MATLAB: Fit function breaches the lower option limits

Curve Fitting Toolboxfit lowerMATLAB

I was trying to do fit with a script generated from cftool. It puts lower limit of 0 on all coefficients and the result returned is still negative. I would like to share the dataset but I am new to this forum and I don't find any option of sharing file. Please help me.

Best Answer

0 votes Edit Delete Amol answered less than a minute ago
ok here is the script
    function [cf_,gof]=myfit(tau,avar,weight)
    %MYFIT    Create plot of datasets and fits
    %   MYFIT(TAU,AVAR,WEIGHT)
    %   Creates a plot, similar to the plot in the main curve fitting
    %   window, using the data that you provide as input.  You can
    %   apply this function to the same data you used with cftool
    %   or with different data.  You may want to edit the function to
    %   customize the code and this help message.
    %

    %   Number of datasets:  1
    %   Number of fits:  1
    % Data from dataset "avar vs. tau with weight":
    %    X = tau:
    %    Y = avar:
    %    Weights = weight:
    %
    % This function was automatically generated on 04-Nov-2009 17:20:51
    % --- Create fit "fit 1"
    fo_ = fitoptions('method','LinearLeastSquares','Lower',[0 0 0 0 0]);
    ok_ = isfinite(tau) & isfinite(avar) & isfinite(weight);
    set(fo_,'Weight',weight(ok_));
    if ~all( ok_ )
        warning( 'GenerateMFile:IgnoringNansAndInfs', ...
            'Ignoring NaNs and Infs in data' );
    end
    ft_ = fittype({'1/(x^2)', '1/x', 'x', 'x^2', '1'},...
         'dependent',{'y'},'independent',{'x'},...
         'coefficients',{'a', 'b', 'd', 'e', 'c'});
    % Fit this model using new data
    [cf_,gof] = fit(tau(ok_),avar(ok_),ft_,fo_);
    % Or use coefficients from the original fit:
    %if 0
    %   cv_ = { 2.8012463154944958529e-09, 4.1224210467149593554e-06, -6.2806159338057854499e-10, 1.1525415994665557154e-11, 5.4419882197796621562e-07};
    %   cf_ = cfit(ft_,cv_{:});
    end
and yes I am sorry for a late response. I seems that i need to turn on some option to get email notification from the forum
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