slaord.f

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*> \brief \b SLAORD
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*  Definition:
*  ===========
*
*       SUBROUTINE SLAORD( JOB, N, X, INCX )
* 
*       .. Scalar Arguments ..
*       CHARACTER          JOB
*       INTEGER            INCX, N
*       ..
*       .. Array Arguments ..
*       REAL               X( * )
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*> SLAORD sorts the elements of a vector x in increasing or decreasing
*> order.
*> \endverbatim
*
*  Arguments:
*  ==========
*
*> \param[in] JOB
*> \verbatim
*>          JOB is CHARACTER
*>          = 'I':  Sort in increasing order
*>          = 'D':  Sort in decreasing order
*> \endverbatim
*>
*> \param[in] N
*> \verbatim
*>          N is INTEGER
*>          The length of the vector X.
*> \endverbatim
*>
*> \param[in,out] X
*> \verbatim
*>          X is REAL array, dimension
*>                         (1+(N-1)*INCX)
*>          On entry, the vector of length n to be sorted.
*>          On exit, the vector x is sorted in the prescribed order.
*> \endverbatim
*>
*> \param[in] INCX
*> \verbatim
*>          INCX is INTEGER
*>          The spacing between successive elements of X.  INCX >= 0.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date November 2011
*
*> \ingroup single_lin
*
*  =====================================================================
      SUBROUTINE slaord( JOB, N, X, INCX )
*
*  -- LAPACK test 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 ..
      CHARACTER          job
      INTEGER            incx, n
*     ..
*     .. Array Arguments ..
      REAL               x( * )
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      INTEGER            i, inc, ix, ixnext
      REAL               temp
*     ..
*     .. External Functions ..
      LOGICAL            lsame
      EXTERNAL           lsame
*     ..
*     .. Intrinsic Functions ..
      INTRINSIC          abs
*     ..
*     .. Executable Statements ..
*
      inc = abs( incx )
      IF( lsame( job, 'I' ) ) THEN
*
*        Sort in increasing order
*
         DO 20 i = 2, n
            ix = 1 + ( i-1 )*inc
   10       continue
            IF( ix.EQ.1 )
     $         go to 20
            ixnext = ix - inc
            IF( x( ix ).GT.x( ixnext ) ) THEN
               go to 20
            ELSE
               temp = x( ix )
               x( ix ) = x( ixnext )
               x( ixnext ) = temp
            END IF
            ix = ixnext
            go to 10
   20    continue
*
      ELSE IF( lsame( job, 'D' ) ) THEN
*
*        Sort in decreasing order
*
         DO 40 i = 2, n
            ix = 1 + ( i-1 )*inc
   30       continue
            IF( ix.EQ.1 )
     $         go to 40
            ixnext = ix - inc
            IF( x( ix ).LT.x( ixnext ) ) THEN
               go to 40
            ELSE
               temp = x( ix )
               x( ix ) = x( ixnext )
               x( ixnext ) = temp
            END IF
            ix = ixnext
            go to 30
   40    continue
      END IF
      return
*
*     End of SLAORD
*
      END