乃是個局域平穩值。注意到這系統只處於平穩狀態。假設,要求這系統處於穩定狀態,則位勢 V {\displaystyle V} 必須是個局域極小值。 柔度法(英语:flexibilitymethod) 拉格朗日力学 哈密頓力学 Lanczos, Cornelius, The Variational Principles of Mechanics
interfaces rather than specific types, well-designed code improves its flexibility by allowing polymorphic substitution. Duck-typing avoids tests using