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Computers and software • Cobaya: How to use tabulated w(a) from CAMB?

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Hello all,

I am a new user of Cobaya and CAMB, and I face some difficulties:
  • The CAMB documentation says one can use the "DarkEnergyEqnOfState" class with a tabulated w(a). However, when I try to give "a" and "w" an array of values (by adding, e.g., "w: [#, #, ..., #]" into the input YAML file to run with "cobaya-run"), I get an error message saying that this parameter can take only numerical values (even when I use "use_tabulated_w: true"). How can I define the tabulated w(a) and feed it into the Cobaya as arrays of values for "a" and "w"?
  • I noticed that the "DarkEnergyEqnOfState" class has the "set_w_a_table(a, w)" function. How can I use CAMB's (or Cobaya's) built-in Python functions and methods in Cobaya's input YAML file (to run with Cobaya-run)?
  • Is there any advantage of running Cobaya from a Python interpreter compared to running it from Shell with cobaya-run and a YAML file?
  • Returning to question number one, can I set up a tabulated w(a) that depends on a sampled parameter? For example, can I set "a: [1, 0.1, 0.001]" and "w: [-x, -0.7x, -0.5x]" where "x" is a sampled parameter?
  • Lastly, are there published guidelines on modifying CAMB to define, e.g., new dark energy classes (new dark energy models)? Is there documentation also for the Fortran side of CAMB? (Generically, will I need to modify also the Fortran code if the answer to the previous question requires defining a new class inheriting from "DarkEnergyEqnOfState"?) Are there examples showing how to use CAMB features with Cobaya? (similar to the CAMBdemo.ipynb but showing how to communicate CAMB to Cobaya.)
Thank you in advance for your response!

Statistics: Posted by Dror Berechya — June 03 2024



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