Derivate a function with two variable dependent of time

hello,

I have the funtion f( r(t) , theta(t) )= r^2 + 0.2cos(theta) -0.03 =0 .

My question how can I define a function to derive f respect to t .

I appreciate any help.

Answer 1

[Birdman]

The following might help:

syms r(t) theta(t) f(r,theta)
f=r^2+0.2*cos(theta)-0.03

To take partial derivative, use functionalDerivative:

functionalDerivative(f,r)

or

functionalDerivative(f,theta)