How to run a fit

Create a configuration file

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Using the code

nnfit runcard

The runcard is written in YAML. The runcard is the unique identifier of a fit, it is also the only required configuration input required for many programs of this repository.

Workflow

  1. Install the code

  2. Create a runcard by taking as template one of the files in <profile_prefix>/config. The <profile_prefix> path is by default <install prefix>/share/NNPDF for source installation while <conda root>/share/NNPDF for conda installation.

  3. Prepare the fit: vp-setupfit <runcard>.yml this command will generate a <runcard_folder> folder in the current directory with a copy of the original YAML runcard. The required resources (such as the theory and t0 PDF) will be downloaded automatically. Alternatively they can be obtained with the vp-get tool.

  4. The nnfit program takes a <runcard_folder> as input, e.g. nnfit <replica_number> <runcard_folder> where replica_number goes from 1-n.

  5. Wait until you have fit results, then use postfit <number_of_replicas> <runcard_folder> to finalize the PDF set by applying post selection criteria. This will produce a set of <number_of_replicas>+1 replicas.

  6. Upload the results using vp-upload --fit <runcard_folder> then install the fitted set with vp-get fit <fit_name>.

  7. Analyze results with validphys, see the vp-guide. Consider using the vp-comparefits tool.