halofit_version: mead vs hmcode diferences?

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Helena Garcia
Posts: 27
Joined: October 05 2021
Affiliation: UCI

halofit_version: mead vs hmcode diferences?

Post by Helena Garcia »

I am using CAMB and CLASS for the same models, including the same likelihoods and parameters sampled. The only difference is the way both codes denominate the nonlinearity in the matter power spectrum. CAMB calls it halofit_version: mead and CLASS non linear: hmcode (from the cobaya documentation both refer to https://doi.org/10.1093/mnras/stab082). In addition, CLASS default runs seat hmcode_min_k_max: 20. Is there a hmcode_min_k_max equivalent parameter when running CAMB? Is the default case the same as CLASS?

Thanks in advance!

CLASS THEORY BLOCK:
theory:
classy:
extra_args:
non linear: hmcode
hmcode_min_k_max: 20
N_ur: 3.044
N_ncdm: 0

CAMB THEORY BLOCK:
theory:
camb:
extra_args:
halofit_version: mead
bbn_predictor: PArthENoPE_880.2_standard.dat
lens_potential_accuracy: 1
num_massive_neutrinos: 0
nnu: 3.044
theta_H0_range:
- 20
- 100
Antony Lewis
Posts: 1959
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: halofit_version: mead vs hmcode diferences?

Post by Antony Lewis »

The default in CAMB is "mead2020". It uses your transfer settings to determine kmax, otherwise doing power law extrapolation.
Helena Garcia
Posts: 27
Joined: October 05 2021
Affiliation: UCI

Re: halofit_version: mead vs hmcode diferences?

Post by Helena Garcia »

Thanks for your answer Anthony! Then, just to clarify, using the default in CAMB is "mead2020" (which uses your transfer settings to determine kmax) would be equivalent to using CLASS with non linear: hmcode and hmcode_min_k_max: 20 right?

Thanks again
Antony Lewis
Posts: 1959
Joined: September 23 2004
Affiliation: University of Sussex
Contact:

Re: halofit_version: mead vs hmcode diferences?

Post by Antony Lewis »

I have no idea about CLASS..
Helena Garcia
Posts: 27
Joined: October 05 2021
Affiliation: UCI

Re: halofit_version: mead vs hmcode diferences?

Post by Helena Garcia »

Ok, thanks anyways!
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