DPOCON (3) Linux Manual Page

dpocon.f –

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine dpocon (characterUPLO, integerN, double precision, dimension( lda, * )A, integerLDA, double precisionANORM, double precisionRCOND, double precision, dimension( * )WORK, integer, dimension( * )IWORK, integerINFO)

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:

November 2011

Definition at line 121 of file dpocon.f.

Author

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