Chimie Théorique » OpenPath

      INTEGER FUNCTION ILADLR(M, N, A, LDA)

      IMPLICIT NONE

!

!  -- LAPACK auxiliary routine (version 3.2) --

!     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..

!     December 2007

!

!     .. Scalar Arguments ..

      INTEGER            M, N, LDA

!     ..

!     .. Array Arguments ..

      DOUBLE PRECISION   A( LDA, * )

!     ..

!

!  Purpose

!  =======

!

!  ILADLR scans A for its last non-zero row.

!

!  Arguments

!  =========

!

!  M       (input) INTEGER

!          The number of rows of the matrix A.

!

!  N       (input) INTEGER

!          The number of columns of the matrix A.

!

!  A       (input) DOUBLE PRECISION array, dimension (LDA,N)

!          The m by n matrix A.

!

!  LDA     (input) INTEGER

!          The leading dimension of the array A. LDA >= max(1,M).

!

!  =====================================================================

!

!     .. Parameters ..

      DOUBLE PRECISION ZERO

      PARAMETER ( ZERO = 0.0D+0 )

!     ..

!     .. Local Scalars ..

      INTEGER I, J

!     ..

!     .. Executable Statements ..

!

!     Quick test for the common case where one corner is non-zero.

      IF( M.EQ.0 .OR. A(M, 1).NE.ZERO .OR. A(M, N).NE.ZERO ) THEN

         ILADLR = M

      ELSE

!     Scan up each column tracking the last zero row seen.

         ILADLR = 0

         DO J = 1, N

            DO I = M, 1, -1

               IF( A(I, J).NE.ZERO ) EXIT

            END DO

            ILADLR = MAX( ILADLR, I )

         END DO

      END IF

      RETURN

      END FUNCTION