def METHOD_NAME(self, inputs, partials):
    """
    Compute the sparse partials for the vector magnitude w.r.t. the inputs.
    Parameters
    ----------
    inputs : Vector
        Unscaled, dimensional input variables read via inputs[key].
    partials : Jacobian
        Sub-jac components written to partials[output_name, input_name]..
    """
    for magnitude in self._magnitudes:
        a = inputs[magnitude['in_name']]
        # Use the following for sparse partials
        partials[magnitude['mag_name'], magnitude['in_name']] = \
            a.ravel() / np.repeat(np.sqrt(np.einsum('ni,ni->n', a, a)), magnitude['length'])