over on "World Building" reminded me of a short story I read a long time ago.  I would have read it in the mid 1990s or earlier.  The story itself would have been much older. In the story, humans are involved in a space war.  It seems things aren't going so well, so they've started building "zombie crewmen" out of the bits of biological debris left over from their dead crewmen.  We're not talking reanimation here.  Think "scrape the dead dudes off the walls and use them as raw material." There is mention of deliveries of "material" as "bales." Like the  that comes out of a car crusher, but made of bits and pieces of multiple dead crewmen. The story itself is about a naturally born, newly promoted commander of a small ship (scout or some such that only needs a few crewmen.) He is sent to the "factory" where they produce the "zombies" to pick up the crew for his new ship. Part of the story involves reminiscences about when the zombies were first produced - slow, stupid, suitable only for menial tasks.  There's specifically mention of having to remember to "turn off" a zombie crewman.  Rather, remember to tell them to stop.  The example was that if you told one to polish the bulkhead, it'd keep on polishing the bulkhead until it had worn through the wall. The newer zombies were better.  As good as naturally born human beings in almost all ways. The new crew was not pleased to meet their new commander.  They had been exposed to a lot of prejudice during their training, and were resentful of their treatment.  That, and the one thing that zombies couldn't do - father children. The commander talks to the crewman to find out why they resent him on first sight - the prejudices of the trainers comes out, as well as the reproduction issue. They assume that the reproductive ability has been held back to differentiate between zombies and humans. The commander knows different.  If the medical folks could give the zombies reproductive powers, then they'd also be able to fix sterility in humans - and the commander is sterile due to a near hit on his previous ship with some kind of radioactive weapon. In the end, the commander and the crew bond over their common disability, with the implication that they are going to go out and be heroes so that they'll at least be remembered for their actions.  The humans call the zombies more nasty things than just "zombies." They also call them "blobs."  There are probably more that I don't remember. The zombies in turn have their own words for naturally born humans.  The commander invites his crew to use them all on him and get it out their systems.  He specifically mentions being called "eutie" and "wombat" because he thought words were cute when used in that context.

I read the story many years ago. The solar system was being invaded by insectoid aliens who greatly outnumbered Earth's population. All available people were involved in the war effort and all women were encouraged to have as many children as possible. The story centers around an officer who must command a war ship crewed by artificial people. The protagonist was sterile, I think. The crew's bodies were made up of the bodies of corpses of war dead.


I have a small question.  Is there any differences between:   - String[] name   and    String name[]

I have recently been thinking about the difference between the two ways of defining an array:   int[] array int array[]   Is there a difference?


I am cleaning up XML files that contain HTML by using RegEx.  Some files contain multiple style-elements and I want to remove them all and content in between. For example:    &lt;STYLE&gt;    group 1 &lt;/STYLE&gt;    Random text here which shall not be removed. &lt;STYLE&gt;    group 2 &lt;/STYLE&gt;    Some more random text here which shall not be removed. &lt;STYLE&gt;    group 3 &lt;/STYLE&gt;   I am using the following RegEx with /s parameter   (&lt;STYLE&gt;).*(&lt;\/STYLE&gt;)   Problem is that this RegEx will match everything between <style> (#1) and last </style> (#3).   I would like to match only group, <style>, and </style> elements. How can this be accomplished?

I have this gigantic ugly string: J0000000: Transaction A0001401 started on 8/22/2008 9:49:29 AM J0000010: Project name: E:\foo.pf J0000011: Job name: MBiek Direct Mail Test J0000020: Document 1 - Completed successfully  I'm trying to extract pieces from it using regex. In this case, I want to grab everything after Project Name up to the part where it says J0000011: (the 11 is going to be a different number every time). Here's the regex I've been playing with: Project name:\s+(.*)\s+J[0-9]{7}:  The problem is that it doesn't stop until it hits the J0000020: at the end. How do I make the regex stop at the first occurrence of J[0-9]{7}?


I can include a jpg to a LaTeX document using the \includegraphic command. In a simulation program, the program writes latex code into a .tex file to create a result pdf. A graphic should appear. If I use includegraphics, I need to copy the included jpg file to the working directory (or another fixed path, but then the simulation is system dependent). I would prefer an inline graphic definition in the LaTeX code, such that beside the created .tex no other files are used. The LaTeX-Source is automatically created, therefore long and difficult to read latex code is no problem. Any solutions for this? Thanks! :)

A commonly asked question on this site is how to embed images directly in a .tex source file, without the need for the image to exist in a separate file. Examples of such questions (often marked as duplicate) are         ...   Unfortunately, the answers are all quite a bit outdated. In particular,    Many users responded (years ago) that "the user should simply not want this" and send multiple files as a zip/tar archive instead. However, in this time and age where automatic generation of .tex file becomes more frequent, and single-file text-only generation is much easier (especially when using predefined frameworks) than multifile and/or binary, that argument no longer holds. A package providing such functionality  no longer exists. Another package  provides this functionality but only for bitmap images (png/jpg), not for svg/eps/pdf/other vector formats, and encodes it as HEX which is pretty wasteful compared to base64.   Therefore I would like to reopen this question and ask this again: how can one create a command \includebase64image such that   \includebase64image{png}{iVBORw0KGgokIA...} \includebase64image{pdf}{weEGE2ewFWE58q...}   yields the result of \includegraphicx{a file with content type #1 and contents #2}, namely the image whose content and type are given, appearing at the current location in the generated PDF file?


What is the impact of activating the critical update 'Enable Improved Caching of Org Schema' in a Salesforce instance? Do we have a list of things that we need to verify to activate this critical update?  Understand the critical update from  question. But it would be great if we have a list of items that we need to test before activating this critical update.

This  sounds like a welcome change, but it's not terribly specific. What does this Critical Update actually entail? Will we still be able to sniff hidden object types using Id.getSObjectType()? Will this somehow make it impossible to leak versioned API fields (e.g. LastViewedDate to a < 28.0 class)? This sounds like a great new feature if it eliminates bugs, but the wording seems a bit vague.


In , does the proof given applies to every $C^1$-function or does it need some changes for it to be true?  More specifically, I want to know if the argument that $λ(K)≤∑_i(b_i−a_i)\frac{2ϵ}{2^i}$ works for $f(x)$ as $C^1$-function?

Show that the image of the curve $\Gamma\in\mathscr{C}^{1}\left([a,b]\to\mathbb{R}^{d}\right)$ has d-dimensional Lebesgue measure zero (of course, $d\geq2$).  This can be proved using the absolute continuity of $\Gamma'$ (since $[a,b]$ is compact and $\Gamma'$ is assumed continuous, hence in $L^{1}([a,b])$) together with the fundamental theorem of calculus to obtain an $\epsilon$-small cover of $\Gamma$ by balls.  But I am trying to prove this using more elementary means (i.e. without integration).  Intuitively, since $\Gamma$ is smooth, we ought to (for fine enough partitions) be able to cover $\Gamma$ by boxes which arise from its tangent line.  And by taking the partition of $[a,b]$ to be finer and finer, the "tangent box" cover ought to also get smaller and smaller.  More rigorously, the vector-version of the mean value theorem can be applied: $$|\Gamma(t_{i-1})-\Gamma(t_{i})|\leq(t_{i}-t_{i-1})|\Gamma'(t_{i}^{\star})|\leq M_{i}\Delta t$$ where $t_{i}^{\star}\in(t_{i-1},t_{i})$ and $M_{i}=\sup_{t\in[t_{i-1},t_{i}]}|\Gamma'(t)|$ which exists and is finite since $\Gamma'$ is continuous.  But to me, it's not quite clear how to rigorously construct a cover by boxes from here.  NOTE:  In the proof I mentioned (using integration), essentially you sum the left hand side over all partition intervals of uniform length $\delta$ (which depends on the $\Gamma'$), and "integrate" the right hand side.  Actually, to be more specific, for each $\epsilon>0$ there exists a $\delta>0$ such that $||P||<\delta$ implies $\int_{t_{i-1}}^{t_{i}}|\Gamma'(t)|dt<\epsilon$ (e.g. absolute continuity).  This allows you to define numbers $\epsilon_{i}=\sup_{t,\bar{t}\in[t_{i-1},t_{i}]}|\Gamma(t)-\Gamma(\bar{t})|\leq\epsilon$ so that $\sum_{i=1}^{\#P}\epsilon_{i}\leq||\Gamma'||_{L^{1}([a,b])}$.  Then you can use these $\epsilon_{i}$ to put balls at each point $\Gamma(t_{i})$ of radius (say) $2\epsilon_{i}$, thus giving you an $\epsilon$-small cover.  Again though, this is harder to establish without integration theory.


I have two SSD hard drives.  Both are advertised as 240Gb capacities.  Meanwhile, Windows shows them as only having ~222Gbs.  I see this trend across different storage mediums like flash drives as well.   Why?

Possible Duplicate:          If one buys a 500 GB hard disk, why it shows only 465 GB. Where does the extra space go? Same for other secondary storage devices like pen drives. What is the reason?


Intuitively, I know $[f(x)]^2\ge0$ so the integral would be the area above the x-axis and it would result in $[f(x)]^2=0$ and then $f(x)=0$.  How do I prove this with proper terms. This is a reimann integral.

I am working on a few examples where my author said this is true if $h$ is continuous. Can someone explain why? Just because the integral is $0$ doesn't mean the integrand is zero as well.   $\int_{a}^b h^2=0\implies h=0$?


I'm holding a B1/B2 visa. My last visit to the USA was 3 months ago and I have stayed in the US for 1 and a half months. That means I visited the US in May and stayed until end of June. Then am I allowed to visit the US again in October? This time I'm only planning to stay for a week.   But I have planed to revisit next year in January and May. All these visits will be for a week or one and a half weeks.  Is this allowed with a B1/B2 visa? Is there a particular time period that I need to stay from my last visit to next visit?

I've been re entering US three times this year. First was last February 13 where I entered using a J1 visa but I had to comeback home after 4 days because of some misunderstanding with the sponsor. And then last March 10 I returned to US using a multi entry tourist (B) visa and left on March 31st. Then the third one was last May 22 and then I came back home recently which was 10th of August. And now I am planning to return next month using a multi entry tourist (B) visa again on the same city and state to visit someone.   Will there be any problem when I return to US with an immigration officer?


