SGETRF(1) LAPACK routine (version 3.2) SGETRF(1)NAME
SGETRF - computes an LU factorization of a general M-by-N matrix A
using partial pivoting with row interchanges
SYNOPSIS
SUBROUTINE SGETRF( M, N, A, LDA, IPIV, INFO )
INTEGER INFO, LDA, M, N
INTEGER IPIV( * )
REAL A( LDA, * )
PURPOSE
SGETRF 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 diago‐
nal elements (lower trapezoidal if m > n), and U is upper triangular
(upper trapezoidal if m < n).
This is the right-looking Level 3 BLAS version of the algorithm.
ARGUMENTS
M (input) INTEGER
The number of rows of the matrix A. M >= 0.
N (input) INTEGER
The number of columns of the matrix A. N >= 0.
A (input/output) REAL array, dimension (LDA,N)
On entry, the M-by-N matrix to be factored. On exit, the fac‐
tors L and U from the factorization A = P*L*U; the unit diago‐
nal elements of L are not stored.
LDA (input) INTEGER
The leading dimension of the array A. LDA >= max(1,M).
IPIV (output) INTEGER array, dimension (min(M,N))
The pivot indices; for 1 <= i <= min(M,N), row i of the matrix
was interchanged with row IPIV(i).
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, U(i,i) 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.
LAPACK routine (version 3.2) November 2008 SGETRF(1)