Provided by: liblapack-doc_3.3.1-1_all #### NAME

```       LAPACK-3 - computes the reciprocal pivot growth factor norm(A)/norm(U)

```

#### SYNOPSIS

```       REAL FUNCTION SLA_SYRPVGRW( UPLO, N, INFO, A, LDA, AF, LDAF, IPIV, WORK )

IMPLICIT  NONE

CHARACTER*1
UPLO

INTEGER   N, INFO, LDA, LDAF

INTEGER   IPIV( * )

REAL      A( LDA, * ), AF( LDAF, * ), WORK( * )

```

#### 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.

```

#### ARGUMENTS

```        UPLO    (input) CHARACTER*1
= 'U':  Upper triangle of A is stored;
= 'L':  Lower triangle of A is stored.

N       (input) INTEGER
The number of linear equations, i.e., the order of the
matrix A.  N >= 0.

INFO    (input) INTEGER
The value of INFO returned from SSYTRF, .i.e., the pivot in
column INFO is exactly 0.

NCOLS   (input) INTEGER
The number of columns of the matrix A. NCOLS >= 0.

A       (input) REAL array, dimension (LDA,N)
On entry, the N-by-N matrix A.

LDA     (input) INTEGER
The leading dimension of the array A.  LDA >= max(1,N).

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

IPIV    (input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by SSYTRF.

WORK    (input) REAL array, dimension (2*N)

LAPACK routine (version 3.2.2)          April 2011                      SLA_SYRPVGRW(3lapack)
```