Advanced usage

Hierarchical compression

1. Htool.VirtualLowRankGenerator which defines the low-rank compression, see Low-rank compression.

Distributed operator

1. Htool.VirtualLocalToLocalOperator defines the interface for an operator taking a local vector and returning a local vector.

2. Htool.RestrictedGlobalToLocalOperator defines the interface for an operator taking a global vector and returning a local vector. When using default compression via Htool.DefaultApproximationBuilder, the resulting Htool.DistributedOperator contains a Htool.HMatrix as his Htool.RestrictedGlobalToLocalOperator.

Htool.DistributedOperator can contain multiple Htool.VirtualLocalToLocalOperator and Htool.RestrictedGlobalToLocalOperator using Htool.DistributedOperator.add_global_to_local_operator() and Htool.DistributedOperator.add_local_to_local_operator().