A Tour of Go: Square root using Netwon's method

exercise-loops-and-functions.go

// https://tour.golang.org/flowcontrol/8
package main

import (
	"fmt"
	"math"
)

func Sqrt(x float64) (z float64) {
	const delta float64 = 1e-10
	z = x
	var z_old float64

	for math.Abs(z_old-z) > delta {
		z_old = z
		z = z - (z*z-x)/(2*z)
	}

	return
}

func main() {
	fmt.Println(Sqrt(2), math.Sqrt(2))
	fmt.Println(Sqrt(2) - math.Sqrt(2))
}