From 103a61bcf8648c50b5999cdb526464d44c75dfe1 Mon Sep 17 00:00:00 2001
From: root <root@eta.mit.edu>
Date: Tue, 27 Jan 2009 14:52:07 -0500
Subject: Added some demo files, journal, tweaks

---
 other/doublepend-examples.scm | 81 +++++++++++++++++++++++++++++++++++++++++++
 other/henon-demos.scm         | 15 ++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 other/doublepend-examples.scm
 create mode 100644 other/henon-demos.scm

(limited to 'other')

diff --git a/other/doublepend-examples.scm b/other/doublepend-examples.scm
new file mode 100644
index 0000000..9f36ee0
--- /dev/null
+++ b/other/doublepend-examples.scm
@@ -0,0 +1,81 @@
+; from project 3
+; 8.351j
+; bryan newbold
+
+; from section 1.6.2
+
+(define ((T-pend m l g ys) local)
+  (let ((t (time local))
+	(theta (coordinate local))
+	(thetadot (velocity local)))
+    (let ((vys (D ys)))
+      (* 1/2 m
+	      (+ (square (* 1 thetadot))
+		 (square (vys t))
+		 (* 2 l (vys t) thetadot (sin theta)))))))
+
+(define ((V-pend m l g ys) local)
+  (let ((t (time local))
+	(theta (coordinate local)))
+    (* m g (- (ys t) (* l (cos theta))))))
+
+(define L-pend (- T-pend V-pend))
+
+(define ((periodic-drive amplitude frequency phase) t)
+  (* amplitude (cos (+ (* frequency t) phase))))
+
+(define (L-periodically-driven-pendulum m l g a omega)
+  (let ((ys (periodic-drive a omega 0)))
+    (L-pend m l g ys)))
+
+(define Hamiltonian->state-derivative
+  phase-space-derivative)
+
+;(se ((Lagrangian->Hamiltonian
+;      (L-periodically-driven-pendulum 'm 'l 'g 'a 'omega))
+;     (up 't 'theta 'p_theta)))
+
+(define (H-pend-sysder m l g a omega)
+  (Hamiltonian->state-derivative
+   (Lagrangian->Hamiltonian
+    (L-periodically-driven-pendulum m l g a omega))))
+
+(define ((monitor-p-theta win) state)
+  (let ((q ((principal-value :pi) (coordinate state)))
+	(p (momentum state)))
+    (plot-point win q p)))
+
+(define window (frame :-pi :pi -100.0 100.0))
+
+(let ((m 1.)
+      (l 9.8)
+      (g 9.8)
+      (A 0.01)
+      (omega 600))
+  ((evolve H-pend-sysder m l g A omega)
+   (up 0.
+       1.5367
+       0.)
+   (monitor-p-theta window)
+   .00001
+   .6
+   1.0e-12))
+
+(define (driven-pendulum-map m l g A omega)
+  (let ((advance (state-advancer H-pend-sysder m l g A omega))
+	(map-period (/ :2pi omega)))
+    (lambda (theta ptheta return fail)
+      (let ((ns (advance
+		 (up 0 theta ptheta)
+		 map-period)))
+	(return ((principal-value :pi) (coordinate ns))
+		(momentum ns))))))
+
+(graphics-close window)
+(start-gnuplot "output")
+
+
+
+
+
+
diff --git a/other/henon-demos.scm b/other/henon-demos.scm
new file mode 100644
index 0000000..c00e3fc
--- /dev/null
+++ b/other/henon-demos.scm
@@ -0,0 +1,15 @@
+;;;;;;; problem 3.13
+
+(define ((henon-map alpha) x y return failure)
+  (if (or (> x 1) (< x -1) (> y 1) (< y -1))
+      failure)
+  (return (- (* x (cos alpha))
+	     (* (- y (square x)) (sin alpha)))
+	  (+ (* x (sin alpha))
+	     (* (- y (square x)) (cos alpha)))))
+
+(define window (frame -1. 1. -1. 1.))
+
+(explore-map window (henon-map 1.21) 2000)
+
+
-- 
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