this.  A pattern of posting rashly and requesting disassociation, over and over again, could lead to suspension.


I'm making a "Spectator Machine" and I need help with detecting if a player is holding a redstone block to return back to their original spot, Im in Minecraft Bedrock and I still don't know if I should use /testfor or /execute and I don't know which one works.

This question was recently split into different questions for each workaround. See   meta posts for more information.   Can you use NBT tags in commands? I’ve tried commands that normally work in Java Edition like: give @s minecraft:planks 30 1 {display:{Lore:["Wooden planks"]}} give @s stone_pickaxe{Unbreakable:1b} give @s item_frame{EntityTag:{Invisible:1b}} summon villager ~ ~ ~ {Offers:{Recipes:[{buy:{id:"emerald",Count:5b},sell:{id:"diamond_sword"}}]}} summon tnt ~ ~ ~ {Fuse:20s}


I'm working through some textbook exercises on fitting models to data, including exponential, logarithmic and now logistic regression. About a 3rd of the way down  is the section on logistic regression. Using a model of the form $y=\frac{c}{1+ae^{-bx}}$ we have to fit a logistic model. I'm using R and any searching for logistic regression in r returns results about binary classification whereas here I'm seeking a numerical result based on a logistic curve. For the 'try it' exercise #3 on the page I linked to above, a data frame is provided: ti3_df <- data.frame(   x = 0:15,   y = c(3.493, 5.282, 6.357, 9.201, 11.224, 12.964, 16.226, 18.137,         19.590, 21.955, 22.862, 23.869, 24.243, 24.344, 24.919, 25.108) )  Along with the question:  Let x represent time in years starting with x=0 for the year 1997. Let  y  represent the number of seals in thousands. Use logistic regression to fit a model to these data.  How can I do this in R?  (Incase someone asks, 'why not just write a custom function based on the model definition above?', I would like to and that's what I'm building to because I don't fully understand how to do that 'by hand' at this stage. My initial goal is to get a result with an out of the box function in r before trying to recreate it myself with a custom function)

I am trying to model vegetation spectral signatures (grey lines) using a two-part piecewise function (black dotted lines). In it, I am trying to use only a few points (red dots) to fit a linear (first part) and logistic function (second part). Basically, the linear part of the function stretches a bit further than the second point (how much it stretches, it will depend on "unknown" parameters, but as a rule of thumb I use 35 "X" units). I currently defined an ifelse function and I am applying a constrained optimization (optim, method="L-BFGS-B"), to find the best parameter values. This has a few handicaps, as the parameters are not normalized/scaled (which makes the search routine less efficient) logistic.fun<- function(K, C, ro, b, Z, a, lambda){       ifelse(test = lambda <= Seq_Bands[2]+25,             yes = a + b*((Seq_Bands[2]+25)- lambda),            no = ((ro*K)/((ro + (K-ro)*exp(-C*(lambda-Seq_Bands[2]+Z))))))}  I would be keen to use nls and fit a 3 parameters logistic regression and also use a fourth parameter to estimate the breakpoint of the linear part (Z parameter code above). Also, I would be keen to avoid jumps such as those seen on left plot below. This means that the functions would have to be differentiable (?) at this breakpoint. I am unsure how to code it. Cheers and thanks!   UPDATE: It was correctly pointed out that the number of variables is higher than the data points presented; which would render the problem under-determined. Consequently, the logistic equation can only be parameterized using 3 variables (Fig 2: R_0_ , K and r. My understanding is that, necessarily, the breakpoint (Z) cannot be estimated, and should be set prior to the optimization process. In context, it is also important to state that the R_0_, and K are not "truly" unknowns, as they are expressed by the measurements (second and fourth red datapoints).


