I\'ve been working with a lot of FORTRAN 77 lately, and though I had reservations at first, I now see some great qualities of the language. It is:
Simple to learn (no object-oriented or functional-programming complications)
Easy to read
Blazing fast at number-crunching
Sounds like C.
Buy Numerical Recipes in C. That pretty much covers all the bases in a clear, readable style.
http://www.amazon.com/Numerical-Recipes-Art-Scientific-Computing/dp/0521431085