How Do I Extract Terms Containing Certain Coefficients From A Polynomial?
More specifically, I am trying to do small signal analysis on a power system, and I have some polynomial like this:
-D*I_L*Ron - I_L*Ron*d - D*Ron*i_L - Ron*d*i_L + D*V_g + V_g*d + D*v_g + d*v_g + D*V_C/n + V_C*d/n + D*v_C/n + d*v_C/n - V_C/n - v_C/n
I would like to take out terms including one of i_L, d, v_g, v_C, but not more. How can I do this?