Root fitting range

I am pretty new to root. My question is maybe simple for you.
I want to fit some data with quadratic function in root but in different ranges ex: 0.12-0.21 and 0.23-0.31.
Can you help me how to do this? I should have the same fit with break between 0.21-0.23.
Thank you in advance!

Dear mcirkovi,

How are your data described? An histogram? Data points (TGraphError)?
For an histogram, you could create a new histogram with only the bins in the ranges to fit.
The same for data points.

G Ganis