version 1.1.1.1, 2010/01/26 15:22:45
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version 1.14, 2018/05/29 06:55:14
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*> \brief \b DSWAP |
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* |
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* =========== DOCUMENTATION =========== |
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* |
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* Online html documentation available at |
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* http://www.netlib.org/lapack/explore-html/ |
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* |
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* Definition: |
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* =========== |
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* |
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* SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) |
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* |
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* .. Scalar Arguments .. |
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* INTEGER INCX,INCY,N |
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* .. |
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* .. Array Arguments .. |
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* DOUBLE PRECISION DX(*),DY(*) |
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* .. |
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* |
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* |
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*> \par Purpose: |
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* ============= |
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*> |
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*> \verbatim |
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*> |
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*> DSWAP interchanges two vectors. |
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*> uses unrolled loops for increments equal to 1. |
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*> \endverbatim |
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* |
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* Arguments: |
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* ========== |
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* |
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*> \param[in] N |
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*> \verbatim |
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*> N is INTEGER |
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*> number of elements in input vector(s) |
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*> \endverbatim |
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*> |
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*> \param[in,out] DX |
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*> \verbatim |
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*> DX is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCX ) ) |
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*> \endverbatim |
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*> |
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*> \param[in] INCX |
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*> \verbatim |
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*> INCX is INTEGER |
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*> storage spacing between elements of DX |
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*> \endverbatim |
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*> |
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*> \param[in,out] DY |
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*> \verbatim |
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*> DY is DOUBLE PRECISION array, dimension ( 1 + ( N - 1 )*abs( INCY ) ) |
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*> \endverbatim |
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*> |
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*> \param[in] INCY |
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*> \verbatim |
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*> INCY is INTEGER |
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*> storage spacing between elements of DY |
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*> \endverbatim |
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* |
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* Authors: |
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* ======== |
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* |
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*> \author Univ. of Tennessee |
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*> \author Univ. of California Berkeley |
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*> \author Univ. of Colorado Denver |
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*> \author NAG Ltd. |
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* |
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*> \date November 2017 |
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* |
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*> \ingroup double_blas_level1 |
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* |
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*> \par Further Details: |
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* ===================== |
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*> |
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*> \verbatim |
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*> |
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*> jack dongarra, linpack, 3/11/78. |
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*> modified 12/3/93, array(1) declarations changed to array(*) |
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*> \endverbatim |
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*> |
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* ===================================================================== |
SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) |
SUBROUTINE DSWAP(N,DX,INCX,DY,INCY) |
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* |
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* -- Reference BLAS level1 routine (version 3.8.0) -- |
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* -- Reference BLAS is a software package provided by Univ. of Tennessee, -- |
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* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..-- |
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* November 2017 |
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* |
* .. Scalar Arguments .. |
* .. Scalar Arguments .. |
INTEGER INCX,INCY,N |
INTEGER INCX,INCY,N |
* .. |
* .. |
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DOUBLE PRECISION DX(*),DY(*) |
DOUBLE PRECISION DX(*),DY(*) |
* .. |
* .. |
* |
* |
* Purpose |
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* ======= |
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* |
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* interchanges two vectors. |
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* uses unrolled loops for increments equal one. |
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* |
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* Further Details |
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* =============== |
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* |
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* jack dongarra, linpack, 3/11/78. |
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* modified 12/3/93, array(1) declarations changed to array(*) |
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* |
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* ===================================================================== |
* ===================================================================== |
* |
* |
* .. Local Scalars .. |
* .. Local Scalars .. |
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INTRINSIC MOD |
INTRINSIC MOD |
* .. |
* .. |
IF (N.LE.0) RETURN |
IF (N.LE.0) RETURN |
IF (INCX.EQ.1 .AND. INCY.EQ.1) GO TO 20 |
IF (INCX.EQ.1 .AND. INCY.EQ.1) THEN |
* |
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* code for unequal increments or equal increments not equal |
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* to 1 |
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* |
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IX = 1 |
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IY = 1 |
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IF (INCX.LT.0) IX = (-N+1)*INCX + 1 |
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IF (INCY.LT.0) IY = (-N+1)*INCY + 1 |
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DO 10 I = 1,N |
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DTEMP = DX(IX) |
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DX(IX) = DY(IY) |
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DY(IY) = DTEMP |
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IX = IX + INCX |
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IY = IY + INCY |
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10 CONTINUE |
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RETURN |
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* |
* |
* code for both increments equal to 1 |
* code for both increments equal to 1 |
* |
* |
* |
* |
* clean-up loop |
* clean-up loop |
* |
* |
20 M = MOD(N,3) |
M = MOD(N,3) |
IF (M.EQ.0) GO TO 40 |
IF (M.NE.0) THEN |
DO 30 I = 1,M |
DO I = 1,M |
DTEMP = DX(I) |
DTEMP = DX(I) |
DX(I) = DY(I) |
DX(I) = DY(I) |
DY(I) = DTEMP |
DY(I) = DTEMP |
30 CONTINUE |
END DO |
IF (N.LT.3) RETURN |
IF (N.LT.3) RETURN |
40 MP1 = M + 1 |
END IF |
DO 50 I = MP1,N,3 |
MP1 = M + 1 |
DTEMP = DX(I) |
DO I = MP1,N,3 |
DX(I) = DY(I) |
DTEMP = DX(I) |
DY(I) = DTEMP |
DX(I) = DY(I) |
DTEMP = DX(I+1) |
DY(I) = DTEMP |
DX(I+1) = DY(I+1) |
DTEMP = DX(I+1) |
DY(I+1) = DTEMP |
DX(I+1) = DY(I+1) |
DTEMP = DX(I+2) |
DY(I+1) = DTEMP |
DX(I+2) = DY(I+2) |
DTEMP = DX(I+2) |
DY(I+2) = DTEMP |
DX(I+2) = DY(I+2) |
50 CONTINUE |
DY(I+2) = DTEMP |
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END DO |
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ELSE |
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* |
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* code for unequal increments or equal increments not equal |
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* to 1 |
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* |
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IX = 1 |
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IY = 1 |
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IF (INCX.LT.0) IX = (-N+1)*INCX + 1 |
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IF (INCY.LT.0) IY = (-N+1)*INCY + 1 |
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DO I = 1,N |
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DTEMP = DX(IX) |
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DX(IX) = DY(IY) |
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DY(IY) = DTEMP |
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IX = IX + INCX |
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IY = IY + INCY |
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END DO |
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END IF |
RETURN |
RETURN |
END |
END |