How to customize the way MATLAB combines an expression with a lot of symbols?

The expression below is combined in terms of phi_dot, theta_dot and psi_dot. I want it to be combined in terms of i_B, j_B and k_B. So how to tell MATLAB what variables I want it to consider when combining the terms of an expression?

Answer 1

[Dyuman Joshi]

Use collect

I assume you already have the Symbolic Math Toolbox

[FAISAL ALQARNI]

Thank you, Dyuman, that was helpful.

[Dyuman Joshi]

Glad to have helped!