The correct way to use ‘f’ with fzero in the posted code is:
y = fzero(@(e)f(e,par), [e,e+0.1]);
There are too many missing variables to be able to run your code (and I have no idea what you are doing with half of a try-catch block).
Also, there may be problems using the limits for fzero, since there may not be a zero-crossing between those values.