TVirtualFitter *fitter1, *fitter2;  //<===NEW

void DoubleFit()

{



double xs[]={1,2,3};

double ys[]={1,0,2};



fitter1 = new TFitter(25);  //<===NEW

fitter2 = new TFitter(25);  //<===NEW



TVirtualFitter::SetFitter(fitter1);  //<===NEW

TGraph mygraph(3,xs,ys);

TF1 myfunc("myfunc","x*[1]+[0]");

TF1 myfunc2("myfunc2","fitfunction(x)*[1]+[0]");

mygraph.Fit("myfunc");

cout<<"\nOk to me!\n\n";

mygraph.Fit("myfunc2");

cout<<"\nReally?\n";

}



double fitfunction(double myy)

{

        double xs2[]={1,2,3};

        double ys2[]={0,myy,0};

        TGraph mygraph2(3,xs2,ys2);

        TVirtualFitter::SetFitter(fitter2); //set new fitter

        mygraph2.Fit("gaus","Q");

        TVirtualFitter::SetFitter(fitter1); //set old fitter

        return  mygraph2.GetFunction("gaus")->GetParameter(0);

}