Question store best fit as float after minimization

[yburkard]

Dear Users,

I have a simple question which I could not find the answer to after looking through the documentation. I am performing a minimisation with TMinuit, and instead of outputting the best fit parameters and their errors, I wanted to store them as floats in my code; is there a direct way of doing this?
Currently performing the minimization with

gMinuit = TMinuit(2)
#[...]
gMinuit.Migrad()

outputs all the information, and I have further found that with

amin, edm, errdef = ctypes.c_double(0.18), ctypes.c_double(0.19), ctypes.c_double(0.20)
nvpar, nparx, icstat = ctypes.c_int(1983), ctypes.c_int(1984), ctypes.c_int(1985)
gMinuit.mnstat( amin, edm, errdef, nvpar, nparx, icstat )
gMinuit.mnprin( 3, amin )

one can get only the best fit parameters and their errors to be printed, but I would like to store them as variables.
Thanks in advance for your help.

[moneta]

Hi,

You can use gMinuit.GetParameter or gMinuit.mnpout.
Otherwise, you can use the recommended Minimizer class. I will provide you an example in Minimization in PyROOT

Lorenzo

[yburkard]

Thanks! Just to clarify things, the initially specified parameter value currentValue and its error currentError can be arbitrary here? Are they just used to allocate the return values to an address?

[moneta]

yes, this is correct. Just used to pass multiple return values.

Lorenzo