If you use 'fmincon' in MATLAB Function block, you have to write codes in a special manner, because the MATLAB Function block relies on code generation technology.
The limitation is written in this document.
You should set an option and pass 10 arguments to 'fmincon'.
options = optimoptions('fmincon', 'Algorithm', 'sqp');
x = fmincon( fun , x0 , A , b , Aeq , beq , lb , ub , nonlcon , options )
Note:
Additional arguments like Aeq, beq,... can be empty: [].
