Logarithm of Gamma Function

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

ASA245 is Applied Statistics Algorithm 245. Source code for many Applied Statistics Algorithms is available through STATLIB.


The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.


ASA245 is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:

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

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

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


Original FORTRAN77 version by Allan Mcleod; C 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 C source codes.

Last revised on 20 November 2010.