--- rpl/lapack/blas/dswap.f 2010/01/26 15:22:45 1.1.1.1 +++ rpl/lapack/blas/dswap.f 2018/05/29 07:19:41 1.15 @@ -1,4 +1,92 @@ +*> \brief \b DSWAP +* +* =========== DOCUMENTATION =========== +* +* Online html documentation available at +* http://www.netlib.org/lapack/explore-html/ +* +* Definition: +* =========== +* +* SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) +* +* .. Scalar Arguments .. +* INTEGER INCX,INCY,N +* .. +* .. Array Arguments .. +* DOUBLE PRECISION DX(*),DY(*) +* .. +* +* +*> \par Purpose: +* ============= +*> +*> \verbatim +*> +*> DSWAP interchanges two vectors. +*> uses unrolled loops for increments equal to 1. +*> \endverbatim +* +* Arguments: +* ========== +* +*> \param[in] N +*> \verbatim +*> N is INTEGER +*> number of elements in input vector(s) +*> \endverbatim +*> +*> \param[in,out] DX +*> \verbatim +*> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) +*> \endverbatim +*> +*> \param[in] INCX +*> \verbatim +*> INCX is INTEGER +*> storage spacing between elements of DX +*> \endverbatim +*> +*> \param[in,out] DY +*> \verbatim +*> DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) ) +*> \endverbatim +*> +*> \param[in] INCY +*> \verbatim +*> INCY is INTEGER +*> storage spacing between elements of DY +*> \endverbatim +* +* Authors: +* ======== +* +*> \author Univ. of Tennessee +*> \author Univ. of California Berkeley +*> \author Univ. of Colorado Denver +*> \author NAG Ltd. +* +*> \date November 2017 +* +*> \ingroup double_blas_level1 +* +*> \par Further Details: +* ===================== +*> +*> \verbatim +*> +*> jack dongarra, linpack, 3/11/78. +*> modified 12/3/93, array(1) declarations changed to array(*) +*> \endverbatim +*> +* ===================================================================== SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) +* +* -- Reference BLAS level1 routine (version 3.8.0) -- +* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- +* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- +* November 2017 +* * .. Scalar Arguments .. INTEGER INCX,INCY,N * .. @@ -6,18 +94,6 @@ DOUBLE PRECISION DX(*),DY(*) * .. * -* Purpose -* ======= -* -* interchanges two vectors. -* uses unrolled loops for increments equal one. -* -* Further Details -* =============== -* -* jack dongarra, linpack, 3/11/78. -* modified 12/3/93, array(1) declarations changed to array(*) -* * ===================================================================== * * .. Local Scalars .. @@ -28,48 +104,50 @@ INTRINSIC MOD * .. IF (N.LE.0) RETURN - IF (INCX.EQ.1 .AND. INCY.EQ.1) GO TO 20 -* -* 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 10 I = 1,N - DTEMP = DX(IX) - DX(IX) = DY(IY) - DY(IY) = DTEMP - IX = IX + INCX - IY = IY + INCY - 10 CONTINUE - RETURN + IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN * * code for both increments equal to 1 * * * clean-up loop * - 20 M = MOD(N,3) - IF (M.EQ.0) GO TO 40 - DO 30 I = 1,M - DTEMP = DX(I) - DX(I) = DY(I) - DY(I) = DTEMP - 30 CONTINUE - IF (N.LT.3) RETURN - 40 MP1 = M + 1 - DO 50 I = MP1,N,3 - DTEMP = DX(I) - DX(I) = DY(I) - DY(I) = DTEMP - DTEMP = DX(I+1) - DX(I+1) = DY(I+1) - DY(I+1) = DTEMP - DTEMP = DX(I+2) - DX(I+2) = DY(I+2) - DY(I+2) = DTEMP - 50 CONTINUE + M = MOD(N,3) + IF (M.NE.0) THEN + DO I = 1,M + DTEMP = DX(I) + DX(I) = DY(I) + DY(I) = DTEMP + END DO + IF (N.LT.3) RETURN + END IF + MP1 = M + 1 + DO I = MP1,N,3 + DTEMP = DX(I) + DX(I) = DY(I) + DY(I) = DTEMP + DTEMP = DX(I+1) + DX(I+1) = DY(I+1) + DY(I+1) = DTEMP + DTEMP = DX(I+2) + DX(I+2) = DY(I+2) + DY(I+2) = DTEMP + 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 + DTEMP = DX(IX) + DX(IX) = DY(IY) + DY(IY) = DTEMP + IX = IX + INCX + IY = IY + INCY + END DO + END IF RETURN END