Remove x0 from plane wave?

[hagenw]

In the current implementation of a plane wave we use x0 besides n0, which is a little bit confusing as you would normally suspect that n0 is everything you need to specify a plane wave.

Is there a reason why we have x0 in addition (it is simply substracted from the grid) or can we just remove it?

[fietew]

I think, one can define the point or more precisely the plane of zero phase/zero delay with x0.

[hagenw]

I'm not sure if we really need this feature.
And if, we should update the formula, which is at the moment:

G(x, w) = e^(-i w/c n x)

and does not contain any x0.

[spors]

• This feature could be important to simulate spatially shifted plane wave decompositions.
• Another reason for the parameter x_0 is that all (secondary) sources should have the same core arguments so that they can be exchanged easily in synthesized.generic(..., source=)

[hagenw]

OK, this sounds reasonable. Then we should keep it and update only the documentation.