Function to numerically determine the parameters of the Higgs potential
    given the physical Higgs VEV and mass.

def vMh2_to_m2Lambda(v, Mh2, C, scale_high):
    """Function to numerically determine the parameters of the Higgs potential
    given the physical Higgs VEV and mass."""
    if C['phi'] == 0 and C['phiBox'] == 0 and C['phiD'] == 0:
        return _vMh2_to_m2Lambda_SM(v, Mh2)
    else:
        def f0(x):  # we want the root of this function
            m2, Lambda = x
            d = m2Lambda_to_vMh2(m2=m2.real, Lambda=Lambda.real,
                                 C=C, scale_high=scale_high)
            return np.array([d['v'] - v, d['Mh2'] - Mh2])
        dSM = _vMh2_to_m2Lambda_SM(v, Mh2)
        x0 = np.array([dSM['m2'], dSM['Lambda']])
        try:
            xres = scipy.optimize.newton_krylov(f0, x0)
        except scipy.optimize.nonlin.NoConvergence:
            raise ValueError("No solution for m^2 and Lambda found")
        return {'m2': xres[0], 'Lambda': xres[1]}