newton.go

package main

import (
	"fmt"
	"math"
)

// NewtonSqrt calculates sqrt by Newton's method
func NewtonSqrt(x float64) float64 {
	const delta = 1e-8
	z, zn := 0.0, 1.0
	for math.Abs(z-zn) > delta {
		z = zn
		zn = z - (z*z-x)/(2*z)
	}
	return zn
}

func main() {
	fmt.Println("NewtonSqrt = ", NewtonSqrt(2))
	fmt.Println("math.Sqrt  = ", math.Sqrt(2))
}