box-o-sand/gotime/gotour-artifacts/exercise-sqrt/main.go

package main

import (
	"fmt"
	"math"
)

// using Newton's method
func Sqrt(x float64) float64 {
	z := x - (x * 0.1)
	for i := 0; i < 1000; i++ {
		newZ := z - (((z * z) - x) / 2 * z)
		diff := math.Abs(newZ) - math.Abs(z)
		if math.Abs(diff) < 0.01 {
			return newZ
		}
		z = newZ
	}
	return z
}

func main() {
	fmt.Printf("stdlib -> %f\n", math.Sqrt(2))
	fmt.Printf("newton -> %f\n", Sqrt(2))
}