Function to_mode_order 

pub(crate) fn to_mode_order(matrix: &Matrix2) -> Matrix2

A coefficient matrix in the mode order of a T-matrix.

mie and mie_cyl index their matrices by helicity (negative, positive), which is the polarization index pol (0, 1). A basis lists pol = 1 before pol = 0, so both axes swap. The swap is its own inverse, so it also takes a cotangent in mode order back to helicity order.