defining generic function?

Hello, here's a brief overview of my problem: I have to diff some ugly equations (lots of terms with cos and sin products) with variables x (position) xdot (speed). Is there anyway I can tell matlab that x and xdot is a function of time (t) so that it can do dx/dt symbolically?

Answer 1

[Walter Roberson]

You can either write all references to x and xdot as x(t) and xdot(t), or you can

neweqn = subs(eqn,{x,xdot},{sym('x(t)'),sym('y(t)')});

to effectively rewrite the equation after it is defined.

[Eduardo]

Dang, such a simple solution! Thank you very much!