I am trying to use stanford nlp pipeline for doing some basic NER and POS. I have slightly modified the core-nlp code to accomodate both ngram and training using a prop file. I feel the problem is with the way I am passing through the pipeline.  public class TestQG {      public static void main(String[] args) throws Exception {          String originaltext = "Obama is the President of America";         String modifiedtext = originaltext.replaceAll("[+,:;=?@#|<>.^*()%!]", "");          stanfordNLPParser(modifiedtext, useCustomNLPModel, customStopWordList, useCustomTokenREGEX);      }  public static void stanfordNLPParser(String modifiedtext, String customStopWordList) throws Exception {      Properties props = new Properties();        props.setProperty("annotators", "tokenize, ssplit, pos, lemma, ner, parse, sentiment, regexner");       props.setProperty("tokenize.language", "es");       props.setProperty("tokenize.whitespace", "true");       props.setProperty("regexner.mapping", "resources/customRegexNER.txt");        String[] args = new String[] { "-props", "resources/tempaSmNER.prop" };       CRFClassifier.main(args);       props.setProperty("ner.model", "resources/ner-model.ser.gz");             StanfordCoreNLP pipeline = new StanfordCoreNLP(props);       List<CoreLabel> tokens = new ArrayList<CoreLabel>();      /*Collections to store the processed N-gram token (nGram tokenizer does not allow the result to be stored as CoreLabel, as required for the pipeline)*/     Collection<String> collectionOfProcessedTokens = new ArrayList<>();      Annotation document = new Annotation(modifiedtext);     pipeline.annotate(document);        /*List of tokens (before performing the nGram operations)*/       List<CoreLabel> tokensPreNgram = new ArrayList<CoreLabel>();       List<CoreMap> sentences = document.get(CoreAnnotations.SentencesAnnotation.class);        for (CoreMap sentence : sentences) {       for (CoreLabel token : sentence.get(TokensAnnotation.class)) {                           tokensPreNgram.add((CoreLabel) token);         }      Collection<String> tokenPreprocessor = StringUtils.getNgramsFromTokens(tokensPreNgram, 1, 6);          for (String tokenNgramPostProcessor : tokenPreprocessor) {            collectionOfProcessedTokens.add(tokenNgramPostProcessor.replaceAll(" ", "_"));                                        }             CoreLabelTokenFactory string2CoreLabel = new CoreLabelTokenFactory();          for (String temp : collectionOfProcessedTokens) {            tokens.add(string2CoreLabel.makeToken(temp, temp, 0, 10));                              }           for(CoreLabel token :tokens){            System.out.println("For TEST: Current Token is  :" + token);                      // generate Parts Of Speech           String tokenPOS = token.get(PartOfSpeechAnnotation.class);           System.out.println("For TEST: POS is   :" + quesGenPOS);              if (token.get(PartOfSpeechAnnotation.class).matches(".*(WP).*")){ System.out.println(quesGentoken.get(TextAnnotation.class));}           String tokenNER = token.get(NamedEntityTagAnnotation.class);           String tokenSentiment = token.get(SentimentClass.class);           String tokenlemma = token.get(LemmaAnnotation.class);        }     }    }   I am facing an null pointer exception at the place i'm performing an POS. While the token is generated correctly, the POS is throwing 'null'. I believe, there most be a problem in the way i construct the pipeline.   The java.lang.NullPointerException is @    `if (token.get(PartOfSpeechAnnotation.class).matches(".*(WP).*")){ System.out.println(quesGentoken.get(TextAnnotation.class));}    because String tokenPOS = token.get(PartOfSpeechAnnotation.class); is not generating the POS  Any pointers as to why?

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?


There are many blogs in which people including who are in love, write their own opinions, stories ,... about life, love ,... ( good or bad aspects)      We call these kind of writings "notes from (my )heart" in Persian, and it implies:" I have written these words just for the sake of my own heart and from the bottom of my heart, no one is obliged to accept or read them!"    PS: These people /bloggers might write to the God, to an imaginary beloved, to a dead person, ..., and they don't necessarily write love notes, they might complain, or confess, or just simply report their daily life events. Actually,they don't care for the number of visitors of their blogs, they write because this gives them, kind of, tranquility.  What do you call these kind of writings?   Something like this:   Please don't close my question!, I'm not looking just for "Billet Doux" , I want to know a more general phrase!

In some languages there is a name for a amicable note that you hand write to a lover or to someone to show appreciation, it's not as long and less formal than a letter. does english have an equivalent for that?


I've got a new pc yesterday, installed 14.04lts and had some problems with my graphics card driver (now fixed I believe). Now I've tried installing steam through various methods and can't get it to work. Any help would be greatly appreciated! Gtx 950 i7 4790k

I've been trying to install steam all day and I've been encountering all kinds of problems, but I'd like a little bit of help with this specific one:  Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation:  The following packages have unmet dependencies:  steam:i386 : Depends: libgl1-mesa-glx:i386 E: Unable to correct problems, you have held broken packages


I am a Ukrainian citizen living in Canada. I am taking a vacation to Ukraine and I am looking at flight options.  Do I need a Schengen visa if I make two stops in the EU, even if I do not leave the airport? It is extremely hard for me to get a Schengen visa as I would need to travel to Vancouver to get this, which is an hour flight or 12 hour drive!!  My flight options are as follows; Edmonton (Canada) - Frankfurt (Germany) - Warsaw (Poland) - Lviv (Ukraine)  OR  Edmonton (Canada) - Calgary (Canada) - London (UK)  - Warsaw (Poland) - Lviv (Ukraine)  I was told by a friend that she had problems when trying to transit between two Schengen countries, without a Schengen visa, even if she was not walking out of either airport, with Ukraine as her final destination.  UK is not schengen, does this mean that I can transit between Canada-UK-Schengen-Ukraine without problem?

I am travelling form Delhi (DEL) to San Francisco (SFO), I have to make a connection flight in Vienna that would take me to Frankfurt (FRA). My flight to SFO is from FRA, I have one ticket for entire journey and the flights are operated by Lufthansa or its subsidiaries.  Do I need a transit visa? My flight arrives at Vienna international airport and leaves from the same, and for second leg it arrives at Frankfurt international airport.  I asked this question as an addendum to my  but was advised to make a new post.  I hold Indian passport and valid US visa.


I was able to show that $z^n$ is normally convergent on the unit disk centred at the origin, but I am not sure how to show that it is not uniformly convergent on the unit disk centred at the origin.  I've read in a few places that this is true, but I have not seen a proof.  My first idea was to fix an $\epsilon$ such that $\epsilon=1/2$.  Then $|z^n|<1/2$.  However, I haven't been able to get this to work out.

For the following sequence of functions and its limit function, we can see that $f_n(x)$ is clearly pointwise convergent  $$f_n(x) = x^n\text{ }\forall x\in[0,1]\text{ and }\forall n\in\mathbb N^*\\ f(x) = \begin{cases}0&\text{if } x\in[0,1)\\1&\text{if } x=1\end{cases}$$  However, I was wondering why this is not uniformly convergent. The condition for uniform convergence is:  $$|f_n(x) - f(x)| < \epsilon,\ \ \ \forall x \text{ when } n > N$$  Now most sources present an argument along the lines of: assume that $f_n(x)$ is uniformly convergent and that $0 < x < 1$, this means that $x^n<\epsilon$ whenever $n>N$. Specifically, this would mean $x^{N+1}<\epsilon$ for some fixed $N$. But if we now pick $x$ such that $1 > x > ε^{\frac{1}{N+1}}$, then this would lead to a contradiction, therefore $f_n(x)$ is not uniformly convergent.  However, I was wondering why couldn't we take $n$ to infinity. If $0 < x < 1$, then $\lim_{n\rightarrow \infty} |f_n(x) - f(x)| = 0$ (which is less than $\epsilon$). Now since $|f_n(x) - f(x)|$ will always be $0$ if $n > \infty$, then wouldn't this be uniformly convergent?


In the final confrontation between Aang and Ozai. Aang touches Ozai and their bodies become blue and orange color respectively, with blue/orange lasers shooting out of their eyes. Can someone explain this phenomenon ?

In the finale of Avatar: The Last Airbender, Aang      learns to energy-bend, and removes the Fire Emperor's ability to firebend.   What are the limits of this power?  Could Aang give Toph sight?  Could he give non-benders the ability to bend?  Could he give a bender the ability to bend more than one element?


I just installed ubuntu-12.04-desktop-i386.iso to my 1GB flash drive via Startup Disk Creator on Ubuntu 12.04. Then, I tried to boot it on my system.  The problem is that it was asking me for username and password.  I tried "ubuntu" with blank password but it didn't work.  The problem has never happened when I installed the same iso file via  on Windows.  Note: There's no option to make passwords in Startup Disk Creator.

When I boot Ubuntu 10.04.3 from a live CD, it asks me to enter a username and password. I have not booted before, and I haven't created an account.


I am working in a Jupyter notebook environment (which uses MathJax to typset math symbols in a Markup cell) writing mathematical physics equations and often related Python Numpy Sympy code in subsequent cells. It is driving me crazy that I cannot find a symbol for the so-called reduced de Broglie wavelength. It is a '\lambda' but with a short horizontal line (like the $\hbar$ version of Planck's constant $h$) midway on the riser of $\lambda$.

I would like to be able to add the symbol "lambda-bar" (see below) into an equation. How can I do this?


I would like to try to drop a  which is a level 29 ring.  I'm afraid of Diablo III levelling system and it's relative things 'cause I know that a player on level 20 only can drop equipment around 1 level down/up of the current player level, but happens the same for the legendary items? then that means I need to be at level 28 (as minimum) or at level 30 (as maximum) to drop my desired ring?.  And please, I dont would like to ask two questions in the same post but someone could tell me where to drop that ring?.

I am almost finished with normal mode in Diablo 3 and I have yet to encounter a single set or legendary item. In Diablo 2, I started finding items like this right away that were appropriate for my current level.   Is there a certain time when they begin to appear (like in nightmare as opposed to normal)?


Does anyone know how to find the radius of convergence of the series $\sum\ z^{n!}$, where $z$ is a complex number?  I tried to use the definition: $$\frac{1}{R}=\limsup\left|\frac{a_{n+1}}{a_{n}}\right|$$ but I wasn't successful.

How to find the radius of convergence of $\sum z^{n!}$?   I'm used to applying the ratio test to power series of the form $\sum a_{n}z^{n}$, but for a different power of $z$, I am a bit stumped. What about $\sum z^{2n+a}$ for another example? Where $a\in \mathbb{R}$.


