Use pgfplots to plot a single column .txt file
Plot a data/Table from Mathematica using `pgfplots`
Why do different humans look different? Although farmers appear to be able to tell their cows apart, cows look very much alike to me. And this similarity in appearance seems to be a general trait across the animal kingdom: one individual of one animal species looks much like another.  Why do human facial and body shapes vary so much?  I understand that human beings live in many different environments (e.g. hot and cold) and have adapted to these (e.g. through lighter or darker skin color), but there seems to be much variation that has no apparent evolutionary purpose. So does the difference have a purpose in itself? That is, did we evlove to vary in appearance, and what is the purpose of this variation? The more I use Stack Exchange, the more it is getting a knowledge-base for me. All questions, that I need for later reference I mark as favorite. Now I need to store these pages locally on my laptop. It is really time-consuming:  I could use Ctrl+S on each favorite question page  on Linux: there could be a solution with wget -N -r -l 1 &quot;https://stackoverflow.com/users/1069083/rubo77?tab=favorites&quot;  this will download all favorite questions but it creates no correct index.html Another approach would be to use the  to automatically follow into all your Stack Exchange-accounts. But that would have to be somehow limited to only favorites links on your  in each stack. cross-platform: You would need a firefox-plugin that downloads links recursively but only within the favorite-area of the  in your stack  Additionally, I would like to  and Javascript function only works if there's an alert Possible bug in hypergeometric function AppellF1 Why is human vision restricted to 400-700 nm? Across the electromagnetic spectrum, 400-700 nm is a narrow spectrum of frequencies and focused in the region of short wavelengths. For example, radio waves cover a large range of frequencies unexploited by the visual system. So what biological reason is there that evolved us to use such a small frequency bandwidth for vision? When I visit  I see this:     The "Congratulations! You've earned (badge)" section has dropped down completely beneath the tabs under it. The "You've earned a new privilege!" section has a gap at the bottom:     Shog9 says in comments how to reproduce this:     Gotta have earned a badge, not dismissed the notification, and be looking at your own profile. Why don't C++ compilers define operator== and operator!=? I am a big fan of letting the compiler do as much work for you as possible.  When writing a simple class the compiler can give you the following for 'free':   A default (empty) constructor A copy constructor A destructor An assignment operator (operator=)   But it cannot seem to give you any comparison operators - such as operator== or operator!=.  For example:  class foo { public:     std::string str_;     int n_; };  foo f1;        // Works foo f2(f1);    // Works foo f3; f3 = f2;       // Works  if (f3 == f2)  // Fails { }  if (f3 != f2)  // Fails { }   Is there a good reason for this?  Why would performing a member-by-member comparison be a problem?  Obviously if the class allocates memory then you'd want to be careful, but for a simple class surely the compiler could do this for you? This is my attempt to prove that, if $a &gt; 0$, then $\frac{1}{a} &gt; 0$, using just field and order axioms.  $$a &gt; 0 \implies a \cdot \left(\frac{1}{a}\right)^2 &gt; 0 \cdot \left(\frac{1}{a}\right)^2 \implies a \cdot \left(\frac{1}{a}\right)^2 &gt; 0 \implies a \cdot \left(\left(\frac{1}{a}\right) \cdot \left(\frac{1}{a}\right)\right) &gt; 0$$  By associativity of multiplication:  $$\left(a \cdot \left(\frac{1}{a}\right)\right) \cdot \left(\frac{1}{a}\right) &gt; 0$$  We know that $a \cdot \left(\frac{1}{a}\right) = 1$, because one is the multiplication inverse of the other.   So we have:  $$1 \cdot \left(\frac{1}{a}\right) &gt; 0 \implies \frac{1}{a} &gt; 0 $$  Which is what we wanted to prove.   My question are:    In the field axioms, there's no axiom that says that $0$ times another number is $0$, but I have used this property. How would you translate it to field and order axioms? I have assumed that $\left(\frac{1}{a}\right)^2$ is positive, have you noticed? Note that I need a positive number in order not to change the $&gt;$ sign. But this is not present in the field or order axioms. How would you explain this? Boot error > no such device: grub rescue After an installation of Ubuntu 12.04, erasing an old partition with Ubuntu 10.10, I can't get grub to load. I can't access my Windows 7 partition either  I get the message:  &gt; error: no such device: 58ABF29C...   grub rescue&gt;   I suppose my master boot record got erased/corrupted. How can I check and fix this? Write to FIFO only if it exists find() function in python2.7.5 I shall assume that the sun is at rest, so before the half mass disappear, the orbit of earth is an ellipse. Too many blanks between summation symbol and its associated expression How to fix pagination for custom loops? I have added a custom/secondary query to a template file/custom page template; how can I make WordPress use my custom query for pagination, instead of using the main query loop's pagination?  