# spocon.f - Man Page

SRC/spocon.f

## Synopsis

### Functions/Subroutines

subroutine **spocon** (uplo, n, a, lda, anorm, rcond, work, iwork, info)**SPOCON**

## Function/Subroutine Documentation

### subroutine spocon (character uplo, integer n, real, dimension( lda, * ) a, integer lda, real anorm, real rcond, real, dimension( * ) work, integer, dimension( * ) iwork, integer info)

**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.

Definition at line **119** of file **spocon.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page spocon(3) is an alias of spocon.f(3).

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK