Modify CAMB+cobaya to introduce a parametrization of linear growth rate f(z)

[Minh Nguyen]

Dear Antony,

I have a question that is similar to one that was asked on this forum a while back. Unfortunately, I could not find a satisfying answer in that old topic. Hence my new topic.

I wonder, is it, in general, feasible and a fine idea, to try to modify CAMB (and cobaya) to allow for a parametrization of the growh rate f(z), e.g.
[math]f(z)=\Omega_m(z)^{\gamma(z)}
after a certain redshift, assuming no massive neutrino?

Even if it's not possible or might be a bad idea, I would really like to learn of why.

Many thanks,
Minh