Incorrect graph, loop error?
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Kailin Johnsson
on 17 Nov 2020
Answered: Kailin Johnsson
on 18 Nov 2020
Hello,
I am trying to run a simple malthusian model, however I have run into this error... Does anyone have an idea as to why this is happening? (I am relativly new to MATLAB).

% Time Interval
a=(1790:10:2010)';
% Population
b= [3.929 5.308 7.239 9.638 12.866 17.069 23.191 31.443 39.818 50.189 62.947 76.212 92.228 106.021 122.775 132.164 150.697 179.323 203.302 226.545 248.709 281.421 308.745]';
%Malthusian Growth Model
% Time interval
t = (1790:10:2010)';
% Previous population
Pn = [3.929 5.308 7.239 9.638 12.866 17.069 23.191 31.443 39.818 50.189 62.947 76.212 92.228 106.021 122.775 132.164 150.697 179.323 203.302 226.545 248.709 281.421, 308.745]';
% Growth Rate Assumption
R = (0.349)';
Labels = [1790:10:2010]';
%Malthusian Model
for i= (2:23)
E(i,1) = (Pn(i-1,1))*(R(1,1)+1)';
end
%PMal(i,1) = (r(1,1)+1)*PMal(i-1,1);
%R2
SST = sum((Pn-mean(Pn)).^2);
SSE = sum((Pn-E).^2);
R2 = 1- (SSE/SST)
% Plot
plot(t,E,'r-*');
hold on
plot (a,b,'bo');
line_color=['r'];
hold off
legend('Malthusian Model','Census Data');
axis([1790 2010 0 500]);
title('US Population Data');
ylabel('Population (Millions)');
3 Comments
Nora Khaled
on 18 Nov 2020
I copied your code to try and run it...
the figure looks different

and I don't understant the model nor the problem
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