int linear_fit_output(linear_fit_parameters *fit_data, char *x_title, char *y_title){
    TApplication* app = new TApplication("Grafici",0,0);

    TCanvas *c1 = new TCanvas("c1","A Simple Graph Example",200,10,700,500);

    c1->SetGrid();

    TGraphErrors *gr_xy_err = new TGraphErrors(fit_data->dots, fit_data->data_in[0], fit_data->data_in[1],
                                                                                                                         fit_data->data_in[2], fit_data->data_in[3]);
    gr_xy_err->SetMarkerColor(4);
    gr_xy_err->SetMarkerStyle(20);
    gr_xy_err->SetTitle("");
    gr_xy_err->GetXaxis()->SetTitle(x_title);
    gr_xy_err->GetYaxis()->SetTitle(y_title);
    gr_xy_err->Draw("AP");

    TF1 *func_fit = new TF1("linear fit", "[0]*x+[1]", gr_xy_err->GetMaximum(), gr_xy_err->GetMinimum());
    func_fit->SetParameter(0, fit_data->m);
    func_fit->SetParameter(1, fit_data->q);
    func_fit->SetLineColor(5);
    func_fit->SetLineWidth(1);
    func_fit->Draw("same");

    app->Run();

    return 0;
}