pub(crate) fn transverse_values(
vector: [Complex; 2],
) -> Result<(Complex, [Complex; 2])>Expand description
The transverse norm sqrt(kx^2 + ky^2) (principal root) and the unit transverse
direction (kx, ky) / norm, which is (cos phi, sin phi) for a real wavevector.
Gives zeros for kx = ky = 0, and an error when a complex (kx, ky) is nonzero
but has a zero algebraic norm, where the direction is undefined.