#include "TF2.h"
#include "TF12.h"
#include "TCanvas.h"
#include "TF1.h"

TF2 *f = new TF2("f", "[0]*[0]*(x^2+y^2)+[1]*(x^2+y^2)", -1, 1, -1, 1);

Double_t intg(Double_t *x, Double_t *par)
{
	f->SetParameters(x[0], x[1]);
	return f->Integral(-1, 1, -1, 1);
}

void par()
{
	f->SetNpx(100);
	f->SetNpy(100);
	f->SetParameters(2, 1);
	f->Draw("colz");
	
	new TCanvas();
	TF2 *ires = new TF2("ires", intg, -1, 1, -1, 1, 0);
	
	ires->SetNpx(100);
	ires->SetNpy(100);
	
	ires->Draw("colz");
}