Cobaya: Requiring the CAMB Pk nonlin_ratio

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Minh Nguyen
Posts: 14
Joined: March 21 2016
Affiliation: Leinweber Center for Theoretical Physics, University of Michigan

Cobaya: Requiring the CAMB Pk nonlin_ratio

Post by Minh Nguyen » December 09 2022


I have introduced some scale-independent scaling into the CAMB nonlinear module halofit.f90, basically modifying the growth factor D^2(z).

Now I wonder if there is a way to access directly the CAMB_PK%nonlin_ratio within the get_requirements() or get_theory() inside a cobaya likelihood class. (I actually need D(z) but I can get that easily from the nonlin_ratio)

I guess I could call get_Pk_grid() twice, one for linear and one for nonlinear, then take the ratio, if there's no direct access.


EDIT: Actually, I had to change get_Pk_grid() -> get_Pk_interpolator() since the latter works, but the former didn't, at least for me. It kept complaining that Matter power delta_tot, delta_tot not computed. Not really sure why, esp. given that the way the delta components are specified is exactly the same for both functions?

Antony Lewis
Posts: 1930
Joined: September 23 2004
Affiliation: University of Sussex

Re: Cobaya: Requiring the CAMB Pk nonlin_ratio

Post by Antony Lewis » December 11 2022

There's no specific support for nonlin_ratio, getting both linear and nonlinear should I guess work.

If you have a reproducible problem, please submit an issue on github with the reproducing test case.

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