Let $P(x)$ be the xth prime, $P(0)=2$  Given a prime $p$, does it always exists a $n$ such $\sum_{x=0}^{n}P(x) = 0$ $(mod$  $p)$ ?  Example :  $p=7$  $2+3+5+7+11=28=4*7$  Best regards


This question here asks about where as a subject in relative clauses:      As can be seen from my specific questions at the end (as opposed to the back-story), the specific question here is more fundamental and more general.    I have a Taiwanese friend who asks me for English help with some regularity. I believe I am almost always able to furnish them with the correct answer, but the latest topic is one of which I'm unable to explain the 'why'.   The sentence in question:      The office will be moved to a place which/where is near my apartment.   I said it should be      The office will be moved to a place which is  near my apartment.   (or: a place that is near my apartment ).  My friend asked '"Why? Doesn't where indicate a place?"  Erm, ... yes, but no... I can't explain the why of it, and now I'm really curious. When should we use where and when which or that? Any input will be much appreciated!

Here's the sentence that was confusing:  He went back to Santa Monica which was his hometown.   Why can't "which" be replaced with "where"?   "Where" can be used as a relative pronoun, but it's doesn't work here, despite Santa Monica being the noun described by the relative/adjective  clause. Why is this?   My theory is that this is because "where" cannot be the subject of the relative clause, that it can only the object, as in the case of:  He went back to Santa Monica where he was born.


How much can your grad school GPA affect your chances of getting into a Phd Program?   Some of my teachers suggested that your motivation to be a researcher is what matters the most, but i am still not ready to buy in on that and would it be an advantage if you have a masters which focuses more on research ?   P.S Sociology major

When applying to a PhD program in the US, how does the admissions process work? If an applicant is weak in a particular area, is it possible to offset that by being strong in a different area?  Note that this question originated from this . Please feel free to edit the question to improve it.


Every time I download a file and try to install, this is what I get in terminal:  seabass@seabass:~$ sudo apt-get install CreepySetup.0.1.94.exe Reading package lists... Done Building dependency tree        Reading state information... Done E: Unable to locate package CreepySetup.0.1.94.exe E: Couldn't find any package by regex 'CreepySetup.0.1.94.exe'   and if I try to click on the .exe file itself, the Archive Manager pulls up and I get this:  Archive:  /home/seabass/Downloads/CreepySetup_0.1.94.exe [/home/seabass/Downloads/CreepySetup_0.1.94.exe]   End-of-central-directory signature not found.  Either this file is not   a zipfile, or it constitutes one disk of a multi-part archive.  In the   latter case the central directory and zipfile comment will be found on   the last disk(s) of this archive. zipinfo:  cannot find zipfile directory in one of /home/seabass/Downloads/CreepySetup_0.1.94.exe or           /home/seabass/Downloads/CreepySetup_0.1.94.exe.zip, and cannot find /home/seabass/Downloads/CreepySetup_0.1.94.exe.ZIP, period.

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


So in noticed every time I edit a text file with gedit, i get a hidden file in this directory with the same name except in the end this file has this symbol ~  So why does the system or gedit creates such files and can I safely delete them.  Interesting thing is that even after i delete the main file this files do not get deleted.

I have observed that in gedit if I edit a file, another file is created in the same directory (the one with the same filename and a tilde '~' suffix). The extra file remains even if I close gedit.  I understand the need for a temp file (eg. in case of a crash), but vim for example deletes the extra file it creates, when I close it.  Is there a way to do the same with gedit? Some configuration perhaps?


Let us assume that someone posted a question about allocating a 2D array in C++, his code doesn't compile because he has errors in it. Now after you read the question, you see that he should use std::vector becuase it's better and more recommended in his case. But he's asking about arrays and not vectors.  Now let's say someone posts an answer that solves his problem (with an explanation), but std::vector is not mentioned in the answer (as OP wasn't asking about vectors).  Should this answer be downvoted because it doesn't suggest a better solution? Or it's fine because it solves OP answer?

Is answering beyond the scope of the question a valid thing? Or should we just stick to the question asked and ignore any potential bugs which might be present (of course OP is unaware of that, as of now).  To make myself more clear, please have a look at this .  There are 3 answers which talk about the issue asked and that's it. If you look at my answer, I've added an additional point about a potential bug which the OP has missed now (may find out later). So is it a good thing to point out such potential bugs or not? Should this practice be encouraged?


I get data from file_get_contents method and convert this data to JSON but when data contain an emoji character, I cannot give this field in JSON file and store it in database. I changed table collation to utf8mb4_general_ci but do not work my code   $update = file_get_contents("php://input"); $update = json_decode($update, JSON_UNESCAPED_UNICODE);   I tried to get JSON in $update and I also tried method below:    $firstname =isset($update["message"]["from"]["first_name"]) ? $update["message"]["from"]["first_name"] : ""; $lastname = isset($update["message"]["from"]["last_name"]) ? $update["message"]["from"]["last_name"] : "";

I'm setting up a new server and want to support UTF-8 fully in my web application. I have tried this in the past on existing servers and always seem to end up having to fall back to ISO-8859-1.  Where exactly do I need to set the encoding/charsets? I'm aware that I need to configure Apache, MySQL, and PHP to do this — is there some standard checklist I can follow, or perhaps troubleshoot where the mismatches occur?  This is for a new Linux server, running MySQL 5, PHP, 5 and Apache 2.


I click on "My link1", i have the alert "I clicked on" -> OK I click on button "Add line",  it adds my link 2 -> OK I click on "My link2" just added, nothing happens. -> KO Any help is welcome. This is my code

my link 1

 <button onclick="addrecepitem();" id="btnrecepajouter">Add line</button>

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


Is there a way to reconnect a linked .blend file that has been moved from its original location?   I have all my files linked together, but I now need them in separate folders, is there a way I can move them without them becoming disconnected, or is there a way I can reconnect them once they are moved?   Thanks!

Is there a way, after a library is linked to move that library to another location? I have a library that is in a different folder than my scene file and for the sake of more easily sending it to a renderfarm I want to move it all into one folder. Is there a way to edit link paths?


How can I specify the resolution of a program to 800*600, and for other programs to full screen or other specific resolutions?

I am looking for a step by step instruction to guide me in the ways of installing, configuring and debugging many of the issues new users have when dealing with Wine in Ubuntu.  What is the recommended way of installing Wine, some of the key issues that it has and how to solve them?  If I have a specific problem with an App in Wine, how do I go about solving it? What are the recommended steps to ensure that I can fix a problem related to an app I wish to use?


I am having major trouble in getting pgfplots to work on my Ubuntu 14 System. I am running the minimum example from  and the result looks like the following.    Does anybody have any idea why this is happening?  according to tex -version I am using TeX 3.1415926 (TeX Live 2013/Debian) and I will also post the part of my logfile that is created by \listfiles below. (btw, I tried various compat=1.x commands, but none of them changed anything)  *File List* article.cls    2007/10/19 v1.4h Standard LaTeX document class   size10.clo    2007/10/19 v1.4h Standard LaTeX file (size option) tikz.sty    2010/10/13 v2.10 (rcs-revision 1.76) pgf.sty    2008/01/15 v2.10 (rcs-revision 1.12) pgfrcs.sty    2010/10/25 v2.10 (rcs-revision 1.24) everyshi.sty    2001/05/15 v3.00 EveryShipout Package (MS) pgfrcs.code.tex pgfcore.sty    2010/04/11 v2.10 (rcs-revision 1.7) graphicx.sty    1999/02/16 v1.0f Enhanced LaTeX Graphics (DPC,SPQR) keyval.sty    1999/03/16 v1.13 key=value parser (DPC) graphics.sty    2009/02/05 v1.0o Standard LaTeX Graphics (DPC,SPQR) trig.sty    1999/03/16 v1.09 sin cos tan (DPC) graphics.cfg    2010/04/23 v1.9 graphics configuration of TeX Live dvips.def    1999/02/16 v3.0i Driver-dependant file (DPC,SPQR) pgfsys.sty    2010/06/30 v2.10 (rcs-revision 1.37) pgfsys.code.tex pgfsyssoftpath.code.tex    2008/07/18  (rcs-revision 1.7) pgfsysprotocol.code.tex    2006/10/16  (rcs-revision 1.4) xcolor.sty    2007/01/21 v2.11 LaTeX color extensions (UK) color.cfg    2007/01/18 v1.5 color configuration of teTeX/TeXLive pgfcore.code.tex pgfcomp-version-0-65.sty    2007/07/03 v2.10 (rcs-revision 1.7) pgfcomp-version-1-18.sty    2007/07/23 v2.10 (rcs-revision 1.1) pgffor.sty    2010/03/23 v2.10 (rcs-revision 1.18) pgfkeys.sty     pgfkeys.code.tex pgffor.code.tex tikz.code.tex pgfplots.sty    2013/10/03 v1.9 Data Visualization (1.9) ***********

I'm trying to plot an image file in a pdfplots axis. This is a minimal example (the files fig2a.eps and fig2a.png both contain the image that should be plotted):   \documentclass{standalone} \usepackage[utf8]{inputenc} \usepackage[english]{babel} \usepackage{tikz,pgfplots} \begin{document} \begin{tikzpicture} \begin{axis} \addplot graphics[xmin=-0.15, xmax=0.15, ymin=0.0, ymax=0.2] {fig2a}; \end{axis} \end{tikzpicture} \end{document}   When compiling with pdflatex, I get exactly what I want. With latex (producing a dvi file), the tick labels are all on top of each other inside the image, so something goes wrong with the positioning.  I suppose version information is useful in this case -- from the output to the screen I have this when running both latex and pdflatex:  This is pdfTeX, Version 3.1415926-2.4-1.40.13 (TeX Live 2012)   What am I doing wrong?


I've just turned on my old Macbook for the first time in a couple years and found that now I have to hold command + Q in order to quit Chrome, whereas I used to be able to just tap it. I prefer the old way. Is there a way to re-enable that?

Has anyone else noticed that Chrome refuses to quit instantly when using CmdQ?  Happens with one or several tabs open...  All the other apps I run can be ended by typing / tapping briefly CmdQ, but Chrome insists that I have to hold for an appreciable period of time.  This is becoming annoying, any ideas?


If $Y|X \sim N(0,1)$, does that mean $Y$ itself is also $N(0,1)$? It looks like it as I can write $$ E[Y] = E[E[Y|X]] = E[0] = 0, $$ and $$ Var[Y] = Var[E[Y|X]] + E[Var[Y|X] = Var[0] + E[1] = 1.  $$ But although I get the correct expectation and variance I don't see how we can say $Y$ is normally distributed? If it is true, does this only hold because we are dealing with the normal distribution?

Suppose we have random variables $X$ and $Y$ such that $Y|X \sim \mathcal{N}(0,1)$. Can we then say that $Y^2|X \sim \chi^2(1)$? If we can, then what about when $Y|X \sim \mathcal{N}(0,\sigma^2/4)$, can we use the results of  to say that $Y^2|X \sim \frac{\sigma^2}{4}\chi^2(1)$? Essentially I want to know if the results of squaring a normal distribution can be applied to the case where a random variable is conditionally normally distributed?


