Unable to Duplicate Meep Python Mie Scattering Tutorial

[cgbsu]

Hello,

I am having some trouble duplicating the [Mie Scattering section](https://meep.readthedocs.io/en/latest/Python_Tutorials/Basics/#mie-scattering-of-a-lossless-dielectric-sphere) of the tutorial. My analytical and numerical results are definitely not in agreement. I dont know a much about Mie Scattering, and I am finding it hard to figure out how to diagnose the problem from a physics perspective.

I wrote my version of the tutorial differently, but I have been over the code a number of times, but it still does not come out right.

I am linking the notebook, you can see clearly the results are way off and see my code.

I tried a couple of suggestions I saw on different Issues/threads from this repo, like disabling the symmetry, but it did not work.

The main difference with this code is the introduction of fluxes/flux regions is procedural, and simulators are automatically generated. All fluxes and flux data arrays are logged. Also fluxes are automatically subtracted.

It seems no combination of fluxes from the control (no geometry) and variable (sphere geometry) or the fluxes themselves changes the qualitative results.

There are more results in the notebook I linked, but this is the result I think should be correct:

The different "Meep" lines are essentially as if I had changed

box_x1_flux0 = mp.get_fluxes(box_x1)

to be a different flux box in the original

Any suggestions?

Thanks!

[smartalecH]

As a sanity check, when you run the existing tutorial as is, you can replicate the reported results, right?

[cgbsu]

Thanks for the reply, its a tad off actually

[cgbsu]

I also discovered I was running the control with until_after_sources set to 100 for both sims, but now that I am doing 10 and 100 it looks somewhat different, maybe a bit closer

[cgbsu]

Hello, just wanted to follow up

[dalarev]

See if this similar discussion helps answer your questions.
At the very least, it could help explain why a copy/paste of the tutorial code doesn't produce the exact same results.