SRC/zla_syrpvgrw.f(3) | Library Functions Manual | SRC/zla_syrpvgrw.f(3) |
NAME
SRC/zla_syrpvgrw.f
SYNOPSIS
Functions/Subroutines
double precision function zla_syrpvgrw (uplo, n, info, a,
lda, af, ldaf, ipiv, work)
ZLA_SYRPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U) for a symmetric indefinite matrix.
Function/Subroutine Documentation
double precision function zla_syrpvgrw (character*1 uplo, integer n, integer info, complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension( ldaf, * ) af, integer ldaf, integer, dimension( * ) ipiv, double precision, dimension( * ) work)
ZLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
Purpose:
ZLA_SYRPVGRW 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.
Parameters
UPLO
UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
N
N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.
INFO
INFO is INTEGER The value of INFO returned from ZSYTRF, .i.e., the pivot in column INFO is exactly 0.
A
A is COMPLEX*16 array, dimension (LDA,N) On entry, the N-by-N matrix A.
LDA
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
AF
AF is COMPLEX*16 array, dimension (LDAF,N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ZSYTRF.
LDAF
LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).
IPIV
IPIV is INTEGER array, dimension (N) Details of the interchanges and the block structure of D as determined by ZSYTRF.
WORK
WORK is DOUBLE PRECISION array, dimension (2*N)
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 121 of file zla_syrpvgrw.f.
Author
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