Simon Cross

I will put in a vote to not add `.compile()` to v5, but to instead write a nice porting HOWTO for the documentation. There will be changes to be made...

I wonder if deprecation is really worth it -- QuTiP 5 has so many changes that we probably can't guarantee that code will work. The principle we're trying to follow...

Would it be okay to use `_path_from_env("XDG_CONFIG_HOME", Path.home() / ".config")` rather than depend on the `xdg` package? How does one know if one is on a system where XDG is...

I've bumped this to QuTiP 5, since that seems a more polite time to change the default configuration directory than 4.7.1.

@fpetiziol It is quite possible that the need to orthogonalize eigenvectors that share an eigenvalue was missed (e.g. it happened #1851 for QuTiP 5). Would you mind checking against QuTiP...

@fpetiziol Thanks for checking. We should fix this for 4.7. It's probably not a very difficult fix (or at least we have logic for making eigenvectors orthogonal elsewhere in QuTiP...

@shemian29 Did this issue occur after you upgraded QuTiP or one of it's dependencies? And how did you install QuTiP? The IPython kernel crash suggests that maybe the installation is...

@shemian29 It's possible that the error is caused by using numpy 1.21.2 with MKL which triggers this bug -- https://github.com/numpy/numpy/issues/20356 -- on Intel CPUs that support AVX512. If that is...

@cgranade Thank you for the detailed write-up. I have some questions below. I have my own ideas of answers to some of these questions, but I'd like to hear yours....

I tagged this as QuTiP 5 (which is not to say it will be part of QuTiP 5, but just that if this does happen, QuTiP 5 is the place...