Fix variable re-use in power spectrum

[JBorrow]

Fixes #218

[Copilot]

Pull Request Overview

This PR fixes a variable re-use issue in the power spectrum calculation by renaming intermediate variables during the particle folding process and updates the corresponding docstrings. Key changes include:

• Introducing new temporary variables (e.g. x_pos_scaled) in deposit to avoid re-using the original coordinate variables.
• Updating the docstrings for deposit and deposit_parallel to clarify the scaling of the positions.
• Removing extraneous characters from the parameter descriptions.

Comments suppressed due to low confidence (4)

swiftsimio/visualisation/power_spectrum.py:40

• The docstring for parameter 'y' incorrectly references 'box_x'. Please update it to 'box_y' to accurately reflect the scaling for y-positions.

array of y-positions of the particles. Scaled by box_x by this function, so ensure they have the same units.

swiftsimio/visualisation/power_spectrum.py:43

• The docstring for parameter 'z' incorrectly references 'box_x'. Please update it to 'box_z' to accurately reflect the scaling for z-positions.

array of z-positions of the particles. Scaled by box_x by this function, so ensure they have the same units.

swiftsimio/visualisation/power_spectrum.py:123

• In the deposit_parallel docstring, parameter 'y' should reference 'box_y' instead of 'box_x' for clarity and correctness in unit scaling.

array of y-positions of the particles. Scaled by box_x by this function, so ensure they have the same units.

swiftsimio/visualisation/power_spectrum.py:126

• In the deposit_parallel docstring, parameter 'z' should reference 'box_z' instead of 'box_x' for clarity and correctness in unit scaling.

array of z-positions of the particles. Scaled by box_x by this function, so ensure they have the same units.

[kyleaoman]

Is "same units" required? Or is "compatible units" enough? cosmo_array should be clever enough now for the latter. Might want to check that mixed physical & comoving inputs give intuitive outputs, do you want to explicitly coerce the box size to match the comoving flag of the coordinates?

[JBorrow]

This function explicitly asks for numpy arrays because of numba acceleration (value arrays; that's also what is passed by calling functions) so all unit coercion should be done before touching it.