one/seven - Add new functions.

New functions:
  - good-enough-alt?
  - sqrt-iter-alt
  - sqrt-sicp-alt

1 files changed, 17 insertions, 1 deletions

diff --git a/one/seven.scm b/one/seven.scm
index 66e06d9..cc3c7b9 100644
--- a/one/seven.scm
+++ b/one/seven.scm
@@ -3,7 +3,10 @@
 ;;; <https://creativecommons.org/licenses/by-sa/4.0/>.
 
 (define-module (one seven)
-  #:export (tolerances-and-sqrt))
+  #:export (tolerances-and-sqrt
+            good-enough-alt?
+            sqrt-iter-alt
+            sqrt-sicp-alt))
 
 (use-modules (one six))
 
@@ -28,3 +31,16 @@
         (cons tolerance custom-sqrt)
         (cons (cons tolerance custom-sqrt)
               (tolerances-and-sqrt x (/ tolerance 10))))))
+;;; start excercise 1.1.7
+(define (good-enough-alt? guess prev-guess)
+  (< (abs (- guess prev-guess)) 0.001))
+
+(define (sqrt-iter-alt guess prev-guess x)
+  (if (good-enough-alt? guess prev-guess)
+      guess
+      (sqrt-iter-alt (improve guess x) guess
+                     x)))
+
+(define (sqrt-sicp-alt x)
+  (sqrt-iter-alt 1.0 2.0 x))
+;;;; end excercise 1.1.7