function ease_inout_elastic(arg0, arg1, arg2, arg3)
{
    var _s = 1.70158;
    var _p = 0;
    var _a = arg2;
    if (arg0 == 0 || _a == 0)
        return arg1;
    arg0 /= (arg3 * 0.5);
    if (arg0 == 2)
        return arg1 + arg2;
    if (!_p)
        _p = arg3 * 0.44999999999999996;
    if (_a < abs(arg2))
    {
        _a = arg2;
        _s = _p * 0.25;
    }
    else
    {
        _s = (_p / (2 * pi)) * arcsin(arg2 / _a);
    }
    if (arg0 < 1)
        return (-0.5 * (_a * power(2, 10 * --arg0) * sin((((arg0 * arg3) - _s) * (2 * pi)) / _p))) + arg1;
    return (_a * power(2, -10 * --arg0) * sin((((arg0 * arg3) - _s) * (2 * pi)) / _p) * 0.5) + arg2 + arg1;
}