The Parameter of ODE is not Updated When the EventCallback Function is Called

I was simulating ODEs which incorporate additional parameter (ydot = f(t,y,P)).

There is an event occurs in the simulation process and the event is processed with odeEvent function.

The eventCallback function is illustrated as follows:

function [stop,Ye,Pout] = impactEventCallback(te,ye,ie,Pin)

    % ... parameter updating calculation

    fprintf("parameter befor updating : %.5f    After updating : %.5f \n",Pin.v,Pout.v); % output updating result  

end   

The simulation result is demonstrated as follows:

parameter befor updating : 0.10000 After updating : 0.37232

parameter befor updating : 0.10000 After updating : 0.08382

parameter befor updating : 0.10000 After updating : 0.06401

...

It seems that every time the impactEventCallback function is called, the parameter before updating (Pin) is not changed.

I suspect that the updated parameter Pout is not used by the governing equations ydot = f(t,y,P).

The expected result should be that the next time the value of Pin is the last time value of Pout.

Can anyone give some advices about how to fix this issue ?

Answer 1

[Chuguang Pan]

I have solved this isssue with the following odeEvent object definition:

E = odeEvent("EventFcn",@impactEvent,"Direction","ascending","CallbackFcn",@impactEventCallback,"Response","callback");

However, the previous definition of odeEvent object is :

E = odeEvent("EventFcn",@(t,y,P) impactEvent(t,y,P),"Direction","ascending","CallbackFcn",@(te,ye,ie,P) impactEventCallback(te,ye,ie,P),"Response","callback");

The difference is that the EventFcn and CallbackFcn are defined utilize function handle syntax explicitly.

I am confused why the implicity syntax of function handle definition is effective yet the explicity syntax is not.

The simulation result after fixing is illustrated as follows:

parameter befor updating : 0.10000 After updating : 0.37243

parameter befor updating : 0.37243 After updating : 0.18519

parameter befor updating : 0.18519 After updating : 0.22448

parameter befor updating : 0.22448 After updating : 0.13929

...