Jacobian matrix evaluation doubt!

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Ushnik Mukherjee
Ushnik Mukherjee 2014-2-4
编辑： Ushnik Mukherjee 2014-2-4
Is there a way to evaluate a jacobian matrix having symbolic variables that change with every time step? Here is the code that I am running:
syms yA yG yC
k1 = 1;
k2 = 1;
k3 = 1;
k0 = k1 + k3;
f = [(-k1-k3)*(yA^(2)); (k1*(yA^(2))) - (k2*yG); (k3*(yA^(2))) + (k2*yG)];
v = [yA yG yC];
J = jacobian(f,v);
t = 0:0.1:10;
yA = 1./(1 + (k0*t));
eta = k2./(k0*yA);
a = (k1*k2)/(k0^(2));
yG = a*exp(-eta).*(((k0/k2)*exp(k2/k0)) - (exp(eta)./eta) + mfun('Ei',eta) - mfun('Ei',k2/k0));
yC = 1-yG-yA;
for i = 1:length(t)
j = J([yA(i) yG(i) yC(i)]);
%j = subs(J, [yA yG yC], [1 0 0]);
lambda = eig(j);
r = double(lambda); %converts a symbolic matrix to a matlab numeric form
b(i) = max(abs(r));
c(i) = min(abs(r));
SR(i) = b(i)./c(i);
end
This line: j = J([yA(i) yG(i) yC(i)]); is not being evaluated properly? Am I wrong somewhere?
Thank you for the help!
Regards
Ushnik

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