Interpolative Decomposition Butterfly Factorization
arXiv:1809.10573
Abstract
This paper introduces a "kernel-independent" interpolative decomposition butterfly factorization (IDBF) as a data-sparse approximation for matrices that satisfy a complementary low-rank property. The IDBF can be constructed in operations for an matrix via hierarchical interpolative decompositions (IDs), if matrix entries can be sampled individually and each sample takes operations. The resulting factorization is a product of sparse matrices, each with non-zero entries. Hence, it can be applied to a vector rapidly in operations. IDBF is a general framework for nearly optimal fast matvec useful in a wide range of applications, e.g., special function transformation, Fourier integral operators, high-frequency wave computation. Numerical results are provided to demonstrate the effectiveness of the butterfly factorization and its construction algorithms.