def is_equal(a, b, tol):
    """Ratio test to check if two floating point numbers are equal.

    Parameters
    ----------
    a: float
        The first floating point number.
    b: float
        The second floating point number.
    tol: float
        The tolerance used.

    Returns
    -------
    bool
        Whether or not the two numbers are deemed equal.
    """
    if a == b or abs(a-b) <= tol * max(abs(a), abs(b)):
        return True
    else:
        return False