Hi again, I had to reinstall Kwant 1.3 and Tinyarray, but I get the following error message when I try to run a script using conservation_laws (script is included at the end): /usr/local/lib/python3.5/dist-packages/matplotlib-2.0.2+4130.g8ae0dbf-py3.5-linux-x86_64.egg/matplotlib/backends/backend_gtk3agg.py:18: UserWarning: The Gtk3Agg backend is known to not work on Python 3.x with pycairo. Try installing cairocffi. "The Gtk3Agg backend is known to not work on Python 3.x with pycairo. " Traceback (most recent call last): File "/home/camilla/spinHall/Kwant/Tests/spin_kwant13.py", line 45, in <module> syst = make_system(t=1.0, W=10, L=10) File "/home/camilla/spinHall/Kwant/Tests/spin_kwant13.py", line 37, in make_system syst.attach_lead(lead) File "/home/camilla/.local/lib/python3.5/site-packages/kwant/builder.py", line 1402, in attach_lead self.leads.append(BuilderLead(lead_builder, tuple(interface))) File "/home/camilla/.local/lib/python3.5/site-packages/kwant/builder.py", line 566, in __init__ self.interface = tuple(sorted(interface)) TypeError: unorderable types: tinyarray.ndarray_int() < tinyarray.ndarray_int() I used pip to install both kwant and tinyarray, using the commands in the notebook here: http://nbviewer.jupyter.org/url/antonakhmerov.org/misc/spin_conductance.ipyn... The versions that pip tells me I have is: Name: kwant Version: 1.3.0a0.dev123+g3961899 Summary: Package for numerical quantum transport calculations (Python 3 version) Home-page: http://kwant-project.org/ Author: C. W. Groth (CEA), M. Wimmer, A. R. Akhmerov, X. Waintal (CEA), and others Author-email: authors@kwant-project.org License: BSD Location: /home/camilla/.local/lib/python3.5/site-packages Requires: numpy, scipy, tinyarray Name: tinyarray Version: 1.2.0 Summary: Arrays of numbers for Python, optimized for small sizes Home-page: https://gitlab.kwant-project.org/kwant/tinyarray Author: Christoph Groth (CEA) and others Author-email: christoph.groth@cea.fr License: Simplified BSD license Location: /usr/local/lib/python3.5/dist-packages Requires: I got into a similar problem earlier, but then it was because I had the wrong version of tinyarray (not dev), but now I think I have installed it correctly. Can you help me? Best, Camilla