The originally intended title exceeds the limit; it is, "Why is a URL shortener rewriting  to  when I want  forwarded to ?"  I posted below a question asked after long using Apache URL rewriting (from 1.3.x when 2.0 wasn't around). A quick check shows my /etc/apache2/sites-enabled to have 121 RewriteRules, including site relocation, switching from HTTP to HTTPS, and other workhorses. I'm also having trouble with a very simple task, simple as putting a RewriteRule to move something to another URL without breaking links or causing the old location to be a 404 error.  I also sanitized servers and identifiers, not because I'm relucant to give this specific raw data, but in an attempt at politeness, partly to avoid spam, and partly because someone can always ask to see the real data.  I have, modulo removing comments and hiding masking e.g. domain names, the following Apache VirtualHost:  <VirtualHost *:80>         ServerAdmin cjshayward@pobox.com         DocumentRoot /home/jonathan/stornge         ServerName cjsh.name         ServerAlias www.cjsh.name         LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\"" combined         CustomLog /home/jonathan/logs/stornge.com combined         RewriteEngine on         #RedirectMatch ^/$ https://cjshayward.com/books/         RewriteRule ^/$ https://CJSHayward.com/books/ [R=301,L]         RewriteRule ^$ https://CJSHayward.com/books/ [R=301,L]         RewriteRule ^/([^?].*)$ http://stornge.com/?$1 [R=301,L]         #RewriteRule ^.*/writings/autobiography/(.*)$ /about/author/ [R=301,L]         #RewriteRule ^/tiki.*$ http://www.facebook.com/pages/CJS-Hayward/9506801167 [R=301,L]         #RewriteRule ^/community/tiki.*$ http://www.facebook.com/pages/CJS-Hayward/9506801167 [R=301,L]         <Directory /home/jonathan/stornge/>             Options ExecCGI Indexes FollowSymLinks MultiViews             AllowOverride None             Order allow,deny             allow from all         </Directory> </VirtualHost>  I'm not sure this is anywhere near optimal; the reasons for involving two servers (for an external site not hosted on either server, three) are mostly historical that could be improved on.  However, I want  to redirect to , and every time I load the homepage at , I am redirected to the homepage for  as a whole.  I can put the URI referral script in a pastebin if others want to see it, but I put what was meant as a "redirect from homepage" URL shortener:  #!/usr/bin/python   import cgi import cPickle import os import re import sys  if (os.getenv('HTTP_HOST') in ['cjsh.name', 'www.cjsh.name', 'stornge.com',   'www.stornge.com' and os.getenv('REQUEST_URI') ==   os.getenv('SCRIPT_NAME')):     print '''Status 301 Moved Permanently Location: https://CJSHayward.com/books/ Content-Type: text/html; charset=UTF-8  Go to bookstore.'''     sys.exit(0)  I've tried a couple of ways of working around it, with clearing caches, switching between browsers, and using (sub)domains I haven't really used for anything else; I don't really use a FQDN of  unless I was trying to circumvent caching expected in .  I do not consider this question to be, "How do you get things basically working with URLs and get work done," but "Why do my quite numerous attempts to redirect  to  end up at the  homepage? These are two very different questions, so far as I know.

This is a  about Apache's mod_rewrite.   Changing a request URL or redirecting users to a different URL than the one they originally requested is done using mod_rewrite. This includes such things as:   Changing HTTP to HTTPS (or the other way around) Changing a request to a page which no longer exist to a new replacement. Modifying a URL format (such as ?id=3433 to /id/3433 ) Presenting a different page based on the browser, based on the referrer, based on anything possible under the moon and sun. Anything you want to mess around with URL   Everything You Ever Wanted to Know about Mod_Rewrite Rules but Were Afraid to Ask!  How can I become an expert at writing mod_rewrite rules?   What is the fundamental format and structure of mod_rewrite rules? What form/flavor of regular expressions do I need to have a solid grasp of? What are the most common mistakes/pitfalls when writing rewrite rules? What is a good method for testing and verifying mod_rewrite rules? Are there SEO or performance implications of mod_rewrite rules I should be aware of? Are there common situations where mod_rewrite might seem like the right tool for the job but isn't? What are some common examples?   A place to test your rules  The  web site is a great place to play around with your rules and test them. It even shows the debug output so you can see what matched and what did not.


I know the magnetic field would need to be very large, but if an organisation like NASA with huge funding and resources could build a large enough device, could a man float in that magnetic field to simulate zero gravity?  I would love to know how large the device may need to be, though presumably it would be in relation to it's power (are we talking 747's or football fields?).  My idea is that this would be safer than astronauts training under water in their enormous pools (and reduce risk of drowning as per recently in the news), and would help them train for the International Space Station etc. without the stop/start effects on the zero-G airplanes.  We can levitate frogs and other small insects (video here: ) so presumably it would be possible to scale everything up for a man or woman - possibly wearing clothing/apparatus to help achieve the zero gravity effect.  I guess the next question would be are there any health effects should a large enough magnetic device be produced?!

There is iron in our blood, which is magnetic. Roughly how strong would a magnet have to be to induce a noticeable attraction? It would be nice to know this for several distances. Also, do electromagnets that strong exist?


what happens when I dial in an f stop of 22 on my old canon xti using a 200mm telephoto 3.5 - 6.3?

I made a series of outdoor shots with Nikon D5000, with the 18-55mm 1:3.5-5.6G VR kit lens.  On some shots, I see in the EXIF info f/11, and in another shot, f/9.    How can that be, that the f-number is greater than 5.6, when that's listed as the maximum in the lens spec?


How do I get my substring method to work?  I keep getting a null pointer exception on this line: copy = copy.next = new Node(curr.data);  public LL substring(int startPosition) {      if (startPosition < 0)         throw new IndexOutOfBoundsException();      LL substring = new LL();     Node curr = first;     for (int i = 0; i < startPosition; i++) {         curr = curr.next;     }     Node copy = new Node(curr.data);     substring.first = copy;      while (curr != null && copy != null) {         curr = curr.next;         copy = copy.next = new Node(curr.data);     }     return substring; }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


Consider the following bash script:  #!/bin/bash echo "${1##*.}"    This script prints the extension of a file if the file name is supplied as the first command line argument, something like following:  $ ./script.sh ./file.pdf   In the above case pdf is printed.  Please explain how the expression ${1##*.} is able to extract the extension of the file.  (I understand what $0, $1, $2, $# do in bash and also understand about regular expressions to some extent)

I'm quite confused about the following regular expressions I found in a shell script:  ${0##*/} ${0%/*}   How do they work?


I'm studying the rolling motion, but, Why the torque by static friction does work? If the point of application is at rest relative to the inclined plane, therefore, the point of application doesn't move.

Consider a cylinder that rolls without sliding on an inclined plane. If it's placed at the top of the plane, with its center of mass at a height $h$ from the bottom, it will have a potential energy $mgh$ (considering the bottom of the plane as the zero point). Then, the cylinder will start rolling down the plane, as its weight does work on it, causing its potential energy to be transformed into rotational and translational kinetic energy. I'm confused about the origin of the rotational kinetic energy of the cylinder. Since the static friction and the normal force are applied at the point of contact with the plane, neither of them can do work on the cylinder (which is why its mechanical energy is conserved), since the cylinder is, by constraint, not sliding. This seems to imply that the cylinder's rotational kinetic energy comes from the work done by its weight. However, I don't understand how this happens, since a rigid body's weight can be seen as being applied on its center of mass, which means it can exert no torque on it. Instead, the only torque exerted with respect to its center of mass comes from static friction. Moreover, if the inclined plane was frictionless, there would be no torque exerted on the cylinder, so it would not rotate. Yet, I don't see how this situation could be distinguished from the previous one by only looking at the cylinder's mechanical energy (since the normal force would still be doing no work). So, my question is: how is gravitational potential energy converted into rotational kinetic energy, and what is friction's role on this?


I am able to download the .exe files but I cannot open or install on Ubuntu. Advice please. My laptop is 1 day old

Can .exe and .msi files (Windows software) be installed in Ubuntu?


I have a curve that isn't a closed loop.    Is it possible to change the start/end handles so the gap is in a different place?

I am fairly new to Blender and I would love some help with this problem. I modeled a bezier curve a couple of days ago, and then wanted to change it.  I know how to connect two vertices of a bezier curve by pressing F to fill it, but how unfill two vertices, such as to disconnect them?  Here are some pictures to help out with my scenario. Picture 1 shows the two vertices I want to fill. Picture 2 shows both the vertices I wish to disconnect. Thanks!  P.s. What is this red line that showed on my curve? (picture 2)


I am confused with the words "use", "employ" and "utilize".  What is the difference in their meanings, and where they are supposed to be used? There is another topic with the same question, but it is poorly explained.  Could it be used in the title of articles as in the examples below?     Utilizing the advantages of Google mail.       Employing external phone numbers in corporate phone system.

The situation is I'm writing a paper, and I want to use different words to express the meaning of "adopt" a method or approach.  All the three words "use", "utilize" and "employ" have the meaning of   to make use of something  So, is there any difference of the three words in aspect of expressing this meaning. And is there a best word to use in some specific conditions?


On a linux shell I have essentially the following script  #!/usr/bin/env bash set -e  python script.py arg1 & python script.py arg2 & python script.py arg3 & wait echo $?   in which some python programs can run in parallel, and I wait until the completion of the programs.   However, when I have only one failing programm for testing purposes which fails, the reported exit status is 0 (SUCCESS). I suspect that is the exit status of the wait command. That is not what I want. I want to report an error (i.e. exit status unequal zero), if ANY of the programs did fail.  Is there a simple way to achieve this?

How to wait in a bash script for several subprocesses spawned from that script to finish and return exit code !=0 when any of the subprocesses ends with code !=0 ?  Simple script:  #!/bin/bash for i in `seq 0 9`; do   doCalculations $i & done wait   The above script will wait for all 10 spawned subprocesses, but it will always give exit status 0 (see help wait). How can I modify this script so it will discover exit statuses of spawned subprocesses and return exit code 1 when any of subprocesses ends with code !=0?  Is there any better solution for that than collecting PIDs of the subprocesses, wait for them in order and sum exit statuses?


