Feature request: evaluate multipole expansion on single axis

[nordic-node]

Hi,

instead of evaluating the multipole expansion point by point, like

phi = np.array([mpe(r, 0, 0, l_max=l_max) for r in rr])

where mpe is a multipole expansion object.

I would rather like to write something like this:

phi = mpe(rr, 0, 0, l_max=l_max)

As far as I can see, the call function just allows to pass a point. and the getitem function wants slices or masks on the same grid
that was used for the charge distribution. Is there a possibility to do the same for outside of that grid?

Cheers, Sara

[nordic-node]

I have just sent a pull request implementing this feature. In fact, it implements even more. Now you
can evaluate the multipole expansion not only on an axis but along arbitrary curves. For instance,
evaluating along some segment of the y-axis would be

mpe(0, np.linspace(20, 30, 50), 0)

But evaluating along a circle of radius 50 in the x-y plane would be

t = np.linspace(0, 2*np.pi, 100)
mpe(100*np.cos(t), 100*np.sin(t), 0)

[maroba]

Yes, I have just merged your pull requests a few minutes ago. Thank you very much! Great work. :-))

[nordic-node]

I see that you already have made a new release with my changes. Thanks! By the way, I have a Jupyter notebook showing how the accuracy of your multipole package scales. Shall I post it to the repo as example?

[maroba]

That would be awesome!

[nordic-node]

Just sent a pull request. 😄