I'm on Ubuntu 16.04  Trying: grep '.*' file1  Output: file nu-mber o-ne second string  Trying: grep '.+' file1  Output is absent  Why plus is not working?

I wrote a regular expression which works well in a certain program (grep, sed, awk, perl, python, ruby, ksh, bash, zsh, find, emacs, vi, vim, gedit, …). But when I use it in a different program (or on a different unix variant), it stops matching. Why?


I use sometimes some Linux distros, e.g. Ubuntu, and I like the feature they have to add a desktop shortcut to every removable device that is plugged in on desktop - for example, when a DVD is inserted, a new icon for that appears on desktop, and with that I can access, eject etc.  I would like to have the same feature for Windows - specifically for Windows XP Professional SP3, but it is interesting to know the solution for other Windows versions...  Any help?  PS1: I would like to have "dynamic shortcuts", i.e, shortcutes that appears on desktop when the removable device is inserted and that disappears when it is removed.  PS2: I'm talking about CD/DVD media and massive storage devices mainly.

Is there way to automatically display connected mass storage devices on the Windows desktop, like most Unix-based operating systems are doing?  I didn't find any native ways to do that, but maybe there are some third-party tools to add that feature.


Plesae give some hint to solve the following problem:  If $A$ and $B$ are two subsets of a topological space $X$ such that $\overline{A}\cap \overline{B}=\emptyset$, then $\partial(A\cup B)=\partial A\cup \partial B$, where $\partial A$ denotes the boundary of $A$.

Assume $\bar A\cap\bar B=\emptyset$. Is $\partial (A \cup B)=\partial A\cup\partial B$, where $\partial A$ and $\bar A$ mean the boundary set and closure of set $A$?   I can prove that $\partial (A \cup B)\subset \partial A\cup\partial B$ but for proving $\partial A\cup\partial B\subset \partial (A \cup B)$ it seems not trivial. I tried to show that for $x\in \partial A\cup\partial B$ WLOG, $x\in \partial A$ so $B(x)\cap A$ and $B(x)\cap A^c$ not equal to $\emptyset$ but it seems not enough to show the result.


Example code: name = "i am a student" print(name[::-1])  Output: tneduts a ma i

I need a good explanation (references are a plus) on Python's slice notation.   To me, this notation needs a bit of picking up.   It looks extremely powerful, but I haven't quite got my head around it.


This is not a duplicate of . The main question there is only if something "special" will happen if someone edits out the automatic text. The answer addresses this question, but it's from an SE employee; I'm asking specifically for the community's opinion on this, which may be different from SE's position.  Should users with gold-badge dupehammer privileges modify older-style duplicate closures where the duplicate targets were edited into the question body by the Community user, into the newer form of closure where the list is an automatic box added above the post? There exists an official response , but I noticed a user going around and doing this, so I was wondering if the community's opinion was different from SE's.  Here's an  where such a thing was done.  In my opinion, there's no advantage to doing this because:   There isn't much visual change made to the post, other than some formatting differences and that the heading now says "This question already has an answer here" instead of "Possible Duplicate". Those posts are unnecessarily bumped when this action is taken, from both the reopening and the subsequent edit to remove the target list from the post body. The original close voters and original closure date is no longer shown in the question's notice; it instead just shows the one user who performed the modification, and makes it seem like a recent unilateral decision rather than a consensus a long time ago.   I can see one potential benefit: normal users can no longer modify the target list, which now requires a user with gold-badge privileges. But there isn't much evidence of this happening on a wider scale, and as the posts are bumped anyway when that happens, that can easily be rolled back as needed.  Should users go around and change all these old-form closures into the new form? What if a user comes across one of those posts, but it's not active in a while? if it's recently active?  What's the community's position on this?

> **Possible Duplicate:**   > [Possible to remove the link to duplicate question?](https://meta.stackexchange.com/questions/50336/possible-to-remove-the-link-to-duplicate-question)    <!-- End of automatically inserted text -->  Some  have this text at the top of the Markdown. I read a bit on the history, and Shog announced this behavior stopped with changes to the system in :  [R]ather than editing in the banner, it's generated as-needed and displayed separately above the question  I'm not able to find much recent information about this, so I'm just wondering what happens if I remove the banner. Does it make a "real" duplicate banner appear? Will it still be closed as a duplicate? Should I remove it or is there some benefit to keeping it there?


I have started functions unit in my C programming. I am confused with pointers with functions. I understand the normal functions without any pointers, but I am really confused with pointers functions. Let's say I have the following function:  #include <stdio.h> int functions_1(double num1, double num2);  int main(void) {      double mark1;     double mark2;     double total;      printf("Enter marks for subject one: ");     scanf("%lf", &mark1);      printf("Enter marks for subject two: ");     scanf("%lf", &mark2);      total = functions_1(mark1, mark2);      printf("Your average is: %.2f \n", total);  /*      if (total > 50) {                 printf("You have passed. \n");         }         else {                 printf("You have failed \n");         }*/     return 0; }  int fucntions_1(double num1, double num2) {      double average;     double averageTwo;      average = num1 + num2;     averageTwo = average / 200;      return averageTwo; }   How am I going to do the same thing using pointers in C programming? I am not asking you to do the coding, but I want to understand the concept! Thanks

Why are pointers such a leading factor of confusion for many new, and even old, college level students in C or C++?  Are there any tools or thought processes that helped you understand how pointers work at the variable, function, and beyond level?  What are some good practice things that can be done to bring somebody to the level of, "Ah-hah, I got it," without getting them bogged down in the overall concept? Basically, drill like scenarios.


I would like assign this text separated comma to IN. Have you got idea how to do it?  DECLARE @TESTTEXT varchar(200)  SET @TESTTEXT = '101,103,104'  SELECT 1 WHERE '101' IN (@TESTTEXT)

How do I parameterize a query containing an IN clause with a variable number of arguments, like this one?  SELECT * FROM Tags  WHERE Name IN ('ruby','rails','scruffy','rubyonrails') ORDER BY Count DESC   In this query, the number of arguments could be anywhere from 1 to 5.  I would prefer not to use a dedicated stored procedure for this (or XML), but if there is some elegant way specific to , I am open to that.


I wanted to remove "Amazon" from my 14.04 and tried to follow the instructions given here:      However, even after logging off and loggin back in, I see that I get the updates to "Amazon":    "Online search results" have been disabled in Security and Privacy settings. I even tried to remove it from the software center by using the button provided in the above question which says there is no package named unity-lens-shopping. And if I again try to remove unity-lens-shopping from the terminal using sudo apt-get remove unity-lens-shopping, unity-lens-home is selected and nothing is actually removed and I get the following output:  Reading package lists... Done Building dependency tree        Reading state information... Done Note, selecting 'unity-scope-home' instead of 'unity-lens-shopping' 0 upgraded, 0 newly installed, 0 to remove and 29 not upgraded.   I just ignore the 29 packages to be upgraded, for now, should be unrelated(?)  Trying to remove unity-lens-home I get a E: Unable to locate package unity-lens-home error.  How do I completely remove the shopping app from 14.04 to stop receiving updates for this application?

How can I disable Amazon search results in the Dash?


Let $A, S$ be commutative rings with identity, and assume $S$ is a finitely generated $\mathbb{Z}^{\geq 0}$-graded $A$-algebra. If $f\in S$ is a homogeneous element of positive degree, $S_f$ is a $\mathbb{Z}$-graded $A$-algebra. Is $(S_f)_0$ (the ring of degree $0$ elements) finitely generated as an $A$-algebra?     It seems to come down to a simple combinatorics problem with exponents that i'm too dumb to do.   (why?: I'm trying to show quasiprojective $A$-schemes have finite type)

Let $S = \bigoplus_{n\ge 0} S_n$ be a graded commutative ring. Let $f$ be a homogeneous element of $S$ of degree $> 0$. Let $S_{(f)}$ be the degree $0$ part of the graded ring $S_f$, where $S_f$ is the localization with respect to the multiplicative set $\{1, f, f^2,\dots\}$. Suppose $S$ is finitely generated algebra over $S_0$. Then $S_{(f)}$ is a finitely generated algebra over $S_0$.


Question: Why do uninitialized objects of built-in type defined inside a function body have undefined value, while objects of built-in type defined outside of any function are initialized to 0 or ''?  Take this example:  #include <iostream> using std::cout; using std::endl;  int ia[10];                   /* ia has global scope */  int main()  {     int ia2[10];              /* ia2 has block scope */      for (const auto& i : ia)         cout << i << " ";     /* Result: 0 0 0 0 0 0 0 0 0 0 */      cout << endl;     for (const auto& i : ia2)         cout << i << " ";     /* Result: 1972896424 2686716 1972303058 8                                  1972310414 1972310370 1076588592 0 0 0 */     return 0; }

Is global memory initialized in C++? And if so, how?  (Second) clarification:  When a program starts up, what is in the memory space which will become global memory, prior to primitives being initialized? I'm trying to understand if it is zeroed out, or garbage for example.  The situation is: can a singleton reference be set - via an instance() call, prior to its initialization:  MySingleton* MySingleton::_instance = NULL;   and get two singleton instances as a result?  See my C++ quiz on on multiple instances of a singleton...


I have both systems right now. I have installed Ubuntu from CD. My XP is divided in two parts (system and local disc). I would like to uninstall XP and install it again fresh.  There is no option to uninstall XP at Add/Remove Programs.  How can I do that with keeping my local disc intact?   Thank you very much! :)  Nikoleta

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!


I have formatted my PC that had windows 7 on it. Before the formatting I have backed up my information.  Now, when I try to access it I encountered a problem:  I have encrypted the files using windows 7 folder encryption and now I have no access to these files. I have the password of the user account.  how do I recover the files?  Thanks

I have a pc with some encrypted file on it (shown in green) these files were created and encrypted by a user who has since then been removed from windows. I can see the files, but when I click on them nog preview (these are jpg files) is shown and I cannot open or copy them.   From what I've read on  there seems to be no solution for this problem unless one has exported their certificate or public/private key, wich this user did not.  Anyone here have or know of a solution for this ?  thanks, Jurjen.


