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man pages->IRIX man pages -> complib/sgecon (3)
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### Contents

```
SGECON(3F)							    SGECON(3F)

```

### NAME[Toc][Back]

```     SGECON - estimate 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[Toc][Back]

```     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[Toc][Back]

```     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[Toc][Back]

```     NORM    (input) CHARACTER*1
Specifies whether the 1-norm condition number or the infinitynorm
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))).

Page 1

SGECON(3F)							    SGECON(3F)

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
SGECON(3F)							    SGECON(3F)

```

### NAME[Toc][Back]

```     SGECON - estimate 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[Toc][Back]

```     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[Toc][Back]

```     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[Toc][Back]

```     NORM    (input) CHARACTER*1
Specifies whether the 1-norm condition number or the infinitynorm
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))).

Page 1

SGECON(3F)							    SGECON(3F)

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

PPPPaaaaggggeeee 2222```
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