SICM Book — A Curated Calculation Rail

This is not a mirror of Structure and Interpretation of Classical Mechanics. The book remains with its publishers and upstream editions.

One sentence, one calculation

“Classical mechanics is deceptively simple.”
— Gerald Jay Sussman and Jack Wisdom, Structure and Interpretation of Classical Mechanics, 2nd edition

The sentence is a short curated excerpt from the CC BY-NC-SA 3.0 online edition. This page adds a browser calculation; it does not reproduce a chapter or speak in the original authors’ voice.

Harmonic-oscillator Lagrange residual READY

(do
  (require '[emmy.env :as e])
  (defn L-harmonic [m k]
    (fn [local]
      (let [q (e/coordinate local)
            v (e/velocity local)]
        (e/- (e/* (e// 1 2) m (e/square v))
             (e/* (e// 1 2) k (e/square q))))))
  (e/simplify
   (((e/Lagrange-equations (L-harmonic 1 1)) e/cos) 't)))

For the path q = cos(t) with m = k = 1, the Euler–Lagrange residual evaluates to exactly zero. The value is computed here rather than copied from rendered book HTML.

Homepage does not own or vendor the external Org source, so the full-book renderer is deliberately absent from this release.