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      SUBROUTINE ZGETF2F( M, N, A, LDA, IPIV, INFO )
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*
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*  -- LAPACK routine (version 3.0) --
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*     Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,
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*     Courant Institute, Argonne National Lab, and Rice University
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*     September 30, 1994
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*
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*     .. Scalar Arguments ..
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      INTEGER            INFO, LDA, M, N
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*     ..
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*     .. Array Arguments ..
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      INTEGER            IPIV( * )
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      COMPLEX*16         A( LDA, * )
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*     ..
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*
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*  Purpose
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*  =======
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*
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*  ZGETF2 computes an LU factorization of a general m-by-n matrix A
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*  using partial pivoting with row interchanges.
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*
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*  The factorization has the form
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*     A = P * L * U
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*  where P is a permutation matrix, L is lower triangular with unit
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*  diagonal elements (lower trapezoidal if m > n), and U is upper
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*  triangular (upper trapezoidal if m < n).
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*
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*  This is the right-looking Level 2 BLAS version of the algorithm.
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*
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*  Arguments
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*  =========
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*
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*  M       (input) INTEGER
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*          The number of rows of the matrix A.  M >= 0.
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*
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*  N       (input) INTEGER
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*          The number of columns of the matrix A.  N >= 0.
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*
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*  A       (input/output) COMPLEX*16 array, dimension (LDA,N)
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*          On entry, the m by n matrix to be factored.
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*          On exit, the factors L and U from the factorization
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*          A = P*L*U; the unit diagonal elements of L are not stored.
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*
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*  LDA     (input) INTEGER
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*          The leading dimension of the array A.  LDA >= max(1,M).
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*
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*  IPIV    (output) INTEGER array, dimension (min(M,N))
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*          The pivot indices; for 1 <= i <= min(M,N), row i of the
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*          matrix was interchanged with row IPIV(i).
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*
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*  INFO    (output) INTEGER
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*          = 0: successful exit
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*          < 0: if INFO = -k, the k-th argument had an illegal value
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*          > 0: if INFO = k, U(k,k) is exactly zero. The factorization
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*               has been completed, but the factor U is exactly
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*               singular, and division by zero will occur if it is used
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*               to solve a system of equations.
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*
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*  =====================================================================
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*
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*     .. Parameters ..
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      COMPLEX*16         ONE, ZERO
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      PARAMETER          ( ONE = ( 1.0D+0, 0.0D+0 ),
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     $                   ZERO = ( 0.0D+0, 0.0D+0 ) )
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*     ..
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*     .. Local Scalars ..
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      INTEGER            J, JP
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*     ..
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*     .. External Functions ..
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      INTEGER            IZAMAX
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      EXTERNAL           IZAMAX
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*     ..
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*     .. External Subroutines ..
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      EXTERNAL           XERBLA, ZGERU, ZSCAL, ZSWAP
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*     ..
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*     .. Intrinsic Functions ..
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      INTRINSIC          MAX, MIN
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*     ..
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*     .. Executable Statements ..
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*
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*     Test the input parameters.
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*
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      INFO = 0
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      IF( M.LT.0 ) THEN
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         INFO = -1
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      ELSE IF( N.LT.0 ) THEN
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         INFO = -2
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      ELSE IF( LDA.LT.MAX( 1, M ) ) THEN
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         INFO = -4
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      END IF
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      IF( INFO.NE.0 ) THEN
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         CALL XERBLA( 'ZGETF2', -INFO )
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         RETURN
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      END IF
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*
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*     Quick return if possible
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*
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      IF( M.EQ.0 .OR. N.EQ.0 )
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     $   RETURN
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*
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      DO 10 J = 1, MIN( M, N )
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*
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*        Find pivot and test for singularity.
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*
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         JP = J - 1 + IZAMAX( M-J+1, A( J, J ), 1 )
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         IPIV( J ) = JP
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         IF( A( JP, J ).NE.ZERO ) THEN
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*
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*           Apply the interchange to columns 1:N.
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*
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            IF( JP.NE.J )
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     $         CALL ZSWAP( N, A( J, 1 ), LDA, A( JP, 1 ), LDA )
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*
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*           Compute elements J+1:M of J-th column.
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*
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            IF( J.LT.M )
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     $         CALL ZSCAL( M-J, ONE / A( J, J ), A( J+1, J ), 1 )
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*
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         ELSE IF( INFO.EQ.0 ) THEN
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*
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            INFO = J
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         END IF
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*
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         IF( J.LT.MIN( M, N ) ) THEN
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*
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*           Update trailing submatrix.
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*
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            CALL ZGERU( M-J, N-J, -ONE, A( J+1, J ), 1, A( J, J+1 ),
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     $                  LDA, A( J+1, J+1 ), LDA )
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         END IF
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   10 CONTINUE
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      RETURN
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*
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*     End of ZGETF2
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*
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      END