Provided by: liblapack-doc_3.3.1-1_all

#### NAME

```       LAPACK-3 - estimates the reciprocal of the condition number of a general real matrix A, in
either the 1-norm or the infinity-norm, using the LU factorization computed by SGETRF

```

#### SYNOPSIS

```       SUBROUTINE SGECON( NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO )

CHARACTER      NORM

INTEGER        INFO, LDA, N

REAL           ANORM, RCOND

INTEGER        IWORK( * )

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

```

#### PURPOSE

```       SGECON estimates the reciprocal of the condition number of a general  real  matrix  A,  in
either the 1-norm or the infinity-norm, using the LU factorization computed by SGETRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as
RCOND = 1 / ( norm(A) * norm(inv(A)) ).

```

#### ARGUMENTS

```        NORM    (input) CHARACTER*1
Specifies whether the 1-norm condition number or the
infinity-norm condition number is required:
= '1' or 'O':  1-norm;
= 'I':         Infinity-norm.

N       (input) INTEGER
The order of the matrix A.  N >= 0.

A       (input) REAL array, dimension (LDA,N)
The factors L and U from the factorization A = P*L*U
as computed by SGETRF.

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

ANORM   (input) REAL
If NORM = '1' or 'O', the 1-norm of the original matrix A.
If NORM = 'I', the infinity-norm of the original matrix A.

RCOND   (output) REAL
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(norm(A) * norm(inv(A))).

WORK    (workspace) REAL array, dimension (4*N)

IWORK   (workspace) INTEGER array, dimension (N)

INFO    (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value

LAPACK routine (version 3.3.1)             April 2011                            SGECON(3lapack)
```