MATLAB: Simultaneous curve fitting using “fmincon”

fminconnonlinearsimultaneous curve fitting

Hi, I'm new with Optimazation function. I m trying to simultaneous fit more than 2 data set but using the same function with different parameters (11) among which 2 vary linearly. I also have to set a boundaries for this parameters according to physically acceptable value.
here is my code for 2 data set:
load E30_data.txt;
load E60_data.txt;
y30 = E30_data(:,2);
y60 = E60_data(:,2);
lambda = E30_data(:,1);
nonlcon = [];
lb = [0.001 1.55 0.002 24000 1000 2.1460 1000 1000 1.3545 1000 02562];
ub = [0.009 2.45 11.8 48000 4000 3.600 8756 5E11 1.90545 8965 6E11];
x0 = [0.004 1.99 2.8 39750 2850 2.8773 6880 2944683560 1.5251 7812 167964024];
options = optimset('Display','iter','MaxFunevals',4000,'TolFun',1e-10 ,'Algorithm','trust-region-reflective','GradObj','on');
fitfunc = @(c)fitfunction(c,y30,y60);
 parameter =fmincon(fitfunc,x0,[],[],[],[],lb,ub,nonlcon,options);
where the function fmincon is:
function error = fitfunction(c,y30,y60)
y1 = mie_extinction(c(1:11));
y2 = mie_extinction(c(12:22));
error = norm(y30 – y1') + norm(y60 – y2');
and the function mie_extinction help for theoretical calculation for y1 and y2.
By compiling my main code I have the error:
Error using fitfunction
Too many output arguments. Error in @(c)fitfunction(c,y30,y60)
Error in fmincon (line 649)
      [initVals.f,initVals.g] =
      feval(funfcn{3},X,varargin{:});
Error in demofitextinction_v200114 (line 55)
 parameter
 =fmincon(fitfunc,x0,[],[],[],[],lb,ub,nonlcon,options);
Caused by: Failure in initial user-supplied objective function evaluation. FMINCON cannot continue.
I try my best solving this problem but I could'nt.
It would be a great help if someone can help me overcome this problem.
thanks in advance

Best Answer

This is because you have GradObj On but your function does not provide gradient vector.
Try something like this:
options = optimset('Display','iter','MaxFunevals',4000,'TolFun',1e-10 ,'Algorithm','interior-point');
fitfunc = @(c)fitfunction(c,y30,y60);
 parameter =fmincon(fitfunc,x0,[],[],[],[],lb,ub,nonlcon,options);
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