JuliaLang/julia — pull request #3226 by johnmyleswhite (2013-05-28 18:13:39+00:00)
Title: Add trigamma and invdigamma functions

This pull request adds the `trigamma` and `invdigamma` functions, which are the major missing instances of the `psigamma` function.

The tests verify that the functions return values that are roughly comparable with the values provided by R.