My question is not about statistical programming. We know how to code the software in a regression with many independent variables. My question is about how the computer software controls for all variables at the same time mathematically.  Simple correlation of two variables is easy to understand, as each variable has the other one's full attention. In multiple regression, however, multiple independent variables are "looking at" the dependent variable at the same time, and each one looks to "subtract out" or explain the variation, but they can't all be in operation with the dependent variable at the same time. If a single given independent variable is given priority to be the first to interact with the dependent variable, and it "takes away" its share of the dependent variable, then what it takes away won't be rightfully eligible to be explained by other independent variables, as it justly should.   My intuitive sense of what happens must be mistaken, and I need an answer that does not involve formulas. The challenge for the teaching profession is how to explain complex ideas narratively or metaphorically for analysts that don't have a fast, intuitive sense for symbolic explanation.  A related question is this: is the process iterative in that initial approximations (of betas) are made, and they incrementally adjusted as each of the other independent variables add more information to the initial beta estimates?

Here is the article that motivated this question:   I liked this article, and it nicely demonstrates the concept of “controlling for other variables” (IQ, career, income, age, etc) in order to best isolate the true relationship between just the 2 variables in question.    Can you explain to me how you actually control for variables on a typical data set?      E.g., if you have 2 people with the same impatience level and BMI, but different incomes, how do you treat these data?  Do you categorize them into different subgroups that do have similar income, patience, and BMI?  But, eventually there are dozens of variables to control for (IQ, career, income, age, etc)  How do you then aggregate these (potentially) 100’s of subgroups?  In fact, I have a feeling this approach is barking up the wrong tree, now that I’ve verbalized it.  Thanks for shedding any light on something I've meant to get to the bottom of for a few years now...!


I want to bypass the ISP's firewall, and succesfully did it on  and  by sending a set of HTTP headers and using CONNECT method to establish an SSH connection to a remote () SSH server. POST http://host.com/ HTTP/1.0[crlf][crlf] CONNECT host.com@[host_port] [protocol][crlf][crlf]  Then I use that connection as a SOCKS5 proxy, and become free of restrictions, imposed by ISP. Now I want to do same on Linux, but I can't find any Linux alternative, and my laptop is pretty weak to have VirtualBox running all the time. Any suggestions? I get that there's probably no nice GUI for this, but I'm not afraid of console

I am really struggling with this.     My host (A) is behind a proxy/firewall (PF) and needs to connect to   host H.   The proxy has HTTP/FTP/SOCK proxy configured and I have no issue to configure in web browser, wget etc.  But when I use...   ssh H //to connect my host    I have no success to pass over the proxy. It seems to try to connect directly instead of going via the PF.  I am using Ubuntu 12.10.


In the latest , the following was posted (emphasis mine):     Licensing         MIT licensing of code was proposed, but held back due to community naysayers.   CC-BY-SA incremented from 3.0 to 4.0. - likely in good faith.   Vast majority of community likely fine with 4.0.   Vast majority not fine with fait accompli.   Some (a very few?) thought that this happened in bad faith.         Stack Overflow:                We have apologized for the fait accompli.     We want to signal our intent to keep up with future changes to CC-BY-SA.     We will create a process and be engaged on licensing issues on Meta.     We have had hours of meetings on this, and it is a big priority.     We have no intention of moving away from creative commons or paywalling users content in any way.           Has that actually happened? Was there any place were SO made any sort of apology related to their actions in the licensing space? The original re-licensing announcement is , and there was a follow up post to it , but I don't see any apologies there, and I don't know of any other posts related to this.   For those suggesting that  question is a dupe of mine, I disagree. It was answered in one week and its possible SO did something since then. The SO leadership seems to have explicitly stated something was made, which is in direct contrast with the answer in that post.

Fifteen days ago, it was suddenly announced that .  The change took immediate and retroactive effect and is still in place.  However, .  To date, there has been no further engagement from Stack Exchange, Inc. on this subject, and consequently there is no indication as to whether these concerns are being considered.  Due to the legal nature of the issue I would understand if Stack Exchange, Inc. has opted to consult their legal partners before making any further statements on the topic.  If that is the case, I respectfully suggest that (at the very least) a short statement to that effect would be in order, as it has already been more than two weeks that the content has been [potentially illegally] re-licensed network-wide. Every day that this is the case, more content is posted, and if indeed the re-licensing of older content is ultimately deemed non-compliant, the technical can of worms involved in remedying the situation grows in mass and squirmishness.  If it is not the case, are there any plans to revisit this topic and feed back to the community as to what the next steps may be to resolve this dispute?  If there are no such plans, please consider that this is not just bikeshedding or whining or complaining or trolling. Licensing of our content, which to a large degree is the Stack Exchange Network, is a serious issue and deserves to be treated seriously.  And, if Stack Exchange, Inc. deems the concerns to be without merit, will we hear a confirmation of that so that we can proceed on that basis?


Here we assume $(a,b) = 1$ and $a^{-1}$ and $b^{-1}$ are canonical (e.g.  $0 < a^{-1} < b)$. Counter example or proof are appreciated!

This is going to sound like a stupid question, but I cannot understand how I get this result (I understand why, but it looks like there is no relation).  $p, q$ primes  why do we have this?  $p \cdot (p^{-1} \mod q) + q \cdot (q^{-1} \mod p) = pq + 1$  I don't see the relation between the left and right side, but still it works.


Many of the latex packages used the term macro what does it mean and what is the definition of macro according to LaTeX and what is the use of this macro? Kindly let me know with examples. Thanking you in advance.

The title pretty much says it all.  If it helps, I found myself asking this question when reading .


This is what I mean by sorting (5 items in this example, this is not code):  [1, 2, 3, 4, 5] [1, 2, 3, 5, 4] [1, 2, 4, 3, 5] etc.   It is some kind of factorial function. Without items repeating.

How do you generate all the permutations of a list in Python, independently of the type of elements in that list?  For example:  permutations([]) []  permutations([1]) [1]  permutations([1, 2]) [1, 2] [2, 1]  permutations([1, 2, 3]) [1, 2, 3] [1, 3, 2] [2, 1, 3] [2, 3, 1] [3, 1, 2] [3, 2, 1]


I need to set up a SQL Server Audit to capture all database activity for all logins except one - the login our application runs under. In this case the login I want to exclude is CPSDOM\cpointedb.  In SQL Server Management Studio under 'Security / Logins' I see the login CPSDOM\cpointedb. But, when I look under 'Databases / dbName / Security / Users', I do not see the user CPSDOM\cpointedb.  When I set up my Database Audit Specification I also do not see a CPSDOM\cpointedb user. I was hoping to see this user listed in the Database Audit Specification so I could check all the users except that one.  Is there a different (better) way to do this? All I want to do is set up an audit that excludes one user.  I like the idea of just auditing all users (public) in the audit and excluding CPSDOM\cpointedb from the analysis, but I am concerned this may cause performance problems. Is that a valid concern?

I'm setting up a database audit.  I'd like to capture any DML change that is issued by database user other than the service account related to the application.    In short, this is to prove to our external auditors that no users are tampering with data outside of the application.  This following script sets up a DML audit that is global to all principles.  CREATE DATABASE AUDIT SPECIFICATION [OurDatabaseAuditSpec] FOR SERVER AUDIT [OurAudit] ADD (DELETE ON OBJECT::[dbo].[SensitiveData] BY [public]), ADD (INSERT ON OBJECT::[dbo].[SensitiveData] BY [public]), ADD (UPDATE ON OBJECT::[dbo].[SensitiveData] BY [public]) WITH (STATE = ON) GO   How do I go about modifying this audit specification to capture everything EXCEPT what is being done by the application service account?    Am I limited to specifying each principle individually or can I specify an exception?  Reading through BOL it seems I can only list principles to audit - not principles to ignore.


Is there a commonly-accepted operator which defines multiple function composition? I have not been able to find one on any of the related Wikipedia pages. In one of my proofs, I've been finding it very tiresome to continually write the following: $$ f_n\circ f_{n-1}\circ\cdots\circ f_0 $$ And I would really appreciate finding out if there is a common notation for what I'm trying to do. The above notation only works for a sequence of functions; I imagine there's probably a way of using this composition operator to compose over an arbitrary ordered set, sort of like $\bigcup_{i\in I}A_i$ allows a union over any (not necessarily countable) indexing set $I$, but without the ordering condition.  I'd use foldl1 (.), but that doesn't seem very appropriate for math homework.    I feel like I should add why I feel like one is necessary, on top of the additional expressiveness we gain from being able to compose over arbitrary ordered sets. The problem itself defines $F_n$ as the above repeated-composition function; indeed, we can define $F_n$ in a recursive manner with $F_0=f_0$ and $F_{n+1}=f_{n+1}\circ F_n$. However, the issue remains because in my proof I frequently need to expand $F_n$ (for instance, calculating $F_n'$), in which case such an operator would come in handy.

I have a repeated composition of functions ${T_n}(z) = {\tau _0} \circ {\tau _1} \circ {\tau _2} \circ  \cdots  \circ {\tau _n}(z)$  By analogy with $\sum\limits_{i = 1}^n {} ,\prod\limits_{i = 1}^n {} ,\bigcup\limits_{i = 1}^n {} ,\bigcap\limits_{i = 1}^n {} ,$ I want to write ${T_n}(z) = \left( {\mathop  \circ \limits_{i = 0}^n {\tau _i}} \right)(z)$ or even ${T_n}(z) = {\mathop  \circ \limits_{i = 0}^n {\tau _i}} (z)$. Can I do this?


Im stuck in this exercise where i have to find the matrix representation of a linear transformation.  Let $P_3(\mathbb{C})$ be a complex vector space of complex polynomial of degree $\leq2$.  Let $\alpha, \beta \in \mathbb{C}, \alpha\neq\beta$ and consider $L:P_3(\mathbb{C})\rightarrow \mathbb{C}^2$ given by  $L(p)= \begin{pmatrix} p(\alpha)\\ p(\beta)\\ \end{pmatrix}$ , $p\in P_3(\mathbb{C})$  Consider the basis  $\mathcal{V}=(1,X,X^2)$ for $P_3(\mathbb{C})$ and the standardbasis $\mathcal{E}=(e_1,e_2)$ for $\mathbb{C^2}$  Find the matrix representation  ${}_{\mathcal{E}}[L]_{\mathcal{V}}$ for $L$ according to $\mathcal{V}$ and $\mathcal{E}$.  I dont know if this is correct, but i have reached the following  $_{\mathcal{E}}{[L]}_{\mathcal{V}}= \begin{pmatrix} \vdots & \vdots & \vdots \\ [L(1)]_\mathcal{E} & [L(X)]_\mathcal{E} & [L(X^2)]_\mathcal{E} \\ \vdots & \vdots & \vdots \end{pmatrix} \in Mat_{2,3}(\mathbb{C})$  I know I have to find $[L(1)]_\mathcal{E},  [L(X)]_\mathcal{E},[L(X^2)]_\mathcal{E}$, but i dont know how to do it.

