Do some regex on a 50GB file in perl
What's the difference between iterating over a file with foreach or while in Perl?
number of edges induction proof Proof by induction that the complete graph $K_{n}$ has $n(n-1)/2$ edges.   I know how to do the induction step I'm just a little confused on what the left side of my equation should be. $E = n(n-1)/2$  It's been a while since I've done induction. I just need help determining both sides of the equation. How do I convert a string to a byte[] in .NET (C#) without manually specifying a specific encoding?  I'm going to encrypt the string. I can encrypt it without converting, but I'd still like to know why encoding comes to play here.  Also, why should encoding even be taken into consideration? Can't I simply get what bytes the string has been stored in? Why is there a dependency on character encodings? When I´m in a secure part of a web-site I´m developing (entering a specific page or folder using https), the relative links to the normal pages are automatically converted to https as well. Is there a way to tell an &lt;a&gt; tag to always use the http protocol instead of the https protocol (or the other way around)? I know it´s easy using the complete link ( or ), but I would like it to work with relative links (index.html, ../index.html, etc.). mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc... expects parameter 1 to be resource I suggest that when a post is migrated from one site to another, that the question vote score get reset to zero (or perhaps only a negative vote score is reset to zero). Often people will downvote a question when the only thing that's "wrong" with it is that it's posted on the incorrect site. After migration, those downvotes hang around as a negative score and may unfairly bias the treatment of the question. Lock your computer after 5 minutes of inactivity How to typeset the symbol “^” (caret/circumflex/hat) I need to display the symbol '^'  d &lt;- dist(fascores, method = "euclidean")^2   How do I do that? OS X Internet Recovery doesn't see SSD drive I wanted to do a clean install and booted from OS X recovery partition. In disk utility I selected "erase" option. SSD was working correctly before that.  Now, if i startup, the only way to proceed is with Internet Recovery  since I cannot boot from hidden recovery partition. After I wait several hours for the recovery image download, I cannot see the SSD either in disk utility or OSX reinstallation.   In terminal   diskutil list   Shows only recovery image 1.8 Gb or so.  So did erase option destroy my ssd? Physics history book with some math I am looking for a book explaining physics from, say, Galileo and Newton till now; the book should be written using some math, similarly to my physics books when I was at the university (Halliday Resnik). I am searching a book that take care of explaining the true "evolution" of reasoning, discoveries, experiment to prove or disprove something.  I do not like a book that gives definitions without explaining what had happened. I also like to find, on that book, explanations on how actual measurements are taken (how can we measure the speed of light, the mass of celestial bodies, the attributes of electron, and how were the measurements taken in the past - how was possible to measure the speed of light in 1700-1800?).  I am not very interested in recent theories like strings, branes.... so it is OK if these are not discussed.  I like to find a lot of discussions on concept that are related, like for instance the implications on space dimensionalities, ether non-existence, strange facts, missing explanations. Reading a file used by another process Convert stored procedure result to model object changed primary email in google account. how to log in? I added gmail to my google account. Now when i try to log into stack exchange using google it prompts me to create a new account instead of using the existing.   The google account is still the same but google changed the primary email adress.  How can i log in again? How to find and replace a string by increasing its numerical part? Is there something I can do from the terminal when a program freezes up and Ubuntu becomes unresponsive? Rigid Simulation freezes at frame 250 I was wondering about the reason of the choose of the X as symbol used to represents the "Close application" operation. How accurate is approximating the Earth as a sphere? What level of error do I encounter when approximating the earth as a sphere? Specifically, when dealing with the location of points and, for example, the great circle distances between them.  Are there any studies on the average and worst case error compared to an ellipsoid? I'm wondering how much accuracy I'd be sacrificing if I go with a sphere for the sake of easier calculations.  My particular scenario involves directly mapping WGS84 coordinates as if they were coordinates on a perfect sphere (with the  defined by the IUGG) without any transformation. Finding the radius of convergence for $\sum_{n=0}^{\infty} \frac{(n!)^kx^n}{(kn)!}$ I'm reviewing some calculus concepts right now, and this series stumped me. I'm trying to figure out what its radius of convergence is, but it's not falling for any of my old tricks. Using the root-test, I want to compute: $$ L_1=\lim_{n\rightarrow\infty} \left|\sqrt[n]{\frac{(n!)^k}{(kn)!}}\right| $$  where $k$ is some positive integer. Passing the limit through the absolute-value bars and $n$th root symbol, I now want to compute the simpler (?) $$ L_2 = \lim_{n\rightarrow\infty} \sqrt[n]{\frac{(n!)^k}{(kn)!}}$$  Which I can't seem to pin down. Numerical tests indicate it goes to 0, and that jives with an intuitive notion I have that there are always $k$ terms on the numerator, but $kn$ terms in the denominator. But since all of these terms themselves depend on $n$, proving that $L_2 = 0$ escapes me. Once we get this result (if it's correct), then clearly $L_1$ is also 0, and the radius of convergence of the series is $\mathbb{R}$. Thanks for any ideas you may have. Why $\sqrt[3]{{2 + \sqrt 5 }} + \sqrt[3]{{2 - \sqrt 5 }}$ is a rational number? A "friends list" on Stack Overflow would be nice