Golang : Ackermann function example

Not really a tutorial, but just want to play with recursive function and toying with Ackermann function. Hope this example can be useful to you.

See http://en.wikipedia.org/wiki/Ackermann_function

 package main

 import (
 "fmt"
 "strconv"
 "os"
 )

 func Ackermann(n, m int64) int64 {
 // http://en.wikipedia.org/wiki/Ackermann_function

 for n != 0 {
 if m == 0 {
 m = 1
 } else {
 m = Ackermann(n, m-1) // recursive
 }
 n = n - 1
 }
 return m + 1
 }

 func main() {

 if len(os.Args) < 3 {
 fmt.Println("[usage] : ackermann integer integer")
 os.Exit(0)
 }

 // convert input (type string) to integer
 first, err := strconv.ParseInt(os.Args[1], 10, 0)

 if err != nil {
 fmt.Println("First input parameter must be integer")
 os.Exit(1)
 }

 second, err := strconv.ParseInt(os.Args[2], 10, 0)

 if err != nil {
 fmt.Println("Second input parameter must be integer")
 os.Exit(1)
 }

 answer := Ackermann(first, second)

 fmt.Println(answer)

 }

Sample output :

./ackermnn 3

[usage] : ackermann integer integer

./ackermnn 3 2

29

References :

http://en.wikipedia.org/wiki/Ackermann_function