trunk/blas/dscal.f

C  dscal.f
C  is freely available from netlib. It is not subject to any GNU License
C  set by the authors of the ASCEND math programming system.
C  $Date: 1998/04/25 14:18:09 $ $Revision: 1.2 $
C
      subroutine  dscal(n,da,dx,incx)
c
c     scales a vector dx by a constant da.
c     uses unrolled loops for increment equal to one.
c     jack dongarra, linpack, 3/11/78.
c
      double precision da,dx(*)
      integer i,incx,m,mp1,n,nincx
c
      if(n.le.0)return
      if(incx.eq.1)go to 20
c
c        code for increment not equal to 1
c
      nincx = n*incx
      do 10 i = 1,nincx,incx
        dx(i) = da*dx(i)
   10 continue
      return
c
c        code for increment equal to 1
c
c
c        clean-up loop
c
   20 m = mod(n,5)
      if( m .eq. 0 ) go to 40
      do 30 i = 1,m
        dx(i) = da*dx(i)
   30 continue
      if( n .lt. 5 ) return
   40 mp1 = m + 1
      do 50 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)
   50 continue
      return
      end

1	C dscal.f
2	C is freely available from netlib. It is not subject to any GNU License
3	C set by the authors of the ASCEND math programming system.
4	C $Date: 1998/04/25 14:18:09 $ $Revision: 1.2 $
5	C
6	subroutine dscal(n,da,dx,incx)
7	c
8	c scales a vector dx by a constant da.
9	c uses unrolled loops for increment equal to one.
10	c jack dongarra, linpack, 3/11/78.
11	c
12	double precision da,dx(*)
13	integer i,incx,m,mp1,n,nincx
14	c
15	if(n.le.0)return
16	if(incx.eq.1)go to 20
17	c
18	c code for increment not equal to 1
19	c
20	nincx = n*incx
21	do 10 i = 1,nincx,incx
22	dx(i) = da*dx(i)
23	10 continue
24	return
25	c
26	c code for increment equal to 1
27	c
28	c
29	c clean-up loop
30	c
31	20 m = mod(n,5)
32	if( m .eq. 0 ) go to 40
33	do 30 i = 1,m
34	dx(i) = da*dx(i)
35	30 continue
36	if( n .lt. 5 ) return
37	40 mp1 = m + 1
38	do 50 i = mp1,n,5
39	dx(i) = da*dx(i)
40	dx(i + 1) = da*dx(i + 1)
41	dx(i + 2) = da*dx(i + 2)
42	dx(i + 3) = da*dx(i + 3)
43	dx(i + 4) = da*dx(i + 4)
44	50 continue
45	return
46	end
47