Cobaya: control nonlinear corrections

Use of Cobaya. camb, CLASS, cosmomc, compilers, etc.
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Zhuangfei Wang
Posts: 27
Joined: October 09 2021
Affiliation: Simon Fraser University

Cobaya: control nonlinear corrections

Post by Zhuangfei Wang » November 24 2022

Hello:

I just have a question about how to control whether to use nonlinear correction globally in a convenient way in Cobaya, I noticed that in CosmoMC we have such commands in .ini files:

use_nonlinear_lensing = T
nonlinear_pk = F

Is there a way to do the same in Cobaya? Particularly, is it possible to set in "extra_args" under the camb block in input.yaml? Thanks.

Antony Lewis
Posts: 1842
Joined: September 23 2004
Affiliation: University of Sussex
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Re: Cobaya: control nonlinear corrections

Post by Antony Lewis » November 25 2022

For lensing the lens_potential_accuracy parameter greater than zero sets non-linear lensing. For the power spectrum, it's up to each likelihood to request the power spectrum if they need it, and specify linear if they only need linear. If you're asking if there is a way to force likelihoods to get linear spectra even if they request non-linear, I think the answer is probably no without code changes.

Zhuangfei Wang
Posts: 27
Joined: October 09 2021
Affiliation: Simon Fraser University

Re: Cobaya: control nonlinear corrections

Post by Zhuangfei Wang » November 26 2022

Thanks a lot, Antony. It is very useful to know this.

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