I want to know why I don't get reputation after accepting my own answer.

What does it mean to accept an answer? How do I accept an answer, and what are the rules? Can I accept my own self-answer? What are the reputation benefits? Which answer should I accept? Should I upvote the accepted answer? What should I do if none of the answers are suitable?      For more information, see "" in the .


Thanks to Oliver for the correct wording. I played back the stream more than once but didn't get it right. As for failing to follow the rules about comments, while I understand the need for courtesy & procedures in online forums, the rules of Stack Exchange make me feel as if I am in a Medieval court of law, and will never manage to figure out which writ I should plead.   So I will bow out, wishing you all well, with apologies for my unseemly behavior.  In the question  the questioner mentions a comment Mycroft made, saying "I'm not given to brotherly love,..." Later in the episode, when Holmes is saying good bye to John beside the airplane, Sherlock says that his brother and sister used to sing a song about the wind to him.  The comments made by Mycroft and Sherlock suggest that the series writers have a Holmes sister in mind. It'll be interesting if she shows up in the next season of the show. It would also add an interesting counterpoint to the fact that John has a sister from whom he is seriously estranged. (Sister Harry didn't accept her invitation to John and Mary's wedding.)  I would have made a comment about this where the question about a third sibling appeared, but I don't have enough reputation to comment.

In His Last Vow, it has been decided that Sherlock will go on the important but ultimately deadly mission as his form of punishment/banishment.  In regards to his involvement with sending Sherlock on this mission, Mycroft is questioned about his feelings for Sherlock and says:      "Don't be absurd. I'm not given to outbursts of brotherly compassion. You know what happened to the other one."    This heavily implies that a third Holmes brother exists.  Is there a third Holmes brother in any canon?


A month ago we add an archive of tens of thousands of pages to our website at once. Now we have lost SEO ranking significantly.  What can I do to resolve this issue ASAP?

What are the best ways to improve a site's position in the Google search results?


When I try to install SQL Server, I get this error:   The following packages have unmet dependencies:  mssql-server : Depends: libcurl3 but it is not going to be installed                 Depends: openssl (<= 1.1.0) E: Unable to correct problems, you have held broken packages.   How can I fix it?

After upgrading from 10.04 to 12.04 I am trying to install different packages.  For instance ia32-libs and skype (4.0).  When trying to install these, I am getting the 'Unable to correct problems, you have held broken packages' error message.   Output of commands:  sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.   After running this:  sudo dpkg --configure -a foo@foo:~$ sudo apt-get install -f Reading package lists... Done Building dependency tree        Reading state information... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.


Platform - Linux  I have a typical requirement, where I need to give higher priority to my function then system provided function.  Lets say I have a third party library or executable. It calls many system functions such strcpy or strlen etc. I can not modify the executable/library as I do not have access to code.  Now I have implemented my own strlen or strcpy functions. When the third party library or executable is executing it should call my functions instead of system library functions.   Is it possible. If yes, can somebody guide me how to do this.  LD_PRELOAD trial result  As per suggestion here, I tried with LD_PRELOAD. I tried to override malloc function.      #include <string.h>      void *malloc(int size)     {         void *ptr = NULL;         printf("Inside my malloc function\n");         ptr = malloc(size);         return ptr;     }   I put the above code in a c file and built mem.so file and executed below command.     export LD_PRELOAD=./mem.so   So now I have overwritten malloc function.  If execute ls or clear command I get below result, which is logical.  Inside my malloc function Inside my malloc function Inside my malloc function Inside my malloc function Inside my malloc function   It looks my overloaded malloc function is invoked recursively. Only one time call I need. How can I achieve that.

I came across a reference to it recently on  and (as of now) it is not explained.  I suspect  might be it, but I don't know for sure.


I tried Googling and haven't been able to find anything reliable that shows me how to generate the CSR. I have multiple domains, that I'd like added so I can't use the usual OpenSSL wizard:  *.domain1.com *.domain2.com   How can I get this generated?

This is a school-network.  Official (outside reachable domain name) is  bgschwechat.ac.at (www.bgschwechat..., mail.bgschwechat... and ftp.bgschwechat..)  Internally the windows domain is named bgs.ac.at  We need (possibly cheap) SSL certificates for Webserver and Exchange-Server  From our firewall (www.bgschwechat.ac.at) (Sophos UTM9) requests get NATed to virtual machines - some of them need SSL   Webserver (running CENTOS - www.bgschwechat.ac.at) Exchange Server (named xch.bgs.ac.at) should be reachable via NAT as mail.bgschwechat.ac.at WSUS Server (dc2.bgs.ac.at) - only for internal clients   My question: What kind of SSL-Certificate would we need to secure eg. both domains (bgschwechat.ac.at AND bgs.ac.at) so that they appear secured from outside when NATTING for example mail.bgschwechat.ac.at to xch.bgs.ac.at ?  Or do we need to rename the interior domain to the official domain name?  ...recommandations where to purchase such certificate?


If $a,b,q=\frac{a^2+b^2}{ab+1}$ are positive integers then $q$ is a perfect square.

Let $a,b$ be positive integers.  When $$k = \frac{a^2 + b^2}{ab+1}$$ is an integer, it is a square.    Proof 1: (Ngô Bảo Châu): Rearrange to get $a^2-akb+b^2-k=0$, as a quadratic in $a$ this has two values: $a$ and $kb - a = (b^2-k)/a$. (The second root is determined in two different ways from the expansion $(x-r_1)(x-r_2) = x^2 - (r_1 + r_2)x + r_1 r_2$.)  Now suppose we have $a,b$ such that $k$ is an integer but not a square, by the investigation about roots we have that the second root is a nonzero integer since $k,b,a$ are integers and $k \not = b^2$, futhermore it is positive which is easily seen from its defining equation.  WLOG assume $a \ge b$ so that the second root is strictly smaller than $a$. This leads to a decent, replacing $a$ with the second root.    Proof 2 (Don Zagier): Apply reduction theory (specifically, Sätze 1 and 2 of Section 13 of my book on quadratic fields) to the quadratic form $x^2 + kxy + y^2$, which is the unique reduced quadratic form in its equivalence class.    Note that Proof 2 is pretty much the same as Proof 1 when written out in explicit detail, but I could not read Zagier's book because I cannot read German.  I would like to know more approaches to this and other alternative proofs of this result if possible! Thanks in advance.  I would also be interested in related problems (especially easier ones of a similar nature) and texts which cover the reduction theory in English.


I read a book many years ago that had a set of short stories about a set of travel gates. It started with the invention and went through many uses. The final story was about a lizard race with 12 digits that took over things at some point noting it was odd to use a 10 digit number system.

I'm looking for a short story collection about different uses/inventions of transporter doors. I think it was just a single author collection, that I read in the early 2000s.  In each story these Transporter Doors exist, I seem to remember them being described as blank grey sheets. You step through them and come out somewhere else. The forward to the book talked about early Rocket stories where the launch of a spaceship would be the end of the tale.  Plots of the individual stories:  Two men one of whom's home is inside an asteroid are discussing the use of Base12 in their society and if it is because they have 12 fingers, one says that "people" used to use base10. The implication is that a different species arrived through the doors and replaced humans.  A man puts the code for his home into a door and is instead transported to prison where he's accused of murdering his wife, which he strongly denies.   Two scientists and a pilot take a probe ship deep into Jupiter's atmosphere, the will return to base via a door that they need to construct while they are down there. The scientists dislike each other and don't work well together. When they finish the door, the hamsters seem woosy out the other side, but the scientists insist it is ready. The pilot says he will go first as he can't fix it if it's wrong. When he arrives on the far side he's mentally damaged and the scientists have to get along without him acting as a buffer while the try to save themselves.


I have a new PC and I want to install Ubuntu on it. I only have a Mac to create the installation medium. How can I create a live USB for installation?

I'd like to create an Ubuntu live USB stick on a Mac to use to install Ubuntu on another machine. How do I accomplish this?


This question is based on Everitt et al. (A Handbook of Statistical Analyses Using R) and I am trying to answer these questions:   Load the Default dataset from ISLR library. The dataset contains information on ten thousand customers. The aim here is to predict which customers will default on their credit card debt. It is a four-dimensional dataset with 10000 observations. The question of interest is to predict individuals who will default . We want to examine how each predictor variable is related to the response (default). Do the following on this dataset:  a) Perform descriptive analysis on the dataset to have an insight. Use summaries and appropriate exploratory graphics to answer the question of interest.  b) Use R to build a logistic regression model.   c) Discuss your result. Which predictor variables were important? Are there interactions?   However, I am more interested in understanding when one should use -1 and the relevance of excluding intercept in a model. Here is the data summary:      # Set up data     data("Default", package = "ISLR")      #create default binary     default_binary     <-       ifelse(regexpr('Yes', Default$default) == -1, 0, 1)     dflt_str <-       ifelse(regexpr('Yes', Default$default) == -1,              "Not Defaulted",              "Defaulted")      stdn     <- ifelse(regexpr('Yes', Default$student) == -1, 0, 1)     stdn_str <-       ifelse(regexpr('Yes', Default$student) == -1, "Not-Student", "Student")      blnc <- Default$balance     incm <- Default$income      df <-       data.frame(default_binary, dflt_str, stdn, stdn_str, blnc, incm)      # with intercept     fm0 <- default_binary ~ stdn + blnc + incm     # no intercept as indicated by -1     fm1 <- default_binary~-1+stdn+blnc+incm     regression_model_without_minus_1 <- glm(fm0, family = binomial())     regression_model_with_minus_1 <- glm(fm1, family = binomial())   and for summary of the model, I get:    Can someone please explain me the difference between results with -1 and without -1 in these models with merits and drawbacks. Thanks for helping me!

I am running linear regression models and wondering what the conditions are for removing the intercept term.   In comparing results from two different regressions where one has the intercept and the other does not, I notice that the $R^2$ of the function without the intercept is much higher. Are there certain conditions or assumptions I should be following to make sure the removal of the intercept term is valid?


The druid's Wild Shape feature in D&D 5e says:  You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so. However, you can't use any of your special senses, such as darkvision, unless your new form also has that sense.  From the warforged's Integrated Protection racial trait:  You gain a +1 bonus to Armor Class  From 's Circle of the Forged Skin of Steel feature:  Starting at 2nd level, while you are transformed by Wild Shape, you gain the following benefits: You gain a +2 bonus to Armor Class...  Warforged druids  because the shape they transform into isn't built like a warforged, but Circle of the Forged clearly lets them keep their wood and metal composition:  While in beast form, your body is made from the same materials as a warforged; your muscles are rootlike tendrils protected by armored plates. It’s obvious to an observer that you are not a normal animal.  So does that mean if you're a Circle of the Forged warforged druid, you get a +3 AC bonus to whatever beast's natural armor you turn into? E.g. Giant spider = 14 + 1 + 2 = 17? This seems like a big difference from normal druids, even moon druids, so I wanted to double check.

