From 15cbcf16248f799ccf351623b9f09c8d348ee084 Mon Sep 17 00:00:00 2001
From: rsiddharth <rsiddharth@ninthfloor.org>
Date: Thu, 24 Mar 2016 08:20:31 -0400
Subject: Add one/seven.scm

---
 one/seven.scm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 one/seven.scm

(limited to 'one/seven.scm')

diff --git a/one/seven.scm b/one/seven.scm
new file mode 100644
index 0000000..66e06d9
--- /dev/null
+++ b/one/seven.scm
@@ -0,0 +1,30 @@
+;;; Under Creative Commons Attribution-ShareAlike 4.0
+;;; International. See
+;;; <https://creativecommons.org/licenses/by-sa/4.0/>.
+
+(define-module (one seven)
+  #:export (tolerances-and-sqrt))
+
+(use-modules (one six))
+
+(define (gen-good-enough tolerance)
+  (lambda (guess x)
+    (< (abs (- (square guess) x)) tolerance)))
+
+(define (sqrt-iter-with-tolerance guess x tolerance)
+  (let ((good-enough? (gen-good-enough tolerance)))
+    (if (good-enough? guess x)
+        guess
+        (sqrt-iter-with-tolerance (improve guess x)
+                   x tolerance))))
+
+(define (sqrt-with-tolerance x tolerance)
+ (sqrt-iter-with-tolerance 1.0 x tolerance))
+
+(define (tolerances-and-sqrt x tolerance)
+  (let* ((guile-sqrt (sqrt x))
+         (custom-sqrt (sqrt-with-tolerance x tolerance)))
+    (if (eqv? guile-sqrt custom-sqrt)
+        (cons tolerance custom-sqrt)
+        (cons (cons tolerance custom-sqrt)
+              (tolerances-and-sqrt x (/ tolerance 10))))))
-- 
cgit v1.2.3