dgetc2()

subroutine dgetc2	(	integer	n,
		double precision, dimension( lda, * )	a,
		integer	lda,
		integer, dimension( * )	ipiv,
		integer, dimension( * )	jpiv,
		integer	info )

DGETC2 computes the LU factorization with complete pivoting of the general n-by-n matrix.

Download DGETC2 + dependencies [TGZ] [ZIP] [TXT]

Purpose:

!>
!> DGETC2 computes an LU factorization with complete pivoting of the
!> n-by-n matrix A. The factorization has the form A = P * L * U * Q,
!> where P and Q are permutation matrices, L is lower triangular with
!> unit diagonal elements and U is upper triangular.
!>
!> This is the Level 2 BLAS algorithm.
!> 

Parameters

[in]	N	!> N is INTEGER !> The order of the matrix A. N >= 0. !>
[in,out]	A	!> A is DOUBLE PRECISION array, dimension (LDA, N) !> On entry, the n-by-n matrix A to be factored. !> On exit, the factors L and U from the factorization !> A = P*L*U*Q; the unit diagonal elements of L are not stored. !> If U(k, k) appears to be less than SMIN, U(k, k) is given the !> value of SMIN, i.e., giving a nonsingular perturbed system. !>
[in]	LDA	!> LDA is INTEGER !> The leading dimension of the array A. LDA >= max(1,N). !>
[out]	IPIV	!> IPIV is INTEGER array, dimension(N). !> The pivot indices; for 1 <= i <= N, row i of the !> matrix has been interchanged with row IPIV(i). !>
[out]	JPIV	!> JPIV is INTEGER array, dimension(N). !> The pivot indices; for 1 <= j <= N, column j of the !> matrix has been interchanged with column JPIV(j). !>
[out]	INFO	!> INFO is INTEGER !> = 0: successful exit !> > 0: if INFO = k, U(k, k) is likely to produce overflow if !> we try to solve for x in Ax = b. So U is perturbed to !> avoid the overflow. !>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Contributors:

Bo Kagstrom and Peter Poromaa, Department of Computing Science, Umea University, S-901 87 Umea, Sweden.