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Fzero: Index exceeds array elements (1)

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Agra Sakti
Agra Sakti on 14 Apr 2021
Commented: Agra Sakti on 24 Apr 2021
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

Answers (1)

Shashank Gupta
Shashank Gupta on 19 Apr 2021
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.
  1 Comment
Agra Sakti
Agra Sakti on 24 Apr 2021
Hi Gupta,
Thanks for your information about it.
I modified the code a bit and now it works.
Have a good day.

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