1 files changed, 36 insertions, 0 deletions
diff --git a/one/six.scm b/one/six.scm
new file mode 100644
index 0000000..ab58664
--- /dev/null
+++ b/one/six.scm
@@ -0,0 +1,36 @@
+(define-module (one six)
+   #:export (sqrt-sicp sqrt-nif square good-enough? new-if improve))
+
+(define (square x)
+  (* x x))
+
+(define (good-enough? guess x)
+  (< (abs (- (square guess) x)) 0.001))
+
+(define (average x y)
+  (/ (+ x y) 2))
+
+(define (improve guess x)
+  (average guess (/ x guess)))
+
+(define (new-if predicate then-clause else-clause)
+  (cond (predicate then-clause)
+        (else else-clause)))
+
+(define (sqrt-iter guess x)
+  (if (good-enough? guess x)
+          guess
+          (sqrt-iter (improve guess x)
+                     x)))
+
+(define (sqrt-iter-nif guess x)
+  (new-if (good-enough? guess x)
+          guess
+          (sqrt-iter-nif (improve guess x)
+                         x)))
+
+(define (sqrt-sicp x)
+  (sqrt-iter 1.0 x))
+
+(define (sqrt-nif x)
+  (sqrt-iter-nif 1.0 x))