Newton–Raphson root finding method

root-finding.go

package main

import (
	"fmt"
	"math"
)

func Sqrt(x float64) float64 {
	z := float64(1)
	s := float64(0)
	for {
		z -= (z*z - x) / (2*z)
		if math.Abs(s-z) < 1e-15 {
			break
		}
		s = z
	}
	return s
}

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

// ref_1: A Tour of Go
// https://www.wikiwand.com/en/Newton%27s_method

// ref_2: Newton's method
// https://www.wikiwand.com/en/Newton%27s_method