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# sgetf2

```
NAME
SGETF2 - compute an LU factorization of a general m-by-n
matrix A using partial pivoting with row interchanges

SYNOPSIS
SUBROUTINE SGETF2( M, N, A, LDA, IPIV, INFO )

INTEGER        INFO, LDA, M, N

INTEGER        IPIV( * )

REAL           A( LDA, * )

PURPOSE
SGETF2 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 algo-
rithm.

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 factors L and U from the factorization A =
P*L*U; the unit diagonal 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 = -k, the k-th argument had an illegal
value

> 0: if INFO = k, U(k,k) is exactly zero. The fac-
torization 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.
```