program pg_basic
c This program demonstrate basic pgplot functions (routines). 
      real y(100), x(100), delta_x, point_y(5), point_x(5)
      integer i, pgopen

      if (pgopen('?').le.0) stop

      delta_x = 5.0/100.0
      do i=1, 100
        x(i) = (i-1)*delta_x
        y(i) = x(i)**2
      end do

      do i=1, 5
        point_x(i) = i
        point_y(i) = i**2
      end do

      call pgenv(0.0, 10.0, 0.0, 20.0, 0, 1)
      call pglab('x','y', 'y=x**2')
      call pgline(100, x, y)
      call pgpt(5, point_x, point_y, 9)
      call pgclos
      end