table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dgecon.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dgecon.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/SRC/dgecon.f
SYNOPSIS¶
Functions/Subroutines¶
subroutine DGECON (norm, n, a, lda, anorm, rcond, work,
iwork, info)
DGECON
Function/Subroutine Documentation¶
subroutine DGECON (character norm, integer n, double precision, dimension( lda, * ) a, integer lda, double precision anorm, double precision rcond, double precision, dimension( * ) work, integer, dimension( * ) iwork, integer info)¶
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. !> 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 dgecon.f.
Author¶
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