Fzero: Index exceeds array elements (1)

Hi, it is my first time here. So I was trying to find parameter value of k1 and k2 by using fzero on the phi = modeling data - experiment data. But the fzero keep giving me an error of "Index exceeds array elements (1)" in "konstanta = fzero (...) line. The kguess array has 2 element and so I write the K(1) and K(2). Where did I code wrong? Thanks in advance, Agra.

function kinetik
kguess = [0.5 0.1];
konstanta = fzero(@fobj,kguess);
k1 = konstanta (1);
k2 = konstanta (2);
end

function phi = fobj(K)
k1 = K(1);
k2 = K(2);
tspan = [0 3.5];
CFFAdata = 0.096;
CMEOdata = 1.636; 
initial = [2.15 2.39 0 0];
[tmodel,Cmodel] = ode23s(@fun,tspan,initial,[],K);
CFFAmodel = Cmodel (length(Cmodel),1);
CMEOmodel = Cmodel (length(Cmodel),3);
phi = (CFFAmodel-CFFAdata)+(CMEOmodel-CMEOdata);

end

function dCdt = fun(t,c,K)

dCdt = zeros(4,1);
dCdt(1) =  -(K(1)+K(2))*c(1)*c(2);
dCdt(2) = -( K(1)+K(2))*c(1)*c(2);
dCdt(3) = K(1)*c(1)*c(2);
dCdt(4) = K(2)*c(1)*c(2);

end

Answer 1

[Shashank Gupta]

Hi Agra,

Looking at the setup of the problem, it seems like you are trying to find out the value of 2 variable. I think fzero function is not suitable for such setup of the problem because the function handle which this function take as input only accept a scalar input, check out the input function handle description here.

I hope this address your issue.

Cheers.

[Agra Sakti]

Hi Gupta,

Thanks for your information about it.

I modified the code a bit and now it works.

Have a good day.