Calculate the absolute visual magnitude (Mv) from the richness
        by transforming the isochrone in the SDSS system and using the
        g,r -> V transform equations from Jester 2005
        [astro-ph/0506022].


        Parameters:
        -----------
        richness : isochrone normalization parameter
        steps    : number of isochrone sampling steps

        Returns:
        --------
        abs_mag : Absolute magnitude (Mv)

def absolute_magnitude(self, richness=1, steps=1e4):
        """
        Calculate the absolute visual magnitude (Mv) from the richness
        by transforming the isochrone in the SDSS system and using the
        g,r -> V transform equations from Jester 2005
        [astro-ph/0506022].


        Parameters:
        -----------
        richness : isochrone normalization parameter
        steps    : number of isochrone sampling steps

        Returns:
        --------
        abs_mag : Absolute magnitude (Mv)
        """
        # Using the SDSS g,r -> V from Jester 2005 [astro-ph/0506022]
        # for stars with R-I < 1.15
        # V = g_sdss - 0.59*(g_sdss - r_sdss) - 0.01

        # Create a copy of the isochrone in the SDSS system
        params = {k:v.value for k,v in self._params.items()}
        params.update(band_1='g',band_2='r',survey='sdss')
        iso = self.__class__(**params)

        # g, r are absolute magnitude
        mass_init, mass_pdf, mass_act, sdss_g, sdss_r = iso.sample(mass_steps=steps)
        V = jester_mag_v(sdss_g,sdss_r)

        # Sum the V-band absolute magnitudes
        return sum_mags(V,weights=mass_pdf*richness)