Experimental implementations of grand.coordinates

This repository contains experimental implementations of grand.coordinates. It requires the ctypes, grand and pint packages and at least Python 3.7. There are two implementations:

• coordinates.py uses grand.libs for coordinates transforms (libturtle).

• ccoordinates.py is an interface to what could be a C implementation of grand_coordinates. The corresponding C source is in the src/ directory. The interfacing to C is done with the cffi package and data are exposed as numpy.ndarray.

  Note that there are no coordinates transforms as for now. This implementation simply illustrates how the same C data can be exposed as different views using numpy, e.g. as a single xyz array or as separate x, y and z arrays. This approach would also provide the same coordinates objects at the C level with seamless interoperability with Python.

In both cases astropy is not used. The pint package is a perfect replacement for astropy.units and Earth coordinates transforms are available from the C TURTLE library also used in the neutrino simulation. It was cross-checked to be consistent with the astropy AltAz, EarthLocation and ITRS coordinates.

Usage

From the root of this repo and assuming that the grand repo is available aside:

source ../grand/env/setup.sh
pip install ctypes pint
python build_coordinates.py

Then the test.py and test-c.py can be used in order to test (showcase) the two implementations.