cgecon3
Part of cgecon.f(3).
Usage
Functions/Subroutines
subroutine cgecon (norm, n, a, lda, anorm, rcond, work, rwork, info)
CGECON
Function/Subroutine Documentation
subroutine cgecon (character norm, integer n, complex, dimension( lda, * ) a, integer lda, real anorm, real rcond, complex, dimension( * ) work, real, dimension( * ) rwork, integer info)
CGECON
Purpose:
!> !> CGECON 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. !> !> 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 COMPLEX array, dimension (LDA,N) !> The factors L and U from the factorization A = P*L*U !> as computed by CGETRF. !>
LDA
!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,N). !>
ANORM
!> ANORM is REAL !> 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 REAL !> The reciprocal of the condition number of the matrix A, !> computed as RCOND = 1/(norm(A) * norm(inv(A))). !>
WORK
!> WORK is COMPLEX array, dimension (2*N) !>
RWORK
!> RWORK is REAL array, dimension (2*N) !>
INFO
!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -i, the i-th argument had an illegal value. !> NaNs are illegal values for ANORM, and they propagate to !> the output parameter RCOND. !> Infinity is illegal for ANORM, and it propagates to the output !> parameter RCOND as 0. !> = 1: if RCOND = NaN, or !> RCOND = Inf, or !> the computed norm of the inverse of A is 0. !> In the latter, RCOND = 0 is returned. !>
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 130 of file cgecon.f.
Releases
14 releases since Debian 1.3 (Bo); the text changed 11 times.