Empty sym: 0-by-1, Why this error occur in this code????

syms Z1 Z2 Z3 Za Zb Zc 

% there are 6 variable, 3 equation 
% then we get only three relation with 6 variable 

eqn1 = Z1+Z3 ==(Za+Zc)*(Za+Zb+Zc)/(Za+Zc+Za+Zb+Zc);
eqn2 = Z2 == (2*Za+Zb+Zc)*Zc/(2*Za+Zb+Zc+Zc);
eqn3 = Z1+Z2+Z3 == (Za+Zb)*(Za+2*Zc)/(Za+Zb+Za+2*Zc);

eqn = [eqn1 eqn2 eqn3];

[Za Zb Zc] = solve(eqn, [Za Zb Zc]);
simplify(Za); simplify(Zb); simplify(Zc);

I dont know that the error message, Empty sym: 0-by-1 occur in this code.

I solved 3 eqn included in 6 vars

I want to get Za, Zb, Zc related with Z1,Z2,Z3.

[Ameer Hamza]

It means that such a solution might not exist or cannot be represented analytically.

[je heo]

Thank you for your answer.

Answer 1

[Walter Roberson]

It turns out that you need to use limits to get the solution, which is

Za = Z1 - Z2 + Z3
Zb = infinity
Zc = Z2

Unfortunately, MATLAB cannot process the limit with respect to Zb = infinity. The result of the limit is

[Z1 + Z3 == Za + Zc, Z2 == Zc, Z1 + Z2 + Z3 == Za + 2*Zc]