Error while passing arguments to events function - matlab

Question

I have a function called initial which takes an argument funname and performs some integration. I wanted to pass multiple arguments to events function. So I did this:
odeopt=odeset('RelTol',1e-5,'AbsTol',1e-5,'Events',#(t,y) events(t,y,prm,funname));
fun=str2func(funname);
[t,y]=ode15s(fun,[0 3600],z,odeopt,prm);
prm is a structure and funname is a string.
This is the events function:
function [value,isterminal,direction] = events(t,y,prm,funname)
isterminal=1;
direction=0;
v=feval(funname,1,y,prm);
value=~all(v<1e-10);
funname is basically the ode function.
It still says too many input arguments.:
??? Error using ==> initial>#(t,y)events(t,y,prm,funname)
Too many input arguments.
Error in ==> odeevents at 29
eventValue = feval(eventFcn,t0,y0,eventArgs{:});
Error in ==> ode15s at 263
[haveEventFcn,eventFcn,eventArgs,valt,teout,yeout,ieout] = ...
Error in ==> initial at 10
[t,y]=ode15s(fun,[0 3600],z,odeopt,prm);
Can't be a problem of version (was using 7.6) because this post which addresses this issue was on 2006.
Any Idea?

Answer 1

Since prm is passed as the last argument in ode15s, it will result in the eventArgs cell passing the value to the event handle. In other words, the line
eventValue = feval(eventFcn,t0,y0,eventArgs{:});
is really doing
eventValue = eventFcn(t,y,prm);
So if prm is needed as an extra parameter in the ODE system, just make prm an input in the event handle:
odeopt=odeset(..., #(t,y,prm) events(t,y,prm,funname));
Also, since the events function is design to locate solutions passing through zeros, the value should be a double such that MATLAB's sign function works properly.