MLFMMTransmitMaps

The MLFMMTransmitMap type calculates the transmission between a MLFMMsource and an IrregularFieldSampling. The MLFMMSource is a hierarchically organized datastructure which splits the source volume into multiple box shaped domains. The source contributions of each box are aggregated and translated towards the observation locations defined in the IrregularFieldSampling according to the Multilevel Fast Multipole Method.

To construct and MLFMMTransmitMap, use the following constructor

MLFMMTransmitMap(
    basisfunctions, #Can be ::SurfaceCurrentDensity, ::DipoleArray, NamedTuple(:points,:sourcefunctions)
    fieldsampling::IrregularFieldSampling,
    wavenumber::T;
    kwargs...
)

The keyword arguments for the construction of a MLFMMTransmitMap are described in the following table

Keyword Argument	Short Description
`expectedaccuracy::Real = 1e-3`	Defines the desired approximation accuracy for all operations involving the `MLFMMsource`. Mainly affects the number of samples used to store the `PlaneWaveRepresentation`s for each box.
`verbose = false`	Determines if (debug) text should be printed to console for all operations involving the `MLFMMSource`.
`minboxlength = π / (2 * wavenumber)`	Side length of the smallest box, defaults to half a wavelength. All larger box side lengths are a $2^n$-multiple of the `minboxlength`.
`orderθ = 8`	Interpolation order along $\theta$ for the `ResampleMap`s used to intrpolate from one box level to the next. Only affects `ResampleMaps` with local interpolation strategies.
`orderϕ = 8`	Interpolation order along $\phi$ for the `ResampleMap`s used to intrpolate from one box level to the next. Only affects `ResampleMaps` with local interpolation strategies.
`samplingtype::Type{SphereSamplingStrategy} = GaussLegendreθRegularϕSampling`	Type of the sampling strategy of the `PlaneWaveRepresentation`s used to represent the accumulated field contributions of each box
`num_bufferboxes::Integer = 1`	Minimum number of empty boxes between a transmit box and a receive box such that an MLFMM translation between them can occur.
`transfertype::AbstractTransfer=PlannedTransfer{samplingtype,Complex{T},T}`	Type of transfer strategy used for the MLFMM transfers.
`mintransferlevel::Integer=0`	Minimum level of the MLFMM tree on which transfers can occur.