When a Warforged Druid uses Wild Shape, how is its Armor Class determined?  Will the AC be based on the 's Integrated Protection trait (E:RftLW, p. 36; WGtE, p. 70), or the animal's natural armor? (Or both?)


I am working through Shankar's Principles of Quantum Mechanics and I am confused about his derivation for the propagator of a free particle from the Schrodinger Equation (Section 5.1).  He states that the propagator is given by the following equation (in terms of an integral over $p$):  $$U(t) = \int_{-\infty}^\infty \lvert p\rangle\langle p\rvert \exp(-ip^2t/2m\hbar)dp\tag{5.1.9}$$  and in Exercise 5.1.1 he states that the propagator, in terms of an integral over $E$, is:  $$U(t) = \sum_{\alpha = \pm} \int_0^\infty \biggl[\frac{m}{\sqrt{2mE}}\biggr]\lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}dE \tag{1}$$  However, from 4.3, the propagator appears to be defined as a sum over $E$ (the eigenvalues of the Hamiltonian):  $$U(t) = \sum_{E} \lvert E\rangle\langle E\rvert e^{-iEt/{\hbar}}\tag{4.3.13}$$  which, when $E$ is continuous, can presumably be written in integral form:  $$ U(t) = \int_{-\infty}^{\infty} \lvert E\rangle\langle E\rvert e^{-iEt/\hbar}dE \tag{2}$$  I am having difficulty reconciling these two forms of the propagator (1 and 2 above), as they appear to contradict. Surely, based on the definition given in 4.3, the propagator for a free particle should be given by:  $$U(t) = \sum_{\alpha = \pm} \int_0^\infty \lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}dE$$  and the extra $\bigl[\frac{m}{\sqrt{2mE}}\bigr]$ term should be present in the $p$ version of the equation?  Note 1:   I am aware of an existing question   that is similar. However, I find the accepted answer not very satisfactory. It's quite brief and doesn't seem to explain the whole story. It suggests there should be an additional term in the propagator integrand to account for a 'Density of States'.   So, what is happening here? Has Shankar glossed over this, in his earlier description of the propagator? If so, why would he do that? Does he address this point anywhere else in his book (as it seems fairly important)?  Can anyone explain more clearly why this Density of States is required and where it comes from? I thought the degeneracy of $H$ was being accounted for by summing over the +/- values of $p$. Why would an extra term be required?  Note 2:   Also, to clarify, I am aware that the extra term comes from changing the integral from $dp$ to $dE$:  $$p = \pm (2mE)^{1/2}$$ $$dp = \frac{m}{(2mE)^{1/2}}dE$$  However, I am confused as to why this factor appears in the integral over $E$, rather then the integral over $p$.

I am going through Shankar's Principles of Quantum Mechanics and am having trouble finding the free particle propagator $U(t)$ that satisfies $$\lvert\psi (t)\rangle = U(t)\lvert\psi (0)\rangle$$ due to the degeneracy of the $E$ eigenkets. Shankar says that if the Hamiltonian has degenerate eigenvalues, we change the propagator equation from $$U(t) = \sum_{E} \lvert E\rangle\langle E\rvert e^{-iEt/{\hbar}}\tag{4.3.13}$$ to $$U(t) = \sum_{E} \sum_\alpha \lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar} $$ where $\lvert E, \alpha \rangle $ are the orthonormal eigenkets for the $E$ eigenspace. This makes sense to me, because it seems like whenever we deal with degeneracy to use a projection. He also says for a Hamiltonian with no degeneracy to change the sum into an integral, so I imagine that for a Hamiltonian with a continuous, degenerate spectrum we would have this propagator: $$ U(t) = \sum_\alpha\int_\Re dE\lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}$$  I tried applying this to the free particle and had some trouble. In the book, after solving for the eigenkets and eigenvalues, $\lvert E\rangle = \lvert p\rangle$ and $p = \pm\sqrt{2mE}$, he chooses the propagator as a function of the momentum eigenvalues $p$ so that $$U(t) = \int_\Re dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m).\tag{5.1.9}$$ I understand how he got to this, but I'm having some trouble because this doesn't appear to be the same expression that I have above. Splitting the integral up, we have $$U(t) = \int_{-\infty}^0dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m) + \int_0^\infty dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m)$$ The left integral can changed to an integral over $-p$, and the bounds switch from $0$ to $\infty$ such that: $$U(t) =  \int_{0}^\infty d(-p)\lvert -p\rangle\langle -p\rvert \exp(-ip^2t/2m) + \int_0^\infty dp\lvert p\rangle\langle p\rvert \exp(-ip^2t/2m)$$ Now we can substitute and interchange $\lvert p\rangle = \lvert E, + \rangle$,  $\lvert -p\rangle = \lvert E, - \rangle$, $E = p^2/2m$, and $dp = \pm mdE/\sqrt{2mE}$ to get: $$U(t) = \sum_{\alpha = \pm} \int_0^\infty dEm/\sqrt{2mE}\lvert E, \alpha\rangle\langle E, \alpha\rvert e^{-iEt/\hbar}. $$ This is the result that we are asked to prove in Exercise 5.1.1. Why is this not the same as the first expression for the propagator? Where did the extra $ m/\sqrt{2mE} $ come from? Am I just wrong in assuming that that is the general expression for a Hamiltonian with continuous and degenerate eigenvalues?


show that $$\int_{0}^{\infty}e^{-x}\ln(x)dx= -\gamma=\Gamma'(1)$$  where $\gamma$ is   I started with $$\Gamma(z)=\left[ze^{\gamma z}\prod_{k=1}^{\infty}\left(1+\frac{z}{k}\right)e^{-z/k}\right]^{-1}.$$  by take log then derivative with respect to z and put z=1 I got $\Gamma'(1)=-1-\gamma+\sum_{k=1}^{\infty}(\frac{1}{k}-\frac{1}{k+1})$  but I dont know how to compute $\sum_{k=1}^{\infty}(\frac{1}{k}-\frac{1}{k+1})$ I know the answer is 1 but how ?   this is my way . can any one show different way ? or give me how to compute $\sum_{k=1}^{\infty}(\frac{1}{k}-\frac{1}{k+1})$

I know that $$ \int_0^\infty \frac{\log x}{\exp x} = -\gamma $$ where $ \gamma $ is the Euler-Mascheroni constant, but I have no idea how to prove this.  The series definition of $ \gamma $ leads me to believe that I should break the integrand into a series and interchange the summation and integration, but I can't think of a good series. The Maclaurin series of $ \ln x $ isn't applicable as the domain of $ x $ is not correct and I can't seem to manipulate the integrand so that such a Maclaurin series will work.   Another thing I thought of was using $ x \mapsto \log u $ to get $ \int\limits_{-\infty}^\infty \frac{\log \log u}{u^2} \ du $ and use some sort of contour integration, but I can't see how that would work out either.


I'm new to Ubuntu, I'd installed Apache2 in Ubuntu but due to errors during installation i uninstalled it. But when i try re-installing it again an error is displayed in terminal..  Error: Module cgid does not exixts. It looks like you've deleted /etc/apache2/mods-available/cgid.load, so mod_cgid cannot be enabled.  To fix this, please purge and reinstall apache2.2-commom.  /etc/init.d/apache2: 51: .: Can't open /etc/apache2/envvars invoke-rc.d: initscript apache2, action "start" failed..   Please help me to solve this error..

I'm trying to install apache2 server, but it gives following error message:  It looks like you've deleted /etc/apache2/mods-available/cgid.load, so mod_cgid cannot be enabled. To fix this, please purge and reinstall apache2.2-common. Setting up apache2 (2.2.17-1ubuntu1.5) ...  I've done the same using ubuntu software center, but getting the same error again.


Given a sphere of radius $r$, and origin $x,y,z$ what is the simplest way I can generate an evenly distributed array of points on the sphere $(x_1,y_1,z_1),(x_2,y_2,z_2),\cdots(x_n,y_n,z_n)$.  Note I will be writing this as a function in Javascript, if it is any help.  EDIT  Essentially, I want to create a perfectly symmetrical shape with $X$ number of vertices that fits perfectly inside a sphere with radius $R$.

I would like to generate a random axis or unit vector in 3D. In 2D it would be easy, I could just pick an angle between 0 and 2*Pi and use the unit vector pointing in that direction.   But in 3D I don't know how can I pick a random point on a surface of a sphere.  If I pick two angles the distribution won't be uniform on the surface of the sphere. There would be more points at the poles and less points at the equator.  If I pick a random point in the (-1,-1,-1):(1,1,1) cube and normalise it, then there would be more chance that a point gets choosen along the diagonals than from the center of the sides. So thats not good either.  But then what's the good solution?


I have an array. I would like to write its items in a random order every time I call. My array is this.    string[] a= {"A","B","C","D","F"}; string[] a= new string[5];   For example the order should be like this  C D F A B  But it should change the order.

What is the best way to randomize the order of a generic list in C#? I've got a finite set of 75 numbers in a list I would like to assign a random order to, in order to draw them for a lottery type application.


So I'm trying to prove that  $$\lim_{n \to +\infty} \frac{2n - 4}{3n - 7} = \frac{2}{3}$$  using the formal definition of the limit of a sequence. Applying it I've got   $$\left|\frac{2n - 4}{3n - 7} - \frac{2}{3}\right| \lt \varepsilon,$$ $$\frac{2}{\left|9n-21\right|} \lt \varepsilon.$$ From here I don't know how to continue, I guess I have to get ripped of the absolute value but I don't know how should I do it. Thank you so much.

I'm trying to prove the general      $$ \lim_{n\to\infty} \frac{an+c}{bn+d} = \frac{a}{b} $$   using the definition of the limit of a sequence, for any $\varepsilon > 0 \,\, \exists N \in \mathbb{N}$ s.t. for every $n \geq N$ $|a_n - a| < \varepsilon$. My (not so valiant) efforts:  \begin{align*}  \left| \frac{an+c}{bn+d} - \frac{a}{b} \right| &< \varepsilon \\ \left| \frac{abn + bc - abn - ad}{b^2n+bd} \right| &< \varepsilon \\ \left| \frac{bc-ad}{bn+d} \right| &< \varepsilon \left| b \right| \\ \left| bn+d \right| &> \left| \frac{bc - ad}{\varepsilon b} \right| \\ \left| bn+d \right| &> \left| \frac{c}{\varepsilon} - \frac{ad}{\varepsilon b} \right| \end{align*}  I'm used to being able to manipulate constants or remove absolute values when solving these kinds of problems, but with general constants I'm not sure what to do next.


How can I split a column data in sql. If hyphen is present, Only display the data before the hpyhen.