I need to show that if $H$ and $K$ are subgroups of $G$, then $H \cap K$ is also a subgroup.  My working:  $I \in H, I \in K$, $I$ is unique $\implies I \in H \cap K$, so identity present in $H \cap K$  $h_c \in H \implies h_c^{-1}\in H$ and   $h_c \in K \implies h_c^{-1}\in K$ so  $h_c \in H, h_c \in K \implies h_c \in H \cap K$ and  $h_c \in H, h_c \in K \implies h_c^{-1} \in H \cap K$  so inverse of every element present in $H \cap K$.  $h_c, k_c \in H \implies h_ck_c \in H$  $h_c, k_c \in K \implies h_ck_c \in K$  $h_c, k_c \in H, h_c, k_c \in K \implies h_c, k_c \in H \cap K$  $h_c k_c \in H, h_c k_c \in K \implies h_c k_c \in H \cap K$  so $H \cap K$ is closed.  Is this correct? Do I need to say anything else?

$P$ and $Q$ are subgroups of a group $G$. How can we prove that $P\cap Q$ is a subgroup of $G$? Is $P \cup Q$ a subgroup of $G$?   Reference: Fraleigh p. 59 Question 5.54 in A First Course in Abstract Algebra.


I'm reading a Javascript (ES6) book, and in Chapter 7 (Scope) there's an obscure example (at least for me as a beginner) that I can't wrap my head around.  const f = (function() {             let count = 0;             return function() {                 return `I have been called ${++count} time(s).`;                 }             })();  f(); // "I have been called 1 time(s)." f(); // "I have been called 2 time(s)." //...   So, the count variable is initialized at 0 but, why is the value of it still "alive" in subsequent calls to the f function? is the first unnamed function still valid behind the scenes somewhere in memory or anything like it?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, variables and the like), but does not understand closures themselves?  I have seen  given on Wikipedia, but unfortunately it did not help.


Related:    Except for the obvious cases $n=0,1$, are there any values of $n$ such that $\sum_{k=1}^n\sqrt k$ is an integer? How does one even approach such a problem? (This is not homework - just a problem I thought up.)

Can a sum of a finite number of square roots of integers be an integer? If yes can a sum of two square roots of integers be an integer?  The square roots need to be irrational.


In many books in Measure Theory area the concept of "$\sigma-field$" was applied to define a new measure especially probability measure. I saw in some papers and books the concept of "$\sigma-algebra$" was applied to define the uncertain measure. Is difference between them?

The subject says it all: is there any difference between the two concepts of $\sigma$-algebra and $\sigma$-field? In probability theory, they seem to be used more or less interchangeably. If there is no difference, is there any historical reason why some people/schools use the term $\sigma$-algebra, while others use the term $\sigma-$field?


I currently have Ubuntu 12.04 but plan to upgrade to the newest version. I have an HP Pavilion a1310n that is about 10 years old. It runs fine and I am hoping to get the last year or two out of it. Does anyone know if I can get an HDMI interface card working with Ubuntu in this PC? What problems am I most likely to run into? I see there have been problems with sound. fyi, I also have a Windows PC and plan to use a KVM switch to connect to my acer H233H monitor, etc.

I'm thinking about installing Ubuntu Desktop, but I don't know what flavor is the best for my system. What are the minimum and recommended hardware requirements? What kind of CPU? How much memory? Should I have Hardware Acceleration? What flavor should I use?  This is an attempt of a canonical answer. My answers have the "official  requirements", the recommended are a mix of official sources and opinion based (along with the answer it's told the source). You can comment or edit if you feel that the information is obsolete or incomplete. It is a good rule of thumb that any system capable of running Windows Vista, 7, 8, x86 (Intel) OS X will almost always be a lot faster with any Ubuntu flavor even if they are lower-spec than described below.


Currentyl I am using a template from our university which is from 2010. I added some packages etc. but now I am not sure if there are "duplicates" of packages I am using.  For example I have   \usepackage{xcolor}  \usepackage{color}  \usepackage{graphicx}   Where I would say {color} is not needed any longer? There are some more packages where I cannot say if there are newer ones which replaces them. So is there some ressource where stand something like:  color -> xcolor (xcolor provide the same as colour and add features)  Or may even a discrete package which test my code if there are "old" packages or if I have some compability issues?

I'm an on and off user of LaTeX so I'm not familiar with every package out there. Having said that, whenever I use LaTeX and need to accomplish a certain goal (i.e. ), I search around and find some kind of solution that involves a package that I didn't know about. I think that's great, I learn something new, and it goes in my template file.  Every now and then, though, my search comes up with a package that, after much wrangling, I find out that it's obsolete. An example of this is just recently I came across the subfigure package and wanted to try it out. Soon after I found out from here that it has become . I usually keep my TeX up-to-date because I like keeping up with new XeLaTeX features.   My question is, is there a map or timeline of what TeX packages should be avoided because there are better ways of doing things? An idea I have is some kind of list of all packages split by what they accomplish, then cancelling out packages whose features are incorporated into and improved upon by newer packages.  Edit: another example is lscape versus pdflscape. The latter implements rotating pages in the final PDF not just for pdftex but also for other drivers such as xetex. The only way I found out about this was Googling latex lscape rotate xelatex, for which the second link leads to the  (PDF).  Great answers so far. I'll check them out and see which one works best for me.  Edit 2: Turns out that my question is a bit of a dupe in the sense that a great answer came up on an unrelated question. The nag package . Gotta try it!


Sometimes, when I click a link it will open a new tab. Is there a way to forbid Chrome from doing so?  Steps to produce the problem.   Go to  On the "CHOOSE DATABASE" drop-down list, choose any database On the "CHOOSE DATASET" drop-down list, choose any dataset Click "Results" on the top left. Click "Go" on the top right. -> A new tab will be create and once the file is downloaded the tab will be closed.

I'm looking for a solution to forbid links in Google Chrome to open new tabs (in most cases it is a target="_blank" issue).  So, I want all links to open pages in currently active tab, not in new tab.  I tried a wide range of addons (for ex. "Death to target=_blank") and greasemonkey scripts that are supposed to remove target=_blank attribute but none of them worked.  It is extremally anoying when I want to switch between accounts in GMail or navigate from GMail to GDrive. I always get the new tab opened and I need to close last tab manually.


The only scene I remember is a bunch of humans being let out of somewhere so that the ogre-like creatures can see what they eat over a cctv I think. At one point a human finds a rat and starts eating it immediately. One ogre creature responds to this by saying something like "eww, don't they want to cook it first."   That's all I can remember.

I saw this movie a while back. I don't remember how it starts, but from where I remember watching it, it may have not been too far from the start. Apparently, Earth has been conquered by some alien empire or something and humanity are basically cavemen being used as slaves. From what I remember, the main antagonist alien is seen taking one of the slaves to a room where a machine is used on him to make him smart; this is apparently a big no-no so the main antagonist and his sidekick have to keep it quiet. The idea was that by making one of the slaves smart, it could increase the work output of the others. Apparently the antagonist is using the slaves on Earth to gather gold bullion  which is apparently still very valuable to the aliens but he's doing it illegally (not the slave labor; that's apparently ok). The protagonist who had the machine used on him becomes the intermediary between the slaves and the aliens and begins teaching the other slaves. I remember him teaching them mathematics and I remember him saying that it was universally accepted (I think he may have been referring to algebra or trigonometry). At some point he becomes aware that they are slaves and organizes a plan to free not only his fellow slaves but the Earth. Some escape and find an old museum which has old flight simulators, and shows that humanity wasn't always a slave race and that it may have been modern times in which Earth was invaded (i.e. no lasers or starships). I think they also find Fort Knox as there is a huge collection of gold bricks and weapons. The protagonist comes up with a plan to destroy some sort of teleporter the aliens use to transport stuff to and from Earth, however that alone wont be enough as they could fight back, which will be bad for humanity, which is still undeveloped. So the plan also includes using the teleporter before destroying it to to transport and detonate a nuclear warhead on the alien home world which apparently cripples any attempt to immediately send a fleet but also as a show of strength. After executing their plan, the main antagonist is captured by the humans and as an insult is locked in a cage surrounded by the gold he sought. If I recall correctly the place is set to detonate as to destroy the precocious gold and that will be used against the aliens should they mobilize a fleet in the future (i.e. attack us and we destroy Earth's supply of gold). The antagonist's side kick for some reason I remember as a big black man from whom the antagonist had removed his hand at some point and also apparently the antagonist was cruel to him. After the antagonist is locked up, he is trying to appeal to his sidekick's loyalty, however the sidekick takes the humans' side, I'm also getting an image that apart from treating him kindly the sidekick's missing hand was restored.


When using tmux, I have issues of ghost characters when using the Up and Down arrow keys in Bash. If I press UpArrow a few times and then press DownArrow a few times, then the first few characters of a previous command remain on the Bash line.  For instance, take this clean Bash line:  $   Now I press UpArrow three times:  $ ls /home/dotancohen/Downloads   Now I press DownArrow three times:  $ ls /home/do   I can reproduce the issue with no ~/.tmux.conf file, after exiting and restarting tmux. How should I diagnose this?  Edit: Here is my $PS1:  $ echo $PS1 \[\] - \h():\W$ \[\]   Note that everything from the second backslash up until the last close bracket is green. This function creates the prompt:  PROMPT_COMMAND=$(     cat<<-'EOF'      retval=$?      RED=$(tput setaf 1)     GREEN=$(tput setaf 2)     STOP=$(tput sgr0)      c=0     for i in $retval ${PIPESTATUS[@]}; do ((c += $i)); done      if (($c == 0)); then         PS1="\[$GREEN\] - \h(${WINDOW}):\W$ \[$STOP\]"     else         PS1="\[$RED\] - \h(${WINDOW}):\W$ \[$STOP\]"     fi EOF )

I've written this nice and colorful prompt for my OS X terminal:   parse_git_branch() {     git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ [\1]/' }  export PS1="\e]2;\w\a\e[1;30;1m\][\u@\[\033[0;36m\]\h\e[1;30;1m\]:\[\033[0;35m\]\w\e[1;30;1m\]] \[\033[0;31m\](\t) \[\033[0;33m\]\$(parse_git_branch)\n\[\033[0m\]\e[1;30;1m\]\$\[\e[0m\]"   I source ~/.bash_profile it and it works fine. except when I use the arrow up to navigate the history I get a weird thing happening.   basically the beginning of the source ~/.bash_profile command in the history, becomes part of the prompt. when I ctrl+c or enter it returns to normal, but as soon as I see the history of the source command the prompt changes again.   Here's an example where I've seen the history and then ctrl+u and typed ls:   [user@host:~/Documents] (14:01:40)  [branch] $source ~/.ls   Any clue about this?


