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# danielrangelmoreira/newtonsqrt.go

Created March 19, 2017 19:37
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Naive way of obtaining square roots with newton's approximation method
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 package main import ( "fmt" //"math" ) func main() { const ( x0 = 54777 epsilon = 1.0e-15 ) var ( result = 0.0 xi = 1.0 delta = 1.0 ) for delta >= epsilon { result = ((xi * xi) + x0) / (2 * xi) delta = result - xi xi = result if delta < 0 { delta = -delta } } fmt.Println(result) //fmt.Println(math.Sqrt(x0)) }

Excellent!!!

### soumojit commented Jul 19, 2018

``````package main

import (
"fmt"
"math"
)

func Sqrt(x float64) float64 {
z := 1.0
// First guess
z -= (z*z - x) / (2*z)
// Iterate until change is very small
for zNew, delta := z, z; delta > 0.00000001; z = zNew {
zNew -= (zNew * zNew - x) / (2 * zNew)
delta = z - zNew
}
return z
}

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

### idmcalculus commented Jul 17, 2021

``````package main

import (
"fmt"
"math"
)

func Sqrt(x float64) float64 {
var zi float64 = x/2
delta := 0.00000001
z := zi - (zi*zi - x) / (2*zi)

for math.Abs(z-zi) > delta {
zi = z
z -= (zi*zi - x) / (2*zi)
fmt.Printf("%v, %v\n", zi, z)
}
return z
}

func main() {
fmt.Println(Sqrt(0.5))
fmt.Println("real value = " + fmt.Sprint(math.Sqrt(0.5)))
}

``````