Hi AJ,
I'm not entirely sure about your question, since you ask to "plot the end points of these variables (a, e, de, da) against Qe" however Qe is a scalar (just a single number) in your code. So maybe you want to plot the variables (a, e, de, da) against Qe, while varying Qe from 6 to 15? That is what I did below. Hope it helps.
%% plotting_endpoints_from_arrays
%% Setup
close all
clear
clc
tic
format long
%% Loop over Qe
Qe = 6:1:15
% Run the calculation one time for each value of Qe
for i = 1:1:length(Qe)
M = 10000002;
a = zeros(M,1);
e = zeros(M,1);
da = zeros(M-1,1);
de = zeros(M-1,1);
T = [0:10000000];
e(1) = 0.0549;
a(1) = 0.3844e9;
for m = 0:10000000
de(m+1) = -(4.04562756e41 + ((2.75561858e40)/Qe(i))) * ((a(m+1))^(-13/2)) * e(m+1);
da(m+1) = (((8.09125512e41)*(e(m+1)^2)) + ((1.16026046e40)/Qe(i))) * (a(m+1))^(-11/2);
e(m+2) = e(m+1) + (de(m+1) * 3.154e7);
a(m+2) = a(m+1) + (da(m+1) * 3.154e7);
end
e = e(1:end-1);
a = a(1:end-1);
% Save endpoints
aEnd(i) = a(end);
eEnd(i) = e(end);
deEnd(i) = de(end);
daEnd(i) = da(end);
end
%% Plot endpoints of each variable vs Qe
subplot(2,2,1)
plot(Qe,aEnd, 'bo')
title('a vs Qe')
subplot(2,2,2)
plot(Qe,eEnd,'bo')
title('e vs Qe')
subplot(2,2,3)
plot(Qe,deEnd,'bo')
title('de vs Qe')
subplot(2,2,4)
plot(Qe,daEnd,'bo')
title('da vs Qe')
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