Solver2x2 does not work with active media

[MarJMue]

As explained in Byrnes' Paper (appendices C and D) the fresnel method can not handle active media that exhibit gain.

We should either check the inputs or give at least a warning if n>0 and k<0.

[domna]

I see. Thank you for researching this!

I think we can just show a warning or even raise an exception for this case. We should then refer to the Solver4x4, because I assume that it can handle gain correctly, right?

[MarJMue]

As far as i can tell 4x4 should work with active media, until the algorithm breaks down due to overflow errors.

[domna]

Ok, then I would say that Solver2x2 is just not suitable for gain media and we should let it fail for negative k and refer to Solver4x4. Agreed?

[MarJMue]

👍