// quick and non-optimised example of TGraphErrors/TGraphAsymmErrors not
// displaying the error of the first point correctly in case one of the points'
// errors are not contained within the displayed range
void ErrorGraphFillStyle(){
    gRandom = new TRandom3(5);
	TH1D *a = new TH1D("a", "a", 10, 0, 7);
    a->SetMaximum(12);
    a->SetMinimum(0);
    //set minimum to -10 to make sure errors don't go outside of range
    // a->SetMinimum(-10);
    Double_t xVal[10];
    Double_t yVal[10];
    Double_t xErr[10];
    Double_t yErr[10];
    //fill the values 
    for(size_t i{1}; i <= a->GetNbinsX(); ++i){
        std::cout << "Setting point " << i-1 << std::endl;
    	xVal[i-1] = a->GetBinCenter(i);
    	xErr[i-1] = a->GetBinWidth(i);
    	yVal[i-1] = abs(gRandom->Uniform(0,7));
    	yErr[i-1] = abs(gRandom->Uniform(1,2));
    }
    
    TGraphErrors *model = new TGraphErrors(10, xVal, yVal, xErr, yErr);
    TGraphErrors *model2 = new TGraphErrors(10, xVal, yVal, xErr, yErr);
    // same behaviour is observed in asymmetric graphs
    // TGraphAsymmErrors *model = new TGraphAsymmErrors(10, xVal, yVal, xErr, xErr, yErr, yErr);
    // TGraphAsymmErrors *model2 = new TGraphAsymmErrors(10, xVal, yVal, xErr, xErr, yErr, yErr);
    a->Draw();
    model->SetFillColorAlpha(kBlue, 0.2);
    model2->SetFillColorAlpha(kRed, 0.2);
	model2->SetFillStyle(3154);
    model->SetFillStyle(1001);
	model->Draw("3,SAME");
	model2->Draw("3,SAME");
}