Recently, I bought a cast iron skillet, which was preseasoned. Still, I did season it a couple of times and since then I season it after every cook. I didn't cook anything crazy, just a dutch baby and a pizza.  Still, even after multiple seasonings, there is a clear hole in my seasoning in the middle of the pan:    How I season it:  I put some oil in it, spread the oil with a paper towel, then heat it on the stove until it starts smoking, then let it cool.  I tried olive oil, which apparently is no good, so I switched to sunflower oil and now I am trying it with canola oil. I also switched from paper towel to regular towel, but still, the hole just seems to be getting bigger and bigger. When I touch it with my finger, I can see black residue on it.  What am I doing wrong here? Yesterday I even did a couple of seasonings one after another (let it cool, oil it, heat it, repeat), but this seems to have been counterproductive.

I'm quite new to cooking as a whole.  A few months back I bought a set of VonShef cast iron pans. When seasoning them, I unfortunately made two errors. First, in my naïveté, I used vegetable oil as the seasoning; and second, I didn't remove the excess oil, leaving a sticky and uneven finish in the pans. After a couple of failed attempts at cooking with this situation, and some food sticking to the pans, I've been putting off using them to avoid further catastrophes.  So how can I go about rectifying my mistakes? I've watched a few videos on YouTube about the proper way of seasoning, and it seems you can clear seasoning by either sanding it down or burning the pan. But how would you also clear off burnt food stuck to the pan?  I hope you can see what I mean in the below pictures.


I'm making a Nintendo NES console. I'm using the latest version of blender, 2.9. All the other versions before this wouldn't work either.  I have modeled the ENTIRE console, but when i add the bevel modifier, nothing happens, literally nothing, the edges are still just as sharp and i see no effect when i try to add segments. I even tried to bevel it manually with CTRL + B, it works but i can't bevel a big complicated model with that many verts, even when i select the whole object and do the CTRL + B it ends up bad. what exactly is the problem? Also the bevel modifier works with simple cubes and simple shaped objects that don't have so many cuts in them but that's it. I researched tons and couldn't find anything. Here is my NES, it looks ok, but it is too sharp on the edges, not smooth like the real console. When I apply the bevel modifier, it still looks exactly like this with no change.

I'm very new to Blender. I've used a loop cut and slide to make the shapes I want to indent in this object, then extruded them inward to get them how they look now, then dissolved the unnecessary leftover edges. I wanted to apply a bevel to some of the edges, so I used Tag Bevel in Edge Select Mode and marked the edges I wanted to Bevel, added the Bevel modifier and set the mode to weight.  On one side, it looks exactly how I want it:    On the other side though, some of the edges aren't being bevelled despite being tagged (the ones closest, on the left side):    Why is it working for every edge other than these ones? This is the wireframe of the object and it doesn't appear to be any different on the side that works to the side that does not:    And these are the bevel's settings just in case (I've tried fiddling with the width and it doesn't seem to have any effect. Incidentally, if I change limit method to None, those edges bevel fine):


Consider the following code:   0.1 + 0.2 == 0.3  ->  false   0.1 + 0.2         ->  0.30000000000000004   Why do these inaccuracies happen?


Imagine, you add an object to the scene and you get the redo-panel (F9 menu). If you want to modify the options of the newly created object but you mistakenly click elsewhere, the menu disappears. That's not a problem, since you can bring back this menu using F9. However, imagine you move the object (using G) first and then want to access the F9 menu again. When you press F9 now, the menu of the translation will appear instead of the initial options for the object! How can I bring back the initial F9-menu?

When you first add a cylinder, you have the option to change the number of vertices, etc, but once you do anything else in blender, it seems you no longer can edit those parameters.   Is there a setting anywhere or an add-on that allows these parameters to be edited later on? If not, how easy would such an addon/feature be to create for anyone reading this?


What is the meaning of the construct "have/had something/someone + adjective"? For example, "He had her tried for treason...".

