# sla_syrpvgrw.f man page

sla_syrpvgrw.f —

## Synopsis

### Functions/Subroutines

REAL functionsla_syrpvgrw(UPLO, N, INFO, A, LDA, AF, LDAF, IPIV, WORK)SLA_SYRPVGRWcomputes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.

## Function/Subroutine Documentation

### REAL function sla_syrpvgrw (character*1UPLO, integerN, integerINFO, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, real, dimension( * )WORK)

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

**Purpose:**

```
SLA_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 SSYTRF, .i.e., the pivot in
column INFO is exactly 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 block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by SSYTRF.
```

*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 SSYTRF.
```

*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 122 of file sla_syrpvgrw.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

sla_syrpvgrw(3) is an alias of sla_syrpvgrw.f(3).