Re: dependence of fit with previous one

Hi Marc,

 The fit is re-initialized correctly when you set the parameters and the errors. In your case, it is probably your function which returns a different result given the same parameters probably due to a numerical error in the function evaluation.

I can see that you have a numerical problem in evaluating your function to minimize by seeing this error message in the log file:  MIGRAD FAILS TO FIND IMPROVEMENT
 MACHINE ACCURACY LIMITS FURTHER IMPROVEMENT. It could be also you are using a MC integration in the function evaluation. In this case this can happen.

 Cheers,

 Lorenzo
On Mar 1, 2011, at 1:08 PM, Marc Escalier wrote:

> Hello,
>
> i observed a dependence of a given fit the previous one, *even* when i reinitialize each of the parameters and their errors
>
> -->is there a way to "reinitialize" the fitter to have reproducibility one one do some previous (or not) fits ?
>
> thanks a lot
>
> -->here is a log of the fits
> http://users.lal.in2p3.fr/escalier/ProblemRoot/
>
> it begins to change here :
> with only one fit :
> 2 CB_mean 1.40000e+02 6.00000e-01 2.01358e-01 2.51098e+02
>
> with *a* previous fit before (and after having reiniatzed the parameter by SetParameter and SetParError) :
> 2 CB_mean 1.40000e+02 6.00000e-01 2.01358e-01 2.51095e+02
>
> at the end of the fit : it gives
> with only one fit :
>
> 1 A 6.19000e+02 fixed 2 CB_mean 1.39795e+02 3.64629e-02 3 CB_sigma 1.95380e+00 3.00964e-02 4 CB_alpha 1.22909e+00 4.12433e-02 5 CB_n 1.00000e+01 fixed 6 Gauss_mean 1.44687e+02 7.63561e-01 7 Gauss_sigma 2.57589e+00 4.29212e-01 8 frac_CB 9.75035e-01 5.66139e-03
>
> with *a* previous fit before (and after having reiniatzed the parameter by SetParameter and SetParError) :
>
> 1 A 6.19000e+02 fixed 2 CB_mean 1.39795e+02 3.72340e-02 3 CB_sigma 1.95381e+00 3.07984e-02 4 CB_alpha 1.22910e+00 4.12501e-02 5 CB_n 1.00000e+01 fixed 6 Gauss_mean 1.44688e+02 7.55733e-01 7 Gauss_sigma 2.57555e+00 4.30838e-01 8 frac_CB 9.75039e-01 5.48416e-03
>
> -->some digits are not exactly the same
>
> thanks
>
Received on Tue Mar 01 2011 - 14:00:34 CET