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camb version variance

Posted: July 11 2019
by Angela Chen
Hi all,

I was writing a wrapper for camb-1.0.3, and in the test comparing to previous wrapper for camb-Jan15, there was a ~5% difference in pk at high k>10^-2 regime. Is this expected as version variance or it's possibly due to some parameter setting difference?

Thanks,
Angela

Re: camb version variance

Posted: July 12 2019
by Antony Lewis
Sounds high, more likely a parameter difference (e.g. different Halofit version).

Re: camb version variance

Posted: July 12 2019
by Angela Chen
Antony Lewis wrote:
July 12 2019
Sounds high, more likely a parameter difference (e.g. different Halofit version).
it was the linear power spectrum difference. Linear power difference transited around k~0.1 from 0 to 5%

Re: camb version variance

Posted: July 12 2019
by Angela Chen
Antony Lewis wrote:
July 12 2019
Sounds high, more likely a parameter difference (e.g. different Halofit version).
One thing I was concerned about is that in the older version of the wrapper, transfer_redshift was set by hand, while in newer version transfer_redshifts are treated as cambdata and calculated by pk_redshifts inputs. could that be the cause of the difference?

Re: camb version variance

Posted: July 13 2019
by Angela Chen
it seems that the difference is correlated to massive neutrino. when setting omnuh2=0 the difference is <0.2%. Could it due to the evolution of camb's treatment for massive nu?

Re: camb version variance

Posted: July 14 2019
by Antony Lewis
Is this a linear effect, or nonlinear? Check settings are the same, and if so please give full reproducing settings.