Wie rechne ich... hintereinander angeordnete Polarisationsfilter?

clear all;
%Konstanten
c = 3e8
c = 300000000
%Gegeben
alpha_1 = 45
alpha_1 = 45
alpha_2 = 65
alpha_2 = 65

Reihenfolge 1-2

alpha_12 = alpha_2 - alpha_1
alpha_12 = 20
Irel = cosd(alpha_1)^2 * cosd(alpha_12)^2
Irel = 0.4415

Reihenfolge 2-1

alpha_21 = alpha_1 - alpha_2
alpha_21 = -20
IrelRev = cosd(alpha_2)^2 * cosd(alpha_21)^2
IrelRev = 0.1577