Hi ROOTers,
I’m trying to fit a TGraphErrors with a function (quite complicated) which has 4 parameters, each with its bounds.
This is what I get:
Error in ROOT::Math::ParameterSettings>: Invalid lower/upper bounds - ignoring the bounds
What is it due to?
Cheers,
Manuel
Hi,
I suppose that you use SetParLimits method. In fact I wrote simple macro:
#include <TRandom.h>
#include <TF1.h>
#include <TH1D.h>
Double_t fit(Double_t *x, Double_t *params){
return params[0]*TMath::Exp(-(x[0]-params[2])*(x[0]-params[2])/params[1]);
}
void root_t(){
TH1D *h = new TH1D("a","a",1000,-1,1);
for(int i=0;i<10000;i++)
h->Fill(gRandom->Gaus(0.4,0.3));
TF1 *f = new TF1("g",fit,-10,10,3);
f->SetParLimits(0,10,1000);
f->SetParLimits(2,0.3,0.9);
f->SetParLimits(1,0.1,0.9);
h->Fit(f);
h->Draw();
}
This code generate the same warning, what is more important they works because without f->SetParLimits I can’t properly fit my histogram. So this “ignore warning” its a lie, I suggest ignore this 
.