def mchirp_q_to_mass1_mass2(mchirp, q):
""" This function takes a value of mchirp and the mass ratio
mass1/mass2 and returns the two component masses.
The map from q to eta is
eta = (mass1*mass2)/(mass1+mass2)**2 = (q)/(1+q)**2
Then we can map from (mchirp,eta) to (mass1,mass2).
"""
eta = conversions.eta_from_q(q)
mass1 = conversions.mass1_from_mchirp_eta(mchirp, eta)
mass2 = conversions.mass2_from_mchirp_eta(mchirp, eta)
return mass1, mass2
def mchirp_q_to_mass1_mass2(mchirp, q):
""" This function takes a value of mchirp and the mass ratio
mass1/mass2 and returns the two component masses.
The map from q to eta is
eta = (mass1*mass2)/(mass1+mass2)**2 = (q)/(1+q)**2
Then we can map from (mchirp,eta) to (mass1,mass2).
"""
eta = conversions.eta_from_q(q)
mass1 = conversions.mass1_from_mchirp_eta(mchirp, eta)
mass2 = conversions.mass2_from_mchirp_eta(mchirp, eta)
return mass1, mass2
def transform_masses(mass1, mass2, mchirp_mod, eta_mod):
"""Modifies masses given a difference in mchirp and eta.
Parameters
----------
mass1 : float
Mass of the larger object (already modified).
mass2 : float
Mass of the smaller object (already modified).
mchirp_mod : tuple of (float, str) or None
Tuple giving the modification value for ``mchirp``, and a string
indicating whether the given modification is a fractional difference
(``'fdiff'``), an absolute difference (``'absdiff'``), or a replacement
(``'replace'``). If ``None``, the chirp mass will not be modified.
eta_mod : tuple of (float, str)
Same as ``mchirp_mod``, but for ``eta``.
Returns
-------
mass1 : float
Modified mass1.
mass2 : float
Modified mass2.
"""
mchirp = conversions.mchirp_from_mass1_mass2(mass1, mass2)
eta = conversions.eta_from_mass1_mass2(mass1, mass2)
if mchirp_mod is not None:
diff, modtype = mchirp_mod
mchirp = apply_mod(mchirp, diff, modtype)
if eta_mod is not None:
diff, modtype = eta_mod
eta = apply_mod(eta, diff, modtype)
# make sure values are physical
if (eta < 0 or eta > 0.25) or mchirp < 0:
raise NoWaveformError("unphysical masses")
m1 = conversions.mass1_from_mchirp_eta(mchirp, eta)
m2 = conversions.mass2_from_mchirp_eta(mchirp, eta)
return m1, m2