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 zla_syrpvgrw.f(3) LAPACK zla_syrpvgrw.f(3)

zla_syrpvgrw.f -

# SYNOPSIS

## Functions/Subroutines

DOUBLE PRECISION function zla_syrpvgrw (UPLO, N, INFO, A, LDA, AF, LDAF, IPIV, WORK)

ZLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

# Function/Subroutine Documentation

## DOUBLE PRECISION function zla_syrpvgrw (character*1UPLO, integerN, integerINFO, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, double precision, dimension( * )WORK)

ZLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
Purpose:
``` ZLA_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 ZSYTRF, .i.e., the pivot in
column INFO is exactly 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 block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by ZSYTRF.
```
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 ZSYTRF.
```
WORK
```          WORK is COMPLEX*16 array, dimension (2*N)
```
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 123 of file zla_syrpvgrw.f.

# Author

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