Version: 2.8.0

Tags: patch

I think PARI/GP should include code for computing the matrix permanent. I've included code, in two different versions. Both implement Ryser's formula, but the first is simple and the second includes specializations for integer matrices and wordsize integer matrices. The time savings for the last are considerable (1/3 the time in my tests at 25x25, more with larger and less with smaller). But even the generic code is a big step up from GP code (about 40% of the runtime).

The code is not beautiful but it attempts to follow the PARI naming conventions.