Wednesday, November 7, 2012

1211.1180 (Chris Johnson et al.)

Numerical determination of partial spectrum of Hermitian matrices using
a Lanczos method with selective reorthogonalization
   [PDF]

Chris Johnson, A. D. Kennedy
We introduce a new algorithm for finding the eigenvalues and eigenvectors of Hermitian matrices within a specified region, based upon the LANSO algorithm of Parlett and Scott. It uses selective reorthogonalization to avoid the duplication of eigenpairs in finite-precision arithmetic, but uses a new bound to decide when such reorthogonalization is required, and only reorthogonalizes with respect to eigenpairs within the region of interest. We investigate its performance for the Hermitian Wilson--Dirac operator (\gamma_5D) in lattice quantum chromodynamics, and compare it with previous methods.
View original: http://arxiv.org/abs/1211.1180

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