I posted a question.  After messing around on my machine for about an hour, I found a solution.  Would it be more appropriate to remove the question, or to add the answer to it just to save some other poor idiot the trouble I went through?  Re: The duplicate.  I was asking in a specific situation whether it is more appropriate to give an answer or delete a question to which I was able to find an answer soon after asking.  I see this as being somewhat different from the situation of the other question.

I might want to answer my own question because:  I arrived at a solution before there were any other correct answers or I like mine better, can I still answer my own question?  I have a folder with lists of code snippets for things I always forget or get wrong, such as regular expressions for processing XML, common WinForms control idioms, etc. Is it considered poor etiquette for Stack Overflow to ask a question I already know the answer to, and then self answer, just so it gets recorded on the website?   Related:          For more information, see "" in the .


I wanted to append a new entry after an ajax request. This works perfectly. Unfortunately the design is messed up, and as I inspected my document the html has been loaded perfectly, but e.g. trying to access the data-status attribute of the recently inserted always fails.  What did I do wrong?  $('.newRoomSubmit').click(function(){                      if($.trim($('.roomName').val()) != "" && $.trim($('.roomDescription').val()) != "" && $.trim($('.building_id').val()) != ""   ){                         $('#myRoomModal').modal('hide');                      $.ajax({                         type : 'POST',                         url : '@routes.Admin.saveNewRoom()',                         data : {                             roomName: $('.roomName').val(), roomDescription: $('.roomDescription').val(), building_id : $('.building_id').val()                         },                         success : function(data) {                           var newReference =  reference.parent().parent().parent().children().eq(1).append(                       '
'+       '
'+$('.roomName').val()+'
'+       '
 '+ '<button class="btn  btn-sm btn-default editableRoom" data-status="'+parseInt(data,10)+';'+$(".roomName").val()+';'+$(".roomDescription").val()+';" data-toggle="modal" data-target="#roomEditModal"></button>'+ '<button class="btn btn-sm btn-danger removableRoom" data-status="'+parseInt(data,10)+';'+$(".roomName").val()+'" data-toggle="modal" data-target="#confirmRoomDelete"></button>'+       '
'+        '
');                          },                          error : function(err) {                              alert(err.responseText);                              }                         });                     } else {                         alert("Das Formular wurde nicht vollständig ausgefüllt!");                     }                  });   The design after my insertion looks like this, I added a red box and 2 red lines by way of illustration, just so that you can distinguish the difference:   The real problem is, that after my insertion I click on the button with the pencil-glyphicon in the inserted row. As my modal shows up, it doesnt get the data-status of the html as input. But as I inspected that row in my browser, I could clearly see that the data-status has been added correctly to the new row.  This is how it should look (example of one row above).   Why does my jquery has problems with it?  The click method of the pencil-icon on the newly inserted row should put the values into my input tags and it looks like this:  $('.editableRoom').click(function(w) {                    w.preventDefault();                    var statusCode = $(this).data('status');                      var felder = statusCode.split(';', 3);                     $('#roomEdit_id').val(felder[0]);                    $('#roomEditName').val(felder[1]);                    $('#roomEditDescription').html(felder[2]);                    $('#editRoomSubmit').click(function(){                         /** on click wird das modal versteckt und                         der User bekommt wieder die neugeladene lab Seite zu sehen*/                         $('#roomEditModal').modal('hide');                     });                 });   I researched here  and here  but it doesn't seem to relate to my problem.  Thanks in advance :), I would really appreciate your help :)!

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.


My attempt:    50! = 50 * 49 *48 ....    Even * even = even number    Even * odd = even number    odd * odd = odd number    25 evens and 25 odds    Atleast 26 of the numbers will lead to an even multiple (24 evens + 1 even * 1 odd) so at most 26 trailing zeros.   50 is divisible by 5: 10 times. Atleast 10 trailing zeros.   What is the answer?

Question: How many  zeroes will there be at the end of $(127)!$  Approach: Considering the fact that when two numbers ending in $x$ and $y$ zeroes are multiplied, the resulting number contains $x+y$ zeroes: The numbers to be multiplied that contain zeroes: $$120,110,100,90,80.....10$$ That comes out to be a total of 13 zeroes. However, that doesn't seem to be the correct answer. Rethinking it, it's obvious that I'm missing out on several cases. For example: $$25*22 = 550$$ This is just one of the cases which will add a zero. How would I account for all these cases?


If I ready the cantrip Gust to push back the first enemy that tries to use a (melee) attack against my party, what happens if the push back was successful?     Does it interrupt the attack? Does the attack simply fail through the push back? Does it allow the enemy to walk forward again and attack anyway?   What exactly happens?

Scenario: A druid ally is in melee range of an enemy berserker and decides to move away, provoking an attack of opportunity from the berserker. My character has readied an action: Cast Eldritch Blast (with Repelling Blast invocation) on the berserker in question if he attacks the druid. What I think happens The druid's movement is interrupted by the attack of opportunity which is in turn interrupted by the readied Eldritch Blast. Assuming the Eldritch Blast hits, I can push the berserker out of melee range of the druid, thereby negating the attack of opportunity. Is this correct? Similar situations What if, rather, the trigger was the druid moving? What if the trigger was the berserker raising his weapon or rearing back in preparation for an attack?


I was assigned by the lecturer to conduct a user experience evaluation on an existing website. Then in the question, he asked us how you quantify user experience and heuristic that you will be using for your expert review. I thought ux is about feelings and experience? how do you quantify it? Is it correct if I say by doing research such as questionnaire?

This morning i was looking online for articles that could lead me to a method that can be used to measure/quantify usability & user experience. The method i was interested in finding more information about, is about whether it is possible to have a set of good practices that can help in grading an overall system, both in it's prototype stage and even when creating mockups.   Obviously heuristic evaluation and user testing are key elements in developing a good user experience, but i was wondering if before these stages begin and testing is conducted there might possibly be a method for grading your mockups/prototypes internally before going forward to stakeholders and begin testing?   All answers and feedback are welcome as of yet i have been unable to find something that is similar to what i'm describing, i've read up about:  SUM (Single Usability Metric) -   System Usability Scale -


I installed these applications on my Ubuntu:   nginx php5-fpm mysql server redis ...   These applications run every time the computer turns on.  How can I prevent these applications from running on start up? So, these applications only run if I do "service nginx start".

I read about how to enable and disable services in Ubuntu and it seems that there are different possibilities to manage them.  The first method I found is update-rc.d to add new services to startup, which aims on the /etc/init.d folder and its contents.  The other one I found is to edit .conf files in the /etc/init folder.  What's the recommended way to enable / disable / add services and why?  Could you please give a short bulletproof step by step example on how to add a service in Ubuntu and enable and disable it?


Judging by a lot of the questions on this site, a career in Academia sounds very grim. Lots of pressure, extreme working ours, few benefits, mediocre salary, and, because one has to work with so many different people (supervisors, students, collaborators, HR, editors, etc., etc), one is more likely to run into social issues, as evidenced by the questions on this site.   So why then do so many people go into Academia? Is it really just a reason not to grow up?   "Passion for the field" doesn't sound very convincing either, when one considers that only a small, small minority of Academia actually produce worthwhile, interesting results. The rest are just scrambling for any sort of recognition by constantly publishing mediocre results that will be cited twice over the course of the next 10 years. Rinse and repeat. Really, a lot of these people are just glorified teachers whose main contribution is giving lectures or conferences. When one considers the rising academic dishonesty, fabrication, plagiarism, and so on, the picture becomes even worse.

This is in reference to my question: .  I was told in the answer of the above linked question that chances of landing a job as an assistant professor in Mathematics are quite slim. Very few people will actually get a permanent position in academia.  An article of 2014 shows only 0.5-3% of PhD graduates will actually get a job as an Assistant Professor.  But I have two questions:        Why do so many people still apply for a PhD in some reputed institutes in India even knowing the harsh reality? I found there are 1500 applications for four PhD scholarship positions.          One answer says that people move to industry, but I still don’t understand how after doing a PhD in suppose differential geometry or algebraic geometry one can do a job in industry if he/she gets no position as an assistant professor.   Will one be satisfied to do some managerial work in some Consultancy firm after doing a PhD in Mathematics?      Are people jobless after a PhD?   Completion of a PhD requires so much effort. So why is there no value after doing it?      NOTE:  In the most up-voted answer below it has been said that many who enroll for  a PhD don't even wish to pursue an academic career.  I have been asking my seniors who are currently pursuing a PhD or are in the verge of completing their degree or who have completed it. They said that they all want to be Professors in some Universities and want to be involved in research because that is the dream job for them.  I am obviously talking about PhD in Mathematics


I am trying to calculate the area draining to a point of 240 separate points using QGIS. At the moment I'm using the Saga - Upslope Area algorithm to individually work this out for each of the 240 points using their coordinates and a DEM input. This is very time-consuming so is there is a quicker more efficient algorithm which would allow me to input the whole vector file for the point data to simultaneously output the upslopes for all the points at once?

In the Upslope Area tool from SAGA it used to be possible to import the point file with multiple points and it would create several catchment/basins areas for those points. Now, it is only possible to MANUALLY enter coordinates for only 1 point. However, for a model we're building, we need to perform this analysis 24 times (as we have 24 different points) so we need to automate this process. I tried to use Run as Batch process + calculate by expression and get the XY coordinates from another layer, however, I run into the problem that I need to reference the XY coordinates that are stored in the other layer and looks like there isn't an easy way of doing so. Any suggestions on how to do that? Tried the geomwithin(targetLayer,targetField) from RefFunctions plugin but that produces empty result  so to resume, I have two questions:   How to calculate upslope areas for multiple points? Is there a way to automatize it in the graphical modeler?


Let $u: \Bbb R^2 \to \Bbb R$ be an harmonic function, then there exists an holomorphic function $f: \Bbb C \to \Bbb C$ s.t. $Re(f)=u$. The only hint I have are the Cauchy–Riemann equations: $$u_x=v_y \\ u_y=-v_x$$ I don't see how I can use it... Can someone pls helps me?

