Method: PendulumAnimationDemo#showPhase

Defined in:
sample/demos-en/pendulum.rb,
sample/demos-jp/pendulum.rb

#showPhase ⇒ Object

Update the phase-space graph according to the current angle and the rate at which the angle is changing (the first derivative with respect to time.)



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# File 'sample/demos-en/pendulum.rb', line 170

def showPhase
  unless @psw && @psh
    @psw = @k.width/2
    @psh = @k.height/2
  end
  @points << @theta + @psw << -20*@dTheta + @psh
  if @points.length > 100
    @points = @points[-100..-1]
  end
  (0...100).step(10){|i|
    first = - i
    last = 11 - i
    last = -1 if last >= 0
    next if first > last
    lst = @points[first..last]
    @graph[i].coords(lst) if lst && lst.length >= 4
  }
end