I'm having trouble with part of homework exercise. Let $\mathcal{P}_3(\mathbb{C})$ be the vector space of complex polynomials of degree 2 or lower and $\alpha,\beta\in\mathbb{C},\alpha\ne \beta$.  Let $L:\mathcal{P}_3(\mathbb{C})\to\mathbb{C}^2$ given by $L(p)=(p(\alpha), p(\beta))^T$ and I want to find the matrix representation of $L$ with respect to the bases $\{1,X,X^2\}$ and $\{\mathbf{e_1},\mathbf{e_2}\}$.  I usually apply $L$ to the elements of the basis for $\mathcal{P}_3$, but with this definition of $L$ I don't know how to do it. Can someone give me a pointer?


I am trying to telnet to different web servers and see what http response messages I get. I've tried telnet some_host_name 80, and then the shell says connected to some_host_name escape character is '^]'. How exactly do I get the http response message?

I have question, is it possible to get header of website by using telnet? Website looks like this domain.name.server.com/~USER (just example). And I want to get it header by telnet.  telnet domain.name.server.com/~USER 80 <-- doesn't work  telnet domain.name.server.com 80 works but I neet to get ~user. Is there any possibility to do this?


I am using Ubuntu 14.04 Trusty Tahr with kernel (3.13.29). A couple of days ago the login screen doesn’t allow me to login. In the error log there is a   gnome-session error Segmentation fault on LibX11.so.6.3 error 4   This line occurs every time I try to log in. I have a Lenovo W530 and I am using the nouveau display driver.  I installed the gnome desktop environment, so at login I can choose the environment I want but this hasn't solved the problem. I re-installed Ubuntu and this error cropped up when I did a distribution upgrade on the system.

My laptop was working perfectly yesterday, and now today I can't log in.  At first, I was only getting a black screen. However, after following instructions in some questions here on AskUbuntu, I first reinstalled lightdm, and then I had to change the ownership of the file ~/.Xauthority to be my user name. Now, I get the log in GUI screen.  However, once I enter my username, it flickers and then comes back to the login GUI. It does not matter if I use Gnome, Unity, or Gnome-Flashback.  I don't know why lightdm needed to be reconfigured, or how ~/.Xauthority got changed, but in any case, what is still standing in my way, preventing me from logging in?  Update: I have tried deleting the .Xauthority file, and the .profile files in my home directory. It has not changed anything.  Logging in as guest also fails to work.  The following commands did not work:  mv ~/.config ~/.config.BAK mv ~/.cache ~/.cache.BAK   Inside .xsession-errors in my home directory, it says:  Gdk-CRITICAL: gdk_x11_display_get_xdisplay: assertion 'GDK_IS_DISPLAY (display)' failed


I would like to know how to generate a random number between two given values.  I am able to generate a random number with the following:  Random r = new Random();  for(int i = 0; i < a.length; i++){     for(int j = 0; j < a[i].length; j++){         a[i][j] = r.nextInt();     }  }   However, how can I generate a random number between 0 and 100 (inclusive)?

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


For almost a year now, deleted answers that have at least one approved spam or offensive flag, . All Good.  However, comments are still being displayed and I don't think there can be any constructive comments on a spam or offensive answer.  Can comments also be hidden by default with a "show comments" link, or just deleted altogether?  The straw that broke the camel's back was : (10k only)         What's the point of hiding the spam/offensive content in the post body, if it's fully visible in its full ugliness in the comments?

Well, this is annoying. Last night some idiot who'd managed to earn the association bonus for his activity on Stack Overflow decided it'd be a brilliant idea to create accounts all over the network and post dozens of comments on other people's posts asking them to take some survey. Ok, no big deal, suspend him and destroy all these bogus accounts, taking the comments with them.  ...oh. Turns out destroying an account doesn't delete the comments. Given the description reads "all content", I'm considering this a bug. Steps to reproduce  Find a user that has commented somewhere. Destroy it. Note that the comments still exist.  Suggested resolution Since destroying an account already deletes all posts associated with that account (implicitly taking the comments with them), all that's really necessary here is to remove any comments that might remain on 3rd-party posts. So, do that.


how to create progress bar when running command that take time   for example ( this take 10 min )   cat GTTfiles* > GTTcentos7.tar.gz   so during that CLI is working how to create some progress that show process is running?  example of output ,  ( only example , we will happy to get other ideas )   |..........                             |

In a bash script sometimes you need the user to wait some seconds for a background process to finish.  I usually use for example:  sleep 10   How can I add a kind of progressbar to the script, so the user knows how long to wait?  I installed the command bar but I don't understand the manual.


Since upgrading to 14.04 LTS (64-bit), my PC will sometimes fail to resume from hibernation (perhaps one time in ten). Symptoms are that it attempts to resume, finds the suspended memory image, and shows the percentage of the image loaded (10%, 20%, etc.) It reaches 100% and then the PC reboots back to the BIOS splash screen. When the GRUB menu reappears, it does not have the usual timeout. I don't know what to try to isolate the cause.  Hibernation worked reliably on the same hardware under 12.04 LTS.

I'm running 14.04 on a new XPS 13. In order to support the newer hardware, I'm running a mainline 3.19 kernel.   Hibernate resume has been iffy with the entire 3.19 kernel line, but recently (3.19.5) pm-hibernate no longer works at all. The screen will either a) switch off momentarily, then back on with all inputs frozen or b) switch off entirely, and fail to resume upon power on (despite displaying the correct resume-from-uuid message).  I have enough swap space (and it has worked in the past), I have checked that the uuid is being correctly referenced, and nothing seems particularly amiss in /var/log/pm-suspend.log (last 200 lines here: )  Thanks for your help.


What is correct form:     I wish I were a king.   or     I wish I was a king.   I need some explanation.

In which cases should I use the subjunctive mood?     I suggest that every applicant fill out the form carefully.        If she were rich, she would live on Long Island.


Let $(X, d)$ be metric space. Define $B_\epsilon = \{ x \in X : \exists b \in B \; d(x, b) \le \epsilon\} $. Let $F(X)$ be a family of all nonempty compact subsets of $X$ (so $\emptyset \notin F(X)$ ). We shall define Hausdorff metric by: \begin{equation}   D(A, B) = \inf \{ \epsilon \in \mathbb{R}^+ : A \subset B_\epsilon \; \land B \subset A_\epsilon \}. \end{equation} Then $(F(X), D)$ is a metric space.  What I would like to know is what is the relation between connectedness of $(X, d)$ and connectedness of $(F(X), D)$.  So far I was able to prove that if $(X, d)$ is not connected, then $(F(X), D)$ also is not connected. Here the main idea was that if (A, B) is a pair of nonempty subsets of $X$ such that $A\cup B = X$ and $A \cap B = \emptyset$ and $A, B$ are open, then $(2^A \cap F(X), F(X) \setminus 2^A \cap F(X))$ is a pair of nonempty, open subsets of $F(X)$ which sum to $F(X)$ and have empty intersection. (Which by contraposition means that connectedness of $(F(X), D)$ implies connectedness of $(X, d)$).  Is the opposite implication true, that is, does connectedness of $(X, d)$ imply connectedness of $(F(X), D)$?

Does anyone know a proof of connectedness of the Hausdorff distance?  I mean a proof of the following:  Theorem  If $(X, \rho )$ is a connected metric space, then $(F(X), d_h )$ is also connected.  Remark:  $F(X) = \{ A \subseteq X | A \text{ is nonempty, closed and bounded } \} $, and $d_h$ stands for the Hausdorff distance.


I was expecting below ways of initialization to result in same output:  a = [{}, {}] b = [{}] * 2 a[0]["assigned"] = 1 b[0]["assigned"] = 1 print(a) print(b)   but the output is as follows:  [{'assigned': 1}, {}] [{'assigned': 1}, {'assigned': 1}]   Looks like in case of b, a single dictionary instance is being created and referenced in all the list elements.  Can someone help me with reason behind this implementation?   Thanks.

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?


The play/pause and backward and forward buttons on my MacBook are not working as they should. When I press the play/pause button, nothing happens or it quickly pauses and plays again. Backward/Forward buttons are skipping previous/next song and play the second one in order.  I don't have Google Play Music installed. I've also reset SMC but it didn't help.   Anyone know what could be a possible problem?  I'm using macOS High Sierra.

I am being driven crazy by the fact that my media keys aren't working for iTunes. Such a pain! How can I fix this? I've tried the whole Chrome Extensions thing, that being I deleted all my extensions. Still, nothing has fixed this. Thanks to all who reply!


I have 8GB Ram installed but in Task Manager it is showing that I am using 93% of my memory, even though I am using no more than 3.5GB. Where is the rest?

Task Manager shows my total memory usage at 90% of my 6 GB total, but no single process is using more than 250 MB RAM, and the sum of RAM use of all running processes is less than 2 GB. I've tried:   Looking at the numbers in the "Memory" column on the "Processes" tab of Windows 8 Task Manager. Looking at the "Working Set", "Private Working Set", "Shared Working Set", and "Commit Size" columns on the "Details" tab of Task Manager. Looking at similar memory-related columns in Process Explorer. I've tried running Sysinternals RAMMap, but while I'm having the low-memory crisis, it crashes at launch. Once I resolve the problem, RAMMap runs normally, but at that point it's too late.   All show a pretty small amount of memory being used.  There are lots of people asking variants of this question, with various versions of windows, all over the Internet. Some of them manage to solve their low-memory problems, often by re-installing software; sometimes by re-installing windows from scratch. I'm looking for an answer to the general questions that these all share, and that never seem to get answered elsewhere:   Why is total used memory much higher than the memory used by all listed processes, no matter how I try to count them? How could windows "know" that memory is used without knowing what program is using it? What processes might possibly use up memory but not show up on the list? Is there any software out there that can give more information about used memory?   Details specific to my own problem: Since upgrading to Windows 8.1, The problem occurs as soon as I log in. I run out of memory as soon as I ran any program. I noticed in Process Explorer that several instances of iexplore.exe were running, apparently started automatically. One particular instance was only using a few MB of RAM, but showed hundreds of millions of page faults. On a whim, I killed that specific process, and memory usage immediately dropped by 70%.  Leading to one specific question:   How could killing one process that supposedly only used a few MB free up several GB?   And a (presumably hard) bonus question:   Short of re-installing Windows, how might I avoid having to go through this every time I reboot my computer?


