Is it possible to use an anonymous function as an event-function when solving an ODE in Matlab

Question

Is it possible to use an anonymous function as an event function in Matlab. What I want to do is basically

opt = odeset('Events', @(t,y) (deal(y(end)-t^2,1,0)));
[T,Y] = ode45(@odefun,[tstart tend],y0,opt);

However, this returns an error complaining that the number of outputs to deal must be matched exactly. Is there some other way to make the anonymous function return multiple arguments?

Answer 1

I noticed this post looking for the answer to the same question. This means that for some people the question may be still valid. Since finally I found the solution by myself, I'd like to give a little bit "outdated" answer.

Actually, yes - it's possible but not straightforward. Try this:

evnt_fun = @(t, f)subsref({'some stop condition', 1, 0}, struct('type', '{}', 'subs', {{':'}}));

I'm not able to fully check the backward-compatibility of the code. However, it works with R2011 and later MATLAB versions.

Answer 2

No, you can't do it. Anonymous functions in Matlab only ever return one value.

Instead, you could define a thin wrapper around deal and pass your wrapper as a handle:

function [a b c] = wrapper(t,y)
    [a b c] = deal('some stop condition', 1, 0);
end

opt = odeset('Events', @wrapper);

[T, Y] = ode45(@odefun, [tstart tend], y0, opt);