'Scale factors for each component\'s direction.
Given unit vectors :math:`\hat{e}_c` and scale factors :math:`f_c`,
a change in one component of :math:`\delta c` corresponds to a change
in representation of :math:`\delta c \times f_c \times \hat{e}_c`.
Returns
scale_factors : dict of `~astropy.units.Quantity`
The keys are the component names.'

def scale_factors(self):

    raise NotImplementedError(u'{}    has    not    implemented    scale    factors.'.format(type(self)))
