demo/low_level.r

In cda: Coupled-Dipole Approximation for Electromagnetic Scattering by Three-Dimensional Clusters of Sub-Wavelength Particles

library(cda)
library(rgl)
library(ggplot2)
library(reshape2)
library(plyr)

material <- data.frame(wavelength=500, epsilon=-10+0.2i)
medium <- 1.0
kn <- 2*pi/material$wavelength * medium
kvec = c(0,0,1)
Evec <- c(1,0,0)
cl <- list(positions = cbind(c(0, 0, 0),
                     c(100, 0, 0)),
           angles = cbind(c(pi/3, 0, 0),
                          c(0, 0, 0)),
           sizes = cbind(c(30, 10, 10),
                         c(30, 10, 10)))

Alpha <- alpha_ellipsoid(cl$sizes, material, medium)
AlphaBlocks <- cda:::cpp_alpha_blocks(Alpha, cl$angles)

R <- cl$positions
A <- cda:::cpp_interaction_matrix(R, as.double(kn), AlphaBlocks)

Incidence <- matrix(0, ncol=3,nrow=4)

Ein <- cda:::cpp_incident_field(Evec, kvec*kn, R, Incidence)

E <- solve(A, Ein)
P <- cda:::cpp_polarization(E, AlphaBlocks)

cext <- cda:::cpp_extinction(kn, P, Ein)
cabs <- cda:::cpp_absorption(kn, P, E)

Scattering <- quadrature_sphere(Nq=50, "gl")
res1 <- cda:::cpp_dispersion_spectrum(kn, medium, cl$positions, Alpha, 
                               cl$angles, matrix(0.0), 0L, 
                               Scattering$nodes, Scattering$weights, 
                               0L, 2L, 
                               50, 1e-4, FALSE)

res <- cda::spectrum_dispersion(cl, material, medium = medium)

subset(res, type=="cross-section" & polarisation == "p")
res1[1:3] 
c(cext[1], cabs[1], cext[1] - cabs[1])/2