Module mie 

Closed-form Mie scattering for a homogeneous sphere.

The axis_ratio = 1 limit of the T-matrix reduces to classical Mie theory. This module provides an independent implementation so parity tests can compare rustmatrix against a reference that does not share the same code path as the general T-matrix solver.

The algorithm follows the standard Bohren–Huffman formulation: compute the logarithmic derivative D_n(mx) by downward recurrence, then the Mie coefficients

  a_n = ( D_n(mx)/m + n/x ) psi_n(x) - psi_{n-1}(x)
        -----------------------------------------------
        ( D_n(mx)/m + n/x ) xi_n(x)  - xi_{n-1}(x)

  b_n = ( m D_n(mx)   + n/x ) psi_n(x) - psi_{n-1}(x)
        -----------------------------------------------
        ( m D_n(mx)   + n/x ) xi_n(x)  - xi_{n-1}(x)

with psi_n(x) = x j_n(x) and xi_n(x) = x (j_n(x) - i y_n(x)) (Riccati–Bessel).

Structs

MieCoefficients

Mie coefficients a_n, b_n for n = 1 .. nmax.

Functions

mie

Compute Mie coefficients for a homogeneous sphere of size parameter x and complex refractive index m.

qext

Extinction efficiency Q_ext for a Mie sphere.

qsca

Scattering efficiency Q_sca for a Mie sphere.