# File yo8body_wrong.rb, line 73
  def yo4(dt)
#    d = [1.351207191959657, -1.702414383919315]
    d = [1.5, -2]           # WRONG values, just for testing!
    leapfrog(dt*d[0])
    leapfrog(dt*d[1])
    leapfrog(dt*d[0])
  end