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matlabreal-timeode

How to display Matlab's ode45 results in real time?

Let's suppose that we have the following solver for a system of first-order ODEs:

   % func.m
   function dydt = func(t,y)
   dydt = [y(2); (1-y(1)^2)*y(2)-y(1)];

and the main code:

% solver.m
tspan=0:1:10;
[t,y] = ode45(@func,tspan,[2; 0]);

How to display in real-time the results, y1(t) and y2(t), for each time step t that the ode45 makes (t=0,1,2,...,10), without waiting for the whole code to finish?

Solution

  • The OutputFcn ode solver option should be used. For example, to plot the solution vs time, the built-in output function odeplot can be used:

    options= odeset('OutputFcn',@odeplot);
[t,y] = ode45(@func,[0 200],[2; 0],options);

    You can use your own output function. Here is an example:

    myOutputFcn= @(t,y,flag)fprintf('t= %s y=  %s\n',mat2str(t),mat2str(y))*0;
options= odeset('OutputFcn',myOutputFcn);
[t,y] = ode45(@f,0:1:10,[2; 0],options);