Provided by: liblapack-doc_3.3.1-1_all
LAPACK-3 - computes the reciprocal pivot growth factor norm(A)/norm(U)
DOUBLE PRECISION FUNCTION ZLA_RPVGRW( N, NCOLS, A, LDA, AF, LDAF ) IMPLICIT NONE INTEGER N, NCOLS, LDA, LDAF COMPLEX*16 A( LDA, * ), AF( LDAF, * )
ZLA_RPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U). The "max absolute element" norm is used. If this is much less than 1, the stability of the LU factorization of the (equilibrated) matrix A could be poor. This also means that the solution X, estimated condition numbers, and error bounds could be unreliable.
N (input) INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0. NCOLS (input) INTEGER The number of columns of the matrix A. NCOLS >= 0. A (input) DOUBLE PRECISION array, dimension (LDA,N) On entry, the N-by-N matrix A. LDA (input) INTEGER The leading dimension of the array A. LDA >= max(1,N). AF (input) DOUBLE PRECISION array, dimension (LDAF,N) The factors L and U from the factorization A = P*L*U as computed by ZGETRF. LDAF (input) INTEGER The leading dimension of the array AF. LDAF >= max(1,N). LAPACK routine (version 3.2.2) April 2011 ZLA_RPVGRW(3lapack)