asa121

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

Licensing:

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

Languages:

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

Related Data and Programs:

asa121_test

asa103, a MATLAB code which evaluates the digamma function.

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

Author:

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

Reference:

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

Source Code:

• trigamma.m, calculates trigamma(x) = d^2 log(gamma(x)) / dx^2
• trigamma_values.m, returns some values of the TriGamma function.