program para
      integer pgopen
      real x(101), y(101),xp(5),yp(5)
      if( pgopen('/xwin') <= 0 ) stop
      call pgenv(0.0, 4.0, 0.0, 20.0, 0,0)
      dx=(4.0-0.0)/100
      do i=1,101
        x(i) = (i-1)*dx
        y(i) = x(i)*x(i)
      end do
      call pgline(101,x,y)
      do i=1,5
        xp(i)=i-1
        yp(i)=xp(i)*xp(i)
      end do
      call pgsci(3)
      call pgpt(5,xp,yp,9)
      call pgclos
      end