Error bars in root

Hi,
is there anyway I can specify the formula of the error bars ? As far as I understand , the default is sqrt(N). But if I am plotting the result of divding two numbers, then I want the error to be:

N=n1/n2

del N/N = sqrt((deln1/n1)^2 + (deln2/n2)^2)

Is there anyway I can specify this ?

You can specify your own error by calling
h.SetBinError(bin,error);
However, what you want is already implemented in TH1::Divide (see also option “B”)

Rene