How to parametrically solve a symbolic system of arbitrary size ?

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TomaszG
TomaszG 2013-3-18
Hello,
I am trying to solve a symbolic system of equations that I automatically generate based on user data. The coefficients and the size of the system can change.
Here is an example of code for a 2x2 system :
--------------------------
eps1 = 1;
eps2 = 1;
eps = [eps1;eps2];
sigma = 1;
k = ones(2,1);
h=[1;1];
Tw = sym(zeros(2, 1));
for i=1:2
Tw(i) = sym(sprintf('Tw%d', i));
end
f = -sigma*eps.*Tw.^4;
Jacf = jacobian(f,Tw);
Tw0 = [293;293];
A = subs(Jacf,Tw,Tw0);
c = subs(f,Tw,Tw0)-A*Tw0;
T = sym(ones(2, 1));
T(1) = sym('To');
T(2) = sym('Ti');
S = sym(ones(2, 1));
for i=1:2
S(i) = sym(sprintf('S%d', i));
end
G = S+h.*(T-Tw)+c+A*T;
solve(G,Tw);
-------------------------
The system is obtained through linearisation of expression f. I would like to obtain Tw as an expression depending on T and S. But when I try to solve for G == 0, the solver solves in T and Tw instead of only Tw...
If I use solve(G,Tw(1),Tw(2)) then I get the good answer, but as the system is of arbitrary size in the general case, I don't know how to adapt this expression to get an answer.
Any idea how to fix this ?
Thanks,
Tomasz

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采纳的回答

Walter Roberson
Walter Roberson 2013-3-18
Twcell = num2cell(Tw);
solve(G, Twcell{:})

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