How do I access and plot thetadot vs. time from function I have created?

function thetadot= oscltr(t,theta)
A= [0 0 0.5 0 0 0; 0.5 0 0 0 0 0.5; 0.5 0.5 0 0 0 0; 0 0.5 0 0 0 0; 0 0 0.5 0 0 0; 0 0 0 0.5 0.5 0]; % edge weight matrix
D= [0.5 0 0 0 0 0; 0 1 0 0 0 0; 0 0 1 0 0 0; 0 0 0 0.5 0 0; 0 0 0 0 0.5 0; 0 0 0 0 0 1]; %Diagonal in-degree matrix
L= D-A; %Laplacian matrix
N=6;
K=50;
wi=[1; 1.1 ;0.9; 0.85; 2; 2.1];
thetadot=wi-(K/N)*L*theta;
end

 Accepted Answer

Please see my response at https://www.mathworks.com/matlabcentral/answers/1818985-how-to-work-variables-outside-function#answer_1068360 discussing why it is unlikely that you want to access the internal variables computed by an ode function: such a record would have far too many entries and would also not have entries for most of the time steps.

More Answers (1)

There are several ways, one of whith would be
Dtheta=diff(theta) %theta = values
Dtime=diff(time) %time = time values.
ThetaDot = Dtheta./Dtime.
plot(Dtheta,time) % you have to be careful in case there is 0/0 somewhere.

2 Comments

I recommend using gradient() instead. The timestep for ode45 is typically irregular.
Just call the function with the values for theta of your choice.

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