Widely known approximations of gamma functions are Stirling's and Lanczos's ones
Thank you Sergey for your answer.
I have already implemented gamma function with the help of stirling approximation.Code and run-time tests can be found here
http://software.intel.com/en-us/forums/showthread.php?t=106032I had a problem with an accuracy in the range [0.001,1.0] and was curious how it was solved by Intel programmers(my problem was solved with the help of minimax approximation in problematic range).
I have a Stegun and Avramovitz classic book which serves me well as source ofvariousformulas for my mathematical library.
I do understand that such a discussion will not be possible here.