How are trigonometric functions handled in CVX?

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.

Try using YALMIP.

Ok, thank you. I’ll try it.