DGECON (3) Linux Manual Page

dgecon.f –

Synopsis

Functions/Subroutines

subroutine dgecon (NORM, N, A, LDA, ANORM, RCOND, WORK, IWORK, INFO)
DGECON

Function/Subroutine Documentation

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

DGECON

Purpose:

 DGECON 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 DGETRF.

 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)) ).

 

Parameters:

NORM

 NORM is CHARACTER*1

 Specifies whether the 1-norm condition number or the

 infinity-norm condition number is required:

 = ‘1’ or ‘O’: 1-norm;

 = ‘I’: Infinity-norm.

N

 N is INTEGER

 The order of the matrix A. N >= 0.

A

 A is DOUBLE PRECISION array, dimension (LDA,N)

 The factors L and U from the factorization A = P*L*U

 as computed by DGETRF.

LDA

 LDA is INTEGER

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

ANORM

 ANORM is DOUBLE PRECISION

 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

 RCOND is DOUBLE PRECISION

 The reciprocal of the condition number of the matrix A,

 computed as RCOND = 1/(norm(A) * norm(inv(A))).

WORK

 WORK is DOUBLE PRECISION array, dimension (4*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 124 of file dgecon.f.

Author

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