pi=acos(-1.0)
	dt=0.001
	t=0.0
	x=0.0
	v=1.0

	do while(t.le.2.0*pi)
	  x=x+v*dt
	  v=v-x*dt
	  t=t+dt
	  print*,t,x,v
	end do
	
	stop
	end