How to take derivatives of this function?

f=sin(a)+cos(b)+a_dot where a and b are 2 angles, a_dot and b_dot are the angular velocity and a_double_dot and b_double_dot are the angular acceleration.

first, take partial derivative of a: df/da=cos(a) then take derivative of df/da w.r.t time t: d(df/da)/dt=-sin(a)*a_dot

Can anyone wrote a code for me to solve this please?

[Jan]

This sounds like a homework question. So please show, what you have tried so far.

Answer 1

[KSSV]

syms t a_dot(t)
a(t) = sym('a(t)') ;
b(t) = sym('b(t)') ;
f = sin(a(t))+cos(b(t))+a_dot ;
f_a = functionalDerivative(f,a(t)) ;
diff(f_a,t)

Question is similar to: http://in.mathworks.com/matlabcentral/answers/303729-how-to-take-time-derivatives-of-an-function