Output additional vectors from ode45
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I am calculating concentrations and radii at all the timesteps within the ode45 loop. What is the best way to output all that information?
1 个评论
Jan
2021-11-28
As diagrams? In 2 or 3 D? As text files? As binary files?
采纳的回答
Adding additional outputs is permitted, providing that they are not used in the ode45 call. Normally, this is not a problem, because unless more outputs are requested in the calling script or function, only the first output is used.
The only way to recover them is to use the returned independent variable (usually time) vector and the solved dependent variables in a for loop and save the other desired output at each step of the loop.
tspan = [0 10];
ic = [0.1; -0.1];
[t,y] = ode45(@odefcn, tspan, ic);
for k = 1:numel(t)
[~,radii(k,:)] = odefcn(t(k),y(k,:));
end
figure
yyaxis left
plot(t,y)
ylabel('y(t)')
yyaxis right
plot(t, radii)
ylabel('Radius')
grid
function [dy,radius] = odefcn(t,y)
dy = zeros(2,1);
radius = hypot(y(1),y(2));
dy(1) = y(1);
dy(2) = radius * cos(y(1)) * sin(y(2));
end
.
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