MOCCA
MOnte Carlo routines for fractional Calculus and linear Algebra is a parallel C++ template library that focus primarily on the efficient computation of matrix functions using Monte-Carlo methods. Documentation.

HighFM
HighFM is a high-performance numerical package with primary focus on the evaluation of matrix functions. Using modern C++ features, HighFM enables users to write high-level code similar to the mathematical notation without sacrificing performance, translating all operations to highly-optimized kernels from well-known BLAS libraries, such as Intel MKL, AMD AOCL or NVIDIA CUDA.

ParKrylovML
Hybrid (both distributed- and shared-memory) parallel implementation of a Krylov method that computes the Mittag-Leffler function of matrices.