Fitting Example



In [1]:

    
import ROOT









    



Welcome to JupyROOT 6.10/06

Inject into the interpreter the functions.



In [2]:

    
%%cpp -d
//Define functions for fitting 
// Quadratic background function
double background(double *x, double *par) {
  return par[0] + par[1]*x[0] + par[2]*x[0]*x[0];
}

// Lorenzian Peak function
double lorentzianPeak(double *x, double *par) {
  return (0.5*par[0]*par[1]/TMath::Pi()) /
    TMath::Max(1.e-10,(x[0]-par[2])*(x[0]-par[2])
    + .25*par[1]*par[1]);
}

// Sum of background and peak function
double fitFunction(double *x, double *par) {
  return background(x, par) + lorentzianPeak(x, &par[3]);
}

Construct the histogram containing the input data



In [3]:

    
# Your code here

Create the function and try to fit it without setting any parameter. Activate the interactive visualisation with %jsroot on. Remember that in order to embed a plot in a notebook, you'll need to create a TCanvas and draw it explicitly.



In [1]:

    
# Your code here

Less than optimal. Set parameters and fit again, draw histogram with error bars



In [2]:

    
# Your code here

Much better. Now time to beautify the plot. Construct a TF1 for the background and Lorentzian functions and draw them in the same canvas. We save the fit results and set the parameters of the functions accordingly



In [3]:

    
# Your code here

We can now add a legend



In [4]:

    
# Your code here