Exiting an ode45 but based on a variable calculated inside the function and not based on output variable y

Hi!

I'm calculating a variable b inside myodefunc, which is further used to solve a quadprog problem.

The output of this quadrpog is what ode45 uses to integrate y.

function [u,b] = myodefunc(t,y)

Q = [1 0; 0 1];
g = zeros(2,0);
A = f1(t,y)
b = f2(t,y); % function of states and time
u = quadprog(Q,g,A,b);

end

I need to exit the ode when variable , where k is a positive constant.

Any help or suggestions would be greatly appreciated.

Thanks

[Akash Singh]

Update:

So I found out it works if I calculate the b again in the event detection function and then implement condition .

function [value,isterminal,direction] = EventsFunc(t,y)
    b = f1(t,y)
    value = b+k;
    isterminal = 1;
    direction = -1;
end

I had another doubt arising out of this. Is the event detection done before next time step is processed by the ode45?

Also, can I pass other input arguments to EventsFunc, for example EventsFunc(t,y,param) ? Do I need to change the function definition in the options('Events',@EventsFunc) for that? Or any other way besides explicitly defining the parameters again inside the function.