# dpocon.f - Man Page

## Synopsis

### Functions/Subroutines

subroutine **dpocon** (UPLO, **N**, A, **LDA**, ANORM, RCOND, WORK, IWORK, INFO)**DPOCON**

## Function/Subroutine Documentation

### subroutine dpocon (character UPLO, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision ANORM, double precision RCOND, double precision, dimension( * ) WORK, integer, dimension( * ) IWORK, integer INFO)

**DPOCON**

**Purpose:**

DPOCON 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 DPOTRF. 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 DOUBLE PRECISION 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 DPOTRF.

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

*ANORM*ANORM is DOUBLE PRECISION The 1-norm (or infinity-norm) of the symmetric matrix A.

*RCOND*RCOND is DOUBLE PRECISION 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 DOUBLE PRECISION 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:**December 2016

Definition at line 123 of file dpocon.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK