Histogram error bars


I want to draw my histogram as a set of points with error bars. I have found the option hist->Draw(“e1p”) which does just this and I assume sets the error bars to sqrt{N}, N being number of points.

However I want to add the systematic error of each datapoint onto the error, so the error bar actually shows sigma / sqrt{N} (where sigma = error on each datapoint, and is the same for each datapoint).

Do you know how I can do this?

One way is to use root.cern.ch/root/html/TGraphAsymmErrors.html