I would like to add to validate_drp a dependency on treecorr and in turn libffi.
This will not add dependencies to lsst_apps or lsst_distrib.
Implementation is likely
1. Create wrapper install packages for libffi, cffi, and treecorr. The Python packages should be trivial. libffi is probably easy but not something I know how to do just off the top of my head; it's also something is likely already instlled on most systems, so we should decide whether to detect the already-installed system version.
2. Add treecorr dependence to validate_drp table file.
TreeCorr is a "[c]ode for efficiently computing 2-point and 3-point correlation functions" and is being proposed for use in validate_drp to calculate the correlation function of the PSF residual ellipticity (
DM-8951). The GitHub repo is here:
TreeCorr depends on the following Python packages.
cffi and fitsio are the two packages that are not already dependencies in lsst_distrib or lsst_sims. The Python package cffi in turns depends on the C library libffi
This present RFC is only to add dependency to validate_drp and thus lsst_ci. However, in the future one can imagine correlation calculations that might be made in parts of lsst_apps and TreeCorr might be of use then.