Is there a way to show that every harmonic function is the real part of a holomorphic function without using integration equations if later theorems are allowed also?


have this class:   public static class Command {     public const string SET_STB_MEDIA_CTRL = "SET STB MEDIA CTRL ";     public static string ECHO = "ECHO";     public static string SET_CHANNEL = "SET CHANNEL ";     public static string GET_VOLUMN = "GET VOLUMN";     public static string GET_MAX_VOLUMN = "GET MAX VOLUMN ";     public string SET_STB_MEDIA_LIST = "SET STB MEDIA LIST "; }   then:   public static class MultimediaConstants {     public const string VIDEO = "video";     public const string AUDIO = "audio";     public const string PHOTO = "photo";     public const string ALL = "all";     public const string BACKGROUND_MUSIC = "background_music";     public const string TV = "tv";     public const string ACTION_PLAY = "play"; }   point is, that I would like to have something like this:   public static string SET_STB_MEDIA_CTRL (MultimediaConstants type,  MultimediaConstants action) {     return Command.SET_STB_MEDIA_CTRL + "type:" + type + "action:" + action; }   So the result of this method should be:    SET STB MEDIA CTRL type:tv action:play   The call of the method will be:    SET_STB_MEDIA_CTRL (MultimediaConstants.TV, MultimediaConstants.ACTION_PLAY);

I have the following enumeration:  public enum AuthenticationMethod {     FORMS = 1,     WINDOWSAUTHENTICATION = 2,     SINGLESIGNON = 3 }   The problem however is that I need the word "FORMS" when I ask for AuthenticationMethod.FORMS and not the id 1.  I have found the following solution for this problem ():  First I need to create a custom attribute called "StringValue":  public class StringValue : System.Attribute {     private readonly string _value;      public StringValue(string value)     {         _value = value;     }      public string Value     {         get { return _value; }     }  }   Then I can add this attribute to my enumerator:  public enum AuthenticationMethod {     [StringValue("FORMS")]     FORMS = 1,     [StringValue("WINDOWS")]     WINDOWSAUTHENTICATION = 2,     [StringValue("SSO")]     SINGLESIGNON = 3 }   And of course I need something to retrieve that StringValue:  public static class StringEnum {     public static string GetStringValue(Enum value)     {         string output = null;         Type type = value.GetType();          //Check first in our cached results...          //Look for our 'StringValueAttribute'           //in the field's custom attributes          FieldInfo fi = type.GetField(value.ToString());         StringValue[] attrs =            fi.GetCustomAttributes(typeof(StringValue),                                    false) as StringValue[];         if (attrs.Length > 0)         {             output = attrs[0].Value;         }          return output;     } }   Good now I've got the tools to get a string value for an enumerator. I can then use it like this:  string valueOfAuthenticationMethod = StringEnum.GetStringValue(AuthenticationMethod.FORMS);   Okay now all of these work like a charm but I find it a whole lot of work. I was wondering if there is a better solution for this.  I also tried something with a dictionary and static properties but that wasn't better either.


With L being a linear operator on a complex vector space $V$ show that $L^{_\dagger}L$ is Hermitian with non negative eigenvalues  I don't really have much of an idea how to do this exercise in such a general example. The proof of non negative eigenvalues is especially eluding me. Any ideas?

Let $L$ be a linear operator on a complex vector space $V$, how to show that eigenvalues of $L^\dagger L$ are positive? I guess this might be a statement taught in a functional analysis class or an advanced linear algebra class?


I design my very own .js file and the file will be import into browser extension to use. One of my friend wanna get the source from me but I don't feel like given my design source code to other, thus I said I would like to share the file to him. But how can I lock the file or encrypt the code, so he is unable to review my source code.  With what I found out here  The result is expected, but the issue is my friend still can open the .bat with editor and review the password to unlock, which is also not very good protection tho.  Expected outcome: Browser extension is still able to read the locked folder. Password is not reviewable from others

I want to make a JavaScript application that's not open source, and thus I wish to learn how to can obfuscate my JS code? Is this possible?


NOT A DUPLICATE OF:  That question diverges off into stuff about calories and energy density and other stuff, which I'm not interested in here. And doesn't seem to talk much about time-frames. The answers either address the calories, or talk about conservation of mass, which is clearly not what is interesting.  Suppose I eat a pound of something (cake, or chocolate, say. Or a second portion of pasta salad).  Obviously, 1 minute after I eat it, I will be 1 pound heavier, but that's not very interesting.  And 1 week later, it seems extremely likely that I will be some amount heavier than I would have been if I had done everything else exactly the same, but not eaten the cake.  Note, that I'm deliberately excluding any behavioural changes! Assume that the difference between eating it and not eating is literally the only the food entering my mouth.   Are there complex biological processes that could lead to me being more than 1 pound heavier, after that week? Or is the weight-gain tied to a single consumption strictly bounded by the mass of that consumption?    For those wondering what I might be imagining ... I don't know, maybe the body stores 2 extra molecules of X (that it would otherwise have not digested at all) for every molecule of Y that it ingested, in the previous day. i.e. having eaten the cake on Monday means that I retain more of the food I ingest on Tuesday, than I would otherwise have retained. Or maybe there's some complex process whereby oxygen in the blood gets captured and stored with the ingested food over time, so that the extra mass comes from air breathed in over the course of the next day. I'm no biologist, so I haven't the faintest idea what could be plausible and what could be utterly ridiculous. Hence the question :)

We all know that about 3500 calories is equivalent to 1 pound (7500 cals for 1kg).  So can a piece of food weighing one pound have more than 3500 calories?  What are the highest and lowest energy dense foods? and will consuming the former make you less full while the latter make you feel fuller for less calories? or do the calories consumed cause you to feel full?  Is there a limit to how many calories can be in 1 pound of food (including artificially made "foods")?


Is there a way in Tikz to have the label angle computed automatically when adding a label on top of an arrow ? Here is what I am looking for : \draw[->] (start) -- node[MAGIC HERE, above]{my label} (end);

I have created a simple node-edge graph in which I would like to have the texts on each edge aligned to the direction of the edge.  \documentclass[class=minimal,border=0pt]{standalone} \usepackage{pgf} \usepackage{tikz} \usetikzlibrary{arrows,automata} \usepackage[latin1]{inputenc} \begin{document}  \begin{tikzpicture}[->,>=stealth',shorten >=1pt,auto,node distance=2.8cm,                     semithick]   \tikzstyle{every state}=[fill=red,draw=none,text=white]    \node[state]         (D)                     {$D$};   \node[state]         (C) [below right of=D]  {$C$};   \node[state]         (B) [above right of=D]  {$B$};   \node[state]         (A) [below right of=B]  {$A$};    \path (D) edge              node {tdc} (C)                     (B) edge              node {tbc} (C)         (C) edge              node {tca} (A); \end{tikzpicture}  \end{document}   For example, I would like the text tbc rotates -90 degrees automatically to be aligned to the direction of the edge connects the node B to the node C. Is that possible?


Any compact subset of  $\mathbb{R}_{l} $ must be a countable set.   Consider the open cover $\{[n,n+1): n \in \Bbb Z\}$ of $\Bbb R $ which has no subcover. So $\Bbb R $  is not compact with respect to .  But how to answer this question?

How to prove that every compact subspace of the  is countable?


Why the function give me the same value when I want it to change every time I choose other radio buttom     <form>     <input type="radio" id="male" name="gender" value="male">     Male
     <input type="radio" id="female" name="gender" value="female">     Female
     <input type="radio" id="other" name="gender" value="other">     Other     <button onclick="addSpan()">Try it</button>  </form>  this is function

I'm using  to go through JavaScript, and it's returning many suggestions to replace == (two equals signs) with === (three equals signs) when doing things like comparing idSele_UNVEHtype.value.length == 0 inside of an if statement.  Is there a performance benefit to replacing == with ===?   Any performance improvement would be welcomed as many comparison operators exist.  If no type conversion takes place, would there be a performance gain over ==?


I have seen that users ask questions related to code and, when they get solution to their current problem, they just make those changes to code in current question itself and change the question asking their next problem. This makes the already given answers irrelevant to the current question.   So is there any way to mark such questions?   I just commented that its better to add a new question than editing same question.

I'm not sure if there's already an existing term for this, so I'm inventing my own. (tl;dr: I call them "chameleon questions" because they change every time you submit or edit an answer.  If you're already intimately familiar with the phenomenon, please skip past the first set of bullet points to where I ask for recommendations.)  I think many of us have experienced this on occasion:  You open up a narrow-looking question, usually dealing with some specific error message.  The question probably contains a snippet of sloppy but not quite awful code; code indicating that the author, typically a new/low-rep user, possibly a , doesn't really know what they're doing.  I'm not trying to be condescending here, they're probably very intelligent and hardworking, but in this specific case, they're clearly in way over their head.  However, as a question, it's not really too bad.  The goal and problem are both clearly stated.  The code is formatted (sort of).  Mort was polite and checked their spelling.  The question looks answerable, although from a rep perspective* it's an obvious dead-end, it's had maybe 3 views in the past 30 minutes.  So you decide, you know what, this person took the time to write up the question properly, they deserve an answer, put on your good citizen hat and throw them a bone.  You slog through the ugly code, find the offending line, direct their attention to it and explain why it's wrong and how it needs to be fixed.  Later, they leave a comment saying that yes, that was indeed the problem and your answer helped them fix it (great!).  Oh, but, now there's another problem (uh-oh...). Something else is broken.  After letting out a long sigh, you read the comment and/or edited question, roll up your sleeves, and write up Take 2, hoping that's the end of it.  And of course it's not the end.  Now maybe the error is gone, but it's not doing what it's supposed to.  If you're anything like me, your patience is now starting to wear thin. It's lousy code and you didn't volunteer to help them rewrite their whole app.  And of course, the question still only has 12 views, and nobody has upvoted either the question or your answer, including the person you're helping, so this is turning out to be a genuinely thankless task in all respects.  Welcome to "Family Tech Support", Web 2.0 Edition.   * Which is of course just an arbitrary number that none of us care about. Not really, anyway. Not very much, at least.  So, here's where I get to my question.  At this point, do you:  Leave a comment, stating as politely as possible that you've done your best to help them answer the original question they asked, and if they have a new problem then they should start a new question?  (I did this once, and actually ended up with an accept, but I felt kind of guilty afterwards, I don't think anybody answered their 2nd question).  Bite the bullet and edit your answer a 3rd, 4th, 5th time, however many times it takes to resolve their issue, knowing full well that they may not even remember to accept the answer once you're done? (I may work for free on SO, but that doesn't mean my time is worthless.)  Just abandon the question, hoping that it will force Mort to start thinking for himself?  Something else?   I've tried all three of the above and none of them ever quite feel right. I do want to help, but at the same time there are a lot more "lucrative" questions I could be answering. And I don't mind spending a lot of time on an answer either, if the question is interesting or important to me, but debugging is dull work. I'd prefer not to reference specific questions here; I'm pretty sure that this is a shared experience, and my objective isn't to point fingers at "misbehaving" members.  I'm more looking for some practical advice on how to dig myself out of these pits of despair. Anybody have any other ideas?


