What is meant by "graph the error"?

Question

How does one graph an error of a function?

Answer 1

Examples of a Graph with error bars
{
//
// To see the output of this macro, click here.
//
gROOT->Reset();
c1 = new TCanvas("c1","A Simple Graph with error bars",200,10,700,500);

c1->SetFillColor(42);
c1->SetGrid();
c1->GetFrame()->SetFillColor(21);
c1->GetFrame()->SetBorderSize(12);

Int_t n = 10;
Float_t x[n] = {-0.22, 0.05, 0.25, 0.35, 0.5, 0.61,0.7,0.85,0.89,0.95};
Float_t y[n] = {1,2.9,5.6,7.4,9,9.6,8.7,6.3,4.5,1};
Float_t ex[n] = {.05,.1,.07,.07,.04,.05,.06,.07,.08,.05};
Float_t ey[n] = {.8,.7,.6,.5,.4,.4,.5,.6,.7,.8};
gr = new TGraphErrors(n,x,y,ex,ey);
gr->SetTitle("TGraphErrors Example");
gr->SetMarkerColor(4);
gr->SetMarkerStyle(21);
gr->Draw("ALP");

c1->Update();

Answer 2

circle it.

like 5 / x^2

the error occurs at 0, although it's not really an error..

Answer 3

That terminology is common in statistics, but I've never heard of it being used elsewhere.