Error in lsqcurvefit with 3 unknown parameters involved

Question

lvenG 2021-10-20

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1567828-error-in-lsqcurvefit-with-3-unknown-parameters-involved

评论： lvenG 2021-10-20

Hi. Would like to ask for any enlightenment here. I am using lsqcurvefit as a curvefitting method.... However, I could't decipher how the error keeps on appearing on the parameters even if I changed the values. As you can see below, the resulting equation is:

but it should be

. Hence the error regarding array.

Hoping for some help here. Thank you.

syms i_x

syms parameter [1 2 3]

YYx=exp((-parameter(1).*valx./parameter(2))+parameter(3).*i_x)

YYHCl =

fun4=matlabFunction(YYx,'vars',{parameter,i_x});

obj=@(P4,I_x) arrayfun(@(i_x) fun4(P4,i_x), I_x);

P40=0.003;

P4=lsqcurvefit(obj,P40,I_x(:),Y_x(:));

Index exceeds the number of array elements. Index must not exceed 1.

Error in symengine>@(in1,i_HCl)exp(i_HCl.*in1(3)-in1(1)./in1(2))

Error in solution (line 14)
obj=@(P4,I_HCl) arrayfun(@(i_HCl) fun4(P4,i_HCl), I_HCl);

Error in solution (line 14)
obj=@(P4,I_HCl) arrayfun(@(i_HCl) fun4(P4,i_HCl), I_HCl);

Error in lsqcurvefit (line 225)
initVals.F = feval(funfcn_x_xdata{3},xCurrent,XDATA,varargin{:});

Caused by:
Failure in initial objective function evaluation. LSQCURVEFIT cannot continue.

Y_HCl_calcc=obj(P4,I_HCl(:));

plot(I_HCl, Y_HCl, 'k*', I_HCl, Y_HCl_calcc, 'g-o')

legend({'Y_HCl exp)', 'Y_HCl calc)'}, 'location', 'best')

parameter1=P4(1)

parameter2=P4(2)

parameter3=P4(3)