pure-Python HistFactory implementation
copied from cf-staging / pyhfThe HistFactory p.d.f. template [CERN-OPEN-2012-016] is per-se independent of its implementation in ROOT and sometimes, it's useful to be able to run statistical analysis outside of ROOT, RooFit, RooStats framework.
This repo is a pure-python implementation of that statistical model for multi-bin histogram-based analysis and its interval estimation is based on the asymptotic formulas of "Asymptotic formulae for likelihood-based tests of new physics" [arXiv:1007.1727]. The aim is also to support modern computational graph libraries such as PyTorch, JAX, and TensorFlow in order to make use of features such as automatic differentiation and GPU acceleration.