CosmoCoffee

[chen lu]

Hi,
I tried to link cosmomc with axionCAMB, a modified code of the old camb in cosmomc which adds something about ultra-light axions.

I have added the two new initial params(m_ax and omaxh2) to cosmomc successfully. But it stopped when the file named *.out showed as follows :
...
max_eta_k = 14000.00
transfer kmax = 5.000000
adding parameters for: lowl_SMW_70_dx11d_2014_10_03_v5c_Ap
adding parameters for: plik_dx11dr2_HM_v18_TT
Fast divided into 1 blocks
23 parameters ( 9 slow ( 0 semi-slow), 14 fast ( 0 semi-fast))

Maybe it occurred because some params about axions are not included in cosmomc. Then I want to transfer them from axionCAMB to CMB because they have been defined and calculated in axionCAMB. So can you guys tell me where I should modify the code in cosmomc/source to do it?

Tks！

[Luke Hart]

Have a look at Calculator_CAMB.f90 in the source folder. I did all my mods in the Calc_CMBtoCAMB bit I think but it might be different for axion stuff I'm not sure? But you just have to find out where the parameters you want are in Camb


(usually denoted by P%ParamType%newparam_CAMB = CMB%new_param)

I've recently done this so if you get stuck, give me another shout! Hope this helps :)

[chen lu]

Thank you for your help.
I have added the new initial params (P%new_params = CMB%new_params) in the subroutine CAMBCalc_CMBToCAMB. But it did not work. Maybe there are other new derived params which are calculated in axionCAMB and I have added the derived params' definitions in cosmomc, but I don't know how to transfer them from axionCAMB to cosmomc. Do you have any ideas about this?
Thank you very much.

[Luke Hart]

Have you made sure that your parameter has also been added to the .paramnames file in the cosmomc directory? I had a problem with that when I set it up.

Chen if you have a look at EFTCAMB and compare to normal CAMB, there is also a version of CosmoMC called EFTCosmoMC you can compare and see how they added in their effective field parameters?

Luke

[Luke Hart]

It definitely looks like (given the number of slow parameters) that CosmoMC is reading in your parameters. You might want to try and see if theres another auxillary file (.o or .e files) that will give you a better idea of the error? If not, then go with the EFTCAMB method I mentioned before.

[chen lu]

Thank you very much!

I'm sure I have added the two new initial parameters successfully because I can check them in chains/test.ranges.

Maybe there's something else wrong and I will check things more than the params.

Tks again for your reply.