How to express rest of expression in terms of other variables

Hi,

In the following code, I would like to get the final expression for p/Phi_V. How can I do that?

syms p K_B Phi_V Phi_G s K_i K_p real;

Phi_G = p/s*(K_p + K_i/s);

p = K_B*(Phi_V - Phi_G)

Answer 1

[Star Strider]

Try this —

syms p K_B Phi_V Phi_G s K_i K_p real;

Phi_G = p/s*(K_p + K_i/s)

Eqn1 = p == K_B*(Phi_V - Phi_G)
Eqn2 = isolate(Eqn1, p)
pretty(Eqn2)                                      % Necessary To Display Reesult

                      2
           K_B Phi_V s
p == ------------------------
      2
     s  + K_B K_p s + K_B K_i

Eqn3 = Eqn2 /  Phi_V
pretty(Eqn3)                                      % Necessary To Display Reesult

                       2
  p               K_B s
----- == ------------------------
Phi_V     2
         s  + K_B K_p s + K_B K_i

EDIT — Added pretty calls. Corrected typographical errors.

.

[Hemanth]

Thank you so much!! you saved my day....

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

If you add:

p_over_Phi_v = matlabFunction(rhs(Eqn3))

you can get an anonymous function for the expression

p_over_Phi_V = function_handle with value:

@(K_B,K_i,K_p,s)(K_B.*s.^2)./(s.^2+K_B.*K_i+K_B.*K_p.*s)

or more simply:

p_over_Phi_V = @(K_B,K_i,K_p,s)(K_B.*s.^2)./(s.^2+K_B.*K_i+K_B.*K_p.*s);

.