I am not an experienced Ubuntu user.  I updated my existing 12.04 until no more updates were available and then I chose to upgrade my system to version 12.10.  All went well (or at least I thought it did) until I was prompted to "Restart" the system.  Once I restarted the system I could hear my HDD doing its thing and then saw the screen come on and it said something about either waiting for something to happen (which I chose to do) or press "S" to skip mounting or something like that (I couldn't read it fast enough).  Anyhow, the computer locked up and it wouldn't boot into Ubuntu.  I powered the system down and restarted it hoping to see the message again, but it didn't return.  It just locked up during the boot process and I haven't seen my login screen again.  I have a dual boot configuration with Windows Vista Home Premium (32-bit) and I have never had a problem upgrading in the past.  My processor is an AMD 64-bit and I have always used the 64-bit version of Ubuntu with no problems.  I would appreciate your help in this matter.  Sincerely,  Dennis

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


So my brother and I are connected to the same network, my brother has hosted a LAN world that my dad can connect to but my computer cannot, he has a mac and I have a windows 8 laptop. I have tried disabling windows firewall completely as well as enabling both private and public connections to Java through windows firewall. I have tried using direct connect, both by entering the ipv4:port of LAN as well as just the port. We are all running minecraft 1.9. Help me please because I am dying inside.

My LAN server won't let my cousin join me or me join my cousin. It won't show up on the multiplayer screen - it keeps saying "scanning for LAN servers" but it never finds it. I am at his house and we use different computers but it won't connect. How can I fix this?


I would like to extend my  and know how to type a comment, using delimiters, in any table cell to be suppressed in the compiled PDF without the need to use, for example, \iffalse...\fi.  For instance, here, the comment delimiters are << and >>.  \documentclass[border=1cm]{standalone} \begin{document}  \begin{tabular}{cc}     \hline      1st entry <<1st comment>> & 2nd entry <<2nd comment>>  \\      \hline  \end{tabular}  \end{document}

I am writing a text which I will review later again and want to comment out only a part of a line (in between), something like this:  Once upon a time, there was %in some galaxy far away% a nice and cute rabbit...   When I review it again, I could decide if it is better to include that part or not.   Is it possible to do such a thing?


I hope this question is not a duplicate (it doesn't seem to be) and that it is appropriate for this site.  If we had a universe with only two bodies. One is ultra massive, and the other is very small. Why could a sufficient distance not mean that gravity could accelerate the smaller object to past the speed of light? If gravity affects all objects from all objects, gravity certainly should be acting on the smaller body (and also the smaller body on the larger).  I would think, in fact, that the relative sizes don't particularly matter. Why doesn't gravity make things accelerate past the speed of light if they are far enough away?

Imagine we have something very heavy (i.e supermassive black hole) and some object that we can throw with 0.999999 speed of light (i.e proton). We are throwing our particle in the direction of hole. The black hole is so heavy that we can assume that in some moment acceleration of gravity would be say 0.0001 speed of light/s^2. So the question is what will be the speed of proton in few a seconds later, assuming we have such distances that it will not hit the black hole before.


I am on a ThinkPad W530 and have just installed Ubuntu. Which one of these drivers do I install?   Does the command sudo apt-get install nvidia-current install current drivers?     EDIT: I used sudo apt-get install nvidia-current and now there is a nvidia_304 driver activated in Additional Drivers:  If you have Optimus enabled in the BIOS, you either have to disable it or install Bumblebee

Well obviously I can do it manually, I was just wondering why aren't these drivers available through "Additional Drivers", and why are the versions available there outdated.


I am a windows user, and I don't know nothing about Ubuntu and how does it works. I don't know how to access my computer, I don't know how to access command prompt nothing.   Just now I installed Ubuntu 14.04 LTS, due to wifi problem I reinstalled Ubuntu and now the wifi is working fine.   Now I am not able to install any of the exe file. I am trying to install file zilla,internet download manager, 7zip, and as a blogger I would like to install some other blogging related tools which install on Adobe Air.   Can any one please help me and instruct me in detail step by step on how to install wine on Ubuntu 14.04.   Or are there any other programs which makes to install windows related applications.

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?


could someone please explain how the enhanced for loop in the code below would look if it was represented by a standard for loop? ex for(int loop = 0; loop < ____; loop++) etc. I am trying to understand what the enhanced for loop does but want to see how it is represented in a standard for loop. public static void main(String[] args) {     // get the list of each winning team by year     ArrayList<String> allWinners = readAndPopulateWinnersList();     int startYear = 1956;     for(String teams : allWinners) {         System.out.println(startYear++ + " : " + teams);     }          }

Consider:  List<String> someList = new ArrayList<String>(); // add "monkey", "donkey", "skeleton key" to someList     for (String item : someList) {     System.out.println(item); }   What would the equivalent for loop look like without using the for each syntax?


#include <iostream> using namespace std;  class Point { private:     int x, y; public:      Point() {         cout << "default constructer" << endl;     }     Point(int x)         : x(x), y(0) {         cout << "1 var constructer" << endl;     }; };  int main() {     Point x;     Point y();     Point z(1);     return 0; }   i understand that x is default constructor but i think y is covered by (void) so i thought y should be default constructor but y isn't but when i change y() to y{} then default constructorcalled why is this work like that?? something i have miss?

Is there any good reason that an empty set of round brackets (parentheses) isn't valid for calling the default constructor in C++?  MyObject  object;  // ok - default ctor MyObject  object(blah); // ok  MyObject  object();  // error   I seem to type "()" automatically everytime. Is there a good reason this isn't allowed?


I know how to use sudo grub-set-default # but I do not know how I can determine what the order is to specify the default boot (without booting and observing the menu).    Is there some way to get grub to echo the menu from the command line?  How can I figure out what 0, 1, 2, etc., are in grub without booting?

I would like to display the grub menu from the command line. Also to select a grub boot menu option and press Enter to see what pre-kernel drivers are loaded and the boot parameters passed when loading the kernel.  The reasons to do this from the command line:   Rebooting to see the grub menu takes time. It is awkward to take a picture of the grub menu and post the image on websites. It is easier grabbing a screen shot when Ubuntu is up and running. To edit grub menu option with e and take a picture is often difficult because screen is hard to read. With this function you could copy and paste instead. It might be easier using this function to reveal all kernel versions rather than apt list --installed | grep linux-image or ls /boot/vml*. To quickly see the grub menu number is valuable for grub-reboot and grub-set-default commands.   How can I paint the grub menu from the command line, see internal grub menu entry numbers and display the boot parameters for a given option?


I have encountered following function in C# code:  Byte[] GetUNIXTimeStamp(DateTime dtVal) {   if (m_bytTimeStamp == null) m_bytTimeStamp = new Byte[14];    Byte[] bytVals = BitConverter.GetBytes((UInt16)dtVal.Day);   m_bytTimeStamp[0] = bytVals[0];   m_bytTimeStamp[1] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Month);   m_bytTimeStamp[2] = bytVals[0];   m_bytTimeStamp[3] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Year);   m_bytTimeStamp[4] = bytVals[0];   m_bytTimeStamp[5] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Hour);   m_bytTimeStamp[6] = bytVals[0];   m_bytTimeStamp[7] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Minute);   m_bytTimeStamp[8] = bytVals[0];   m_bytTimeStamp[9] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Second);   m_bytTimeStamp[10] = bytVals[0];   m_bytTimeStamp[11] = bytVals[1];   bytVals = BitConverter.GetBytes((UInt16)dtVal.Millisecond);   m_bytTimeStamp[12] = bytVals[0];   m_bytTimeStamp[13] = bytVals[1];    return m_bytTimeStamp; }   …and just wondering if there is some shortest and cleanest way to achieve the same effect?

There is this example code, but then it starts talking about millisecond / nanosecond problems.  The same question is on MSDN, .  This is what I've got so far:  public Double CreatedEpoch {   get   {     DateTime epoch = new DateTime(1970, 1, 1, 0, 0, 0, 0).ToLocalTime();     TimeSpan span = (this.Created.ToLocalTime() - epoch);     return span.TotalSeconds;   }   set   {     DateTime epoch = new DateTime(1970, 1, 1, 0, 0, 0, 0).ToLocalTime();     this.Created = epoch.AddSeconds(value);   } }


I tried to search about that, but didn't find anything. I used links to modify data via parameters in C++. In C#, for example, I can use like that:  bool foo(ref string r) {     r+= " is text"; }  bool bar() {     string s = "text";     foo(ref s); // and now s == "text is text" }   Is it possible to do it in actionscript3?

Actionscript 3.0 (and I assume Javascript and ECMAScript in general) lacks pass-by-reference for native types like ints. As a result I'm finding getting values back from a function really clunky.  What's the normal pattern to work around this?    For example, is there a clean way to implement swap( intA, intB ) in Actionscript?


I have been searching for something like this, but all what I have found was Fixed test order or completely random.  I have this kind of a test structure:  // imports  @RunWith(Suite.class)  @Suite.SuiteClasses({         // Tests })  public class TestRunSuite { }   and what do I want to do:  // imports  @RunWith(Suite.class)  @Suite.SuiteClasses({         testToExecuteFirst.class,         // Tests in random order         testToExecuteLast.class })  public class TestRunSuite { }   or  Is there a way how to make TestSuite execute in the middle of 2 functions ? What do I mean:  authentificationSetUp(); // somehow calling TestRunSuite authentificationSetUpBack();   The reason why do I want to do this, is that I need to change the timeout of authentification on one website, but the thing is, that I need to logged in as an admin and tests are for other roles. So instead of going through all of those tests and putting to each @BeforeClass and @AfterClass these 2 tests.

