user ambrus     Image:  gravitational anomaly, somewhere in France, August 2007. Favourite pentomino pattern: <TABLE border="5" cellspacing="0"> <COLGROUP span="10" width="25"></COLGROUP> <TR height="25"><TD bgcolor="#8000c0" colspan="2"><TD bgcolor="#ffff81" colspan="5"><TD bgcolor="#40ff40" colspan="3"> <TR height="25"><TD bgcolor="#8000c0" colspan="1"><TD bgcolor="#80c000" colspan="3"><TD bgcolor="#4040ff" colspan="4"><TD bgcolor="#0080c0" colspan="1"><TD bgcolor="#40ff40" colspan="1"> <TR height="25"><TD bgcolor="#8000c0" colspan="1"><TD bgcolor="#00c080" colspan="2"><TD bgcolor="#80c000" colspan="2"><TD bgcolor="#4040ff" colspan="1"><TD bgcolor="#0080c0" colspan="3"><TD bgcolor="#40ff40" colspan="1"> <TR height="25"><TD bgcolor="#8000c0" colspan="1"><TD bgcolor="#81ffff" colspan="1"><TD bgcolor="#00c080" colspan="2"><TD bgcolor="#c00080" colspan="1"><TD bgcolor="#ff4040" colspan="1"><TD bgcolor="#0080c0" colspan="1"><TD bgcolor="#ff81ff" colspan="1"><TD bgcolor="#c08000" colspan="2"> <TR height="25"><TD bgcolor="#81ffff" colspan="2"><TD bgcolor="#00c080" colspan="1"><TD bgcolor="#c00080" colspan="2"><TD bgcolor="#ff4040" colspan="1"><TD bgcolor="#ff81ff" colspan="3"><TD bgcolor="#c08000" colspan="1"> <TR height="25"><TD bgcolor="#81ffff" colspan="2"><TD bgcolor="#c00080" colspan="2"><TD bgcolor="#ff4040" colspan="3"><TD bgcolor="#ff81ff" colspan="1"><TD bgcolor="#c08000" colspan="2"> </TABLE> <a href="http://www.math.bme.hu/~ambrus/sc/">My homepage</a> doesn't have anything interesting on it. Here's an old listing of [http://www.math.bme.hu/~ambrus/pu/fav.html|some books I like]. To determine if a number is odd or even, the worst way is: <code> $odd=0;{local($SIG{__WARN__},$^W)=(sub{$odd++})x2;+{1..abs($n)}}; </code> There are several completely different programming concepts called a select statement. They are <ul> <li> The select system call in unix, which is the most common way a process can wait for events and give up the process's claim on CPU. Its prototype is <C>int select(int, fd_set *, fd_set *, fd_set *, struct timeval *);</c>. It also has a perl interface: the select builtin function which has three or four arguments. <li> The one-argument select function of perl, which selects a filehandle to be the default filehandle, so that unqalified print operations and a few special variables would refer to it. This accidentally has the same name as the previously mentioned select function, and can only be distinguished by the number of arguments. <li> The select special command in bash-like shells, which is a loop construct that prints a simple text-based menu and reads user input. <li> The SELECT construct in the SQL language. <li> The SELECT special statement in newer dialects of BASIC, which is similar to pascal or scheme case statements. It dispatches between multiple choices comparing a single value to different constants for each branch. In earlier BASICs, the ON ... GOTO construct was used instead. <li> It is not a statement, but smalltalk and ruby have a select method which filter elements from a list, similarly to perl's builtin function grep. Also both maple and mathematica have functions called select and Select resp., and these serve the same purpose. <li> Also not a statement, but HTML has a select element that is a form control displaying a dropdown list. Related to this, the CGI perl module has a Select function and method, and the WWW::Mechanize module has a [id://701312|select] method. (One could say though that this has the same etimology as the select statement in shells.) <li> However, HTML DOM also has a select event (unrelated to the select element) and HTML has a corresponding onselect attribute, which is called when the user changes the selection in a text input field. <li> The Magma computer algebra system has a select keyword which it uses in the [http://magma.maths.usyd.edu.au/magma/htmlhelp/text10.htm|conditional expression]. </ul> Ok, after all this rant, here's something that's actually useful to know. The formulae to solve the quadratic equation a x^2 + b x + c = 0 are: x_1 = -(b + sgn(b) sqrt(b^2 - 4 a c))/(2 a) x_2 = c/(a x_1) Perl Quiz of The Week #21 (20040805): Task scheduling. [http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/2005|my solution] [http://article.gmane.org/gmane.comp.lang.perl.qotw.quiz-of-the-week/102|discussion]. Perl Quiz of the Week Expert #22 (20040825): Word ladder. [http://article.gmane.org/gmane.comp.lang.perl.qotw.discuss/2118|my solution] [http://article.gmane.org/gmane.comp.lang.perl.qotw.quiz-of-the-week/109|discussion]. 2013-05-24 09:21:51 18307 358307 371752 2611 Budapest Europe/Rome on on