/*--------------------------------------------------
created by smtuttle at Tue Oct 19 14:46:26 PDT 2010
--------------------------------------------------*/
#include <iostream>
#include <cmath>
using namespace std;


/*--------------------------------------------------
 Contract: abs_value : double -> double
 Purpose: expects a number and produces its absolute
         value

 Examples: abs_value(-3) == 3
          abs_value(5) == 5
          abs_value(0) == 0
--------------------------------------------------*/

double abs_value(double num)
{
    if (num < 0)
        return -1 * num;
    else
        return num;
}