Problem in running lsqnonlin

Question

Shalini 2012-3-10

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/31809-problem-in-running-lsqnonlin

I'm new to matlab and I understand that lsqnonlin requires a function for its call.

Actually, I have run the cftool through GUI and have got reasonable results.I thought I will reduce the error and get still better results through 'lsqnonlin' but I'm not able to run lsqnonlin , below are the problems I'm facing, can anyone help-it's really URGENT!!!

I have coded the function,which is required for lsqnonlin here it is:

function diff = fit_simp(x,X,Y)

% This function is called by lsqnonlin.
% x is a vector which contains the coefficients of the
% equation.  X and Y are the option data sets that were
% passed to lsqnonlin.
A=x(1);
B=x(2);
n=x(3);
diff = (A+B*(X.^n)) - Y;
end

Now, I write the following script in command window;

>> X=xlsread('QS2T.xls',9,'V638:V1835');
Y=xlsread('QS2T.xls',9,'W638:W1835');
X0=[800 1537 0.1448];
>> option.Algorithm='trust region'
option = 
      Algorithm: 'trust region'

Then I call lsqnonlin.I expect the algorithm to be used is trust region and not levenberg marquardt.

>> x=lsqnonlin(@fit_simp,X0,[],[],options,X,Y);

I get this warning:

Warning: Options LevenbergMarquardt and LargeScale will be ignored in a future release. Running Levenberg-Marquardt method. To run the Levenberg-Marquardt method without this warning, set option Algorithm to 'levenberg-marquardt' instead. > In optim\private\lsqncommon at 60 In lsqnonlin at 240 Optimization terminated: the relative change in the sum-of-squares of the functions is less than options.TolFun

Please can anyone advice what to do?