From a5ba7c63b1b96c3df89f07a80f6ec91300377b7a Mon Sep 17 00:00:00 2001
From: "Stephen M. McQuay" <smcquay@fusionio.com>
Date: Thu, 2 Aug 2012 14:39:21 -0600
Subject: [PATCH] solution to exercise 1

---
 loopfuncs/go.go | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 loopfuncs/go.go

diff --git a/loopfuncs/go.go b/loopfuncs/go.go
new file mode 100644
index 0000000..4aa0bd2
--- /dev/null
+++ b/loopfuncs/go.go
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+const min_threshold = 1e-200
+
+func Sqrt(x float64, threshold float64) (z float64, iterations int) {
+	z = x
+	old_z := z
+	for {
+		z = z - (z*z-x)/(2*x)
+		if math.Abs(z-old_z) < threshold {
+			break
+		}
+		old_z = z
+		iterations++
+	}
+	return
+}
+
+func main() {
+	threshold := 1.0
+	right_answer := math.Sqrt(2)
+	for threshold > min_threshold {
+		answer, iterations := Sqrt(2, threshold)
+		fmt.Printf("%0.4g %0.4g %0.20f %0.20f %0.2d\n",
+			threshold, right_answer-answer, right_answer, answer,
+			iterations)
+		threshold = threshold / 10.0
+	}
+}