Using SQL Server, how do I split a string so I can access item x?  Take a string "Hello John Smith". How can I split the string by space and access the item at index 1 which should return "John"?


I have Chromium and I have installed the flash player for it. The flash videos are fine, on youtube, facebook, but the miniclip game does not load. What do I have to do?

I've deleted ~/.macromedia and ~/.adobe contents and after a restart chromium can't detect flash plugin. It works just fine in Firefox  I have only "Chromoting Viewer" on chrome://plugins/  chromium-browser 34.0.1847.116-0ubuntu2 adobe-flashplugin 11.2.202.350-0trusty1   I have profile-sync-daemon active (tried stopping it, of course) and broken PolicyKit as in   Does the detection depend on PolicyKit? What else can I do?


I'm seeing a severe drop off in Google impressions.  See attached screenshot from Google Analytics:    I haven't been able to attribute this to any changes on the site.  As you can see, this started happening on Oct 21st.  Does anyone know if this corresponds to a Google Search update?  Otherwise, does anyone have any suggests for tracking down the cause?  I'm pretty stumped.

There has been a significant drop (90%) in traffic from Google to one of my well-established sites (6+ years) in the last week. Searches show that the top 3 wide keywords all dropped 4 spots. Searches for other keywords do not show ANY results in the first 10 to 25 pages of results, while previously one 1st or 2nd page at most.  Since there are , the question really is:  What steps are necessary to figure out what caused such a drop?  There have been no major changes during this period or the last month on the site and certainly not in the homepage which has dropped in rank. Over all the years of running this site and plenty of others, I have never experienced this. There are is duplicate content on my site and I have rigorously used canonical links for the last few years to ensure it is not misinterpreted as such.


$A$ and $B$ are two matrices, when is $(A-B)(A+B)=A^2 - B^2$

I know that matrix multiplication in general is not commutative. So, in general:  $A, B \in \mathbb{R}^{n \times n}: A \cdot B \neq B \cdot A$  But for some matrices, this equations holds, e.g. A = Identity or A = Null-matrix $\forall B \in \mathbb{R}^{n \times n}$.  I think I remember that a group of special matrices (was it $O(n)$, the ?) exist, for which matrix multiplication is commutative.  For which matrices $A, B \in \mathbb{R}^{n \times n}$ is $A\cdot B = B \cdot A$?


I would like to send my form to the server through jQuery's Ajax method. I have text boxes, text areas, select boxes, checkboxes, radio buttons and most importantly, files in my form.  What I was using for a form that did not have files in it is this:  $('form').serialize();   However now if I have a file field in my form I can't seem to do it. What the best practice (common practice) to send over a big list of form elements including files to the backend server with jQuery - without having to add each element manually to the FormData()?

I would like to upload a file asynchronously with jQuery.     $(document).ready(function () {     $("#uploadbutton").click(function () {         var filename = $("#file").val();          $.ajax({             type: "POST",             url: "addFile.do",             enctype: 'multipart/form-data',             data: {                 file: filename             },             success: function () {                 alert("Data Uploaded: ");             }         });     }); });  File <input type="file" id="file" name="file" size="10"/> <input id="uploadbutton" type="button" value="Upload"/>     Instead of the file being uploaded, I am only getting the filename. What can I do to fix this problem?


The dataset 'left_right_merge' at the bottom of my screen shot shows the dataset that I'm currently working with.  The NODE values indicate a single point feature, but is duplicated with many attributes.  I want to collapse the dataset so that it looks like the 'test_data_nodes' at the top of the screen shot.  How would I do this in python?

I have a data set that contains intersection data.  Each intersection node has up to 6 links which is identified by IN_LINK and OUT_LINK attributes.  I want to create a new dataset that includes the intersection node value (NODE) and all of its accompanying links as a single record.    [NODE] [LINK_1] [LINK_2] etc...  5465    45687    9831    etc...  How would I code this in python?


I am running a Linux mint 18.3 and Windows 7 in a dual boot  and I would like to replace the Linux mint with Ubuntu 18.04

I am already dual booting windows 10 with Linux Mint, and I am trying to replace Mint with Ubuntu. I have already created a bootable usb for Ubuntu.  When I try to install Ubuntu, I don't see any option to install Ubuntu alongside windows 10. Rather, I see "install Ubuntu alongside Linux Mint". I didn't find any option to keep my windows 10. How can I replace Mint with Ubuntu in this dual boot system? Mint is installed on an ext4 partition and I have a Linux swap partition.


Selling a PC that is currently running Ubuntu. I need to switch back to windows 10 for the buyer. It previously had windows 10 installed. I downloaded the windows 10 iso file,and copied all of the files to a formatted USB drive. I have rebooted from the USB drive, but I dont think its working. I installed unetbootin to make a bootable USB drive that way, but i cannot find the iso file in unetbootin. It was difficult to find the iso file just to copy it to the USB drive manually, i had to find its location through the internet browser i used to download the file, but i cannot find it from my desktop. When I can find it, there is a "lock" icon over the file, im not sure if that is relevant as I am pretty bad with computers. How can I re-install windows and get rid of Ubuntu the easiest way? I dont care what happens to any of my data.

I'd like to create a Windows bootable USB stick, but I don't have a Windows machine with me at the moment to do so. How could I achieve the same using Ubuntu?


Every metric space is first countable, but what about the converse? Does it always hold? If not, can anyone give a counterexample? Thanks

Does anyone know any example of such topology?


I am using smartphone xolo play. I tried to download the gujarati font library to support Gujarati Font. But not able to achieve it. So please guide me how can I support Gujarati font in my xolo play smart phone. Thanks in advance. Bskania.

I am trying to display a Powerpoint slide deck on an android tablet, but the slides contain fonts that don't exist in android.  Is there a way to install custom fonts on the tablet?  If so, how?


Here's my attempt. Any tips on a better solution?:  // for loop to convert 32 to 16 bits uint32_t i; int32_t * samps32 = (int32_t *)&(inIQbuffer[0]); int16_t * samps16 = (int16_t *)&(outIQbuffer[0]); for( i = 0; i < ( num_samples * 2/* because each sample is two int32 s*/ ); i++ ) {     overflowCount += ( abs(samps32[i]) & 0xFFFF8000 ) ? 1 : 0;      samps16[i] = (int16_t)samps32[i]; }  // Only report error every 4096 accumulated overflows if( ( overflowCount & 0x1FFF ) > 4096 ) {     printf( "ERROR: Overflow has occured while scaling from 32 "             "bit to 16 bit samples %d times",              overflowCount ); }   Here's the part that actually checks for overflow:  overflowCount += ( abs(samps32[i]) & 0xFFFF8000 ) ? 1 : 0;

I was writing a program in C++ to find all solutions of ab = c, where a, b and c together use all the digits 0-9 exactly once. The program looped over values of a and b, and it ran a digit-counting routine each time on a, b and ab to check if the digits condition was satisfied.  However, spurious solutions can be generated when ab overflows the integer limit. I ended up checking for this using code like:  unsigned long b, c, c_test; ... c_test=c*b;         // Possible overflow if (c_test/b != c) {/* There has been an overflow*/} else c=c_test;      // No overflow   Is there a better way of testing for overflow? I know that some chips have an internal flag that is set when overflow occurs, but I've never seen it accessed through C or C++.    Beware that signed int overflow is undefined behaviour in C and C++, and thus you have to detect it without actually causing it. For signed int overflow before addition, see .


I have an old iPhone 4 that has been sitting unused since I got my new phone - it has now sold and I have to clean it out so it's ready for the next person.  Here's the problem:   The wifi doesn't work and the phone's inactivated (so I can't get online). It is asking for a restrictions passcode I don't ever remember setting.   I tried the default (0000) but no luck. What can I do to get this phone back to factory settings?

Is there a way to change the restrictions passcode on an iPhone without restoring the phone? I haven't forgotten the passocde; I just want to change it.


I want to learn that how How can I plan server hardware capacity by a project. But I need scientifically and    provable solution for this planning.   For example I have a project. That has 1000 unique users, 20 database tables, Used java programming language, etc. These are parameters of projects. But my process may be long running or database selection response. So I will use these parameters and get a result like this: You need 4 Core 2.4 Ghz CPU, 8GB Ram, 100Gb hdd etc.  Is there any way to do this plan?

This is a  about  Related:      I have a question regarding capacity planning. Can the Server Fault community please help with the following:   What kind of server do I need to handle some number of users? How many users can a server with some specifications handle? Will some server configuration be fast enough for my use case? I'm building a social networking site: what kind of hardware do I need? How much bandwidth do I need for some project? How much bandwidth will some number of users use in some application?


Let's say I have a sentence similar to      When a scientist publishes results, she must be careful to not enter the incorrect data.   However, I am confused as to what I should use in place of the "she".  Using a "she" to refer to an arbitrary scientist, to me, seems just as weird as referring to an arbitrary scientist as "he", while "they" just seems grammatically incorrect.  I have been told that the grammatically correct, gender neutral form of the sentence would be     When a scientist publishes results, he/she must be careful to not enter the incorrect data.   But, come on, I'm not going to write "he/she" every time I have to refer to someone of unspecified gender.   How do I go about dealing with this? I understand that I could simply rephrase the sentence as      When scientists publish results, they must be careful to not enter incorrect data.   This is what I do in most cases when I am confronted with this problem.  My question is:   What should I do if I want to stay as close as possible to the original sentence structure (for instance, maintaining the singular form of scientist? What should I do in general when I am confronted with situations like this one? What options are there (e.g. converting to plural)?

Is there a pronoun I can use as a gender-neutral pronoun when referring back to a singular noun phrase?  Each student should save his questions until the end. Each student should save her questions until the end.


I'm working with the definition:  A smooth embedding of M into N is an injective immersion $F:M\rightarrow N$ that is also a topological embedding.  I'd like to explain why the klein bottle cant embed in $\mathbb{R}^3$. The immersion is not injective, thus results in self intersections, correct?

How does one prove that the Klein bottle cannot be embedded in $R^3$? I'm talking about smooth embeddings.


I am researching Test Management tool for creating test plan, test cases, test coverage, test matrix, reports and also should integrate with automation tools with providing some features for e.g. test modifications, duplication, test coverage etc.

I'm looking for a some sort of management/reporting tool that collects the results of tests, stores them for reporting, then lets users generate reports based on those tests.  We have numerous test running tools that run on a variety of platforms, but all output test results in the JUnit format.  The test are not specific to hardware or platform, but rather generic.  What we would like to do is have an automated (or manual) test run be able to submit it to a central location along with additional information, like platform, OS, hardware configuration and maybe user defined data.  The management/reporting tool would store this data.  Then, a manager would be able to go to the tool and request (or more likely, access a dashboard that developers have setup) an update on the current status.  This could be a list of test results that were run in a particular configuration, or a hardware status, or just the results of specific test(s).  EDIT: I am not looking for software that manages the TESTS.  We already write our own tests in other tools.  I want something that can manage the test RESULTS without having to create the TESTS.  Probably makes my question too specialized...  Any suggestions?


