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  4. zla_porpvgrw(3)

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zla_porpvgrw.f(3) LAPACK zla_porpvgrw.f(3)

NAME

zla_porpvgrw.f

SYNOPSIS

Functions/Subroutines


double precision function zla_porpvgrw (UPLO, NCOLS, A, LDA, AF, LDAF, WORK)
ZLA_PORPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.

Function/Subroutine Documentation

double precision function zla_porpvgrw (character*1 UPLO, integer NCOLS, complex*16, dimension( lda, * ) A, integer LDA, complex*16, dimension( ldaf, * ) AF, integer LDAF, double precision, dimension( * ) WORK)

ZLA_PORPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.

Purpose: 



 ZLA_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 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 triangular factor U or L from the Cholesky factorization


     A = U**T*U or A = L*L**T, as computed by ZPOTRF.

LDAF



          LDAF is INTEGER


     The leading dimension of the array AF.  LDAF >= max(1,N).

WORK



          WORK is DOUBLE PRECISION array, dimension (2*N)

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

June 2016

Definition at line 109 of file zla_porpvgrw.f.

Author

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