How to handle warnings in SimBiology within series of simulations?

To perform a sensitivity analysis I am running *.sbproj coded models using 'biosimulate' in a for-loop and see for some parameter combinations the following warning:

Warning: The right-hand side of the system of SimBiology ODEs results in complex numbers. The imaginary part of the result will be ignored. 
> In sbioodeflux_298d036b_ba03_4469_9210_25b32c7bbb2b (line 44)
  In sbiosimulate (line 140)
  In GSA (line 107) 

Can I trust the solutions? If not, how can I exclude the solutiuons which resulted in the warning above, i.e. is there a way to find programatically if a warning was produced?

Update

I added assignment of NaN's in case of fatal errors but still don't know how to handle the warnings.

        try
            ...
            [t,y] = sbiosimulate(m1);
            
            f1(i,j) = trapz(t,y(:,varNo));          % f1 AUC
            f2(i,j) = y(end,varNo);                 % f2 endPoint
        catch me
            disp( getReport( me, 'extended', 'hyperlinks', 'on' ) )
            f1(i,j) = NaN;
            f2(i,j) = NaN;
            disp('Found an error-----------------------')
        end

Answer 1

[Arthur Goldsipe]

Hi,

It's difficult to say for sure whether you can trust the simulation results when you see this warning. I would definitely encourage you to try to understand why you are getting complex numbers. I see this most commonly when a model using exponentiation (such as with Hill kinetics) and a concentration becomes negative. To prevent this warning from occurring, I will sometimes replace terms like x^n with max(0,x)^n.

If you decide you need to programmatically detect when a simulation issues a warning, you can use the lastwarn function. For example, here is how I would modify your sample code to turn any warning that occurs during simulation into an error:

try
    %...
    lastwarn('', '');
    [t,y] = sbiosimulate(m1);
    [msg, msgID] = lastwarn;
    if ~isempty(msgID) % or check for a specific warning ID
        error(msgID, msg);
    end
    f1(i,j) = trapz(t,y(:,varNo));          % f1 AUC
    f2(i,j) = y(end,varNo);                 % f2 endPoint
catch me
    disp( getReport( me, 'extended', 'hyperlinks', 'on' ) )
    f1(i,j) = NaN;
    f2(i,j) = NaN;
    disp('Found an error-----------------------')
end