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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