dgecon.f man 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

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

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

Sat Nov 16 2013 Version 3.4.2 LAPACK