Numerical Recipes
"Numerical Recipes" was originally the title of a book that
implemented numerical algorithms in different computer languages.
They have expanded with a number of books and also offer the
algorithms in different electronic forms: both via diskettes and
on-line. At this site, they offer information and news on
themselves, an on-line store (i.e. you can purchase the routines
and books on-line), instructions for their use, free upgrades and
bug reports, related information on the Internet, and associated
information.
http://www.nr.com/