Daisy World Simulation Help?

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Morgan McCarthy
Morgan McCarthy 2015-11-10
编辑： Morgan McCarthy 2015-11-10
Hello! I'm doing a simple (or least I thought it would be) Daisy World simulation. However, the area of the black daisies and white daises come out to be the same after 200 time steps, which is definitely wrong. Could anyone look over this code and tell me where I went wrong?
function dy= DaisyWorld(t,y)
%Initial Conditions WhiteArea=0; BlackArea=0; UncoveredArea=1; tspan=[0,200];
%Influences blackAlbedo= 0.25; %albedo measures the reflectivity of a surface
uncoveredAlbedo= 0.5;
whiteAlbedo= 0.75;
deathRate= 0.3;
heatAbsorpFact= 20; %this controls how the local temps of the daisies differ from the average planetary temp
sbConstant= 5.669e-8;
solarFluxConstant= 917;
i=0; for t=1:200; %time steps i=i+1;
end
solarLuminosity= 0.6+(i*(1.2/200)); %solar luminosity increases with time
planetaryAlbedo=(UncoveredArea*uncoveredAlbedo)+(BlackArea*blackAlbedo)+(WhiteArea*whiteAlbedo);
avgPlanetTemp=((solarLuminosity*solarFluxConstant*(1-planetaryAlbedo)/sbConstant)^0.25)-273;
tempBlackLand=heatAbsorpFact*(planetaryAlbedo-blackAlbedo)+avgPlanetTemp;
tempWhiteLand=heatAbsorpFact*(planetaryAlbedo-whiteAlbedo)+avgPlanetTemp;
tempDeadPlanet=((solarLuminosity*solarFluxConstant*(1-0.5)/sbConstant)^0.25)-273;
blackGrowthFact=1-.003265*((22.5-tempBlackLand)^2);
whiteGrowthFact=1-.003265*((22.5-tempWhiteLand)^2);
db= BlackArea*(UncoveredArea*blackGrowthFact-deathRate)+0.001;
dw= WhiteArea*(UncoveredArea*whiteGrowthFact-deathRate)+0.001;
dy=[db;dw]
Run code:
%initial conditions WhiteArea=0; BlackArea=0; UncoveredArea=1; IC=[0,0]; tspan=[0,200];
[t,dy]=ode45(@DaisyWorld,tspan,IC);
plot(t,dy(:,1))%blackarea
legend('blackarea')
hold on;
plot(t,dy(:,2))%white area
legend('whitearea')
title('Area vs. Time')
xlabel('Time')
ylabel('Area')

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