copies a vector, x
, to a vector, y
.
Type | Intent | Optional | Attributes | Name | ||
---|---|---|---|---|---|---|
integer | :: | n | ||||
real(kind=wp) | :: | dx(*) | ||||
integer | :: | incx | ||||
real(kind=wp) | :: | dy(*) | ||||
integer | :: | incy |
subroutine dcopy(n,dx,incx,dy,incy) integer incx,incy,n real(wp) dx(*),dy(*) integer i,ix,iy,m,mp1 if (n<=0) return if (incx==1 .and. incy==1) then ! code for both increments equal to 1 ! clean-up loop m = mod(n,7) if (m/=0) then do i = 1,m dy(i) = dx(i) end do if (n<7) return end if mp1 = m + 1 do i = mp1,n,7 dy(i) = dx(i) dy(i+1) = dx(i+1) dy(i+2) = dx(i+2) dy(i+3) = dx(i+3) dy(i+4) = dx(i+4) dy(i+5) = dx(i+5) dy(i+6) = dx(i+6) end do else ! code for unequal increments or equal increments ! not equal to 1 ix = 1 iy = 1 if (incx<0) ix = (-n+1)*incx + 1 if (incy<0) iy = (-n+1)*incy + 1 do i = 1,n dy(iy) = dx(ix) ix = ix + incx iy = iy + incy end do end if end subroutine dcopy