My question is simple:  Should I use fseek with SEEK_END to get to the end of a file and then get the length of it ? Because in the man it is said:        Library implementations are allowed to not meaningfully support SEEK_END (therefore, code using it has no real standard portability).      Right now I am using stat (from C) which is better ?

How can I figure out the size of a file, in bytes?  #include <stdio.h>  unsigned int fsize(char* file){   //what goes here? }


When leveling up one of your skills in Stardew Valley, you are frequently told that you have gained efficiency in using a particular tool. For example, gaining a level in farming gave me +1 to Watering Can and Hoe efficiency.  What do these actually do? They don't appear to make the tools any more effective. Am I correct in assuming that it has something to do with energy usage (the only other thing I can think of related to tool use)?

When you level up Mining for example, the game will state that you get +1 in Mining proficiency. What does this actually do?  Does it decrease the amount of swings needed to smash rocks?  Or does this just mean that you leveled up 1 level?


Is there a canon mention that Kenobi, Windu, Palpatine, the Skywalkers etc. are the same human species as all the other humans in  like Han Solo?  They look like humans, but we know that they're different in at least one characteristic: midi-chlorian hosting, which I suppose humans can't do as per definition.    Answers only from Canon, please. EU is welcome...

Related:   This is a subtly different question because I'm not asking whether there's a historical relationship between the two lineages.  I am asking this question because answers to these questions:      are making assumptions about the appearance of Padme while pregnant, the period of gestation, and appearance of newborn babies.  All of these presuppose that the "humans" of the Star Wars Galaxy are 100% biologically equivalent to us.   In fact, as far as I know, we don't actually know any of those facts from canon.   (Do we?)   All we know is that "human" children and adults look like us.  So, do we have any canon or out-of-universe commentary that tells us that Star Wars humans and Earth humans are biologically equivalent?  Another way to put this would be  If presented with a Star Wars human and a Milky Way human, would the best doctors or the best medical droids be able to distinguish them?


This is from Stein and Shakarchi  This exercise shows how the mean square convergence dominates the uniform convergence of analytic functions. If $U$ is an open subset of $\mathbb{C}$ we use the notation $$||f||_{L^2(U)}=(\int_U{|f(z)|^2dxdy})^{1/2}$$ for the mean square norm, and $$||f||_{L^\infty(U)}=sup{|f(z)|}$$ for the sup norm. (a) If $f$ is holomorphic in a neighborhood of the disc $D_r (z_0)$, show that for any $0<s<r$ there exists a constants $C>0$ (which depends on $s$ and $r$) such that $$||f||_{L^\infty(D_s(z_0))}\leq C||f||_{L^2(D_r(z_0))}$$ (b) Prove that if ${f_n}$ is a Cauchy sequence of holomorphic functions in the mean square norm $||\cdot||_{L^2(U)}$, then the sequence ${f_n}$ converges uniformly on every compact subset of $U$ to a holomorphic function. [Hint: Use the mean-value property]  I have managed to solve part (a). I'm really lost for (b). Can you give me any tips? This seems like a generalization of real analysis but I don't really understand how to approach this.

If $U$ is an open subset of $\mathbb C$, the mean square norm is defined as:  $$||f||_{L^2 (U)} = {\left(\int_U |f(z)|^2 dxdy\right)}^{1/2}$$  And the norm supremum is defined as:  $$||f||_{L^{\infty} (U)} = \sup_{z \in  U} |f(z)|$$  If $f$ is holomorphic in a neighborhood of $D_r(z_0)$, show that for any $0 < s < r,  \exists C > 0$, a constant, which depends on $s$ and $r$ such that:  $$||f||_{L^{\infty} (D_s(z_0))}\le C||f||_{L^{2} (D_r(z_0))}$$  And prove that if $\{f_n\}$ is a Cauchy sequence of holomorphic functions in the mean square norm, then the sequence $\{f_n\}$ converges uniformly on every compact subset of $U$ to a holomorphic function.


I am looking to buy either of the following two laptops but wanted to ensure they were compatible with Ubuntu. Both seem to match laptop names as 'okay' but the details of the specs seem to be slightly different, which leaves me confused!   HPM6-1205SO/i5/8GB (HP Envy M6 ??)  HP15-J028EO/i5/12G (HP Envy 15 ??)   Your help much appreciated.  Many thanks, Melanie

How can I find out if Ubuntu supports a particular hardware component, that is, if it works in Ubuntu?  I am going to put together a computer and I am choosing components.   How do I know if Ubuntu supports this or that motherboard, or this or that sound card, or this or that graphics card, etc? How do I know that there is no conflict in Ubuntu between this and that hardware component?   What resources are there to help with such situations?  I know that there are computers with Ubuntu pre-installed and that there are  for whole computers but this is not what I'm looking for. I'm looking for resources to find out support for particular hardware components and conflicts among particular hardware components.


I add an element with its own unique id using jquery and after that i want to chek a click event on that added element using its id.  Here is the code and it doesn't work for some reason.  I'm a new to this programming stuff, so maybe I don't see something obvious.  $(document).ready(function () {         $("#type").click(function () {             $(".footer").prepend('

');             $("#next").click(function () {                 $(".current")                     .removeClass("current")                     .addClass("done")                     .next()                     .removeClass("notdone")                     .addClass("current");             });         });

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


I'm currently studying shell commands, one of the exercises consists in creating a structure with various directories and subdirectories.  I wrote ls -laR > hello, it was supposed to create a text file named hello. However, I get the following message bash: hello: permission denied, even when I type sudo in the beginning.  The command worked in another Linux distribution. Also, I used a few minutes ago ls -la in the directory where I want to create the file and it gave me this:  drwxr-xr-x 2 root root 4096 Nov 26 10:56 . drwxr-xr-x 5 root root 4096 Nov 26 10:56 ..   According to the first triad I have writing privileges?

When using sudo to allow edits to files, I regularly get 'permission denied'.  For example, my mouse is jittery and sluggish, so I want to disable polling:  sudo echo "options drm_kms_helper poll=N">/etc/modprobe.d/local.conf   I'm prompted for a password, and then get:  bash: /etc/modprobe.d/local.conf: Permission denied   So I tried to do a temporary change to disable polling by using:  sudo echo N> /sys/module/drm_kms_helper/parameters/poll   Yet again the system responded with:  bash: /sys/module/drm_kms_helper/parameters/poll: Permission denied   Any ideas?


I'm soon moving to a different country and am wondering if it is possible to change the country details in Stack Exchange, if so, how? The option doesn't seem to appear on my profile

This is probably a noob question, but I forgot how to edit my profile.   Can anyone help me? There is no visible button for me.


What is the correct way to mount a disk image so all users (guest included) are able to access it?  I'm currently stuck after mounting it with:  sudo mount -o loop,users,ro,offset=262145048576 '/path/Disk Image.img' '/media/guest-Folder/Disk'   My normal user session can access it, but on a guest session I get an error: "This location could not be displayed. You don't have the permissions necessary to view the contents of Disk" while trying to view the contents in Nautilus.

In Ubuntu 11.04 I could mount a file system in /media/foo and run chown guest:guest /media/foo/bar -R and have full access in the guest account. After the upgrade to 12.04 I changed my routine to reflect the new guest usernames (chown guest[id]:guest[id] /media/foo/bar -R) but I still can't access it as a guest user, as I don't have access privileges to /media as guest:     ls: cannot open directory /media: Permission denied   (Very interestingly this does work if I su into the guest account as root). I understand this is meant as a  but I don't see how it is done. ls -l / reports   drwxr-xr-x  11 root root  4096 Sep  9 22:28 media   Thus my two questions: How does this restriction work and how can I access a mounted file system as a guest user, ideally without allowing access to all of the other mounted file systems?


I am an Mphil student from India. My field of interest is complex analysis. I plan to go abroad for my PhD. I know the process of GRE exams and all. But I want to ask, is talking to any professor, with whom you wish to work for PhD, from your desired university, helpful in getting admission?  Can it be helpful somehow?

I know many master's students who get an opportunity to talk to their potential PhD advisors well before applying. In most cases this opportunity is available by the professors with whom they worked for their master's. Moreover, there are many others who establish a contact with professors by mailing them and enquiring about PhD vacancies.   My questions are:   How important is knowing an advisor prior to applying for PhD?  Does an email interaction play a vital role when the department makes its admit decisions? If email contact is important, can a student send out mails to 2-3 professors (working in the same area) in case one of them does not bother to reply? To sum up, is applying of any use (especially in top universities) when you have no contacts and only your credentials to bank on?


Its is known every continuous function between topological spaces is sequentially continuous. Also sequentially continuity implies continuity if the domain space is first countable. I am interested in example of the function between topological spaces (where domain space is not first countable, as I say) that is sequentially continuous but not continuous.

Can you give me an example of a function which is sequentially continuous but not continuous? (I know that in first-countable spaces this is equivalent, but what about in spaces without this condition?)  Thank you :)


How can I do this symbole in latex ? (if possible with the barre of the middle more straight).

Is there in LaTeX a symbol or a macro for the average integral with a horizontal slash? I know about \strokedint, but I'd prefer the dash to be horizontal.


I do not understand why there is this error in my VBScript:  'Déclaration des variables Dim objExcel, objWorkbook, CurrAddin 'Création des Objets Set objExcel = CreateObject("Excel.Application") objExcel.Visible = True  For Each CurrAddin In objExcel.AddIns     If CurrAddin.Installed Then         CurrAddin.Installed = False         CurrAddin.Installed = True     End If Next CurrAddin  Set objWorkbook = objExcel.Workbooks.Open("C:\rd\python_scripts\private_bank_mini3.xlsx") 'Set objWorkbook = objExcel.Workbooks.Open("C:\rd\python_scripts\Test.xlsx")  'Pause de 10 secondes WScript.Sleep 10000 'Pause de 8 heures 'WScript.Sleep 28800000  'Enregistrement objExcel.EnableEvents = False objWorkbook.Close False objExcel.EnableEvents = True  'Fermeture de Excel 'objExcel.Quit  'Désallocation mémoire  Set objExcel = Nothing Set objWorkbook = Nothing  'Fermeture du Script WScript.Quit   Please find below my error messages:    My script works with the file "Test.xlsx" but not with the "private_bank_mini3.xlsx", the difference between those is the charging of a Add-In at the opening of the second file.  Have you got an idea to manage it please?

I am trying to create a new instance of Excel using VBA using:  Set XlApp = New Excel.Application   The problem is that this new instance of Excel doesn't load all the addins that load when I open Excel normally...Is there anything in the Excel Application object for loading in all the user-specified addins?  I'm not trying to load a specific add-in, but rather make the new Excel application behave as though the user opened it themself, so I'm really looking for a list of all the user-selected add-ins that usually load when opening Excel.


