# sla_porpvgrw (3) - Linux Man Pages

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