solution to exercise 1

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
+	}
+}