Propagate uncertainty.

    :param jc: the Jacobian and covariance matrix
    :type jc: sequence

    This method is mainly designed to be used as the target for a
    multiprocessing pool.

def prop_unc(jc):
    """
    Propagate uncertainty.

    :param jc: the Jacobian and covariance matrix
    :type jc: sequence

    This method is mainly designed to be used as the target for a
    multiprocessing pool.
    """
    j, c = jc
    return np.dot(np.dot(j, c), j.T)