1 files changed, 30 insertions, 0 deletions
diff --git a/chapters/0-Prologue.scm b/chapters/0-Prologue.scm
new file mode 100644
index 0000000..3a5f44d
--- /dev/null
+++ b/chapters/0-Prologue.scm
@@ -0,0 +1,30 @@
+
+; mostly typing these up to confirm that they display as expected
+
+(define ((Gamma w) t)
+  (up t (w t) ((D w) t)))
+
+(define ((Lagrange-equations Lagrangian) w)
+  (- (D (compose ((partial 2) Lagrangian) (Gamma w)))
+     (compose ((partial 1) Lagrangian) (Gamma w))))
+
+(define ((L-harmonic m k) local)
+  (let ((q (coordinate local))
+        (v (velocity local)))
+    (- (* 1/2 m (square v))
+       (* 1/2 k (square q)))))
+
+(define (proposed-solution t)
+  (* 'a (cos (+ (* 'omega t) 'phi))))
+
+(show-expression
+  (((Lagrange-equations (L-harmonic 'm 'k))
+    proposed-solution)
+   't))
+; didn't simplify the way The Book shows it, but is equivalent
+
+(show-expression
+  (((Lagrange-equations (L-harmonic 'm 'k))
+    (literal-function 'x))
+   't))
+