program para
      real x(100),y(100),xx(5),yy(5)
      if(pgopen('/xwin')<=0) stop
      call pgenv(0.0,5.0,0.0,20.0,0,1)

      delta_x=(5.0-0.0)/99
      do i=1,100
        x(i) = 0.0 + (i-1)*delta_x
        y(i) = x(i)*x(i)
      end do

      do i=1,5
        xx(i)=i
        yy(i)=i*i
      end do

      call pgline(100,x,y)

      call pgpt(5,xx,yy,9)

      call pgclos
      end