Patent ID: 8209138

Claim:
A method for determining a source function given an excitation of a material object having a system interaction matrix that is characteristic of the material object, comprising: spatially grouping unknown sources of the source function according to their distances from one or more reference points so that the system interaction matrix exhibits low rank for a given error tolerance; partitioning the system interaction matrix into off-diagonal blocks and on-diagonal blocks; computing a compressed block factorization of the system interaction matrix, wherein off-diagonal blocks of the factorization are computed in compressed form; and wherein computing the compressed block factorization of the system interaction matrix further comprises: further partitioning the on-diagonal blocks into off-diagonal sub-blocks and on-diagonal sub-blocks; and computing a compressed block factorization of the on-diagonal blocks, wherein off diagonal sub-blocks of the factorization are computed in compressed form; and determining the source function from the compressed block factorizations.