Scripting Reference
Mathf.Abs

static function Abs (f : float) : float

Description

Returns the absolute value of f.

JavaScript 
    // prints 10.5
    print(Mathf.Abs(-10.5));
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        print(Mathf.Abs(-10.5F));
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        print(Mathf.Abs(-10.5F))

static function Abs (value : int) : int

Description

Returns the absolute value of value.

JavaScript 
    // prints 10
    print(Mathf.Abs(-10));
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Example() {
        print(Mathf.Abs(-10));
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Example():
        print(Mathf.Abs(-10))