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ja-vazquez / SimpleMC

Updated version of a simple MCMC code for cosmological parameter estimation where only expansion history matters.
GNU General Public License v2.0
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Understading Prefact Option #35

Closed camarman closed 2 years ago

camarman commented 2 years ago

I did not quite understand the prefact option and how its set. In the Readme its claimed

BaseCosmology deals with integrating the above to various distance moduli. It also handles the prefactors of the form c/(H0rs). We can either have h=H0/100 as a parameter and then believe that rs is whatever it is, or have the entire phenomenological prefactor c/(H0rs) as a free parameter. One can switch this on as demonstrated in Run/TestRun.py with T.setVaryPrefactor().

I did not find any file named Run/TestRun.py ? Furthermore I did not understand which prefact option (pre and phy) corresponds to which circumstance ?

For instance, if I choose pre, $h_0$ is the free parameter and with phy $c/h_0r_s$ is the free one or other way around ?

Any help would be appreciated. Thanks

camarman commented 2 years ago

I have noticed that T.setVaryPrefactor() is located in simplemc/DriverMC.py and in line 124 its written as; if self.prefact == "pre": T.setVaryPrefactor().

So does this means, prefact = pre option varies $c/H_0r_s$, and prefact=phy option varies only $h_0$ ?

camarman commented 2 years ago

Okay, I have understood the difference.

phy options varies h_0, meanwhile the pre option varies the c/(H_0r_s). The prefactor parameter can be adjust from cosmo/paramDefs.py and the default value is set to

 # Prefactor parameter, c/rdH0.
 Pr_par = Parameter("Pr", 28.6, 4, (5, 70), "c/(H_0r_d)")