[SciPy-Dev] PR to add get_array_bandwidth, issymmetric, ishermitian functions

[Ilhan Polat]

Update mail for the aforementioned PR. After using the hint from Eric
Moore, it got slightly faster but probably there is more room for
improvement. Evgeni raised the issue of approximate checks instead of
identical checks for zero, mostly the use case of an array contaminated
with numerical noise. I am not sure about the business case for it but I'd
like to fish for some feedback here too. The main issues I can see is that
int types have no room for noise and also the tolerance adjustment would be
quite difficult to pull off since it would depend on the magnitudes of the
nonzero entries to decide what constitutes as noise.

Finally, though I started this in SciPy, I still have some doubts whether
this should go into NumPy or not. But we can do that anytime later.

If it looks OK then I'd like to put these in well before the 1.8 deadline
since I want to attempt to get the generic linalg functions solve, eig, and
svd context aware, that is to say using these functions eig will dispatch
to eigh or triangular solvers, linalg.solve will dispatch to different
solvers depending on the structure etc.

Hence any feedback is welcome.

Best,
ilhan



On Wed, Sep 8, 2021 at 1:25 PM Ilhan Polat <ilhanpolat at gmail.com> wrote:

> Dear all,
>
> There is now a PR for scipy.linalg module including functions mentioned in
> the title. The idea is actually to enable a central place to provide these
> rather occasionally needed functionalities with some basic benchmarking
> available. If and when these are in then we can work on the context aware
> eig, solve functions much easier delegating the right structure to the
> right algorithm.
>
> Feedback is most welcome.
>
> https://github.com/scipy/scipy/pull/14701
>
> best,
> ilhan
>
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