116

2 files changed, 30 insertions, 0 deletions

diff --git a/chapter115.rkt b/chapter115.rkt
new file mode 100644
index 0000000..0a026c6
--- /dev/null
+++ b/chapter115.rkt
@@ -0,0 +1,14 @@
+#lang sicp
+(define counter (box 0))
+
+(define (cube x) (* x x x))
+(define (p x) 
+  (set-box! counter (+ (unbox counter) 1))
+  (- (* 3 x) (* 4 (cube x))))
+(define (sine angle)
+  (if (not (> (abs angle) 0.1))
+    angle
+    (p (sine (/ angle 3)))))
+(sine 1250.0)
+(println "\n")
+(println (unbox counter))
diff --git a/chapter116.rkt b/chapter116.rkt
new file mode 100644
index 0000000..61b8e6f
--- /dev/null
+++ b/chapter116.rkt
@@ -0,0 +1,16 @@
+(define (square x) (* x x))
+
+(define (fast-expt b n)
+  (cond ((= n 0) 1)
+        ((even? n) (square (fast-expt b (/ n 2))))
+        (else (* b (fast-expt b (- n 1))))))
+
+(define (fie a b n)
+  (cond ((= n 0) a)
+        ((even? n) (fie a (square b) (/ n 2)))
+        (else  (fie (* a b) b (- n 1)))))
+
+(define (fast-expt b n)
+  (fie 1 b n))
+
+(fast-expt 3 4)