program straight

      x=0.0
      y=0.0
      xold=x
      yold=y
      vx=3.0
      vy=0.0
      ax=0.0
      ay=-9.8
      if(pgopen('/xwin')<=0)stop
      call pgenv(-2.0,2.0,-2.0,2.0,1,0)
      dt=0.0001
      do i=1, 1000000
        vx = vx + ax*dt
        vy = vy + ay*dt
        x = x + vx*dt
        y = y + vy*dt
        call pgbbuf
c       call pgsci(0)
c       call pgpt(1,xold,yold,20)
c       call pgpt(1,xold,yold,9)
        call pgsci(1)
c       call pgpt(1,x,y,20)
        call pgpt(1,x,y,9)
        call pgebuf
        xold=x
        yold=y
      enddo

      call pgclos
      end