This is because the "int" function does not come with the base MATLAB, but the Symbolic Math Toolbox:
You can check whether you have the Symbolic Math Toolbox installed by executing the following command in MATLAB's Command Window:
>> ver
If "Symbolic Math Toolbox" is not listed as the output of the "ver" command, you can still do numerical integration in MATLAB using the "integral" function:
For example, in MATLAB you can do:
>> fun = @(x) exp(-x.^2).*log(x).^2;
>> q = integral(fun,0,Inf)
