Logarithm of Gamma Function

ASA245 is a FORTRAN90 library which evaluates the logarithm of the gamma function, by Allan Mcleod;

ASA245 is Applied Statistics Algorithm 245.


ASA245 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

FN, a FORTRAN90 library which approximates elementary and special functions using Chebyshev polynomials, by Wayne Fullerton.

GSL, a C++ library which includes many routines for evaluating special functions.

SLATEC, a FORTRAN90 library which evaluates many special functions.

SPECFUN, a FORTRAN77 library which evaluates certain special functions using fitted data.

TEST_VALUES, a FORTRAN90 library which contains sample values for a number of distributions.

TOMS291, a FORTRAN77 library which evaluates the logarithm of the Gamma function.


Original FORTRAN77 version by Allan Mcleod; FORTRAN90 version by John Burkardt.


  1. Cornelius Lanczos,
    A precision approximation of the gamma function,
    SIAM Journal on Numerical Analysis, B,
    Volume 1, 1964, pages 86-96.
  2. Allan Mcleod,
    Algorithm AS 245: A Robust and Reliable Algorithm for the Logarithm of the Gamma Function,
    Applied Statistics,
    Volume 38, Number 2, 1989, pages 397-402.

Source Code:

Examples and Tests:

List of Routines:

You can go up one level to the FORTRAN90 source codes.

Last revised on 13 January 2008.