Mathf.Atan

static function Atan (f : float) : float

Description

Returns the arc-tangent of f - the angle in radians whose tangent is f.

JavaScript
    print (Mathf.Atan(0.5));

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void Example() {
print(Mathf.Atan(0.5F));
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def Example():
print(Mathf.Atan(0.5F))