Sgetc2.f -
subroutine sgetc2 (N, A, LDA, IPIV, JPIV, INFO)
SGETC2 computes the LU factorization with complete pivoting of the general n-by-n matrix.
SGETC2 computes the LU factorization with complete pivoting of the general n-by-n matrix.
Purpose:
SGETC2 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
N is INTEGER
The order of the matrix A. N >= 0.
A
A is REAL 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:
November 2013
Contributors:
Bo Kagstrom and Peter Poromaa, Department of Computing Science, Umea University, S-901 87 Umea, Sweden.
Definition at line 112 of file sgetc2.f.
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