NAME

ZGETF2 - compute an LU factorization of a general m-by-n matrix A using partial pivoting with row interchanges

SYNOPSIS

SUBROUTINE ZGETF2(
M, N, A, LDA, IPIV, INFO )

INTEGER INFO, LDA, M, N

INTEGER IPIV( ∗ )

COMPLEX∗16 A( LDA, ∗ )

PURPOSE

ZGETF2 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.
 

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) COMPLEX∗16 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 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 version 2.0  —  08 October 1994