saxpyz Subroutine

      subroutine saxpyz(a,x,y,z,n)
      implicit double precision (a-h,o-z)
      dimension x(*),y(*),z(*)
      if (a==0.D0) then
        do i=1,n
          z(i)=y(i)
        end do
      else
        do i=1,n
          z(i)=y(i)+a*x(i)
        end do
      end if
      end subroutine saxpyz