LAPACK  3.4.1
LAPACK: Linear Algebra PACKage
cswap.f
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00001 *> \brief \b CSWAP
00002 *
00003 *  =========== DOCUMENTATION ===========
00004 *
00005 * Online html documentation available at 
00006 *            http://www.netlib.org/lapack/explore-html/ 
00007 *
00008 *  Definition:
00009 *  ===========
00010 *
00011 *       SUBROUTINE CSWAP(N,CX,INCX,CY,INCY)
00012 * 
00013 *       .. Scalar Arguments ..
00014 *       INTEGER INCX,INCY,N
00015 *       ..
00016 *       .. Array Arguments ..
00017 *       COMPLEX CX(*),CY(*)
00018 *       ..
00019 *  
00020 *
00021 *> \par Purpose:
00022 *  =============
00023 *>
00024 *> \verbatim
00025 *>
00026 *>   CSWAP interchanges two vectors.
00027 *> \endverbatim
00028 *
00029 *  Authors:
00030 *  ========
00031 *
00032 *> \author Univ. of Tennessee 
00033 *> \author Univ. of California Berkeley 
00034 *> \author Univ. of Colorado Denver 
00035 *> \author NAG Ltd. 
00036 *
00037 *> \date November 2011
00038 *
00039 *> \ingroup complex_blas_level1
00040 *
00041 *> \par Further Details:
00042 *  =====================
00043 *>
00044 *> \verbatim
00045 *>
00046 *>     jack dongarra, linpack, 3/11/78.
00047 *>     modified 12/3/93, array(1) declarations changed to array(*)
00048 *> \endverbatim
00049 *>
00050 *  =====================================================================
00051       SUBROUTINE CSWAP(N,CX,INCX,CY,INCY)
00052 *
00053 *  -- Reference BLAS level1 routine (version 3.4.0) --
00054 *  -- Reference BLAS is a software package provided by Univ. of Tennessee,    --
00055 *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
00056 *     November 2011
00057 *
00058 *     .. Scalar Arguments ..
00059       INTEGER INCX,INCY,N
00060 *     ..
00061 *     .. Array Arguments ..
00062       COMPLEX CX(*),CY(*)
00063 *     ..
00064 *
00065 *  =====================================================================
00066 *
00067 *     .. Local Scalars ..
00068       COMPLEX CTEMP
00069       INTEGER I,IX,IY
00070 *     ..
00071       IF (N.LE.0) RETURN
00072       IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN
00073 *
00074 *       code for both increments equal to 1
00075          DO I = 1,N
00076             CTEMP = CX(I)
00077             CX(I) = CY(I)
00078             CY(I) = CTEMP
00079          END DO
00080       ELSE
00081 *
00082 *       code for unequal increments or equal increments not equal
00083 *         to 1
00084 *
00085          IX = 1
00086          IY = 1
00087          IF (INCX.LT.0) IX = (-N+1)*INCX + 1
00088          IF (INCY.LT.0) IY = (-N+1)*INCY + 1
00089          DO I = 1,N
00090             CTEMP = CX(IX)
00091             CX(IX) = CY(IY)
00092             CY(IY) = CTEMP
00093             IX = IX + INCX
00094             IY = IY + INCY
00095          END DO
00096       END IF
00097       RETURN
00098       END
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