Polynomial Fit

ROOT
1

Hi,

I need to apply a polynomial fit to an efficiency plot and i use the polynomial:

y-axis = efficiency
x-axis = pT

eff = ax^4+bx^3+cx^2+dx

I require the parameters to be calculated when range of x is fixed (e.g. from 0 to 20) and at the same time the return values of the function should be bounded from 0 to 1 since i refer to efficiency. Is there any way to do this in root?

PS: I am not asking about y-AXIS range, BUT the values that this 4th degree polynomial returns should be between 0 and 1.

Cheers,
Steven

2

Hi,

you can perform a fit with the Fit method of both TH1s and TGraphs (among the others). E.g.:

myHistogram.Fit("pol4");

You can find more information on the reference guide and in this section* of the primer.

Cheers,
Danilo

root.cern.ch/root/htmldoc/guide … seudo-data