Re: problem with leasqr fitting

[przemek klosowski]

If you plot (temp,intensity,temp,f2) it does a so-so job of fitting your data. Are you concerned about corp1 and covp1?

Your model does not seem to conform very well with the data, so probably the minimum is very shallow and parameters are poorly correlated.

NB, the code uses data-smoothing and signal packages, so they need to be loaded to replicate.

On 3/18/21 9:07 AM, mrodrig via Help-octave wrote:

> Hello,
>
> I am trying to perform a fitting and I am obtaining the following results
> pfit1 =
>
>    375.11773
>     83.26345
>      0.29860
>
> kvg = 1
> iter =  3
> corp1 =
>
>     NA    NA    NA
>     NA    NA    NA
>     NA    NA    NA
>
> covp1 =
>
>     NA    NA    NA
>     NA    NA    NA
>     NA    NA    NA
>
> I attach the data for consideration
>
> thanks
>
> datam= xlsread ('data1.xlsx');
>
> temp=datam(1:173,1)+273;
> [intensity, lambda] = regdatasmooth (temp, datam(1:173,2));
>
> k=8.6170e-005;
>
> [pks, loc]=findpeaks (intensity,"DoubleSided");
>
> imaxi=intensity(loc(index=find(pks==max(pks))));
> tmaxi=temp(loc(index=find(pks==max(pks))));
>
>
> eacti1= 0.2;
>
> parTLi1 = [tmaxi,imaxi,eacti1];
>
> F1=@(temp,parTLi1)(imaxi*exp(1+parTLi1(3)./(k*temp).*(temp-parTLi1(1))/parTLi1(1)-temp.^2/parTLi1(1).^2*(1-(2*k*parTLi1(1))/parTLi1(3)).*exp(parTLi1(3)./(k*temp).*(temp-parTLi1(1))/parTLi1(1))-(2*k*parTLi1(1)/parTLi1(3))));
>
> wt_tl=ones(size(temp));
> iter_tl=800;
> tol_tl=0.1;
> dFdp_tl="dfdp";
> dp_tl=0.0001*ones(size(parTLi1));
>
> %tolerance
> tmax_max=tmaxi+2;
> tmax_min=tmaxi-2;
> imax_max=imaxi+100;
> imax_min=imaxi-100;
> eact_max=1.3;
> eact_min=0.5;
>
> bounds= [tmax_min,tmax_max; imax_min, imax_max; eact_min,eact_max];
>
>
> f2=0;
>
> [f2, pfit1, kvg, iter, corp1, covp1, covr1,r2] = leasqr (temp, intensity,
> parTLi1, F1,tol_tl, iter_tl,wt_tl, dp_tl, dFdp_tl, bounds)
>
> data1.xlsx <https://gcc02.safelinks.protection.outlook.com/?url="">  
>
>
>
>
> --
> Sent from: https://gcc02.safelinks.protection.outlook.com/?url="">
>
>
>