It's known that:  $$\lim \limits_{x \to \infty} \space f({x})=0$$  $$|f''(x)| < M$$  How do I prove that:  $$\lim \limits_{x \to \infty} \space f'({x})=0$$  I tried using the mean value theorem, but I don't really know how to approach the question.

I'm looking for a good proof for the following problem. I think it's pretty intuitive why this is true, but I'm having trouble expressing it rigorously.     Suppose that $f$ is twice differentiable and that $f''$ is bounded on   $(0, \infty)$. Furthermore, suppose that $\lim_{x\to \infty} f(x)=0$.   Prove that $\lim_{x\to\infty} f'(x)=0$.   I've already tried writing out the Taylor expansion for $f$ and tweaking that, but I haven't had much success. Any insight would be greatly appreciated.


I came across this problem in which we had to evaluate $$\sum\limits_{k=3}^{k=7} {(k+1)\choose (7-k)}$$ All I could think of was to put in the values of k and get $${4\choose4}+{5\choose3}+{6\choose2}+{7\choose1}+{8\choose0} = 34$$ Is there a more efficient way (possibly using binomial concept) to solve this sum?

Accidentally, I had seen this relation. I tried to find the formula  Here is my try:-  $$f_0= {{0}\choose{0}}  $$  $$f_1={{1}\choose{0}} $$  $$f_2={{2}\choose{0}}+ {{1}\choose{1}} $$  $$f_3= {{3}\choose{0}}+ {{2}\choose{1}} $$  $$f_4= {{4}\choose{0}}+ {{3}\choose{1}}+{{2}\choose{2}} $$ $$...$$  Generalizing,  $$f_n=\sum_{s+r=n,s\ge r}{{s}\choose{r}}, 0\le s,r \le n $$  How to write the correct formula of n-th term. Why this pattern is coming. I could verify using calculation for upto n=10. How to give a rigorous proof?.


i wanted to make a survey in SharePoint 2013, but, didnt want users to see results so i cut the following          SharePoint:FeatureMenuTemplaterunat="server" FeatureScope="Site"               Location="Microsoft.SharePoint.StandardMenu"               GroupId="ActionsMenuForSurvey"               UseShortId="true"   .   .   .   .   runat="server"   from C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\TEMPLATE\CONTROLTEMPLATES\DefaultTemplates and was ok. After  server restart I noticed that even if i have admin rights i cant upload document, create new folder, use library setting etc. So i copy it back and saved it but things are the same. I have admin rights

I was trying to exclude the "Export to Spreadsheet" from survey for users and after I got into this.      When i pressed one of the issues in Central Admin, I got this:    I wanted to make a survey in SharePoint 2013 but I didn't want users to see the results so I removed the following code:  <SharePoint:FeatureMenuTemplaterunat="server" FeatureScope="Site"             Location="Microsoft.SharePoint.StandardMenu"             GroupId="ActionsMenuForSurvey"             UseShortId="true"             ...             runat="server">   from the file C:\Program Files\Common Files\microsoft shared\Web Server Extensions\15\TEMPLATE\CONTROLTEMPLATES\DefaultTemplates and was ok. After  server restart I noticed that even if I have admin rights I can't upload documents, create new folders, use library setting etc. So I restorede it back and saved it but things are the same. I still have admin rights.


I have a CSV file in Traditional Chinese and it is coded as ANSI. The file can be read correctly on Traditional Chinese Windows versions. But when I open it on Windows 10 English version, it looks like this:  Is there a way  to convert ANSI text to Unicode correctly in C# without installing language pack onto the English Windows version?

I've got a FileUpload control in an ASP.NET web page which is used to upload a file, the contents of which (in a stream) are processed in the C# code behind and output on the page later, using HtmlEncode.   But, some of this output is becoming mangled, specifically the symbol '£' is output as the Unicode FFFD REPLACEMENT CHARACTER. I've tracked this down to the input file, which is Windows 1252 ('ANSI') encoded.   The question is,   How do I determine whether the file is encoded as 1252 or UTF8? It could be either, and How do I convert it to UTF8 if it is in Windows 1252, preserving the symbol £ etc?   I've looked online but cannot find a satisfactory answer.


Why doesn't the electron collapse onto the proton in a hydrogen atom?   One explanation seems to be given by the Heisenberg uncertainty principle, which follows from the purely physical assertion that the wave function in the position representation is the Fourier transform of the wave function in the momentum (or more precisely the wave number) representation.   A different explanation is obtained by solving (or inspecting) the Schrӧdinger equation.  To what extent are these explanations independent? To what extent is the latter more fundamental? Is the latter explanation more correct, or more complete?  The hydrogen atom is just an example, a more general form of the question would be to what extent it is correct to use the Heisenberg uncertainty principle to answer this kind of questions, as is often done in popular science texts?  Elaborating a bit on what I mean to ask, the fact that the Fourier transform of the  position wave function is the momentum wave function seems to allow us to draw conclusions about the behaviour of a system from this principle alone.  However, when loosely drawing these conclusions, we tend to invoke our classical idea of momentum, whereas the dynamics of the system are really governed by the Schrӧdinger equation.

I have came across two separate explanations for why atoms have a positive atomic radius (as opposed to electrons "collapsing" into the nucleus).    The first is via Heisenberg Uncertainty Principle, where decreasing the atomic radius would raise momentum and hence kinetic energy (while potential energy decreases) - the atom would "choose" a radius that minimizes energy.  The second is kind of "just set-up and solve the Schrodinger equation" and obtain a certain atomic radius.   Are these two explanations just two sides of a single coin/a matter of interpretation? I have briefly heard that there is an equivalence between "Heisenberg" and "Schrodinger" formulation of QM - is this an instance of the equivalence?


I have made a few batch files the hard way by CD-ing into the directory by typing all the way from root drive to folder. I have seen a few example codes use percent signs enclosing a few key words and continue from there, eg:  %user_files%\programs\destination folder   They have always worked too.

I recently followed some instructions to reset GitHub for Windows by deleting two folders found within %AppData% and %LocalAppData%, and I've seen these paths before, but never understood them, and searching for them didn't yield the information I wanted to find. What does the percent sign mean in file paths on Windows, as opposed to navigating to C:\Users\etc, and what are the folders %AppData% and %LocalAppData%?


I am facing the following scenario:  I need a square shape in which there will be three people with points of (x,y) with 0 ≤ x ≤ 100 and 0 ≤ y ≤ 100. I need to use a method that assigns a random point of (x,y) between 0-100 to these three people  My question is how can I assign a random point?   This is something I come up with to help me understand Java properly.

How do I generate a random int value in a specific range? I have tried the following, but those do not work: Attempt 1: randomNum = minimum + (int)(Math.random() * maximum);  Bug: randomNum can be bigger than maximum. Attempt 2: Random rn = new Random(); int n = maximum - minimum + 1; int i = rn.nextInt() % n; randomNum =  minimum + i;  Bug: randomNum can be smaller than minimum.


I wrongly entered   chmod -700 /.    My entire system collapsed. All applications shutdown automatically. Then I restarted my computer. I could no longer login. What happened, and how can I fix it?

I accidentally executed the following command on the etc directory:  sudo chmod -R 700 /etc   I know that I have done something very wrong. My terminal now prints:  I have no name!@ubuntu: /$   How can I revert my etc directory to its earlier state?  I tried changing the permissions but it is failing now. Also, it would be very helpful if someone can explain what actually went wrong when I executed that command on etc. It was only file permissions. Then why does the whole system seems completely blown up? Why is it that no login passwords are working now? I know that there is a file in etc directory that has to do with users. But how did changing permissions jeopardize everything? Some technical details about this would be very helpful.


Trying to rename a postgres database:  $ psql -d some_other_database some_other_database=# ALTER DATABASE myapp_development RENAME TO myapp_development_old some_other_database-# \l                 Name                |  Owner  | Encoding |   Collate   |    Ctype    |  Access privileges ------------------------------------+---------+----------+-------------+-------------+---------------------  myapp_development                  | rails   | UTF8     | en_US.UTF-8 | en_US.UTF-8 |   No feedback whatsoever after ALTER DATABASE...!  I am logged in as a Superuser and not aware of any current connections (but not sure how to be certain of that). What am I missing?  Edit: I erroneously transcribed my prompt in my original question so 2nd line had =# when, indeed (thanks Daniel), it should have had -#. Fixed above, now.

What is the difference between postgres=# and postgres-#? I tried googling it and looking on the official site but could not get a hit for the symbols.


I noticed that Adobe-related, .NET-related and Android-related products tag names have a nice and neat logo attached. I like it because it makes visual filtering easier (even though the "interesting tags" and "ignored tags" are great features, they can't cover it all - most people are, like myself, lazy, and don't want to put every single tag they could in those lists).   To my knowledge, C or C++, for instance, do not have a logo (though one could wonder why), so it's normal that the tag would not have one attached to it. But Java does have a logo, doesn't it? The little coffee cup? My question: why isn't that logo in the "Java" and other Java-related tags?  (All right, this question is not really a big big problem, but it's been bugging me and I just want to know why things are the way they are :)).

What does an icon on the tag mean, for example the "rg" before the sql-server tag as pictured below?


Find $\lim_{x\to 1}(\frac{p}{1-x^p}-\frac{q}{1-x^q})$    My attempt: I took LCM and applied lhospital but not getting the answer.Please help


I'm trying to prove the following inequality for $a$, $b$ $\in \mathbb{R}_{>0}$, $n$ $\in \mathbb{Z}_+$  $(a + b)^{\frac{1}{n}} \leq a^{\frac{1}{n}} + b^{\frac{1}{n}}$  At first glance I thought this would be provable by induction but had little luck so far. The next approach I've tried is to prove that the inverse holds instead as following  $(a + b)^{n} \geq a^{n} + b^{n}$  which is easily done using the the binomial theorem when $n$  is an integer but it feels like it needs to be done for all real $n$ for the argument to hold to prove the previous inequality.

