OpenBLAS/lapack-netlib/BLAS/SRC/cswap.f

*> \brief \b CSWAP
*
*  =========== DOCUMENTATION ===========
*
* Online html documentation available at 
*            http://www.netlib.org/lapack/explore-html/ 
*
*  Definition:
*  ===========
*
*       SUBROUTINE CSWAP(N,CX,INCX,CY,INCY)
* 
*       .. Scalar Arguments ..
*       INTEGER INCX,INCY,N
*       ..
*       .. Array Arguments ..
*       COMPLEX CX(*),CY(*)
*       ..
*  
*
*> \par Purpose:
*  =============
*>
*> \verbatim
*>
*>   CSWAP interchanges two vectors.
*> \endverbatim
*
*  Authors:
*  ========
*
*> \author Univ. of Tennessee 
*> \author Univ. of California Berkeley 
*> \author Univ. of Colorado Denver 
*> \author NAG Ltd. 
*
*> \date November 2011
*
*> \ingroup complex_blas_level1
*
*> \par Further Details:
*  =====================
*>
*> \verbatim
*>
*>     jack dongarra, linpack, 3/11/78.
*>     modified 12/3/93, array(1) declarations changed to array(*)
*> \endverbatim
*>
*  =====================================================================
      SUBROUTINE CSWAP(N,CX,INCX,CY,INCY)
*
*  -- Reference BLAS level1 routine (version 3.4.0) --
*  -- Reference BLAS 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 INCX,INCY,N
*     ..
*     .. Array Arguments ..
      COMPLEX CX(*),CY(*)
*     ..
*
*  =====================================================================
*
*     .. Local Scalars ..
      COMPLEX CTEMP
      INTEGER I,IX,IY
*     ..
      IF (N.LE.0) RETURN
      IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
*
*       code for both increments equal to 1
         DO I = 1,N
            CTEMP = CX(I)
            CX(I) = CY(I)
            CY(I) = CTEMP
         END DO
      ELSE
*
*       code for unequal increments or equal increments not equal
*         to 1
*
         IX = 1
         IY = 1
         IF (INCX.LT.0) IX = (-N+1)*INCX + 1
         IF (INCY.LT.0) IY = (-N+1)*INCY + 1
         DO I = 1,N
            CTEMP = CX(IX)
            CX(IX) = CY(IY)
            CY(IY) = CTEMP
            IX = IX + INCX
            IY = IY + INCY
         END DO
      END IF
      RETURN
      END