Hello I am currently trying to create a computer game\program and the main thing that it uses is input from the user, commands, in a JTextField. So I already have a basic text field set up called "question"  (JTextField question = new JTextField(15);) in a JFrame and an OK button to enter the text. Next is a String "answer". This is:       String answer = question.getText().toUpperCase();  This is how the field is set up. Net is the 3 if statements that give an error if no text is entered, if it is not the right word, and of course, the correct answer. They are as follows:  Public class ButtonListener extends ActionListener {      publix void actionPerformed(ActionEvent e)      {           if(e.getSource() == buttonOK)           {            String answer = question.getText().toUpperCase();            if(answer.length() == 0)           {                JOptionPane.showMessageDialog(                     Window.this,                     "ERROR: NO INPUT",                     "ERROR",                     JOptionPane.INFORMATION_MESSAGE);           }            if(answer == "XENIX")           {                JOptionPane.showMessageDialog(                     Window.this,                     "Welcome, Sir",                     "Greetings",                     JOptionPane.INFORMATION_MESSAGE);           }            if(answer != "XENIX" && answer.length > 0)           {                JOptionPane.showMessageDialog(                     Window.this,                     "ERROR: INCORECT PASSWORD",                     "ERROR",                     JOptionPane.INFORMATION_MESSAGE);           }   This is how the if statements react when text is entered and the ok button is pressed. Everything works but when I type in "Xenix", it says "ERROR: INCORRECT PASSWORD". The, "Welcome, Sir" message never shows, even though using a print method it shows it is clearly getting "XENIX" from the answer. Why is it not working? Is there another method I'm supposed to use? Please respond soon! Thanks!

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


I am an Indian citizen and am travelling from New York to India via Emirates Airlines. There is a 7-hour layover at Dubai international Airport (DXB). I want to visit Dubai for a couple of hours. Do I need a transit visa? If so, how do I obtain one?

I am travelling to Calgary from Delhi. I have an Air India flight from Delhi to Dubai then British Airways flight from Dubai to London and Air Canada flight from London to Calgary. My query is "Do I require a transit visa." Plz help as I am travelling in four days


I am looking for an example for such a module, because I want to find a module for which the set of torsion elements is not a submodule of $M$.

Clearly if $A$ is a commutative domain then the torsion elements of an $A$-module form a submodule.   I'm having trouble finding an example of an $A$-module such that $A$ is a noncommutative domain and the torsion elements of the module do not form a submodule.  Is anyone aware of a good example of this?  Thanks in advance


As a post-graduate student at a renowned university, I am supposed to make an assignment (see attached images) which is obviously inspired on  licensed scikit tutorial.  Since the assignment (code) instructions are identical to the licensed code, I have two questions:   Is the scientific integrity of the teacher challenged by posing this question? Should I report this at the university's fraud office?    In the assignment is no reference or citation included.

This question is specifically about a high school course, but it should be applicable to any online course in general.  I was taking a physics course online to skip it in school, those courses are really expensive, so I took the cheapest one that my school was allowing me to take, and it was understandably low quality. This much was ok and expected.  What wasn't ok however, was that all the questions on the quizzes and exams were stolen from the internet. Every single question was taken from some school's "Ch 3 Review Sheet" or "2008 XYZ High School Physics Final Exam" etc. that was made public online.  My parents paid $500 for this course and the people didn't actually write anything themselves, and I'm pretty angry.  So my question is twofold:   Is it ok for a course to do this? If not, is there any official organization I can complain to.


how to setup Elementary OS Loki 0.4 Desktop on ubuntu 16.04 LTS?

I want to install Pantheon desktop environment from elementaryOS on Ubuntu, is that possible?


i installed ubuntu 14.04 on my windows8.1. i tried to do a dual boot, but i accidentally click the wrong option and now, the windows8.1 gone and currently, ubuntu14.4 is my only OS. i do have the windows8.1 iso. so, how to install the windows8.1 again?

I have Ubuntu on my laptop. Now I want install Windows 7 in a dual-boot. How can I do this? I can't lose my Ubuntu files, and I'm afraid that I might break . Go  for UEFI only!


Often, I encounter situations (particularly with software or electronics, though occasionally with people) where bugs or strange events happen that cause me to lose trust in said software maintaining the integrity of my data, or said technology being reliable 'in the clutch' (or even scenarios where a person or business entity change a predictable, relied-on pattern of behavior, belief or expectation).   Sometimes I feel so strongly about the broken trust, that I feel forced to stop trusting (even if such events leading to the distrust were unintentional). I may still use said software, but I continue to do so very cautiously at that point.   The word I believe I'm looking for is similar to 'ized' words, in that it describes a state of 'forced distrust' assigned to myself, not the state or act of the object/person breaking the trust (e.g. "I've been/become xxxxxxxized by such-and-such...").   I often want to use the word 'disenfranchised' to describe such a state, but I'm not sure that's 100% suitable to the various contexts or the concept of lost trust (even though whatever trust I had was likely unfounded anyway, simply because, at least in the context of software, that trust is simply the lack of distrust due to having not yet experienced any bugs/issues that have built up a negative rapport with said software and what I expect it to do without fail).   So what's the word I'm looking for, if such a single word exists?

Does a word exist for a person who has lost faith?    I am looking for a single word that represents a person who lost faith, e.g. in religion, humanity, himself. The more general, the better.


Is it possible to change nls_characterset only for one table? If it not, could I change or create new tablespace with different nls_characterset?

I'm working with Oracle databases from 10g-r1 to 11g-r2. They are set as ISO-8859-15 (WE8ISO8859P15) character set.  I need to create a tablespace set as UTF-8 (AL32UTF8) character set inside these databases. Is it possible? What is the correct syntax?


Are the spells in the magical world of Harry Potter invented or discovered?  Maybe someone just said “Avada Kedavra” and the rest is history.

In the Harry Potter series, are wizards capable of creating their own spells, or are they limited to the spells that they're taught/learn?  I seem to remember something about Snape creating sectumsempra, but I'm not sure if that really is the case.


I am user_a and I have a password for user_b, so I can use su user_b to do things as user_b.  I want to copy a file from user_a to user_b.  I don't want other users besides user_a and user_b to see the file, and I don't have root on the machine.  So the usual trick of moving the file to /tmp is not acceptable.

I have a couple of files that I want to move to another's user home directory. I don't have permissions to write to that user's home directory, but I know his password.  I know how to copy the file using scp (see ). However, if I want to move the file, copying and then removing the original file is inefficient. Is there a way to move the file, without using sudo (I don't know the root's password)?


I can't install Photoshop CS6 or any version. Any time I run it with Wine , when I need to upen it it gives me a : "Photoshop needs to run on a windows 7 machine" .. something like that. PLEASE HELP. I am a designer. I changed to Ubuntu for beautifulness, if I would've know I maybe shouldn't change to it. Please help. I have a macbook, if this help (I installed Ubuntu over my MacOS)

How can I install photoshop cs6 on ubuntu 14.04? Anyone help me ?


I'm struggling to get this code more simple but Python is case-sensitive a lot. Is there to turn this code cleaner???? @client.event async def on_message(msg):     if 'Marcelo' in msg.content:         print('Keyword found in message')         await msg.channel.send("oh this shit again!")     if 'marcelo' in msg.content:         print('Keyword found in message')         await msg.channel.send("oh this shit again!")     if 'MARCELO' in msg.content:         print('Keyword found in message')         await msg.channel.send("oh this shit again!")

How can I do case insensitive string comparison in Python?  I would like to encapsulate comparison of a regular strings to a repository string using in a very simple and Pythonic way. I also would like to have ability to look up values in a dict hashed by strings using regular python strings.


I need to find information regarding an Avianca Flight from Baltra Island (Galapagos Islands) to Quito.  We had a stop in the Guayaquil Airport.  We were not to depart the plane but then they cancelled our flight to Quito with no help to change our flights as the Quito Airport was not accepting flights due to the unrest in the country.

Where can I find historical data on flights, specifically Delta international flights?  I need to find out about cancellations, diversions and any other flight data pertaining on particular route at a given time.  This source has to be official and stand up to legal scrutiny.


The axion is the pseudo-Goldstone boson associated to the breaking of the conjectured Peccei-Quinn Abelian symmetry. The axion couples to the SM gauge fields in a CP-invariant manner (e.g. $aF\tilde F \sim a\ \vec E\cdot \vec B$), which means that the axion has to be a pseudoscalar.  Do we assume that the axion is a pseudoscalar? Or is there a means to realise that it is indeed so?    EDIT: Note that I am NOT asking for a proof of why claiming that the axion $a$ is a pseudoscalar ensures that $aF\tilde F$ is CP-invariant (which is the content of ). I understand that very well. The fact is when I ask why $aF\tilde F$ is CP-invariant, the usual answer given is that because $a$ is a pseudoscalar. Therefore, either one has to first establish that $a$ is a pseudoscalar without making an appeal to consequences (namely that it makes $aF\tilde F$ CP-invariant), or establish that $aF\tilde F$ is indeed CP-invariant which should prove that $a$ is a pseudoscalar.  The only other safe alternative is to claim it is so by definition.    To make it absolutely clear that this question is not a duplicate, define proposition $A$ as "the axion $a$ is a pseudoscalar" and proposition $B$ as "$aF\tilde F$ is CP-invariant".   The linked question asks for a proof of $A\Leftrightarrow B$. I accept the truth of this proposition. However, I ask for a proof of $A$ alone (or a clarification that it is indeed so by defintion of $a$). Note that if you can prove $B$, then $A$ follows from $A\Leftrightarrow B$.

My professor has given me the following action stating that $a(x)$ is an axionic field and told us in class that for this action to be Lorentz invariant the field must be a pseudoscalar.  $$ S = -\int d^4x  \frac{1}{2} \partial^\mu a \partial_\mu a - \frac{1}{4} F_{\mu \nu} F^{\mu \nu} - \frac{1}{f}[aF_{\mu \nu} \left.^* F^{\mu \nu} - 2 \partial_\mu (a A_\nu \left.^*F^{\mu \nu}) \right. \right.]$$  This is the first time that I encounter such fields in my life. I tried googling around to find some information but I didn't even understand what such a field is.  I tried proving that $S$ is Lorentz invariant iff $a$ is a pseudoscalar using the definition of a Lorentz transformation  $$\delta x^b = \delta \omega^b_a x^a$$  But the computations seem to be too difficult to me. Is there any shortcut or alternative way to prove this?


