def eta_mass1_to_mass2(eta, mass1, return_mass_heavier=False, force_real=True):
    """
    This function takes values for eta and one component mass and returns the
    second component mass. Similar to mchirp_mass1_to_mass2 this requires
    finding the roots of a quadratic equation. Basically:

    eta m2^2 + (2 eta - 1)m1 m2 + \eta m1^2 = 0

    This has two solutions which correspond to mass1 being the heavier mass
    or it being the lighter mass. By default the value corresponding to
    mass1 > mass2 is returned. Use the return_mass_heavier kwarg to invert this
    behaviour.
    """
    return conversions.mass_from_knownmass_eta(mass1, eta,
        known_is_secondary=return_mass_heavier, force_real=force_real)
def eta_mass1_to_mass2 ( eta , mass1 , return_mass_heavier = False , force_real = True ) : return conversions . mass_from_knownmass_eta ( mass1 , eta , known_is_secondary = return_mass_heavier , force_real = force_real )
This function takes values for eta and one component mass and returns the
    second component mass. Similar to mchirp_mass1_to_mass2 this requires
    finding the roots of a quadratic equation. Basically:

    eta m2^2 + (2 eta - 1)m1 m2 + \eta m1^2 = 0

    This has two solutions which correspond to mass1 being the heavier mass
    or it being the lighter mass. By default the value corresponding to
    mass1 > mass2 is returned. Use the return_mass_heavier kwarg to invert this
    behaviour.