Newton's methods for calculating the square root in golang

newton.go

package main

// newton's method for calculating square roots

import (
	"fmt"
	"math"
)

func Sqrt(x float64) float64 {
	if x == 0 {
		return 0
	}
	z := float64(1)

	var prev float64

	for math.Abs(z-prev) > .000000001 {
		prev = z
		z = z - (z*z-x)/(2*z)
	}
	return z
}

func main() {
	for i := float64(0); i <= 9; i++ {
		fmt.Println("sqrt of", i, "is", Sqrt(i), "versus", math.Sqrt(i))
	}
}