H2Opus implements hierarchical matrices in the H^2 flavour.
It supports CPU or NVIDIA GPUs.
For CPU only builds, use ./configure --download-h2opus --download-thrust to install PETSc to use H2Opus.
In order to run on NVIDIA GPUs, use ./configure --download-h2opus --download-magma --download-kblas.
For details and additional references, see
"H2Opus: A distributed-memory multi-GPU software package for non-local operators",
available at https://arxiv.org/abs/2109.05451.