fzero (MATLAB Functions)
The fzero command finds a point where the function changes sign. If the function is continuous, this is also a point where the function has a value near zero.
How to use fzero in MATLAB
There are several problems in your code: fzero tries to find a zero of the function supplied as first argument.
fzero
The fzero command is a function file. The algorithm, created by T. Dekker, uses a combination of bisection, secant, and inverse quadratic interpolation methods. Description · Examples · Input Arguments · Output Arguments