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dla_syrpvgrw.f(3) LAPACK dla_syrpvgrw.f(3)

NAME

dla_syrpvgrw.f -

SYNOPSIS

Functions/Subroutines


double precision function dla_syrpvgrw (UPLO, N, INFO, A, LDA, AF, LDAF, IPIV, WORK)
 
DLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

Function/Subroutine Documentation

double precision function dla_syrpvgrw (character*1UPLO, integerN, integerINFO, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, double precision, dimension( * )WORK)

DLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
Purpose:
 DLA_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 DSYTRF, .i.e., the pivot in
     column INFO is exactly 0.
A
          A is DOUBLE PRECISION 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 DOUBLE PRECISION array, dimension (LDAF,N)
     The block diagonal matrix D and the multipliers used to
     obtain the factor U or L as computed by DSYTRF.
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 DSYTRF.
WORK
          WORK is DOUBLE PRECISION array, dimension (2*N)
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 122 of file dla_syrpvgrw.f.

Author

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