lapack/ilaslc.f

*> \brief \b ILASLC
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*> \htmlonly
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*> \endhtmlonly 
*
*  Definition:
*  ===========
*
*       INTEGER FUNCTION ILASLC( M, N, A, LDA )
* 
*       .. Scalar Arguments ..
*       INTEGER            M, N, LDA
*       ..
*       .. Array Arguments ..
*       REAL               A( LDA, * )
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> ILASLC scans A for its last non-zero column.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] M
*> \verbatim
*>          M is INTEGER
*>          The number of rows of the matrix A.
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The number of columns of the matrix A.
*> \endverbatim
*>
*> \param[in] A
*> \verbatim
*>          A is REAL array, dimension (LDA,N)
*>          The m by n matrix A.
*> \endverbatim
*>
*> \param[in] LDA
*> \verbatim
*>          LDA is INTEGER
*>          The leading dimension of the array A. LDA >= max(1,M).
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date November 2011
*
*> \ingroup realOTHERauxiliary
*
*  =====================================================================
      INTEGER FUNCTION ILASLC( M, N, A, LDA )
*
*  -- LAPACK auxiliary routine (version 3.4.0) --
*  -- LAPACK is a software package provided by Univ. of Tennessee,    --
*  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
*     November 2011
*
*     .. Scalar Arguments ..
      INTEGER            M, N, LDA
*     ..
*     .. Array Arguments ..
      REAL               A( LDA, * )
*     ..
*
*  =====================================================================
*
*     .. Parameters ..
      REAL             ZERO
      PARAMETER ( ZERO = 0.0D+0 )
*     ..
*     .. Local Scalars ..
      INTEGER I
*     ..
*     .. Executable Statements ..
*
*     Quick test for the common case where one corner is non-zero.
      IF( N.EQ.0 ) THEN
         ILASLC = N
      ELSE IF( A(1, N).NE.ZERO .OR. A(M, N).NE.ZERO ) THEN
         ILASLC = N
      ELSE
*     Now scan each column from the end, returning with the first non-zero.
         DO ILASLC = N, 1, -1
            DO I = 1, M
               IF( A(I, ILASLC).NE.ZERO ) RETURN
            END DO
         END DO
      END IF
      RETURN
      END