DGETF2 (3) Linux Manual Page
dgetf2.f –
Synopsis
Functions/Subroutines
subroutine dgetf2 (M, N, A, LDA, IPIV, INFO)DGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).
Function/Subroutine Documentation
subroutine dgetf2 (integerM, integerN, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, integerINFO)
DGETF2 computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm). Purpose:
DGETF2 computes an LU factorization of a general m-by-n matrix A
using partial pivoting with row interchanges.
The factorization has the form
A = P * L * U
where P is a permutation matrix, L is lower triangular with unit
diagonal elements (lower trapezoidal if m > n), and U is upper
triangular (upper trapezoidal if m < n).
This is the right-looking Level 2 BLAS version of the algorithm.
Parameters:
- M
M is INTEGER
N
The number of rows of the matrix A. M >= 0.N is INTEGER
A
The number of columns of the matrix A. N >= 0.A is DOUBLE PRECISION array, dimension (LDA,N)
LDA
On entry, the m by n matrix to be factored.
On exit, the factors L and U from the factorization
A = P*L*U; the unit diagonal elements of L are not stored.LDA is INTEGER
IPIV
The leading dimension of the array A. LDA >= max(1,M).IPIV is INTEGER array, dimension (min(M,N))
INFO
The pivot indices; for 1 <= i <= min(M,N), row i of the
matrix was interchanged with row IPIV(i).INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, U(k,k) is exactly zero. The factorization
has been completed, but the factor U is exactly
singular, and division by zero will occur if it is used
to solve a system of equations.
Author:
- Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
- September 2012
Definition at line 109 of file dgetf2.f.