H2Lib is a software library for hierarchical matrices and H2-matrices developed mainly by the Scientific Computing Group of Kiel University.

The library offers

• functions for setting up cluster trees and block trees,

• functions for converting dense matrices and partially compressed matrices into hierarchical and H2-matrices,

• functions for creating hierarchical matrices and H2-matrices for boundary element methods using various compression techniques like Chebyshev interpolation, ACA, HCA, and Green quadrature,

• functions for creating hierarchical matrices and H2-matrices for finite element methods,

• functions for performing arithmetic operations on hierarchical matrices like truncated matrix multiplication, inversion, and factorization.