| SRC/sla_porpvgrw.f(3) | Library Functions Manual | SRC/sla_porpvgrw.f(3) |
NAME
SRC/sla_porpvgrw.f
SYNOPSIS
Functions/Subroutines
real function sla_porpvgrw (uplo, ncols, a, lda, af, ldaf,
work)
SLA_PORPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.
Function/Subroutine Documentation
real function sla_porpvgrw (character*1 uplo, integer ncols, real, dimension( lda, * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf, real, dimension( * ) work)
SLA_PORPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.
Purpose:
!> !> !> SLA_PORPVGRW computes the reciprocal pivot growth factor !> norm(A)/norm(U). The 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. !>
NCOLS
!> NCOLS is INTEGER !> The number of columns of the matrix A. NCOLS >= 0. !>
A
!> A is REAL 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 REAL array, dimension (LDAF,N) !> The triangular factor U or L from the Cholesky factorization !> A = U**T*U or A = L*L**T, as computed by SPOTRF. !>
LDAF
!> LDAF is INTEGER !> The leading dimension of the array AF. LDAF >= max(1,N). !>
WORK
!> WORK is REAL array, dimension (2*N) !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 103 of file sla_porpvgrw.f.
Author
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