asa121, a MATLAB code which evaluates the trigamma function, by BE Schneider. This is a version of Applied Statistics Algorithm 121.


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


asa121 is available in a C version and a C++ version and a FORTRAN90 version and a MATLAB version.

Related Data and Programs:


asa103, a MATLAB code which evaluates the digamma function.

test_values, a MATLAB code which contains sample values for a number of special functions.


Original FORTRAN77 version by BE Schneider; MATLAB version by John Burkardt.


  1. BE Schneider,
    Algorithm AS 121: Trigamma Function,
    Applied Statistics,
    Volume 27, Number 1, 1978, pages 97-99.

Source Code:

Last revised on 25 November 2018.