jipolanco

using StaticArrays
using LinearAlgebra

# Compute eigendecomposition of a 3×3 Hermitian matrix.
# Uses closed-form expressions by Deledalle et al. 2017:
# https://hal.archives-ouvertes.fr/hal-01501221/document
function fast_eigen(
        C::Hermitian{T, <:SMatrix{3,3,T}};
        sortby::F = identity,
    ) where {T, F}