Find the chemical potential where analytic and calculated seebeck are identical
        and then calculate the seebeck effective mass at that chemical potential and 
        a certain carrier concentration n

def seebeck_eff_mass_from_seebeck_carr(seeb, n, T, Lambda):
    """
        Find the chemical potential where analytic and calculated seebeck are identical
        and then calculate the seebeck effective mass at that chemical potential and 
        a certain carrier concentration n
    """
    try:
        from fdint import fdk
    except ImportError:
        raise BoltztrapError("fdint module not found. Please, install it.\n"+
                            "It is needed to calculate Fermi integral quickly.")

    eta = eta_from_seebeck(seeb,Lambda)
    mass = seebeck_eff_mass_from_carr(eta, n, T, Lambda)
    return mass