I want to do some functional testing on a (restful) webservice. The testsuite contains a bunch of test cases, each of which performs a couple of HTTP requests on the webservice.  Naturally, the webservice has to run or the tests will fail. :-)  Starting the webservice takes a couple of minutes (it does some heavy data lifting), so I want to start it as infrequently as possible (at least all test cases that only GET resources from the service could share one).  So is there a way to do set up me the bomb in a test suite, before the tests are run like in a @BeforeClass method of a test case?


How can one mathematically demonstrate that angular displacement is not a vector and is not commutative?

Are angular quantities vector?   ... It is not easy to get used to representing angular quantities as vectors. We instinctively expect that something should be moving along the direction of a vector. That is not the case here. Instead, something(the rigid body) is rotating around the direction of the vector. In the world of pure rotation,a vector defines an axis of rotation, not a direction in which something moves.   This is what my book (authored by Halliday, Walker, Resnick) says. But they mentioned with a caution that      Angular displacements cannot be treated as vectors. ....to be represented as a vector, a quantity must also obey the rules of vector addition..... Angular displacements fail this test.   Why do they fail in this test? What is the reason?


Is there a simple way to flatten a list of iterables with a list comprehension, or failing that, what would you all consider to be the best way to flatten a shallow list like this, balancing performance and readability?  I tried to flatten such a list with a nested list comprehension, like this:  [image for image in menuitem for menuitem in list_of_menuitems]   But I get in trouble of the NameError variety there, because the name 'menuitem' is not defined.  After googling and looking around on Stack Overflow, I got the desired results with a reduce statement:  reduce(list.__add__, map(lambda x: list(x), list_of_menuitems))   But this method is fairly unreadable because I need that list(x) call there because x is a Django QuerySet object.  Conclusion:   Thanks to everyone who contributed to this question.  Here is a summary of what I learned.  I'm also making this a community wiki in case others want to add to or correct these observations.  My original reduce statement is redundant and is better written this way:  >>> reduce(list.__add__, (list(mi) for mi in list_of_menuitems))   This is the correct syntax for a nested list comprehension (Brilliant summary !):  >>> [image for mi in list_of_menuitems for image in mi]   But neither of these methods are as efficient as using itertools.chain:  >>> from itertools import chain >>> list(chain(*list_of_menuitems))   And as @cdleary notes, it's probably better style to avoid * operator magic by using chain.from_iterable like so:  >>> chain = itertools.chain.from_iterable([[1,2],[3],[5,89],[],[6]]) >>> print(list(chain)) >>> [1, 2, 3, 5, 89, 6]


In the following table:  \documentclass[12pt]{article} \usepackage{tabularx} \usepackage{multirow} \usepackage{float} \begin{document}     \begin{table}[H]         \centering         \small         \begin{tabular}{|c|c|c|c|c|c|}             \hline             \textbf{Representation}     & \textbf{Configuration}             & \textbf{Correlation} & \textbf{p-value}                 & \textbf{\begin{tabular}[c]{@{}c@{}}Correlation\\ coefficient\end{tabular}} & \textbf{\begin{tabular}[c]{@{}c@{}}\# classes with\\ significant\\ correlation\end{tabular}} \\ \hline             \multirow{6}{*}{Test suite} & \multirow{6}{*}{Without reduction} & Coverage and AC      & \multirow{6}{*}{\textless 0.001} & $−0.18$                                                      & 9                                                                                \\ \cline{3-3} \cline{5-6}              &                                    & Coverage and ND      &                                  & $−$ 0.2                                                                       & 4                                                                                \\ \cline{3-3} \cline{5-6}              &                                    & Coverage and NV      &                                  & −0.19                                                                      & 9                                                                                \\ \cline{3-3} \cline{5-6}              &                                    & Coverage and IC      &                                  & 0.21                                                                       & 8                                                                                \\ \cline{3-3} \cline{5-6}              &                                    & Coverage and PIC     &                                  & 0.2                                                                        & 4                                                                                \\ \cline{3-3} \cline{5-6}              &                                    & Coverage and DBI     &                                  & 0.21                                                                       & 9                                                                                \\ \hline         \end{tabular}     \end{table} \end{document}   The negative numbers in the column Correlation coefficient are shown as positive. The negative sign - is not shown. I tried both $-18$ and $-$ 0.2 but none of them works.   How to solve this issue?

So I want to write a Cobb-Douglas function F = Kα * L1-α. I've written this in LaTeX:  \(Y = K^{\alpha}L^{1−\alpha}\)   Everything is fine except that the minus sign that should be between 1 and alpha in superscript above L is missing. What am I doing wrong?


I am creating a minecraft 1.14 puzzle map. I would like to know how to set a spawnpoint for any player that downloads the map. Can anyone help me with this?

Whenever I respawn, I will either spawn into my map, or outside. This happens everytime, even when I set the worldspawn to the correct location.  Am I supposed to use the sort of contraption where you can play a title when you die, but instead use it to teleport when they are dead?    I'll be very thankful if you could tell me anything!


This works as intended:  for rcount in {0..10}; do     echo "${rcount}" done   But I have a variable that I want to use as a loop range:  var1=10  These don't work:  Trial 1:  for rcount in {0..var1}; do     echo "${rcount}" done   Trial 2:  for rcount in {0..${var1}}; do     echo "${rcount}" done   How can I do this?

How do I iterate over a range of numbers in Bash when the range is given by a variable?  I know I can do this (called "sequence expression" in the Bash ):   for i in {1..5}; do echo $i; done   Which gives:     1    2    3    4    5   Yet, how can I replace either of the range endpoints with a variable? This doesn't work:  END=5 for i in {1..$END}; do echo $i; done   Which prints:     {1..5}


I installed ubuntu and was running it for a month before I wanted windows back to run some programs that I couldn't run on ubuntu. I had accidentally deleted my recovery partition and overwrote windows when I installed ubuntu. I eventually got windows 7 back on my computer but now I don't know how to boot up ubuntu again. I still have ubuntu on a bootable partition and windows is on it's on bootable partition. Can anyone tell me how I can boot up ubuntu again? thanks :)

I installed Windows 7, which ate Ubuntu's boot file. When starting up the computer, it now goes straight to Windows, without giving me the option of booting Ubuntu.   How can I get Ubuntu back?


I read  this text:     If you want to get a copy of an existing Git repository – for example, a project you’d like to contribute to – the command you need is git clone.   I need to get complete repository (with all branches).  But when I use the command git clone <address> <output_directory_name> then I get clone with one branch only. I see it through the git branch command. If I use the git clone <address> -b <branch_name> <output_directory_name> then I get only that branch (I see it through the git branch command again).  How can I get full content of a git repository with all branches? The repositories which I cloned are located on Bitbucket website.

I have a master and a development branch, both pushed to . I've cloned, pulled, and fetched, but I remain unable to get anything other than the master branch back.  I'm sure I'm missing something obvious, but I have read the manual and I'm getting no joy at all.


The play's set was completely painted, but Jennifer laid the freshly-painted board face down on the floor.

How do I know when to use lay and when to use lie, and what are the different forms of each verb? I'm always getting them confused.


Attempting to catch a flying bird by accidentally releasing the one in hand.  For example, pursuing other attractive objects for getting more benefit but accidentally losing the benefits from the existing owned objects. Is there such a proverb in English with the above meaning?

Someone asked me why I am looking for a new job while I am currently working. This got me thinking if there is a idiom that says something about it being wise to not leave your current job until you have another sure thing lined up etc.


I want to display a single string connected to values from a list displayed using a for loop  For example I have this:  nums = [1,2,3,4,5] print("Numbers: ") for i in nums:     print(i)   but I would like it to be displayed with the 1 starting after "Numbers:"  e.g  Numbers: 123...  How would I format the code to enable this to happen?

I'd like to do it in Python. What I'd like to do in this example in C: #include <stdio.h>  int main() {     int i;     for (i=0; i<10; i++) printf(".");     return 0; }  Output: ..........  In Python: >>> for i in range(10): print('.') . . . . . . . . . . >>> print('.', '.', '.', '.', '.', '.', '.', '.', '.', '.') . . . . . . . . . .  In Python print will add a \n or space, how can I avoid that? Now, it's just an example, don't tell me I can first build a string then print it. I'd like to know how to "append" strings to stdout.


I want to get a .html or .txt file from a folder with PHP, but this file is UTF-8 encoded, and if I use $html=file_get_contents('somewhere/somewhat.html'); and after that I echo $html; then this won't be UTF-8 encoded. I see many "�" in the text. Any idea? How can I prevent this?

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 am making a magazine that is due to be printed tomorrow. I am working in InDesign and need to export it to a PDF (Print) for printing.  It needs to have a 3mm bleed.  I have done this, and checked the 'crop marks' and 'bleed marks' on the export settings - but the double page spreads are showing up strangely: one sliver of the opposite page shows on each page. I've attached a screen shot to show what I mean  I don't know if this is normal, but I presume it won't print correctly like this? What do I need to do to fix this?

lately I had a problem that I neved faced before now, I'll try to explain quickly: usually I setup documents in InDesign CS6 with side-by-side pages and work with pictures that run over two (side-by-side) pages, then I export to PDF.  The problem is that a printing service asked me to export to PDF only in single pages with page bleed on each size and each page, but of course in the "middle side" of the two pages, there is no bleed (on the left page there is no bleed on the right side, and on the right page there is no bleed on the left side).  Is there a way to achieve that result, or I have to work since the beginning with single pages? For example, if I want one big image on two side-by-side page, should I import two times the same image and position it cutting it properly (half image each page)? Isn't it very uncomfortable?  I tried many things but couldn't find any solution.    Thanks a lot for your answer that are great, but I'm adding some details to explain myself better (sorry but english is not my mother language and also my InDesign is in Italian).  The method explained works fantastic with the images if you add them into the pages, but if you have something in the "master" pages, they will overlap on the pages, I did an example to explain better.  This one is with a banner on the master page right and left, with different colors.    You can see that a yellow part of the title background overlap the right page, and vice-versa. How do you manage this problem?


