def _get_magnitude_scaling(self, C, mag):
        """
        Implements the magnitude scaling function F(M) presented in equation 4
        """
        if mag < self.CONSTANTS["mh"]:
            return C["e1"] + C["b1"] * (mag - self.CONSTANTS["mref"]) +\
                C["b2"] * ((mag - self.CONSTANTS["mref"]) ** 2.)
        else:
            d_m = self.CONSTANTS["mh"] - self.CONSTANTS["mref"]
            return C["e1"] + C["b3"] * (mag - self.CONSTANTS["mh"]) +\
                (C["b1"] * d_m) + C["b2"] * (d_m ** 2.)
Implements the magnitude scaling function F(M) presented in equation 4