Running Cosmolike projects

In this tutorial, we assume the user installed Cocoa via the Conda installation method, and the name of the Conda environment is cocoa. We also presume the user's terminal is in the folder where Cocoa was cloned.

Step 1️⃣: activate the cocoa Conda environment, go to the cocoa/Cocoa/projects folder, and clone the Cosmolike LSST-Y1 project:

  conda activate cocoa
  cd ./cocoa/Cocoa/projects
  ${CONDA_PREFIX}/bin/git clone --depth 1 https://github.com/CosmoLike/cocoa_lsst_y1.git --branch v4.0-beta5 lsst_y1 

⚠️ Cocoa scripts and YAML files assume the removal of the cocoa_ prefix when cloning the repository.

⁉️ If the user is a developer, then type the following instead (at your own risk!)

  ${CONDA_PREFIX}/bin/git clone [email protected]:CosmoLike/cocoa_lsst_y1.git lsst_y1

Step 2️⃣: go back to the Cocoa main folder and activate the private Python environment

  cd ../
  source start_cocoa.sh

⚠️ Remember to run the start_cocoa.sh shell script only after cloning the project repository (or if you already in the (.local) environment, run start_cocoa.sh again).

Step 3️⃣: compile the project

  source ./projects/lsst_y1/scripts/compile_lsst_y1

⁉️ The script compile_cocoa.sh also compiles every Cosmolike project on the cocoa/Cocoa/projects/ folder.

Step 4️⃣: select the number of OpenMP cores (below, we set it to 4), and run a template YAML file

  export OMP_PROC_BIND=close; export OMP_NUM_THREADS=8

One model evaluation:

  mpirun -n 1 --oversubscribe --mca btl vader,tcp,self --bind-to core:overload-allowed --rank-by core --map-by numa:pe=${OMP_NUM_THREADS} cobaya-run ./projects/lsst_y1/EXAMPLE_EVALUATE1.yaml -f

MCMC:

  mpirun -n 4 --oversubscribe --mca btl vader,tcp,self --bind-to core:overload-allowed --rank-by core --map-by numa:pe=${OMP_NUM_THREADS} cobaya-run ./projects/lsst_y1/EXAMPLE_MCMC1.yaml -f

Deleting Cosmolike projects

Do not delete the lsst_y1 folder from the project folder without first running the shell script stop_cocoa.sh. Otherwise, Cocoa will have ill-defined soft links.

⁉️ Where the ill-defined soft links will be located?

 Cocoa/cobaya/cobaya/likelihoods/
 Cocoa/external_modules/code/
 Cocoa/external_modules/data/ 

⁉️ Why does Cocoa behave like this? The shell script start_cocoa.sh creates symbolic links so Cobaya can see the likelihood and data files. Cocoa also adds the Cobaya-Cosmolike interface of all cosmolike-related projects to the LD_LIBRARY_PATH and PYTHONPATH environmental variables.

MCMC Convergence Criteria

We are strict in our convergence criteria on EXAMPLE_MCMC[0-9].YAML MCMC examples.

Rminus1_stop: 0.005
# Gelman-Rubin R-1 on std deviations
Rminus1_cl_stop: 0.15

These settings are overkill for most applications, except when computing some tension and goodness of fit metrics. Please adjust these settings to your needs.