PaStiX (Parallel Sparse matriX package) is a scientific library that provides a
high performance parallel solver for very large sparse linear systems based on
direct methods. Numerical algorithms are implemented in single or double
precision (real or complex) using LLt, LDLt and LU with static pivoting (for non
symmetric matrices having a symmetric pattern). This solver also provides some
low-rank compression methods to reduce the memory footprint and/or the
time-to-solution.

It is bundled with SPM (SParse Matrix Package).
See also https://gitlab.inria.fr/solverstack/spm