I was wondering whether there is the possibility of switching off the calculation of the Cls in CAMB and only have it calculate the background expansion, and if so how to do this.

To give some more background (no pun intended!): I am running a likelihood which only cares about background quantities (much like BAO and Pantheon). Overall the likelihood seems to run fine and relatively quickly, however I keep getting some error messages such as:

Code: Select all

` WARNING: mismatch in integrated times (CAMB: CalcScalarSources) `

Code: Select all

` 'Calculator_CAMB: negative C_l (could edit to silent error here)' `

If this is the case, this seems to be quite inconvenient because 1) occasionally these errors (especially the negative Cls) make the chains die and especially 2) the likelihood could run much more quickly if CAMB did not have to compute the Cls at each step of the MCMC. Therefore, is there any way I can switch off the computation of the Cls in CAMB?

I have a related question. What is the "mismatch in integrated times" error indicating, and how can it be solved (or is it mostly harmless)? The negative Cl bit probably comes from the fact that when only using this background likelihood, rather extreme values of the model parameters are explored (I have no such problem when combining this likelihood with the Planck likelihood).

Thanks in advance for your help!

Cheers,

Sunny