A question on my math homework asks us to show that if $0 < p < 1$ and $a, b > 0$, then $a^p + b^p > (a + b)^p$. I have no idea how to do this, any pointers?


I feel that my question is probably too wide, I'm willing to focus my question more if needed and possible. Please comment.  I have a hard-drive (2.5" Toshiba) which was installed in a notebook. The notebook fell from a table (on the side) while running. Since then the disk makes the click-of-death-sound and is no longer recognized either by the system or when attached to a SATA-USB-adapter on another PC.  In the past, for another hard-disk with the same symptoms, I did/tried a transfer of the hard-drive-heads from a working disk to the non-working one. I was unable to make the broken disk work again - the click-of-death remained. The data was lost.   At that time I only transplanted the hard-drive heads. I was as careful as possible. I saw that the heads of the broken drive were visibly damaged. The donor-drive was the same model, but not the same creation date.   When done, I let the disk run while being semi-open. I saw what created the click-of-death: it's the heads running over the whole disk and then returning abruptly onto their parking position - this is when it is clicking. The controller instructed the drive to do it again and again. It was surely looking for some "known-data".  Now, for my current broken disk, I have a working model of the same revision and date ready to be a donor. But I'm unsure - this time I really would love to get back the data.  What causes the controller to scan the disks again and again? What is it looking for?  Why does replacing a physically damaged head not help?  Is there some kind of calibration stored on the PCB which is adapted for the heads?  Transferring the heads was relatively easy. Was it too easy? Did I probably break something, even though I was really careful?

Upon bootup I have a drive that will spin up click and few times then spin down.  I have a spare drive (same model number) I attempted to transfer the heads from with no luck, HOWEVER, the heads from the bad drive work fine in the spare drive.  Swapping the PCB has no effect either.  So although it seems to spin up fine, could the problem be with the platter motor?


I recently googled for a topic, found a very similar question of the same topic in Stack Overflow, and posted my question. After a few days nobody had answered it, but I found the answer on my own and posted it, then accepted the answer. Minutes later the question was marked as off topic, and there was a suggestion that this type of question is better suited for Super User community. In the off topic notice there was no indication that the question could be moved to another community, and being a new contributor, I wouldn't have enough points to do so anyway (unless a change in policy is made in SE to allow authors to move their questions when someone closes them for being off topic). but what should appear there is a button (like the DELETE button that does appear there) The DELETE button doesn't work, by the way, as a vague error message says in general that people have contributed to it. Well, it turns out the contributor of the answer was myself and there was no indication in that message that I should first un-accept my answer, delete it, then delete the original post, or wait for people with higher reputation to move it on my behalf as my hands are tied at that point. It is frustrating for newbies and I suppose many would walk away at that point, but if it's going to be fixed it has to be reported. Is this something that should be changed? And how to go about it without spending a whole lot of time on it - I don't work for SE and can't spend too much time dealing with it.

Currently it is often clear to a user that a question really belongs on another site. This is especially true after a comment to that effect is received on the question by another user. Migration by the user however means:   registering on the other site going back to the original site, editing the question, copying the content creating another question on the other site pasting in the content (which is hopefully still in the clipboard) going back to the other site, cancelling the edit and then deleting the question, hoping that no answer has been given.   This is not very obvious, user friendly or efficient. Besides that, in my experience, people don't like to be asked to delete their questions if you hint to them what they should do.  So I would propose that we let users migrate their own unanswered questions instead. Possibly this requires some safeguard, e.g. a trusted user notifying them about the other site. If the user does not exist on the other site the user could be automatically asked to register for the other site as well so that the other site does not have to deal with unregistered users all the time.


Just upgraded boot partition to a 480gb SSD and its so much quicker, but.. Now my primary partition  is divided as followed. [111.16GB System Reserved][224.53GB NTFS][111.333GB Recovery Partition] It pretty much split up all my storage into Recovery and Reserve leaving me with a very small portion of the disk. How can I shrink or remove this?

Is there a free way to clone a full Windows 7 installation from HDD to SSD? (The free part is important, I know I can pay for Acronis True Image.)      SSDs are usually much smaller than HDDs which complicates matters. For instance, I have about 50GB data, my new SSD is 80GB but I still can't use Windows clone/restore system if my HDD is something like 300GB.  Therefore, I'm looking for a third party tool that will be able to:   Create a clone of my C: partition Store it onto an external USB drive Boot from some rescue / restore CD Load the image onto the new SSD   Acronis True Image seems like a tool that should support this but it's a paid-for software and the trial version cannot create clones. Acronis Migrate Easy is a fully functional tria for 15 days but need both the HDD and SSD connected at the same time which is a bit of a problem for me as a laptop user.  P.S. I almost got there combining Windows image backup combined with Acronis True Image restore CD (which can load .vhd's) but was not able to boot as some boot information were probably lost and could not be repaired using the Win7 installation DVD.


I am in war with my textbook. It says that $\int \sin^n{x}\cos^m{x}\ dx=\frac{\sin^{n+1}x\cos^{m-1}x}{n+m}+\frac{m-1}{n+m}\int \sin{x}\cos^{m-2}\ dx$.  Then I wrote the proof. Here is what I got. \begin{equation*} \begin{split} \int \sin^n{x}\cos^m{x}\ dx&=\int \sin^n{x}\cos^{m-1}{x}\cos{x}\ dx\\ &=\int \sin^{n}{x}\cos^{m-1}\ d(\sin{x})\\ &=\cos^{m-1}x\frac{\sin^{n+1}{x}}{n+1}-\int \frac{\sin^{n+1}{x}}{n+1}(m-1)\cos^{m-2}{x}\ dx\\ &=\frac{\sin^{n+1}{x}\cos^{m-1}{x}}{n+1}-\frac{m-1}{n+1}\int\sin^{n+1}{x}\cos^{m-2}{x}\ dx \end{split} \end{equation*}  Maybe you know what I missed?

$$\displaystyle\int \:\sin^n\left(x\right)\cos^m\left(x\right)\mathrm  dx=\frac{\sin^{n+1}x\cos^{m-1}x}{m+n}+\frac{m-1}{m+n}\int \:\sin^nx\cos^{m-2}x\,\mathrm dx$$  I have been trying to solve for over a week now can someone please help me.


I have a drive which is showing signs of bad sectors. Errors are "Current Pending Sector Count" and "Uncorrectable Sector Count". Crystal Disk Info did that buzz sound which I really hate. Next thing, my system froze. So I yanked the USB from its port, which, I know I shouldn't have done. Doing this unfroze everything however, using Truecrypt to try and attempt to mount the drive has become impossible now. It just renders TrueCrypt non responsive. So I'm thinking maybe the only way for me to recover data is to do a quick format of the drive (which I haven't done yet, mind) and try and rescue the data using data recovery software? I probably know the answer to this, so before I commit to it, will it work? I have backups already, but the way the files was re-arranged on this drive is the reason why I want to recover it.

What steps can I take to try to recover lost or inaccessible data from any storage device?  Answers:   This applies to any computer storage device, e.g. internal/external hard drives, USB sticks, flash memory. The most important thing is to STOP using it, any type of I/O can ruin your chances of a recovery.     We have separate questions covering common problems with USB flash drives in greater detail:


I have my laptop AMD E1-1200 with 1.4GHz but 4GB RAM with a AMD Radeon 7310 HD graphics card. I was trying to move to using Linux and someone advised me to install Ubuntu, but what should I do? Should I download Ubuntu 14.04 32-bit or 64-bit for this laptop? And what's the difference?

What is the difference between 32-bit and 64-bit Ubuntu? I've heard the 64-bit platform performs better and can detect more than 4GB of RAM. Also, while some apps haven't ported to 64-bit yet, ia32-libs lets a 64-bit machine run them.  If so, why not promote 64-bit over 32-bit?


I am using the RevTex 4.2 template from Overleaf, found here.   When I try and do a Word Count, I get an error message saying "Could not identify document class"  Here is the (unedited) documentclass declaration.   \documentclass[% reprint, %superscriptaddress, %groupedaddress, %unsortedaddress, %runinaddress, %frontmatterverbose,  %preprint, %preprintnumbers, %nofootinbib, %nobibnotes, %bibnotes,  amsmath,amssymb,  aps, %pra, %prb, %rmp, %prstab, %prstper, %floatfix, ]{revtex4-2}   This error occurs with the basic template files, even before I changed anything. Any ideas?

I'm trying to count words in a cyrillic LaTeX document with .  I run the command perl texcount.pl index.tex and get following output:  D:\wd>perl texcount.pl index.tex  !!! Could not identify document class. !!! File: index.tex Encoding: utf8 Words in text: 0 Words in headers: 5 Words outside text (captions, etc.): 0 Number of headers: 1 Number of floats/tables/figures: 0 Number of math inlines: 0 Number of math displayed: 0  (errors:1)   index.tex starts with following line:  \documentclass[a5paper,pagesize,10pt,bibtotoc,pointlessnumbers, normalheadings,DIV=9,twoside=false]{scrbook}   So documentclass tag is present.  How can I fix this error?


I'm using Ubuntu 18.04 LTS. Every now and then, I like to escape the noise of windows by pressing Ctrl + Alt + F3 where I login using to one of the ready to use terminal windows.  If I cat a file and the contents scroll past the screen height, how can I view what's gone off the top of the screen? Pressing Page Up does nothing. Page Down appears to echo a ~ character.

How can I scroll in bash using only the keyboard? If it's not possible in bash, are there any other shells that support this?


I just noticed this in my inbox:        Same appears in the global inbox of the network profile.  This looks like  , with the difference that it happens only if the word containing the special character is the last when truncating the message.  Can it please be fixed? Since it's hard to know which word will be the last, it's hard to reproduce hence not sure if it affects only chat notifications or other types of notifications as well.

The messages in the inbox get chopped if they too long, and the chop can occur in the middle of an HTML character reference as can be seen in this screenshot:    The character being chopped is [ and it appears inside a code snippet, in case it makes a difference.