Addendum  I have modified the main loop query via . Why isn't pagination working, and how do I fix it? Robocall claiming to be IRS saying they are about to sue - Is it legit? We got a recorded call with a message claiming to be from the IRS.  It said they were giving final notice and preparing to file a lawsuit against us.  In our case, the message went to voicemail so the end was cut off, but it seemed like a scam all the way. (We don't have any pending problems with the IRS as far as we know.)  The question was whether this is a known scam? Statements equivalent to the Axiom of Choice The Axiom of Choice reads:     The product of a collection of non-empty sets is non-empty.   As you know well, this axiom is equivalent to many other statements. A few examples (probably the most known) are the following:   Zorn's lemma: Let $(P,\ge)$ be a poset in which every chain has an upper bound. Then $P$ has a maximal element.   This is used in a number of different places to prove very powerful theorems. A couple of examples I can think of right now are: the proof that every ring has a maximal ideal (commutative algebra) and the  (functional analysis).   Well ordering theorem: Every set can be well-ordered (i.e. it admits a total order such that every subset has a least element). Tychonoff's theorem: Every product of compact topological spaces is compact.   This is used for example in the proof of  (again functional analysis).   gives various more. Among them:   Tarski's theorem: If $A$ is an infinite set, then there is a bijection $A\to A\times A$.   (As @Wicht dutifully commented, Tarski's theorem is the name given to the implication $|A|=A\times A \Rightarrow$ Axiom of Choice, while the other implication was known before the proof of this fact by Tarski.)   Every vector space has a basis.   My question is: what are other useful statements which are equivalent to the axiom of choice? Where are they used, and to prove what?  P.s.: By "useful statements" I mean either statements which are important theorems by themselves (as Tychonoff's theorem) or that are directly used in (simple versions of) the proof of important theorems (as Zorn's lemma). Is there any actual written dialog for the astromech droids? When R2-D2 and BB-8 converse in The Force Awakens for example, is there any written record of what the two characters were saying to each other?  I mean actual dialog, if it exists, and not something like ”BB-8 beeps excitedly”. Im very new at LaTeX and I would appreciate some help solving this problem. I have created a BibTeX file containing all references to a document. In this text file BibTeX items are inserted and no other text are written, for instance @article{...}. When I call for this bib file from the main.tex file I use the commands:  \bibliographystyle{plain} \bibliography{thebibliography}   Now to my question. All i get when I compile this main.tex is the title (bibliography) for this chapter, otherwise the textfield is blank. Is this error occurring because I should write anything in the bib file or have I missed any lines in the main.tex file. Does commutativity imply Associativity? Does commutativity imply associativity? I'm asking this because I was trying to think of structures that are commutative but non-associative but couldn't come up with any. Are there any such examples?  NOTE: I wasn't sure how to tag this so feel free to retag it. Consider the following piece of Markdown code:  This is some regular text.      &gt;&gt;&gt; def factorial(n):     ...     return 1 if n &lt; 2 else n * factorial(n - 1)     ...   * This is a list item.      &gt;&gt;&gt; def factorial(n):     ...     return 1 if n &lt; 2 else n * factorial(n - 1)     ...    Notice that the second code block is preceded by a list item.   Why is the factorial code not properly formatted under these circumstances? To demonstrate the problem, I'll insert the Markdown code show above:    This is some regular text.  &gt;&gt;&gt; def factorial(n): ...     return 1 if n &lt; 2 else n * factorial(n - 1) ...     This is a list item                 def factorial(n):       ...     return 1 if n &lt; 2 else n * factorial(n - 1)       ...               This applies to numbered as well as unnumbered lists.