This port installs the module SPEX, previously known as SLIP_LU, of SuiteSparse.

SPEX is a software package used to solve a sparse systems of linear equations
exactly using the Sparse Left-looking Integer-Preserving LU factorization.

SPEX Purpose: Exactly solve a sparse system of linear equations using a given
input matrix and right hand side vector file. This code can output the final
solution to a user specified output file in either double precision or full
precision rational numbers.