I played a multiplayer match with my friend and we built an alliance. I was able to trade my technologies with my friend, but for some reason my friend can't offer me any technologies from his tech tree. I also realized that not all technologies from my military tree were able to be traded.   Are there some restrictions with what can be traded?

I can't figure out what the limitations are for trading technologies to my human ally.  At first I had a large list of techs to give him.  Since we are doing a co-op vs AI we decided to research in different trees and just trade each other new techs.  After several turns of this the game stopped letting me trade him tech even when I had just finished something that I knew he didn't have.  Can anyone shed some light on this?


Are there any packages for project management charting - PERT charts, Gantt charts etc. I have seen flow chart packages, but not the others. Help will be appreciated.

What packages do you use and recommend for creating graphics in your LaTeX documents?     As this is a community wiki post, please add your package to the accepted answer (or add a comment, and someone with >100 rep will add it to the CW answer), and include a brief description of what differentiates it from others and how it can be used (GUI drawing tool which generates code, type in raw text, or generates image for inclusion in document).   We'll eventually sort these answers under headings.


I know that the random classifier score in ROC AUC (Area under the curve) is always 0.5. My question is: how to calculate the Area under the precision-recall curve for the random classifier?

I'm trying to understand precision recall curve, I understand what precision and recall are but the thing I don't understand is the "baseline" value. I was reading this link    and I don't understand the baseline part as shown in "A Precision-Recall curve of a perfect classifier" what does it do? and how do we calculate it? Is it just a random baseline we select? For example I have twitter data with attributes like retweet,status_count etc and my class label is Favorited 1 if Favorited and 0 if not Favorited and i apply  naive bayes on it and now I want to draw precision-recall curve, how should I set my baseline in this case?


Recall that a matrix $A$ is skew-symmetric if and only if $A^T = -A$. Prove that if $A$ is skew-symmetric, then $X^TAX = 0$ for all $X = [x_1 x_2 \cdots x_n]^T$

Let $A$ be an $n\times n$ skew symmetric matrix. Show that $x^TAx =0 \ \forall x \in \mathbb R^n$.  How to prove this?


I have a floorplan diagram which consists of over 100 different paths and compound paths.  I need to combine all of these elements into a single shape layer.  I have tried selecting all of them and using both the "Unite" and "Merge" options in the Pathfinder window.  This didn't work.  I have also tried "Make Compound Shape."  Not only does this not create a single shape layer, it also messes up the drawing by creating blocks of color where there were none before.  I have even tried a hack workaround by copying all of these paths and compound paths in Illustrator, pasting them into Photoshop, and creating a single shape layer out that, which I could then copy back into Illustrator.  The trouble is, as soon as I click "combine," Photoshop freezes and crashes.  I guess the shape just has too many points for it to handle.  It's too large a file.  What can I do to create a single shape layer?

I am very new to Illustrator, in fact I am only experimenting with it in an attempt to help my friend develop a logo for a new business venture. I managed to draw out the shell of the logo using the line tool and modifying the lines with the anchor tool to get the shape I wanted.  However, I would like to somehow take all of these paths and create one object, or symbol which I can then apply a drop shadow, fill and various other effects too. Currently when I try to do this I get unwanted effects...  I'd appreciate any help on the subject.


We have a need to fit a database in 4GB in order to use SQL Server Express Edition. I started from a 7GB database, and found a lot of unneeded records, and deleted them. After shrinking, the database size is 4.6GB, and 748 MB is free (according to database properties).  However, when I execute exec sp_spaceused, I have interesting results:  DatabaseName    Database_size   unallocation space xxxxxx          4726.50 MB      765.42 MB   Reserved        Data          index_size      unused 3899472 KB      1608776 KB    1448400 KB      842296 KB   Any ideas, how can I release at least some of this unused space? Also I know table, which occupied it.  Update: is it worth to trying to rebuild table indexes?  ALTER INDEX ALL ON Production.Product REBUILD

This question is asked in various forms here but the question boils down to:  I know shrinking a database is risky. In this case, I've removed so much data and I'll never use it again.   How can I shrink my database? What files do I shrink?  What should my considerations be while doing this?  Should I do anything after? What if it is a large database? Can I shrink it in smaller increments?


Very new to blender, first time question.  I could not find a similar problem searching existing answers.  I have a rendering, and no matter how many lights or suns I add, this model stays dark.  That's a light colored wood texture that appears dark.  This is an imported STL file.  It seems like no matter how many lights I add, it stays the same amount of dark.  You can see my settings in the next photo.  I have a sun, a point light, and spot light all by the model, but no difference weather I turn them on or off.    Thank you for any help.

When I apply a glossy shader to the material of my text, the text becomes just black. Why?    I have lamp and everything, but the problem persists. The text is red before I add the glossy shader.  I'm using Cycles render.   Thanks!


I am really confused about this. I want to understand what is the difference between caching of data and loading data from database tables on server or application startup? Please guide me.

I'm constantly hearing about person y had performance issue x which they solved through caching. Or, how doing x,y,z in your programs code can hurt your caching ability. Even in one of the latest podcasts, Jeff Atwood talks about how they cache certain values for speedy retrieval. There seems to be some ambiguity in the terms "cache" and "caching" and it has led me to be confused about it's meaning in different cases.  Whether you are referring to application or database caching, cpu, etc and what that means. What is caching and what are the different types?  From context I can get a sense of it, to store an oft retrieved value into main memory and have quicklook up access to it.  However, what is it really? This word seems to be used in a lot of different contexts with slightly different meaning (cpu, database, application, etc) and I'm really looking to clear it up.  Is there a distinction between how caching works in your applications vs your database caching?  When someone says that they found a piece of code that would hurt caching and after they fixed it, it improved the speed of their app, what are they talking about? Is the program's caching something that is done automatically?  How do you allow values to be cached in your programs?  I've often read users on this site say that they cached a value in their application, I sit here and wonder what they mean. Also, what does it really mean when someone talks about database caching?  Is this simply a feature they turn on in their database?  Do you have to explicitly cache values or does the database  pick which ones to cache for you?  How do I begin caching items myself to improve performance?  Can you give me some examples of how I can begin caching values in my applications?  Or again, is this something that is already done, under the hood and I simply have to write my code in a particular way to allow "caching"? What about database caching, how do I begin that?  I've heard about things like memcache.  Is this type of utility required to cache in databases?  I'm looking to get a good distinction between caching in applications vs databases, how they are used and how it is implemented in both cases.


Is there a word for a person who acts a certain way to become friends with others of a higher or more important social status? Someone who will act falsely to impress others for their own gain (i.e to then show off about it to "lesser" people, in a "look who i'm friends with" style)?

Is there a single noun or adjective for a person who is always flattering friends and acquaintances, not only to be liked and accepted but, at other times, to curry favor with them as well ?  I'm not looking for regionalisms but a word that will be understood in any English speaking country.


In the code segment below, I want to create the array object inside the GenericStack class constructor. I understand why this is a problem. As per my understanding, "T" can be any class as far as the compiler is concerned. This class T can be an abstract class and hence cannot be instantiated. For example, java.lang.Number class is an abstract class and I could very well pass java.lang.Number for T. My question now is the following: Is there a way to tell the compiler (by some bounded parameters or perhaps something else) that the class that I am going to pass in place of T will be a concrete class that can be instantiated ? I know that I could easily create the array inside the main and then pass a reference but I find that to be a bit cluttered approach to implementing such requirement. public class GenericStack<T> {          //Data for the stack is an array but can be changed to list.     public static final int stackSize = 10;     private T[] stackData;     private int tos;      public GenericStack(int size) {         stackData = new T[size];  // This line will error out         tos = -1;     }      public T pop() {         try {             return stackData[tos--];         } catch (Exception e) {             System.out.println("Stack empty.Cannot POP from an empty stack.");             return null;         }     }      public void push(T stackObj) {         try {             stackData[++tos] = stackObj;         } catch (ArrayIndexOutOfBoundsException e) {             System.out.println("Stack is full. Cannot push a element into a full stack.");         }     }      public static void main(String[] args) {         GenericStack<Integer> intStack = new GenericStack<Integer>(GenericStack.stackSize);         GenericStack<String> stringStack = new GenericStack<String>(GenericStack.stackSize);     } }

Due to the implementation of Java generics, you can't have code like this:   public class GenSet<E> {     private E a[];      public GenSet() {         a = new E[INITIAL_ARRAY_LENGTH]; // error: generic array creation     } }   How can I implement this while maintaining type safety?  I saw a solution on the Java forums that goes like this:  import java.lang.reflect.Array;  class Stack<T> {     public Stack(Class<T> clazz, int capacity) {         array = (T[])Array.newInstance(clazz, capacity);     }      private final T[] array; }   But I really don't get what's going on.


I ain't worried 'bout nothin'  I want to know the meaning of this line. I found it in a song named fifth harmony.

In the 2016 film Ghostbusters Dan Aykroyd states:      I ain't afraid of no ghost!   To which a lady who looks like Jennifer Anniston replies:     That's a double negative! That means you ARE afraid of ghosts!   Is this interpretation technically correct? I would've thought that a literal interpretation would've implied that he does not fear the absence of ghosts (or the absence of a ghost, or the ghost), rather than that he fears ghosts.   Which is correct?


I am reading a paper which has a mathematical argument: $X \subset V \setminus \{0\}$.  Can anyone explain this statement to me? Especially the "$\setminus \{0\}$".  Many thanks in advance!

In a Linear Algebra textbook I am reading, the following is stated: $b\notin \operatorname{span}(A \cup \{a\})\setminus \operatorname{span}(A)$. It does so without explaining what "$\setminus$" means. I apologize if this question does not belong here but I just want to understand what it means. I can close the question if someone just comments on its meaning.


Good afternoon,  I have been working on creating some pieces of terrain in Blender 2.78 and have not had any issues with Texture Painting until today.  When I went to start painting, instead of the texture I want solidly covering the ground, it does nothing but draw my brush circle and then when I drag, it gives a dashed line from where I started to where the circle is.  If I drag far enough, it does paint, but it is always transparent and I can see the grid squares.   I am guessing it is some kind of setting that I accidentally hit a shortcut for, but it is driving me crazy and halted my progress last night.  Thank you for any assistance I can get.  EDIT:  Solved the question about the lag behind in the painting, but now I don't know why with even full weight I cannot cover the grid image...  And here are my brush settings.