I am wondering if gravity gets or would get stronger with ultra-compression (relativistic level) of matter? This may sound stupid but this is how my thought process went.  Let us assume we have an object at position $x$ and now let us assume we want to pin-point the exact position of the object therefore we start compressing the object to get exact position therefore our $\Delta x$ will get closer and closer to $x$ however if you think about it in quantum sense you will discover that the Heisenberg uncertainty will start to act, so we can say the $\Delta \vec p$ will increase in other words the velocity will increase because of the inequality:  $$\Delta x \Delta \vec p \geq \frac{\hbar}{2}$$   Now since using the Special relativity transformations we can say as a velocity of an object is increased the mass must also increase by:  $$m' = \frac{m} {\sqrt{1 - \frac{v^2}{c^2}}}$$  I can therefore say since the mass increase while compressing due to the uncertainty in momentum.  As a result of this we can say that the overall-mass will increase $m'$ due to compression and now if we were to substitute these into the Newtonian Gravity equations we will get more gravitational force than expected after compression:  $$F' = \frac{Gm'}{r^2} $$   Which is definitely bigger than if the object was not compressed, to express this we can mathematically make this into a inequality:  $$\frac{Gm'}{r^2} > \frac{Gm}{r^2}$$  As a result I could back-up my theory, but using this can we say that the gravity near neutron-stars or black-holes is slightly stronger than expected by the gravitational equation. Is there any proof of this happening or if not what is wrong with my ideology and could someone correct it for me?

Black holes are thought to originate when a star burns out and collapses to a smaller physical size. This compresses it's matter, but would that increase it's gravity? And would it be enough to capture light? If that star's light could have been observed prior to it's collapse, how could it's burning out and collapse enable it to become a black hole and capture light?


This is a homework problem. In the first part of the problem, I managed to use a combinatorial problem to prove the following identity:  $\sum_{k=0}^{n}(-1)^k {2n-k \choose k} 2^{2n-2k} = 2n+1$  But I actually have problem with the second part of the problem which asked me to prove this identity "directly", probably using some form of generating functions/algebra method.  There was a hint given but I got stuck: The hint says to calculate   $\Sigma_{n=0}^\infty\Sigma_{k=0}^{n}(-1)^k {2n-k \choose k} 2^{2n-2k} x^{2n}$  and that it would be useful to consider the fact that $ \Sigma(2n+1)x^{2n}= \frac{d}{dx}\frac{x}{1-x^2} $ and $(1-x)^{-a-1}=\Sigma_{j=0}^\infty {a+j \choose j}x^j$.  I am able to prove both these "possibly useful facts" in the hint, but I don't see how to calculate the suggested double sum or prove the identity. [I would have thought that the combinatorial proof is harder to find!] [You may assume that I am familiar with the formal treatment of power series.]  Any help would be greatly appreciated.

I am dealing with problem 10F in the textbook A Course in Combinatorics by J. H. van Lint and R. M. Wilson.   Problem 10F: Prove directly the equality  $\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}} {2n - k}\\k\end{array}} \right){2^{2n - 2k}} = } 2n + 1$.  Sketch of the proof: Evaluate  $\sum\limits_{n = 0}^\infty  {\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}}{2n - k}\\k\end{array}} \right){2^{2n - 2k}}{x^{2n}}} } $. To do this, use Hint 1. Then, use Hint 2.  Hint 1: $\sum\limits_{j = 0}^\infty  {\left( {\begin{array}{*{20}{c}}{a + j}\\j \end{array}} \right){x^j} = {{\left( {1 - x} \right)}^{ - a - 1}}} ,\,\,a \in {\mathbb{Z}^ + }$.  Hint 2:  ${\sum\limits_{i = 0}^\infty  {\left( {2i + 1} \right){x^{2i}} = \left( {\frac{x}{{1 - {x^2}}}} \right)} ^\prime }$.   Attempt: It is enough to show that  $\sum\limits_{n = 0}^\infty  {\sum\limits_{k = 0}^n {{{\left( { - 1} \right)}^k}\left( {\begin{array}{*{20}{c}} {2n - k}\\ k \end{array}} \right){2^{2n - 2k}}{x^{2n}}} }  = {\left( {\frac{x}{{1 - {x^2}}}} \right)^\prime }$. But I can not use Hint 1.


As I was about to edit a question on Stackoverflow (and Meta) I noticed the sidebar notes overflow into the footer. This also seems to be happening in meta.  Happens to me on:   Chrome 41 OS X Firefox 37 OS X Safari 8       Update  Since there is a , let me update my question and target specifically Meta. Since the question already has an answer and it states the sidebar is more important, then maybe on sites like Meta.SE where the sidebar is transparent, there should be a white background.

I have noticed that while asking questions and scrolling to the bottom of the page, the right sidebar containing recent questions covers the footer partially. Also, a part of it goes beyond the browser's boundary. It may not be a big problem but it still doesn't look good.    This also happens on the  page


My goal is to show that the sequence   $$\left(\frac{1}{n} +1\right)^n = e^1$$  is strictly increasing. My attempt was to show this by induction. After checking for $n=1$ and $n=2$ I assumed it to be true for $n-$ and $n$:  $$\left(\frac{1}{n-1} +1\right)^{n-1} < \left(\frac{1}{n} +1\right)^n = $$  And then to show the inequality for $n$ and $n+1$. This led me nowhere. Another attempt was to secretly assume that I can view $n$ as a real parameter and then differentiate with respect to $n$. My thought was that if the resulting derivative was strictly positive for positive $n$ or rather $n\geq 1$ then the statement would hold. But I strongly suspect that this is not so easy as it seems.  Can anyone offer help?

Show that $U_n:=\left(1+\dfrac{1}{n}\right)^n$, $n\in\Bbb N$, defines a monotonically increasing sequence.   I must show that $U_{n+1}-U_n\geq0$, i.e. $$\left(1+\dfrac{1}{n+1}\right)^{n+1}-\left(1+\dfrac{1}{n}\right)^n\geq0.$$  I am trying to go ahead of this step.


As far as I understood,  gives a prediction of the transition rate in a perturbed quantum system $H_0+V$ between two eigenstates of the unperturbed system $H_0$, say from $\left| i\right>$ to $\left| f\right>$ with eigenenergies $E_i,E_f$. The prediction is perturbative in the first order of $V$.  The result is, that the rate equals  $$\gamma_{i\to f} = 2\pi |\left<f|V|i\right>|^2 \delta(E_i-E_f)$$  This rate is defined as  $$\gamma_{i\to f}=\frac{d}{dt} |\left<f|U(t)|i\right>|^2.$$  My question: How should one interpret this differential "rate" physically?   My thoughts so far: Apparently it is the derivative of the transition probability with respect to time, so it is not a probability itself. In literature it is often called decay rate, but for an exponentially decaying probability $p(t)\sim e^{-\lambda t}$ the decay rate $-\lambda$ would not be computed as $dp/dt$, but $(dp/dt)/p$.

This is a question I asked myself a couple of years back, and which a student recently reminded me of. My off-the-cuff answer is wrong, and whilst I can make some hand-waving responses I'd like a canonical one!  In the derivation of Fermi's Golden Rule (#2 of course), one first calculates the quantity $P(t)\equiv P_{a\rightarrow b}(t)$ to lowest order in $t$. This is the probability that, if the system was in initial state $a$, and a measurement is made after a time $t$, the system is found to be in state $b$. One finds that, to lowest order in the perturbation and for $\left< a \mid b \right > = 0$, $$P(t) \propto \left( \frac{\sin(\omega t/2)}{\omega/2} \right)^2, \qquad \hbar\omega = E_b - E_a $$  Then one says $P(t) = \text{const.} \times t \times f_\omega(t)$ where as $t$ increases $f$ becomes very sharply peaked around $\omega=0$, with peak of height $t$ and width $1/t$, and with total area below the curve fixed at $2\pi$. In other words, $f_t(\omega)$ looks like $2\pi \delta(\omega)$ for large $t$.  Now suppose we consider the total probability $Q(t)$ of jumping to any one of a family of interesting states, e.g. emitting photons of arbitrary momenta. Accordingly, let us assume a continuum of states with density in energy given by $\rho(\omega)$. Then one deduces that $Q(t) \sim \text{const.} \times t \rho$, and defines a "transition rate" by $Q(t)/t$ which we note is independent of time.  The issue I have with this is the following: $Q(t)/t$ has the very specific meaning of "The chance that a jump $a \to F$ (for a family $F$ of interesting states) occurs after making a measurement a time $t$ from the system being in state $a$, divided by the time we wait to make this measurement." It is not immediately clear to me why this is a quantity in a physical/experimental context which is deserving of the name "transition rate". In particular, note that   $t$ must be large enough that the $\delta$ function approximation is reasonable, so the small-$t$ regime of the formula is not trustworthy; $t$ must be small enough that the perturbation expansion is reasonable (and also presumably so that the $\delta$ function approximation is not insanely sensitive to whether there is a genuine continuum of states or simply very finely spaced states) so the large-$t$ regime of the formula is not trustworthy. Therefore the physical setup in which one measures $P(t)/t$ events per unit time must use properties as if some measurement/decoherence occurs made in some intermediate range of $t$. What is the microscopic detail of this physical setup, and why is this intermediate range interesting? Edit: Also I would like to emphasize that the nature of $P(t),Q(t)$ is such that whenever one "makes a measurement", the "time since in initial state" is reset to 0. It seems that the "time between measurements" is in this intermediate range. (Of course, this isn't necessarily about measurements, but might be to do with decoherence times or similar too, I'm simply not sure.) People tell me that the Golden Rule is used in calculating lifetimes on occasion, so I would like to understand why this works!     Succinct question: In what sense is $Q(t)/t$ a transition rate?


I have a webform where users can upload images. For easier administration, I created a view of these submissions.  The default behavior of the field is to display as a link. However, I would like to preview the images by displaying them in an image tag.   I looked at the field re-write behavior, but it only gives me the entire href.   How can I display image field values as images in a webform view?

I have created webform with title, description and upload file fields. And I have created views to display submission data in a grid view.   For images, it just giving me the image name with URL to image but it is not displaying as an image. I tried everything, but didn't find any solution. Please give me solution for displaying images in views.


I need the step-by-step solution for this question.  If X and Y are aleatory independent variables with a Poisson distribution whose parameters are $\lambda_1$ and $\lambda_2$, respectively. Show that the aleatory variable $W=X+Y$ has a Poisson distribution too.

$X \sim \mathcal{P}( \lambda) $ and $Y \sim \mathcal{P}( \mu)$ meaning that $X$ and $Y$ are Poisson distributions. What is the probability distribution law of $X + Y$. I know it is $X+Y \sim \mathcal{P}( \lambda + \mu)$ but I don't understand how to derive it.


If the the sentence is started with "'ello 'ello 'ello" should the "e" at the beginning be capital or should I count the omitted "H" still and have it lower case? Because I don't want to be ungrammatical as well as being arrested for impersonating a police officer...

A new Victorian-set British novel begins sentences containing h-dropping with lower-case e's, as in " 'e took my money, 'e did." This seems incorrect but I'm at a loss to find the rule.