Follow this link http://dlmf.nist.gov/ to find a quick reference to mathematical functions. The library is compiled by the National Institute of Standards and Technology (NIST). The Digital Library of Mathematical Functions project was initiated to perform a complete rewrite of Abramowitz and Stegun’s Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables (a 1964 work) updated for current needs.
The initial release is a five-chapter preview of the 36-chapter reference tool. The 31 additional chapters will be released in early 2009.
Jonathan Erickson (2008).Math Functions: Online, Quick Reference. DrDobbs Report Editor’s Note http://www.ddj.com/