Complex frequency (wavelength)

[myurkin]

In a discussion Helge Dobbertin mentioned that to simulate certain physical phenomena (like Casimir forces) it is required to solve classical electromagnetic problem for complex frequency (wavelength or wavenumber). In this respect I see the following questions:

• Will ADDA break down if we just redefine corresponding variables as complex? What additional changes are required and for what computed quantities? I guess, internal fields will be the easiest, while far-fields or radiation forces may require additional effort.
• How the calculation of Sommerfeld integrals (for surface mode) would be affected?
• Is it possible to define wavelength etc. always as complex without significant increase of computational time? (and without excessive use of if-s).

This issue may also be related to simulations for particles inside an absorbing medium - the latter is mentioned in #91.

[myurkin]

@Sunmosk

[Sunmosk]

For now, I'm going to make the WaveNum variable complex and change all the downstream variables and functions accordingly. Not sure it will solve this issue, but let's try :)