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 GNU LGPL 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.