# spocon.f man page

spocon.f —

## Synopsis

### Functions/Subroutines

subroutinespocon(UPLO, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO)SPOCON

## Function/Subroutine Documentation

### subroutine spocon (characterUPLO, integerN, real, dimension( lda, * )A, integerLDA, realANORM, realRCOND, real, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)

**SPOCON**

**Purpose:**

```
SPOCON estimates the reciprocal of the condition number (in the
1-norm) of a real symmetric positive definite matrix using the
Cholesky factorization A = U**T*U or A = L*L**T computed by SPOTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
```

**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 order of the matrix A. N >= 0.
```

*A*

```
A is REAL array, dimension (LDA,N)
The triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, as computed by SPOTRF.
```

*LDA*

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

*ANORM*

```
ANORM is REAL
The 1-norm (or infinity-norm) of the symmetric matrix A.
```

*RCOND*

```
RCOND is REAL
The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
estimate of the 1-norm of inv(A) computed in this routine.
```

*WORK*

`WORK is REAL array, dimension (3*N)`

*IWORK*

`IWORK is INTEGER array, dimension (N)`

*INFO*

```
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
```

**Author:**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**

November 2011

Definition at line 121 of file spocon.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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