I just want to do the fitting in a Loop, and I hope that the initial values of the parameters would be the same for each entry. But you know, the fitting would change the value of the parameters…
I guess there must be a easy way to do this somewhere, Maybe two lines would be enough, but how?-
// save the values
// set the initial values.
Thank you very much.
There is an easy way. To save the ‘original’ values you first do this
// Get list of parameters of a p.d.f given set of observables
RooArgSet* params = pdf.getParameters(observables) ;
// Make a snapshot of the parameterlist
RooArgSet* savedParams = params->snapshot() ;
Then in your fitting loop you can restore at any point the
p.d.f parameters to the save values as follows
*params = *savedParams ;