I'm playing around with learning how to paint textures in blender, and must have somehow enabled a strange drawing mode that causes the drawing head of my brush to lag behind the place where I'm actually drawing the stroke.  I was able to paint normally earlier.  Now when I draw a stroke, there's this line from the center of my cursor to a point where my brush was earlier, and the stroke is drawn there.  It makes painting much harder and I can't figure out how to turn it off.


I would like to be able to open Chromium in incognito mode automatically. I'm new to Linux and I love it so far but I haven't yet found a way to do this. I'm using Ubuntu 14.04.

In previous Ubuntus (GNOME, not unity) I could add "--incognito" to the end of the executable file command of Chrome to make Incognito default.  I cannot find an executable file for Chrome in 12.04. How do I make Incognito default for Chrome in 12.04?


I am confused about the difference between the nominal and the actual .  Say we are trying to estimate the fraction of the current population of the US that has been diagnosed with cancer.  We get a sample (e.g. 10,000 individuals) and then estimate this fraction ($f$) and a confidence interval around it $[a,b]$ with $\alpha$ (confidence level) $=0.95$.  At this point, if I understood things correctly, the nominal coverage probability is $\alpha$, i.e. $0.95$.  But what about the actual coverage probability? To me, there is only one true value of $f$, e.g. say $5\%$, and it doesn't make sense to talk about the actual probability that $f$ is  within the interval $[a,b]$. It either is or it isn't within $[a,b]$.   What's wrong with this reasoning? And how would one obtain the actual coverage probability in practice?

I was reading an entry level statistics textbook. In the chapter on maximum likelihood estimation of the success proportion in data with binomial distribution, it gave a formula for calculating a confidence interval and then nonchalantly mentioned     Consider its actual coverage probability, that is, the probability that the method produces an interval that captures the true parameter value. This may be quite a bit less than the nominal value.    And goes on with a suggestion to construct an alternative "confidence interval", which presumably contains the actual coverage probability.   I was confronted with the idea of nominal and actual coverage probability for the first time. Making my way through old questions here, I think I got an understanding for it: there are two different concepts we call probability, the first being how probable it is that a not-yet-happened event will produce a given result, and the second is how probable is that an observing agent's guess for the result of an already-happened-event is true. It also seemed that confidence intervals only measure the first type of probability, and that something called "credible intervals" measure the second type of probability. I summarily assumed that confidence intervals are the ones which calculate "nominal coverage probability" and credible intervals are the ones which cover "actual coverage probability".   But maybe I have misinterpreted the book (it is not entirely clear on whether the different calculation methods it offers are for a confidence interval and a credible interval, or for two different types of confidence interval), or the other sources I used to come to my current understanding. Especially a comment which I got on another question,      Confidence intervals for frequentist, credible for Bayesian    made me doubt my conclusions, as the book did not describe a Bayesian method in that chapter.   So please clarify if my understanding is correct, or if I have made a logical error on the way.


How can I convert all color images to Grey scale? I am using MikTeX 2.9, LaTeX->dvips->ps2PDF for conversion.  Also, please advise if possible to change all RGB color image to CMYK format...

Is there a way to convert a colored image to grayscale both for printing as well as screen viewing through pdfLaTeX?


I want to use the same font as this paper (title, section, subsection)  I have asked the author, he said they only used \documentclass[letterpaper]{article}. Does anyone know how to obtain this font? Thanks.

Is it possible to identify the font used in a specific document/picture?  Answers to this question should identify:   Possible methods to do this (perhaps one answer per method) and adequately describe how to use it (as opposed to merely stating it); Ways of finding the identified fonts, if possible (free or not); and Any prerequisites associated with the method used, if required (for example, "In order to use method X, your document has to be in format Y").   This question is meant as an FAQ, based on an . Its aim is to facilitate the community with the general procedures involved in font identification. Similar cases are solved on a per-usage basis on 's  tag.


I have got a free domain at , which I use to host my website, and to receive email.  About a month ago, I used an A record to point [Blank] and www to the A record of my webhosting. I also had a MX record to my email provider, .  Now that I changed webhosting, I only have a CNAME to point my domain to. Since I changed it, I don't receive mail anymore, altough I can still send mail. When I remove my CNAME, my mail starts working again. Is there any way to use both my email, and the CNAME record?  For the people who think this is a duplicate of : My problem is that the MX and the CNAME records interfere, not about CNAME not working, or whether I should or shouldn't use a CNAME for my site root

This is a  about CNAMEs at the apices (or roots) of zones   It's relatively common knowledge that CNAME records at the apex of a domain are a taboo practice.  Example: example.com. IN CNAME ithurts.example.net.  In a best case scenario nameserver software might refuse to load the configuration, and in the worst case it might accept this configuration and invalidate the configuration for example.com.  Recently I had a webhosting company pass instructions to a business unit that we needed to CNAME the apex of our domain to a new record. Knowing that this would be a suicide config when fed to BIND, I advised them that we would not be able to comply and that this was bunk advice in general. The webhosting company took the stance that it is not outright forbidden by standard defining RFCs and that their software supports it. If we could not CNAME the apex, their advice was to have no apex record at all and they would not provide a redirecting webserver. ...What?  Most of us know that  insists that A CNAME record is not allowed to coexist with any other data., but let's be honest with ourselves here, that RFC is only Informational. The closest I know to verbiage that forbids the practice is from :     If a CNAME RR is present at a node, no other data should be   present; this ensures that the data for a canonical name and its aliases   cannot be different.   Unfortunately I've been in the industry long enough to know that "should not" is not the same as "must not", and that's enough rope for most software designers to hang themselves with. Knowing that anything short of a concise link to a slam dunk would be a waste of my time, I ended up letting the company get away with a scolding for recommending configurations that could break commonly used software without proper disclosure.  This brings us to the Q&A. For once I'd like us to get really technical about the insanity of apex CNAMEs, and not skirt around the issue like we usually do when someone posts on the subject.  is off limits, as are any other Informational RFC applicable here that I didn't think of. Let's shut this baby down.


Set $A \subset R^2$, set B is projection of A on x-axis. Do you know a counterexample to the statement: if A is closed, then B is closed.

Consider $\mathbb{R}^2$ as $\mathbb{R} \times \mathbb{R}$ with the product topology.  I am simply trying to show that the two projections $p_1$ and $p_2$ onto the first and second factor space respectively are not closed mappings.  It seems like this should be easy, but I have not been able to come up with a closed set in $\mathbb{R}^2$ whose projection onto one of the axes is not closed.  I don't really have any work to show...I've really just tried the obvious things like closed rectangles and unions of such, the complement of an open rectangle or union of open rectangles, horizontal and vertical lines, unions of singletons, etc., and haven't come up with anything non-obvious, which I hope is where the answer lies.  It's bothering me that I can't come up with an answer, and I'd appreciate some help.  Thanks.


If I download any Ubuntu add ons  such as ubuntu-restricted-extras package  where will they be stored? I am just using ubuntu to go online and view some windows Excel programs that I download ,alter and upload again to the cloud Ubuntu  works great for all of this I shut down the computer, no hard drive to infect I am often prompted to install addins for enclosed videos I am worried that they will be installed on and damage the Ubuntu Boot USB flash drive Do I need to Partition the Flash Drive? Add another flash drive? How will it know to install them there? Or is the computer's Ram enough to store them If so How? Thank You

Possible Duplicate:          I am a new user of Ubuntu. I would like to install a persistent Ubuntu 11.04 to my USB stick, and it should be able to work as a guest OS running on Windows so that I can boot it on other computers other than the one which I used for the installation. I have used several creators such as unetbootin, however from my understanding it can only create Live Linux which I am unable to save my configurations and files. If it's possible I would like to bypass the BIOS, that is to say that I can just load from the virtual machine without having to restart the computer. Thanks in advance!    Thanks for all the replies! Hi Mike, I am able to create a virtual machine and run it from my USB drive using a portable virtualbox. How do I go about from there, do I have to proceed with the installation? Could you elaborate more on the steps for the installation? Thanks again!


Need to create 26 JButtons(A-Zbuttons) when i click one of the button the only 1 JLabel will display the letter) for example if i click QButton the Label will display "Q".  Need to use GridLayout and 5 JPanel(first 4 panels hold 6 letters and the 5th panel hold 2 button and 1 JLabel).  package JFileCaninet; import javax.swing.*; import java.awt.event.*; import java.awt.*; public class AlphabetFiles extends JFrame implements ActionListener     {      private JPanel panel1;     private JPanel panel2;     private JPanel panel3;     private JPanel panel4;     private JPanel panel5;     private JLabel displayLabel;     private JButton[] alphabetButton = new JButton[26];     //char[] abc = new char[26];         public AlphabetFiles()     {          super("file sort");          setSize(400,300);          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);          buildedPanel();          add(panel1);         add(panel2);         add(panel3);         add(panel4);         add(panel5);          panel1.setLayout(new GridLayout(1,6));         panel2.setLayout(new GridLayout(1,6));         panel3.setLayout(new GridLayout(1,6));         panel4.setLayout(new GridLayout(1,6));         panel5.setLayout(new GridLayout(1,6));          setVisible(true);         }         private void buildedPanel()        {         int num=0;         for(char i='a'; i<='z'; i++)         {              alphabetButton[num++] = new JButton(""+i);              alphabetButton[num++].addActionListener(this);          }          for(int i=0 ; i<6 ;i++)//a to f         {             panel1.add(alphabetButton[i]);         }         for(int i=6 ; i<12 ;i++)//g to l         {             panel2.add(alphabetButton[i]);         }         for(int i=12 ; i<18 ;i++)//m to r         {             panel3.add(alphabetButton[i]);         }         for(int i=18 ; i<24 ;i++)//r to x         {             panel4.add(alphabetButton[i]);         }         for(int i=24 ; i<27 ;i++)//r to x         {             panel5.add(alphabetButton[i]);         }           panel5.add(displayLabel);         }         public void actionPerformed(ActionEvent e)        {         JButton holder8 =(JButton) e.getSource();         displayLabel.setText(holder8.getActionCommand());        }         }      package JFileCaninet;  public class Main {      public static void main(String[] args) {         //AlphabetFiles al =         new AlphabetFiles();         /*try         {             new AlphabetFiles();         }         catch(NullPointerException nullPointer)         {             System.out.println("NullPointer occur");         }*/      }  }

What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them?  What methods/tools can be used to determine the cause so that you stop the exception from causing the program to terminate prematurely?


