cgecon (l)  Linux Man Pages
cgecon: estimates the reciprocal of the condition number of a general complex matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by CGETRF
NAME
CGECON  estimates the reciprocal of the condition number of a general complex matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by CGETRFSYNOPSIS
 SUBROUTINE CGECON(
 NORM, N, A, LDA, ANORM, RCOND, WORK, RWORK, INFO )
 CHARACTER NORM
 INTEGER INFO, LDA, N
 REAL ANORM, RCOND
 REAL RWORK( * )
 COMPLEX A( LDA, * ), WORK( * )
PURPOSE
CGECON estimates the reciprocal of the condition number of a general complex matrix A, in either the 1norm or the infinitynorm, using the LU factorization computed by CGETRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed asRCOND
ARGUMENTS
 NORM (input) CHARACTER*1

Specifies whether the 1norm condition number or the
infinitynorm condition number is required:
= aq1aq or aqOaq: 1norm;
= aqIaq: Infinitynorm.  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 1norm of the original matrix A. If NORM = aqIaq, the infinitynorm 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 ith argument had an illegal value