MAN page from OpenSuSE 12.X lapack-man-3.3.1-15.1.noarch.rpm

CGECON

Section: LAPACK routine (version 3.3.1) (1)
Updated: April 2011
Index

NAME

LAPACK-3 - estimates the reciprocal of the condition number of a general complex matrix A, in either the 1-norm or the infinity-norm, using the LU factorization computed by CGETRF

SYNOPSIS

SUBROUTINE CGECON(: NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK,INFO )
: CHARACTERNORM
: INTEGERINFO, LDA, N
: REALANORM, RCOND
: REALRWORK( * )
: COMPLEXA( LDA, * ), WORK( * )

PURPOSE

CGECON estimates the reciprocal of the condition number of a generalcomplex matrix A, in either the 1-norm or the infinity-norm, usingthe LU factorization computed by CGETRF.
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)) ).

ARGUMENTS

NORM (input) CHARACTER*1: Specifies whether the 1-norm condition number or the
infinity-norm condition number is required:

= aq1aq or aqOaq: 1-norm;

= aqIaq: Infinity-norm.
N (input) INTEGER: The order of the matrix A. N >= 0.
A (input) COMPLEX array, dimension (LDA,N): The factors L and U from the factorization A = P*L*U
as computed by CGETRF.
LDA (input) INTEGER: The leading dimension of the array A. LDA >= max(1,N).
ANORM (input) REAL: If NORM = aq1aq or aqOaq, the 1-norm of the original matrix A.
If NORM = aqIaq, the infinity-norm of the original matrix A.
RCOND (output) REAL: The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(norm(A) * norm(inv(A))).
WORK (workspace) COMPLEX array, dimension (2*N)
RWORK (workspace) REAL array, dimension (2*N)
INFO (output) INTEGER: = 0: successful exit

< 0: if INFO = -i, the i-th argument had an illegal value

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