asa121, a FORTRAN77 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 and a Octave version and a Python version.
asa103, a FORTRAN77 library which evaluates the digamma function.
test_values, a FORTRAN77 library which contains sample values for a number of special functions.
Original FORTRAN77 version by BE Schneider; This version by John Burkardt.