Hello, I want to use cvx to solve my optimization problem, but I have encountered some problems. Trigonometric functions (sin, cos, tan) are used in my constraints, and then the following error occurs when I execute the code: **check whether there are incorrect parameter data types or missing parameters in the call to the function cos**. Here are some of my constraints，where x, y, th, v, delta and a are variables

```
x(n+1) == x(n)+Ts*(v(n)+Ts/2*a(n))*cos(th(n));
y(n+1) == y(n)+Ts*(v(n)+Ts/2*a(n))*sin(th(n));
th(n+1) == th(n)+Ts*(v(n)+Ts/2*a(n))*tan(delta(n)/WB);
```

This problem makes me unable to continue my work. Please give me some suggestions to deal with this problem. Thank you for your help.