program plot_para
      real x(100), y(100)
      i_temp=pgopen('/xwin')
      call pgenv(0.0,5.0,0.0,20.0,0,0)

      xmin=0
      xmax=5
      delta_x = (xmax-xmin)/99
      do i=1,100
        x(i)=xmin+(i-1)*delta_x
        y(i)=x(i)*x(i)
      end do
      call pgline(100,x,y)
      call pgclos
      end