clear; clc; close all;
h=6.626e-34;
c=3e8;
k=1.3806e-23;
c1 = 1e-7*2*pi*h*c^2;
c2 = h*c/k;

L = 4.05:0.1:17.95;
L = L*1e-6;

Ts = 273.15+(-50:50:550);
colors = hot(length(Ts)+4);

f = figure('Position',[50,50,600,450]);
hold on;
for ii = length(Ts):-1:1
    T = Ts(ii);
    I = c1./( L.^5 .* ( exp(c2./L/T) -1 ) );
    plot(L*1e6,I,'Color',colors(ii,:),'LineWidth',2);
    Int(ii) = 1e6*sum(I(L>8e-6&L<14e-6))*mean(diff(L));
    labels{length(Ts)+1-ii} = sprintf('%+d °C \\rightarrow %d µW/m²',T-273.15,round(Int(ii)));
end
M = 40;
plot(8*[1,1],[0,M],'k-','Linewidth',2)
plot(14*[1,1],[0,M],'k-','Linewidth',2)
ylim([0,M])
xlim([4,18])
xlabel('Wellenlänge / µm')
ylabel('Spektrale Intensität W/m²/nm')
h=legend(labels)
set(h,'Position',[0.2261 0.1726 0.2900 0.4844])
print(f,'IR_8_14_a.png','-dpng','-r150');

f = figure('Position',[50,50,380,350]);
hold on;
plot(Ts-273.15,Int,'k-');
for ii = 1:length(Ts)
    scatter(Ts(ii)-273.15,Int(ii),20,'MarkerEdgeColor',colors(ii,:),'MarkerFaceColor',colors(ii,:));
end
xlim([-55,555]);
xlabel('Temperatur / °C');
ylabel('Intensität zwischen 8 µm und 14 µm  / µW/cm²')
grid on;
print(f,'IR_8_14_b.png','-dpng','-r150');