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Saving output values from a function into an array (to plot later)

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So I have written a loop that runs a function for a given m to give a specific time_hours value (for that given m). The program works and I get all the values I need, but how would I save these values in an array to plot against m later on? I'm not sure how this would work as I have used fzero to calculate the time_hours values on each iteration and fzero values cannot be indexed? Thanks for any help, here is my code:
alpha = 0.7e-7; rho = 0.1 .^(1/3); %m = [4:0.1:8];
for m = 4:0.1:8
[term, scarysum, summation_t, f, time_seconds, time_hours] = tcalc(alpha, rho, m);
end
function [term, scarysum, summation_t, f, time_seconds, time_hours] = tcalc(alpha, rho, m)
scarysum = 0;
for k = 1:30
syms t
term = ((-1).^(k-1))./k .* sin(k.*pi.*rho) .* exp((-1 .* k.^2 .* pi.^2 .*alpha.*(1360.*pi).^(2/3).*t)./m.^(2/3));
scarysum = scarysum + term;
end
summation_t = matlabFunction(scarysum);
f = @(t) (2./(pi*rho) .* (summation_t(t))) - 0.7125;
time_seconds = fzero(f,14400);
time_hours = time_seconds ./ 3600;
disp(time_hours)
end

Respuesta aceptada

Allen
Allen el 18 de Dic. de 2019
Editada: Allen el 18 de Dic. de 2019
If your function is returning scalar values that are being overwritten during each iteration of your for-loop, try the following as a replacement to your for-loop.
[term, scarysum, summation_t, f, time_seconds, time_hours] = arrayfun(@(m) tcalc(alpha, rho, m), 4:0.1:8);
% This is essentially the same as rewriting the for-loop to something like this, which changes the size
% of the output variables each iteration and appends the new value to the end of each variable.
rng = 4:0.1:8;
for m = length(rng)
[term(m), scarysum(m), summation_t(m), f(m), time_seconds(m), time_hours(m)] = tcalc(alpha, rho, rng(m));
end
  1 comentario
Sid Halder
Sid Halder el 18 de Dic. de 2019
Thank you so much! It's honestly so convenient that arrayfun exists, perfect function to use in my case. Ran into a few problems with arrayfun as my output variables contained exponential terms (which aren't scalar) so MATLAB had issues creating the new arrays but I think I've sorted it all out. Thanks once again.

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Cameron B
Cameron B el 18 de Dic. de 2019
options = optimset('PlotFcns',@optimplotfval);
scarysum = 0;
for k = 1:30
syms t
term = ((-1).^(k-1))./k .* sin(k.*pi.*rho) .* exp((-1 .* k.^2 .* pi.^2 .*alpha.*(1360.*pi).^(2/3).*t)./m.^(2/3));
scarysum = scarysum + term;
end
summation_t = matlabFunction(scarysum);
f = @(t) (2./(pi*rho) .* (summation_t(t))) - 0.7125;
[time_seconds,fval,exitflag,output] = fzero(f,14400,options);
time_hours = time_seconds ./ 3600;
disp(time_hours)
fig = gcf;
dataObjs = findobj(fig,'-property','YData');
y1 = dataObjs(1).YData;
x1 = dataObjs(1).XData;
You'll have to save y1 and x1 each time, but that's how you'd extract the data.

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