sicp.org: tried ex. 1.9.

1 files changed, 40 insertions, 0 deletions

diff --git a/sicp.org b/sicp.org
index b338700..db960ea 100644
--- a/sicp.org
+++ b/sicp.org
@@ -107,3 +107,43 @@ For a number as large as 1000000000, guile's =sqrt= function and
 =sqrt-sicp-alt= returns 31622.776601683792, =sqrt-sicp= returns
 31622.776601684047; =sqrt-sicp= being slightly more precise than the
 other functions.
+*** 9
+**** recursive process
+
+#+BEGIN_SRC scheme
+(define (+ a b)
+  (if (= a 0)
+      b
+      (inc (+ dec a) b)))
+#+END_SRC
+
+#+BEGIN_SRC
+(+ 4 5)    ----+
+(inc (+ 3 5))  |----+
+(inc (inc (+ 2 5))) |------+
+(inc (inc (inc (+ 1 5))))  |------+
+(inc (inc (inc (inc (+ 0 5)))))   |
+(inc (inc (inc (inc 5)))) +-------+
+(inc (inc (inc 6))) +-----|
+(inc (inc 7)) +-----|
+(inc 8) +-----|
+9 <-----|
+#+END_SRC
+
+**** iterative process
+
+#+BEGIN_SRC scheme
+(define (+ a b)
+  (if (= a 0)
+      b
+      (+ (dec a) (inc b))))
+#+END_SRC
+
+#+BEGIN_SRC
+(+ 4 5 --+
+(+ 3 6)  |
+(+ 2 7)  |
+(+ 1 8)  |
+(+ 0 9)  |
+9 <------+
+#+END_SRC