Large Errors on perturbation.sigma_r Calculations

[Ben Horowitz]

Hello Everyone,

I've been playing around with cosmolopy and have found it very useful! I am attempting to calculate some halo mass functions, but things seem to always be a bit off... When I pried deeper I found the following behavior for the perturbation.sigma_r function.

from cosmolopy import perturbation

cosmo = {'omega_M_0':0.3, 'omega_lambda_0':0.7, 'omega_b_0' : 0.045,'omega_k_0':0.0, 'N_nu' : 0,'omega_n_0' : 0.0, 'h':0.72, 'n' : 1.0, 'sigma_8' : 0.9}

perturbation.sigma_r(8.0,0.0,**cosmo)

>> (1.1211481117191608, 0.40881272454848305)

with the former being the result and the later being an estimated "error". Why is there such high error in this calculation? For a sigma_8 as specified as 0.9, a value of 1.12 +/- 0.4 seems pretty wide for precision cosmology.

Thanks for your help!

Ben

[Roban Kramer]

I'm afraid this package isn't being actively maintained at the moment. You might try to see if astropy has the functionality you need. Otherwise, if you dig into the code you can figure out where the numerical integration is done and look into tweaks that might improve the precision of the answer. I can try to help if you find the functions in question and have further questions about what to change.

Good luck,

Roban