I have a situation where I'm having to take binary data (for PDFs, word docs, etc) via ajax and allow users to download the file by clicking on a link.  Currently I am doing this by opening a new browser window with the binary data.  window.open("data:application/pdf;base64,"+ binaryFileData);   This works for opening the file, but the file name generated is always the actual binary string and not anything human-readable.    Is there a way to give the opened file a specific name?

If for example you follow the link:  data:application/octet-stream;base64,SGVsbG8=  The browser will prompt you to download a file consisting of the data held as base64 in the hyperlink itself.  Is there any way of suggesting a default name in the markup?  If not, is there a JavaScript solution?


I want to install Ubuntu 16.04.  , but after choosing "Try Ubuntu" or "Install Ubuntu", there is only the , which seems to be loading, and stops.  After this, nothing moves. There is only the Ubuntu Screen but no Desktop or Installation Process.   Only command line opens.  What can I do to install Ubuntu 16.04 properly on UEFI (PC model: ASUS GL522 V)?

I am trying to boot Ubuntu on my computer.  When I boot Ubuntu, it boots to a black screen.  How can I fix this? Table of Contents:


I'm studying Friedman and Susskind's Special Relativity and Classical Field Theory. In Lecture 6, they derive $$m{dU_\mu\over d\tau}=eF_{\mu\nu}U^\nu,\tag{6.33}$$ but only when $\mu=1, 2, 3$. ($F_{\mu\nu}$ stands for $\partial_\mu A_\nu-\partial_\nu A_\mu$.) To prove that this equation also holds for $\mu=0$, they give the following argument.  If the equations are Lorentz invariant, and the three space comonents of a certain 4-vector are equal to the three space components of some other 4-vector, then we know automatically that their zeroth components (the time components) must also match.  I can see that both, the LHS and the RHS of the above equation are 4-vectors. But I don't see how the equality of the LHS and the RHS for $\mu=1,2,3$ implies their equality for $\mu=0$. Please help me prove it.  I found that this question has been asked  on SE. But I couldn't understand the posted answer (by Prahar) there—it used gauge invariance concepts and I'm not yet familiar with that. But I'll appreciate if someone can explain me enough to understand that answer.

We consider in Lorentz spacetime, $(x^0,x^1,x^2,x^3)=(t,x,y,z)$, choose the unit of time such that $c=1$.   Given a four vector $A_\mu$, and let the Lagrangian  $$L(x^i,\dot x^i,t)=-m\sqrt{1-\dot x_i\dot x^i}+qA_0+qA_i\dot x^i,\tag{1}$$ where we use Einstein's convention for summation. (See  with electron charge $q=-e$.)    By the Euler-Lagrange equation $$\frac{d}{dt}\frac{\partial L}{\partial\dot x^i}-\frac{\partial L}{\partial x^i}=0\tag{2}$$ we can get three equations, and if we use the fact that  $$\frac{d}{d\tau}=\frac{1}{\sqrt{1-\dot x_i\dot x^i}}\frac{d}{dt}\tag{3}$$  then these equations are, for $i=1,2,3$ $$m\frac{d^2x^i}{d\tau^2}=q(\frac{\partial A_\mu}{\partial x^i}-\frac{\partial A_i}{\partial x^\mu})\frac{dx^\mu}{d\tau}\tag{4}$$  My question follows, can we obtain a fourth equation which is just letting $i=0$?   The  says that this fourth equation is from the property that the action is invariant under Lorentz transformation. But I think this is not very convincing. I tried to view the first three equations as two four vectors having three equation space components, but I do not think this fact can lead to the equality for the last time component.  References:   L. Susskind, .


I have a large T-SQL query (I only put a part here because I very sure the rest is working nice):   WHERE /*                 ******* missing filter *******                 this line should filter the risks by @LoggedInPersonID via role                  ******************************           AND */(@PropertyID IS NULL OR p.PropertyID = @PropertyID)           AND (@PCodePattern IS NULL OR p.PCode LIKE @PCodePattern)           AND (@ZipCodeIDS IS NULL                   OR p.ZipCodeID IN (@ZipCodeIDS))   You notice that @ZipCodeIDS is a list... Well, I populate this from code with some ids. When @ZipCodeIDS contains a SINGLE id it works perfectly but if I try to send multiple ids (eg: "14,15") it gives me error....  Do you have any clue?  Ps: Of course I made @ZIpCodeIDS varchar because we do not have array in T-SQL...  UPDATE: If I directly hardcode in the query: IN (14,11) it perfectly works... so somehow I do not correctly send this parameter from my code for multiple values I think it does not see "," as a separator...  UPDATE 2: Tried to split the lists and put the ids into a table... When zipCodeIDS has only one id the query works perfectly. For multiple ones, not... Do you see something strange on ELSE?      IF @ZipCodeIDS IS NOT NULL BEGIN     IF CHARINDEX(',', @ZipCodeIDS) = 0     BEGIN         insert @listofIDS values(@ZipCodeIDS)     END     ELSE     BEGIN         WHILE CHARINDEX(',', @ZipCodeIDS) != 0         BEGIN             insert @listofIDS values(Left(@ZipCodeIDS, PatIndex(',', @ZipCodeIDS) - 1))             SET @ZipCodeIDS = SUBSTRING(@ZipCodeIDS, CHARINDEX(',',@ZipCodeIDS)+1, LEN(@ZipCodeIDS) - CHARINDEX(',',@ZipCodeIDS))         END     END END

How do I parameterize a query containing an IN clause with a variable number of arguments, like this one?  SELECT * FROM Tags  WHERE Name IN ('ruby','rails','scruffy','rubyonrails') ORDER BY Count DESC   In this query, the number of arguments could be anywhere from 1 to 5.  I would prefer not to use a dedicated stored procedure for this (or XML), but if there is some elegant way specific to , I am open to that.


i've got some issues with my program: minimap = pygame.Surface((100, 100)) background = pygame.Surface((minimap.get_width(), minimap.get_height())) background.fill((0, 0, 0)) background.set_alpha(0) minimap.blit(background, (0, 0, minimap.get_width(), minimap.get_height())) pygame.image.save(minimap, "minimap.png")  the thing is, I want the background to be transparent because I display it on something else later on and i want to see behind it, so I've used another surface where I've set a color and put the alpha to 0, after that the background is set to minimap. If you have any clue please let me know

Can someone give me some example code that creates a surface with a transparent background in pygame?


I have a variable:  var code = "de";   And I have an array:  var countryList = ["de","fr","it","es"];   Could someone help me as I need to check to see if the variable is inside the countryList array - my attempt is here:      if (code instanceof countryList) {         alert('value is Array!');     }       else {         alert('Not an array');     }   but I get the following error in console.log when it's run:     TypeError: invalid 'instanceof' operand countryList

What is the most concise and efficient way to find out if a JavaScript array contains a value? This is the only way I know to do it: function contains(a, obj) {     for (var i = 0; i < a.length; i++) {         if (a[i] === obj) {             return true;         }     }     return false; }  Is there a better and more concise way to accomplish this?


If a hydrogen atom in the sun absorbs a photon of frequency f that was heading towards the earth. Wouldn't the atom re-emit that shortly after in the same direction? (to conserve linear momentum) Why would see any gaps then in the emission spectrum in the sun that correspond to Hydrogen's spectral lines?

I was looking at  on why  and emission lines don't cancel out:      An experiment shining light on the material and looking at the   reflected spectrum will see absorption lines at those frequencies,   because the relaxation of the excited electrons will emit back   radiation all around randomly, whereas the reflected spectrum is at a   specific angle.   However it is not totally convincing to me. The photons that get emitted towards the center of the Sun (by the electrons in higher energy states that absorbed a photon earlier) would get absorbed again when they hit a different electron (and then re-emitted) and would eventually make it out. So why don't absorption and emission lines cancel out in our Sun?


So, I recently asked  and got a closed question and a downvote without comments, even though I asked where should I then ask this question. So, I'm asking here - where should I post such a question? I'm no low rep user and have a decent understanding but was just wondering about this particular subject, and was wondering to hear the thoughts of Stack Exchange people as I have quite a high oppinion of the answers here. I looked at  but am biased to post the question there and get another downvote, so can you please suggest?

Is it appropriate to ask questions about software licenses/licensing on ? Or is the appropriate place  ? Or is there no appropriate site currently and we should suggest such a site on ?


The problem is simple. I want to continuously execute a function while I wait for another task to finish, like in this silly example:  #!/usr/bin/env php <?php  $timer = function() {   static $seconds = 0;   while(1) {     sleep(1);     echo "\r", $seconds++;   } }  $timer(); // I want to run this in parallel  $service = new Service(); $response = $service->goGetSomething('from far far away');  // I want to kill the timer here   I do parallel processing with other languages all the time, but have no idea how to achieve this with PHP. Requirements:   The simplest solution as possible, ++ if you use only PHP extensions enabled by default. I don't need Windows support :)   PS: Don't tell me to use nodejs or [your-favorite-language] that doesn't suck :)

Is there a realistic way of implementing a multi-threaded model in PHP whether truly, or just simulating it. Some time back it was suggested that you could force the operating system to load another instance of the PHP executable and handle other simultaneous processes.  The problem with this is that when the PHP code finished executing the PHP instance remains in memory because there is no way to kill it from within PHP.  So if you are simulating several threads you can imagine whats going to happen.  So I am still looking for a way multi-threading can be done or simulated effectively from within PHP. Any ideas?


If electromagnetic waves are the same as photons would gravitational waves be the same as gravitons?

For electromagnetic waves there exists a wave/particle duality: light sometimes behaves as a wave, and other times as a particle (photons).  Does such a duality exist for gravitational waves? In other words would we expect gravitational waves to sometimes behave has particles (gravitons)?


The badge “Analytical” says “Visited every section of the FAQ (retired)”. This sounds like nobody can get this badge anymore, but, still, there are some people who earned it recently:     How did they do that?

I was browsing badges right now, and saw that the Analytical badge has been retired. I tried searching how to get one, but found out that it cannot be obtained now - thanks to  question.   Well, I was shocked to see that on clicking on that badge, there were several users who had obtained the badge recently - as recently as 3 hours ago. Is that a bug, or is there some hidden way to obtain the badge still?