Fixed order of return values of :func:.space_ops.cartesian_to_spherical

[Viicos]

Overview: What does this pull request change?

As mentioned in #2095, the returned array in cartesian_to_spherical is not in the correct order. spherical_to_cartesian is unpacking them correctly as r, theta, phi but cartesian_to_spherical returns the array in that order: r, phi, theta.

position_tip was also edited to be in accordance with the correct order.

Motivation and Explanation: Why and how do your changes improve the library?

Links to added or changed documentation pages

Further Information and Comments

Reviewer Checklist

• The PR title is descriptive enough for the changelog, and the PR is labeled correctly
• If applicable: newly added non-private functions and classes have a docstring including a short summary and a PARAMETERS section
• If applicable: newly added functions and classes are tested

[PhotonSpheres]

Thanks for fixing this! It seems like that a specific test is failing now, can you look into that? Feel free to ask if you need help.

[Viicos]

Thanks for fixing this! It seems like that a specific test is failing now, can you look into that? Feel free to ask if you need help.

Woops forgot to check if tests went good after my commit, forgot they were added in #2095.

[PhotonSpheres]

Great! LGTM

[behackl]

This is just a general remark: what do you think about using named tuples in cases like these?

[Viicos]

This is just a general remark: what do you think about using named tuples in cases like these?

Could be a good idea to avoid having situations like this one where the tuple order was incorrect, but we wouldn't be able to take advantage of the numpy arrays operations.

[behackl]

This is just a general remark: what do you think about using named tuples in cases like these?

Could be a good idea to avoid having situations like this one where the tuple order was incorrect, but we wouldn't be able to take advantage of the numpy arrays operations.

I wonder whether this would really be so much of a drawback. But maybe we'll come back to it eventually.

In any case, thank you for your efforts!