kopia lustrzana https://github.com/Dsplib/libdspl-2.0
137 wiersze
2.9 KiB
Fortran
137 wiersze
2.9 KiB
Fortran
*> \brief \b DSCAL
|
|
*
|
|
* =========== DOCUMENTATION ===========
|
|
*
|
|
* Online html documentation available at
|
|
* http://www.netlib.org/lapack/explore-html/
|
|
*
|
|
* Definition:
|
|
* ===========
|
|
*
|
|
* SUBROUTINE DSCAL(N,DA,DX,INCX)
|
|
*
|
|
* .. Scalar Arguments ..
|
|
* DOUBLE PRECISION DA
|
|
* INTEGER INCX,N
|
|
* ..
|
|
* .. Array Arguments ..
|
|
* DOUBLE PRECISION DX(*)
|
|
* ..
|
|
*
|
|
*
|
|
*> \par Purpose:
|
|
* =============
|
|
*>
|
|
*> \verbatim
|
|
*>
|
|
*> DSCAL scales a vector by a constant.
|
|
*> uses unrolled loops for increment equal to 1.
|
|
*> \endverbatim
|
|
*
|
|
* Arguments:
|
|
* ==========
|
|
*
|
|
*> \param[in] N
|
|
*> \verbatim
|
|
*> N is INTEGER
|
|
*> number of elements in input vector(s)
|
|
*> \endverbatim
|
|
*>
|
|
*> \param[in] DA
|
|
*> \verbatim
|
|
*> DA is DOUBLE PRECISION
|
|
*> On entry, DA specifies the scalar alpha.
|
|
*> \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
|
|
*
|
|
* 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 3/93 to return if incx .le. 0.
|
|
*> modified 12/3/93, array(1) declarations changed to array(*)
|
|
*> \endverbatim
|
|
*>
|
|
* =====================================================================
|
|
SUBROUTINE DSCAL(N,DA,DX,INCX)
|
|
*
|
|
* -- 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 ..
|
|
DOUBLE PRECISION DA
|
|
INTEGER INCX,N
|
|
* ..
|
|
* .. Array Arguments ..
|
|
DOUBLE PRECISION DX(*)
|
|
* ..
|
|
*
|
|
* =====================================================================
|
|
*
|
|
* .. Local Scalars ..
|
|
INTEGER I,M,MP1,NINCX
|
|
* ..
|
|
* .. Intrinsic Functions ..
|
|
INTRINSIC MOD
|
|
* ..
|
|
IF (N.LE.0 .OR. INCX.LE.0) RETURN
|
|
IF (INCX.EQ.1) THEN
|
|
*
|
|
* code for increment equal to 1
|
|
*
|
|
*
|
|
* clean-up loop
|
|
*
|
|
M = MOD(N,5)
|
|
IF (M.NE.0) THEN
|
|
DO I = 1,M
|
|
DX(I) = DA*DX(I)
|
|
END DO
|
|
IF (N.LT.5) RETURN
|
|
END IF
|
|
MP1 = M + 1
|
|
DO I = MP1,N,5
|
|
DX(I) = DA*DX(I)
|
|
DX(I+1) = DA*DX(I+1)
|
|
DX(I+2) = DA*DX(I+2)
|
|
DX(I+3) = DA*DX(I+3)
|
|
DX(I+4) = DA*DX(I+4)
|
|
END DO
|
|
ELSE
|
|
*
|
|
* code for increment not equal to 1
|
|
*
|
|
NINCX = N*INCX
|
|
DO I = 1,NINCX,INCX
|
|
DX(I) = DA*DX(I)
|
|
END DO
|
|
END IF
|
|
RETURN
|
|
END
|