请问m函数中能否构建传递函数

求教，m函数中能够构建传递函数
function y = fcn(u)
%#codegen
num=[1 0];
den=[1 2 1];
sys=tf(num,den);
y = sys*u;
报错如下
The 'tf' class does not support code generation.

Function 'MATLAB Function' (#38.58.69), line 5, column 5:
"tf(num,den)"
Launch diagnostic report.
Component: MATLAB Function | Category: Coder error