@smaret I googled and found nothing to suggest that openblas gives performance improvements over lapack. I am sure you are right but do you have some evidence? A suite of performance tests? A reference? I found this: https://github.com/bmcage/odes/blob/master/ipython_examples/Performance%20tests.ipynb but have not tried running it yet. Maybe you know something better? Or maybe we can email the SUNDIALS mailing list?

@idontgetoutmuch You can find a comparison between the reference LAPACK (liblapack in nixpkgs), OpenBLAS and Intel MKL here:
https://markus-beuckelmann.de/blog/boosting-numpy-blas.html

For SUNDIALS/CVODE specifically, I did a benchmark with this code. For a system of 500 ODEs, it runs four times faster when SUNDIALS is linked against OpenBLAS rather than the reference LAPACK.

@GrahamcOfBorg build sundials

Using OpenBLAS for performance sounds reasonable.

In terms of building and passing tests: The sundials pass on both linux amd64 and aarch64 - for some reasons ofborg hasn't reported back about macos yet, and I lack the hardware to properly test this.

ofborg hasn't reported back about macos

It does not build on macos unless you are a trusted user. However I've built and tested the package on my local macos machine.

I am going to try building on macos now.

Builds for me on macos so 👍