MATLAB: Please help a student: How can you estimate these 5 parameters by using nonlinear least squares

Question

For following kinetic model, I've got to estimate: "K0", "E", "Ka", "Kf" and "Kg", and I have experimental data for: rA, Na, Nb, Nc, Nd, Kp, and T. I tried some methods, including a levenberg-marquardt function but they didn't work. This was the first thing that I tried:

% p(1) = K0

% p(2) = E

% p(3) = Ka

% p(4) = Kf

% p(5) = Kg

rA = [15×1 double];

Na = [15×1 double];

Nb = [15×1 double];

Nc = [15×1 double];

Nd = [15×1 double];

Kp = [15×1 double];

T = [15×1 double];

R = 8.314

fun = @(p)((p(1).*exp(-p(2)./(8.314.*T))).*(Na-((((Nc.^2)).*(Nd).^6)./(Kp.* (Nb).^3)))./(1+p(3).*Na+(p(4).*Nc.*Nd.^3./Nb)+(p(5).*Nc.*(Nd^3)/((Nb.^2)))).^2)-rA;

p0 = [100,10,250,200,5,1];

options.Algorithm = 'levenberg-marquardt';

p = lsqnonlin(fun,p0,[],[],[],[],[],options)

Just started my first matlab basic course, I apologize for the mistakes. Any help would be really appreciated!

Answer 1

1. p0 has 6 elements, but you only use 5 paramters. This should be modified.

2. In the last term of the denominator, replace Nd^3 by Nd.^3 and /((Nb.^2)) by ./((Nb.^2))

If you still receive an error message, please post it.

Best wishes

Torsten.