To install, you also need the difxcalc11 source code, and have numpy installed (as well as pytest for running tests).
Assuming you are at the top of the directory of pycalc11, you can do the following:
git svn clone https://svn.atnf.csiro.au/difx/applications/difxcalc11/trunk difxcalc11
pip install -e .If you already have the difxcalc11 source and data directories somewhere, either create a symbolic link to its location, or set the environment variable DIFXCALC11 with the path to it.