IPQRDecomposition

Compute the QR factorization of a set of vectors.

Synopsis

#include "slepcip.h" 
PetscErrorCode IPQRDecomposition(IP ip,Vec *V,PetscInt m,PetscInt n,PetscScalar *R,PetscInt ldr)
Collective on IP

Input Parameters

ip - the eigenproblem solver context
V - set of vectors
m - starting column
n - ending column
ldr - leading dimension of R

Output Parameter

R - triangular matrix of QR factorization

Notes

This routine orthonormalizes the columns of V so that V'*V=I up to working precision. It assumes that the first m columns (from 0 to m-1) are already orthonormal. The coefficients of the orthogonalization are stored in R so that V*R is equal to the original V.

In some cases, this routine makes V B-orthonormal, that is, V'*B*V=I.

If one of the vectors is linearly dependent wrt the rest (at working precision) then it is replaced by a random vector.

See Also

IPOrthogonalize(), IPNorm(), IPInnerProduct().

Location: src/ip/iporthog.c
Index of all IP routines
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Index of all manual pages