public static double atan(double arg)
    {
        if(arg > 0) {
            return msatan(arg);
        }
        return -msatan(-arg);
    }
Rounds to keep <em>precision</em> decimals. Rounds towards even numbers.
@param x the number to round
@param precision the precision to round to. A precision of 3 will for instance round 1.65432 to 1.654
@return the rounded number
main/src/main/java/cgeo/geocaching/wherigo/kahlua/stdlib/MathLib.java