DGETF2  -  compute an LU factorization of a general m-by-n
       matrix A using partial pivoting with row interchanges


SYNOPSIS

       SUBROUTINE DGETF2( M, N, A, LDA, IPIV, INFO )

           INTEGER        INFO, LDA, M, N

           INTEGER        IPIV( * )

           DOUBLE         PRECISION A( LDA, * )


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.


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) DOUBLE PRECISION 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 ille­
               gal value
               > 0: if INFO = k, U(k,k) is exactly zero. The fac­
               torization has been completed, but the factor U is

               if it is used to solve a system of equations.


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