[WIP] Download IDAKLU from pybammsolvers

[kratman]

Description

This will separate the IDAKLU C++ code from pybamm.

Fixes #3564

Type of change

This should speed up CI by skipping the build of the C++ code.

• Optimization (back-end change that speeds up the code)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[kratman]

A new link error cropped up, but it looks like we could get a lot of savings on time with this update.

Edit: Most of the run time appears to be in the integration tests, so unfortunately the time savings are not as good as I would have hoped.

[agriyakhetarpal]

The linkage error is the same one as #3783, coming from CasADi's plugin system. I am not sure if it's worth fixing it, since it was fixed by @martinjrobins for the linear interpolant case by dropping down to Python but IIRC there wasn't a way in CasADi for doing it for the cubic

[kratman]

@agriyakhetarpal Yeah I was looking at that issue as well. As far as I can tell CasADI sets a path for plugins. I am trying to see if there is a decent workaround since this was part of #4464

My guess is that the wheels for the next release will be broken as well, but I have not confirmed it yet

[agriyakhetarpal]

There is a workaround for Linux and macOS, but not for Windows (different toolchain); sadly, it's not decent enough to include. I think I'll raise a PR upstream in CasADi to get one part of the linkage going and see if we can migrate to a non-MSVC toolchain (which can potentially help provide that workaround for this on Windows later on). It's been on my list of things to do for a while, but I've yet to do it.

[kratman]

This is fixed locally with this: export CASADIPATH=.venv/lib/python3.12/site-packages/casadi

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.68%. Comparing base (4223be8) to head (772e782).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4487      +/-   ##
===========================================
- Coverage    99.26%   98.68%   -0.59%     
===========================================
  Files          302      302              
  Lines        22889    22879      -10     
===========================================
- Hits         22721    22577     -144     
- Misses         168      302     +134     

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[agriyakhetarpal]

This is fixed locally with this: export CASADIPATH=.venv/lib/python3.12/site-packages/casadi

Yes, won't work with Windows

[martinjrobins]

I had a look at this. The linker error is the same as I came across for the case of linear interpolation. The solution there was to swap to using the direct casadi function rather than their plugin system, which won't work if the casadi function is evaluated in C++ for windows as we compile everything statically.

I think I might be able to access the direct bspline interface by calculating the spline coefficients in scipy and then use the casadi Function.bspline function to construct a bspline. Cross fingers this doesn't use the plugin system anywhere! Going to try this out in #4570

[kratman]

I had a look at this. The linker error is the same as I came across for the case of linear interpolation. The solution there was to swap to using the direct casadi function rather than their plugin system, which won't work if the casadi function is evaluated in C++ for windows as we compile everything statically.

I think I might be able to access the direct bspline interface by calculating the spline coefficients in scipy and then use the casadi Function.bspline function to construct a bspline. Cross fingers this doesn't use the plugin system anywhere!

Yeah I was going to approach this by seeing if I could just change the build itself. It is something that should work if we are compiling and delivering everything correctly. If that does not work, then I will look at workarounds for interpolation

[kratman]

I expect to work on this again next week, I have been caught up with other stuff