dgetc2-f(3)

dgetc2.f –

Synopsis

Functions/Subroutines

subroutine dgetc2 (N, A, LDA, IPIV, JPIV, INFO)
DGETC2 computes the LU factorization with complete pivoting of the general n-by-n matrix.

Function/Subroutine Documentation

subroutine dgetc2 (integerN, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, integer, dimension( * )JPIV, integerINFO)

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

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:

 N is INTEGER
 The order of the matrix A. N >= 0.

 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.

LDA

 LDA is INTEGER
 The leading dimension of the array A. LDA >= max(1,N).

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).

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).

INFO

 INFO is INTEGER
 = 0: successful exit
 > 0: if INFO = k, U(k, k) is likely to produce owerflow 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.

Date:

September 2012

Contributors:

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

Definition at line 112 of file dgetc2.f.

Author

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