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sla_porpvgrw.f(3) LAPACK sla_porpvgrw.f(3)

NAME

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*1UPLO, integerNCOLS, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, 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 "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.
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.
Date:
September 2012
Definition at line 105 of file sla_porpvgrw.f.

Author

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