.. highlight:: go

functions3.go
=============

::

    // functions3.go

    package main

    import (
        "fmt"
        "math"
    )

    func derivative(f func(float64) float64, a, h float64) float64 {
        return (f(a+h) - f(a)) / h
    }

    func main() {
        fmt.Println(derivative(math.Sqrt, 2, 0.001))
        fmt.Println(derivative(math.Sin, 2, 0.001))
        f := func(x float64) float64 {
            return x*x*x - x
        }
        fmt.Println(derivative(f, 2, 0.001))
        fmt.Println(derivative(func(x float64) float64 {
            return 1 / x
        }, 2, 0.001))
    }