I will have it done by tomorrow    Would you please by some example describe what does the bold part mean?   I think the bold part is passive, isn't it?  Thanks in advance


I am reading computer science texts, which tend to include a lot of summations and set logic. In set logic, formulas commonly use a capitalized variable to reference a whole set, i.e. $\Omega$, and a lowercase variable to represent a given member, i.e. $\omega$. Given that, how does one read something like:  $$ 0\leq Pr(\omega)\leq 1\mathrm{\quad and \quad}\sum_{\omega\in\Omega}{Pr(\omega)} = 1 $$  Perhaps it's due to my [poor] command of math, but I tend to read this out loud to myself, and it's odd to say "The sum of the probability of omega, where omega is a member of omega..."

This is a soft question. We can read the letters $\bf A$, $\bf B$, etc. as bold A, bold B, etc. We can read the letters $\textit{A}$, $\textit{B}$, etc. as italic A, italic B, etc. We can read the letters $\mathcal A$, $\mathcal B$, etc. as calligraphic A, calligraphic B, etc. But how do we read letters such as $\mathbb A$, $\mathbb B$, etc., or $\mathfrak A$, $\mathfrak B$, etc.?


My US-born daughter has triple citizenship - Brazil, US and UK. We live in Texas and I would like to start saving for her education. My wife and I are also considering sending her to private elementary/middle/high school, and as far as I know, under the new tax rules the 529 savings (or part of them) can be used for that purpose as well.   If my daughter goes to university in Brazil (where many universities are free), can I get the money out of the 529 plan back to myself as a regular investment provided that I pay the income tax that was deferred for all these years (and possibly a penalty)? i.e. can I "convert it" back to a regular investment account? More importantly, would it be worth it? I know some universities in some countries (Canada, for exampe) accept 529 plans for the tuition costs. However, if she goes to university in another country that doesn't officially accept a 529 plan, is there any way I can withdraw the money to pay for her tuition, provided that I present proof to the 529 administrator? If I never use the money to pay for college tuitions, is it OK if I use the 529 account for the sole purpose of paying for private school? I know there's a limit of how much I can use for that purpose. For my specific situation, how do 529 plans compare to Roth IRAs?

My son is a freshman this year.  We live in and he attends school in California.  We pulled out the first $ from our Utah 529 plan.  I had the money deposited in my account since I paid the registration and dorm & meal plan.  Our friend has a son a year ahead and he has the exact same 529 plan.  He warned me that he got hit with a small tax penalty when he withdrew the money to his account and not to an account in his son's name.  I called the 529 administrator and they said it shouldn't matter either way.  Other online blogs agree.  They say the only difference is that my son would get the tax forms and have to file if it went to his account. Nevertheless, my friend did get a penalty.  Any clarity would be appreciated!


Is there a method in java which round up double to Long in java?  eg. double d=2394867326.23; I need to round this up to 2394867327. The result is not an integer, so I think cannot use Math.ceil.  Do we have a method in java which return the Long instead of int?

What is the best way to convert a double to a long without casting?  For example:  double d = 394.000; long l = (new Double(d)).longValue(); System.out.println("double=" + d + ", long=" + l);


Let $n$ be a positive integer. If $2+2\sqrt{28n^2+1}$ is an integer, then it is a perfect square.    My work: $2+2\sqrt{28n^2+1}=m \implies 4(28n^2+1)=m^2-4m+4 \implies m=2k$ $28n^2+1=k^2-2k+1 \implies 28n^2=k^2-2k \implies k=2q \implies 28n^2=4q^2-4q$ $7n^2=q^2-q \implies 7n^2=q(q-1)$ Now, we have $q$ and $q-1$ to be co-prime. Here, two cases arises. (i) $q=7x^2,q-1=y^2 \implies 7x^2-y^2=1$. This cannot occur because $y^2 \equiv 6 \mod7$  is not possible. (ii) $q=x^2,q-1=7y^2$. Now, what am I supposed to do? Please help.

As written in title, I want to prove that      If $n$ is an integer, show that if $2+2\sqrt{28n^2+1}$ is an integer than it must be perfect square.    I m struggling in making a start . Please help.