DNLASO.f

DNLASO FINDS A FEW EIGENVALUES AND EIGENVECTORS AT EITHER END OF THE SPECTRUM OF A LARGE SPARSE SYMMETRIC MATRIX. THE SUBROUTINE DNLASO IS PRIMARILY A DRIVER FOR SUBROUTINE DNWLA WHICH IMPLEMENTS THE LANCZOS ALGORITHM WITH SELECTIVE ORTHOGONALIZATION AND SUBROUTINE DNPPLA WHICH POST PROCESSES THE OUTPUT OF DNWLA. HOWEVER DNLASO DOES CHECK FOR INCONSISTENCIES IN THE CALLING PARAMETERS AND DOES PREPROCESS ANY USER SUPPLIED EIGENPAIRS.DNLASO ALWAYS LOOKS FOR THE SMALLEST (LEFTMOST) EIGENVALUES. IF THE LARGEST EIGENVALUES ARE DESIRED DNLASO IMPLICITLY USES THE NEGATIVE OF THE MATRIX.

References in zbMATH (referenced in 1 article )

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  1. Gubernatis, J.E.; Booth, T.E.: Multiple extremal eigenpairs by the power method (2008)