In an interview it was asked from me to show the implementation of hashcode and equals method in an efficient manner so i have constructed the below pojo but the interviewer said that this is not the correct and the best implementation as it can result in an collision , can you please advise is the below implementation of hashcode is correct or not   public class Emp  {      String name, job;     int salary;      public Emp(String n, String j, int s) {         this.name = n;         this.job = j;         this.salary = s;      }      public int hashcode() {         return name.hashCode() + job.hashCode() + salary;     }      public boolean equals(Object o) {          Emp e1 = (Emp) o;         return this.name.equals(e1.name) && this.job.equals(e1.job) && this.salary == e1.salary;     }     }

How do we decide on the best implementation of hashCode() method for a collection (assuming that equals method has been overridden correctly) ?


I have this portion of the code. I want to know how can I read the url as the current page instead a fix url  Here is the portion of the coding:  var str='';       if(model_id != 0 ) str = model_id+"+";       if(year_id != 0 ) str +=year_id+"+";        url='http://store.ijdmtoy.com/SearchResults.asp?Search='+str; top.location.href=url;   You see currently it has a fix reading the url    For example, I am currently on   How can I change the code so it will automatically read as

I am using jQuery. How do I get the path of the current URL and assign it to a variable?  Example URL:  http://localhost/menuname.de?foo=bar&amp;number=0


We say that we live on earth but we say the earth moves round the sun. When earth is a planet and we use the definite article the before the names of planets, why can't we say we live on the earth and say on  earth.  Most people say we live on the earth knowingly or unknowingly. So is it wrong to say if we say I live on the earth instead of on earth?

"Welcome. You've come to Earth." ()  There seems to be a definite article or not in front of earth in dictionaries. For which meaning, there isn’t one in the example? For what meaning, is there one in other cases?


I'm curious about this matter and have no true explanation for it. As I pinpointed in the title, when does Should precede the subject? I mean the example below (copied):  Should your work habits not like...  Why did Should come before the subject "your work"? Why wasn't it arranged as "Your work should not habit like..."? By the way, the sentence was on the beginning of the line.

Conditionals in English are usually formed by using if with normal word order; but for the three past (subjunctive) forms were, should, and had, it is also possible to express the conditional through subject–auxiliary inversion alone, with no if in the conditional clause.  Does forming conditionals in this manner differ semantically from if-conditionals? Is some aspect of the conditional statement or the conditionality emphasised more in one version than in the other? Or are there differences in how and when they are used? Or are they simply completely interchangeable?  For example:     If I were you, I would try it again   Were I you, I would try it again      If I had seen it, I would have told you   Had I seen it, I would have told you      If you should drink, don’t get behind the wheel   Should you drink, don’t get behind the wheel


Does anyone know what might be causing this to happen with my renders? It's like part of the material doesn't want to show but I'm using a very basic setup.  It looks even worse with cycles:  My rock looks perfectly fine though on the viewport.  Here are the files for it

It's kind of an interesting result.  Here is how render viewport should look on frame 1:    Here is what happens when I press F12:    It's like I have a second camera (although I don't) somewhere below. What is even weirder is that If I place the camera behind the wall...    it shows everything correctly (example cube is seen):    As you can see, my camera is following an object that is on Bezier curve WHILE being on Bezier curve (right) itself. This animation is working perfectly on rendered viewport but not if I use ctrl+F12. Just the same grey viewpoint.  What could be the issue?


I have a circle with a centre at position $(0, 0)$ and I have a point in the circle at $(-5, 2)$. How can I get the angle of the point towards the centre?  I thought to use the theorem Al Kashi (law of cosines) but we need an another point to form a triangle but I don't have it.  Thanks, your help will be appreciated.

How to calculate angle in a circle. Please see the diagram to get the idea what I want to calculate? I have origin of circle that is $(x_1,x_2)$. I have a point on circumstance of circle that is $(x_2,y_2)$. Also I know the radius of circle that is R.  How to calculate the angle between these two lines -- line starting from origin and ending on circumstance at 0 degree -- line starting from origin and ending on $(x_2,y_2)$.


During my update from 14.10 something failed and my machine only boots into Memtest. I booted from a boot-repair USB drive and performed the automatic repair, but the machine continues to boot into memtest. Grub also only shows memtest to boot.  Here's the report:   I have a suspicion that I need to reinstall the kernel since I tried to clean /boot from older one and I might have overlooked something... However, if I would have to do this, I would have no idea how to proceed from here.  EDIT If this is a Kernel issue, the very thorough linked answers do not help unfortunately, probably because I have encrypted my volume. I failed to chroot /mnt with the error: failed to run command 'bin/bash/': No such file or directory

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


I am trying to understand the level of a test better and was wondering if the level of a hypothesis is essentially equal to the probability that the null hypothesis is true. I have been trying to think of a counter example but haven't been able to confirm nor deny this association. Could anyone be kind enough to shed light on my understanding? Thank you!

I recently came across the paper . The author raised a few common misconceptions regarding hypothesis testing and p-values, about which I have two specific questions:   The p-value is technically $P({\rm observation}|H_{0})$, which, as pointed out by the paper, generally does not tell us anything about $P(H_{0}|{\rm observation})$, unless we happen to know the marginal distributions, which is rarely the case in "everyday" hypothesis testing. When we obtain a small p-value and "reject the null hypothesis," what exactly is the probabilistic statement that we are making, since we cannot say anything about $P(H_{0}|{\rm observation})$? The second question relates to a particular statement from page 6(652) of the paper:      Since the p-value, or range of p-values indicated by stars, is not set a priori, it is not the long-run probability of making a Type I error but is typically treated as such.   Can anyone help to explain what is meant by this statement?


I installed Ubuntu from a USB flash drive using .  I chose the option to keep my Windows 10 OS as well (not pictured in the tutorial).  Now I can't seem to find out how to return to Windows 10. Did I delete my OS?

I installed Windows on my computer, followed by an installation of Ubuntu. However, now I'm unable to boot into my Windows install.  What can I do to fix this?


I was wondering if someone can tell me what the logic behind converting fractional exponents to radicals is?  For example, the exponent 1/2 is a square root, 1/3 is a cube root, and 2/3 is the cube root of x squared and so on.  Can someone explain this in a very easy way for me?  Thanks :P

Why is ${x^{\frac{1}{2}}}$ the same as $\sqrt x $?   I'm currently studying indices/exponents, and this is a law that I was told to accept without much proof or explanation, could someone explain the reasoning behind this.  Thank you.


I´m studying Cech cohomology through Hartshorne´s algebraic geometry and EGA, and I´m stuck in two exercises, I wonder if you can help me. The first one is the exercise III.4.4, we want to prove that $$\varinjlim_{\mathfrak{U}}\check{H}^{1}(\mathfrak{U},\mathcal{F})=H^{1}(X,\mathcal{F})$$ where $\mathfrak{U}$ is a covering of $X$. (I attach a photo of the exercise)   I have just proved $a)$ and $b)$.  I´m also stuck with the last exercise of this section: Let $X$ be a topological spaces, $\mathcal{F}$ a sheaf of abelian groups, and $\mathfrak{U}=(U_{i})$ an open cover. Assume for any finite intersection $V=U_{i_{0}}\cap\cdots\cap U_{i_{p}}$ of open sets of the covering, and for any $k>0$, that $H^{k}(V,\mathcal{F}_{\mid V})=0$. Then prove that for all $p\geq 0$, the natural maps  $$\check{H}^{p}(\mathfrak{U},\mathcal{F})\rightarrow H^{p}(X,\mathcal{F})$$ of the last exercise (III. 4.4) are isomorphisms.  Thank you for your time.

I´m stuck with the section $c)$ of the following Hartshorne´s exercise  I have just proved $a)$ and $b)$. I wonder if you can help me. Thank you for your time


I am trying to prove that the group of rotations in $D_{2n}$ is a normal subgroup.  I know this group has a cardinality $n$, and the ratio of the $D_{2n}$ and $R$ is $2.$  I am trying to construct a homomorphism that sends $<R>$, generator group of rotations to an identity element...   Any clues?

I ran into this question when I was studying for my abstract algebra midterm.     Show that the subgroup $H$ of rotations is normal in the dihedral group $D_n$. Find the quotient group $D_n/H$.   I'm not quite sure where to begin. I know that for a Dihedral group of $n\geq 3$, then $r^n=1$ where $r$ is a rotation, and $s^2=1$ where $s$ is a reflection, and $srs=r^{-1}$. I was not sure how to prove something is a normal subgroup from here. Any advice, thanks!


My post got deleted because it is idle. So can anyone help me please? Here are what I said there: Every time I go to the desktop I see "Windows is not genuine". I was annoyed and researched. I found the slmgr -rearm. I opened cmd in administrator mode and did this: C:\Users\********> slmgr -rearm  I didn't know what I was doing and didn't know it would delete my product key or whatever. Can anyone please help me? I don't own this PC.

Recently, my Acer Aspire 5050 that came with a copy of Vista, went through a series of Automatic Upgrades.  Now, in the bottom of the desktop, I get "This copy of Windows is not genuine".  Apparently, because of this, I cannot open "Properties" on Computer, or open the Control Panel, etc.  This makes gathering information (like the Service Pack) difficult at best.  I've gone through several steps to prove/disprove that this is correct.  I've verified the product key by following the instructions on .  I did the steps with slmgr.vbs -ipk AND slmgr.vbs -ato.  This told me that my product was successfully activated.  To me, this would imply that this is a Genuine product.  I've also called the US Activation number, which gave me a response, which was successful.  Never on the phone was I given any information suggesting that the Activation code generated was invalid (I have been given the suggestion on an improper install of XP).  However, when I downloaded , it tells me that I have an Invalid License.  The product key it lists matches what I show on the bottom of the machine.  The install media was requested directly from Acer, since they didn't provide any disks initially.  Looking at the disk they sent, however, it looks like what they sent me was a Windows Anytime Upgrade disk.  Is this the correct disk?  If not, will I need to reinstall to fix the problem?  If so, does anyone know where I can get an OEM 32bit Vista ISO?