gh-519: test array API compliance of legacy mode functions

[Saransh-cpp]

Description

Add array API tests for legacy mode functions added in glass.algorithm. The functions added in other modules do not fully support the array API standard; therefore, those functions can be dealt with once we add full support.

Closes: #519

Checks

• Is your code passing linting?
• Is your code passing tests?
• Have you added additional tests (if required)?
• Have you modified/extended the documentation (if required)?
• Have you added a one-liner changelog entry above (if required)?

[Saransh-cpp]

The typing and rng issues need to be worked out ideally before merging this. Hence, marking as draft.

[ntessore]

Thanks @Saransh-cpp! What is the issue with array.reshape() here?

[Saransh-cpp]

Thanks, @ntessore! array.reshape() exists in JAX and NumPy but it is not a part of the array API (array_api_strict tests fail).

[paddyroddy]

Just checking why dropping where/out?

[Saransh-cpp]

array_api_strict.divide does not support those arguments. out is not testing anything here and the where argument is probably just reducing the number of computations (which is not very large in this case).

[ntessore]

norm > 0 is necessary if dealing with rank-deficient matrices, e.g. to get the correlation matrix of this covariance matrix:

$$\begin{pmatrix}2 & 0 & 1 \\ 0 & 0 & 0 \\ 1 & 0 & 3\end{pmatrix}$$

To be fair, I don't we are testing that case currently

[Saransh-cpp]

There is no diag function or alternative in array API standard.

[paddyroddy]

Given the size of this, that doesn't seem like a problem really

[Saransh-cpp]

array_api_strict.divide does not support those arguments. out is not testing anything here and the where argument is probably just reducing the number of computations (which is not very large in this case).

[Saransh-cpp]

This should finally be ready now, @paddyroddy @ntessore!

[paddyroddy]

This looks really clean 👌

[Saransh-cpp]

Merging this so that it does not go stale again!