Unexpected unknown exception from MEX file..

Hey,

I wrote my bottleneck function as a mex function and it works well so far, but at a sudden point in my programm I just get a "Unexpected unknown exception from MEX file.." error.

I already found out that this happens when some of the input arrays exceed a certain length, but since I cant put any break points I dont know where the error exactly appears.

The function looks like following:

function [A]=function_name(a,b,c,d,e,f,g)
'a'
a'=NaN(length(a),1);
'b'
b'=NaN(length(a),1);
'c'
c'=NaN(length(a),1);
'd'

parfor i=1:length(a)
    n=d(:,i);
    n_d=a(n);
    n_r=b(n);
    dia=a(e);
    rho=b(e)
    
    [a'(i),b'(i)]some_other_function(n_d,n_r,dia,rho,e,f,g)
    

end

'j'
end

The error always seems to occur when the nx1 arrays a and b and the nxn loical matrix c exceed the size of about n=44000.

I put some letters in the code that should be displayed after a line is executed, I hoped that I could figure out where the error occurs since I cant put breakpoints anymore when its a mex function.

But it seems that I dont even get to the 'a' line in the iteration when the error occurs. My last display is 'j', which is the last output of the previpous error-free iteration, and then I get "Unexpected unknown exception from MEX file..", nothing more, only that it is this function where it happens.

Since I dont even get an 'a' displayed, I dont think that it is the overhead of variables a and b, the error muts happen when calling the function and the reason must be something with the input size of the variabkes a,b and c... but I dont know how to proceed further to find out whats going wrong.

Maybe somebody coukld give me a hint how to find out whats happening here

If you need the original code, I can provide it, but I prefer to not do so since its about my Phd research.

Many thanks in advance

Best regards.