#include "RooRealVar.h"
#include "RooAddPdf.h"
#include "RooGaussian.h"
#include "RooExponential.h"
#include "RooMultiVarGaussian.h"
#include "RooDataSet.h"
#include "RooFitResult.h"
#include "RooStats/RooStatsUtils.h"

int test()
{
	RooRealVar * x = new RooRealVar("x","x",100.,0.,200.);
 	RooRealVar * f = new RooRealVar("f","f",0.6,0.,1.);
	RooRealVar * f2 = new RooRealVar("f2","f2",0.1,0.,1.);
	RooRealVar * m = new RooRealVar("m","m",100.,0.,200.);
	RooRealVar * s = new RooRealVar("s","s",10.,0,100.);
	RooRealVar * s2 = new RooRealVar("s2","s2",0.2,0.,1.);
	RooRealVar * b = new RooRealVar("b","b",-0.1,-10.,0.);

	RooGaussian * gauss1 = new RooGaussian("gauss1","gauss1",*x,*m,*s);
	RooGaussian * gauss2 = new RooGaussian("gauss2","gauss2",*x,*m,*s2);
	RooExponential * exp = new RooExponential("exp","exp",*x,*b);

	RooAddPdf * totpdf = new RooAddPdf("totpdf","totpdf",RooArgSet(*gauss1,*gauss2,*exp),RooArgSet(*f,*f2));
	
	RooDataSet * data = totpdf->generate(*x,500);

        // set s2 to be fixed parameter 
        s2->setConstant(true);
        
	RooFitResult * res = totpdf->fitTo(*data,RooFit::Save(), RooFit::Minimizer("Minuit2"));

        printf("FIT COV MATRIX");
        res->covarianceMatrix().Print();

	RooArgSet * pars = totpdf->getParameters(RooDataSet("v","",*x));
        // remove the constant parameters from the list
        RooStats::RemoveConstantParameters(pars); 
	RooMultiVarGaussian * multigauss = new RooMultiVarGaussian("multigauss","multigauss",*pars,res->covarianceMatrix());
	

        RooDataSet * variations = multigauss->generate(*pars,1000);
	variations->Print();
        return 0;

}