CAMB: calculating derivatives of Cl's wrt parameters
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- Posts: 36
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CAMB: calculating derivatives of Cl''s wrt parameters
Is there any way to have CAMB calculate derivatives of CMB power spectra with respect to cosmological parameters? I.e. quantities like [tex]\frac{\partial C_{\ell}}{\partial(\Omega_ch^2)}[/tex]
I can numerically estimate derivatives by perturbing parameters and re-running but wanted to check if there's some better / more efficient way.
Thanks
I can numerically estimate derivatives by perturbing parameters and re-running but wanted to check if there's some better / more efficient way.
Thanks
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- Posts: 1951
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- Affiliation: University of Sussex
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Re: CAMB: calculating derivatives of Cl''''s wrt parameters
That's usually the best way. (unless you really want parameter errors/forecasts - in which case run CosmoMC).
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- Posts: 36
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- Affiliation: Johns Hopkins University
CAMB: calculating derivatives of Cl''s wrt parameters
OK. How about if I want to evaluate these derivatives at each step of a CosmoMC chain? Can I have CAMB called multiple times at each step with slightly different parameters?
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Re: CAMB: calculating derivatives of Cl''''s wrt parameters
You probably could, but it might take some thought on how to code it.
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- Posts: 36
- Joined: July 17 2014
- Affiliation: Johns Hopkins University
CAMB: calculating derivatives of Cl''s wrt parameters
Hmm OK. I think I'll start with figuring out how much the derivatives are really varying in case I don't need to do the recalculation each step. Thanks.