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Dscal.py
# -*- coding: utf-8 -*-
"""
Created on Fri May 17 16:20:21 2019
@author:
"""
import math
"""
*> \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)
def 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(*)
dxSize = 1 + (n-1)*abs(incx)
#dxOut = [0.0e0 for i in range(dxSize)]
#* ..
#*
#* =====================================================================
#*
#* .. Local Scalars ..
#INTEGER I,M,MP1,NINCX
i = 0
m = 0
mp1 = 0
nincx = 0
#print("DSCAL: n ", n, " incx ", incx, " da ", da)
#print("dx in ", [dx[kk] for kk in range(n)])
#* ..
#* .. Intrinsic Functions ..
#INTRINSIC mod
#* ..
#IF (n.LE.0 .OR. incx.LE.0) RETURN
if ( (n > 0) and (incx > 0) ):
#IF (incx.EQ.1) THEN
if (incx == 1):
#*
#* code for increment equal to 1
#*
#*
#* clean-up loop
#*
m = n % 5
#IF (m.NE.0) THEN
if (m != 0):
#DO i = 1,m
for i in range(m):
dx[i] = da*dx[i]
#print("DSCAL 1: i ", i, " dx ", dx[i])
#IF (n.LT.5) RETURN
#END IF
#if ( (m == 0) and (n >= 5) ):
if ( n >= 5 ):
mp1 = m + 1
#DO i = mp1,n,5
# print("DSCAL: n ", n, " m ", m, " mp1 ", mp1, " da ", da)
for i in range(mp1-1, n, 5):
# print("DSCAL 2: i ", i, " dx(i... i+4) ",\
# dx[i], dx[i+1], dx[i+2], dx[i+3], dx[i+4])
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]
#print("DSCAL 2: i ", i, " dx(i... i+4) ",\
# dx[i], dx[i+1], dx[i+2], dx[i+3], dx[i+4])
else:
#*
#* code for increment not equal to 1
#*
nincx = n*incx
#DO i = 1,nincx,incx
for i in range(0, nincx, incx):
dx[i] = da*dx[i]
#print("DSCAL 3: i ", i, " dx ", dx[i])
return dx