“The Magnetic Pendulum - Demonstrating the butterfly effect with a magnetic pendulum”. https://beltoforion.de/en/magnetic_pendulum/ StackExchange. “The magnetic pendulum model”. https://physics.stackexchange.com/questions/736473/the-magnetic-pendulum-model Prof. Daishin Ueyama 「微分方程式の数値解法(ルンゲ・クッタ法)」 https://sites.google.com/site/dueyama/home-jp/python_simulation/4