#! /usr/bin/env python
"""
 ntpSaved.py: Example PyROOT program which stores data
to a ROOT TNtuple then saves this data as a ROOT objects in
a ROOT TFile.



Paul Eugenio
PHZ4151C
Florida State University
April 1, 2019

"""

from __future__ import division, print_function
import numpy as np 
import ROOT 


def func( aX ):
	""" ... """
	return np.exp( -aX ) * np.sin( 3.0 * aX )**2  


# Open a ROOT TFile
rootFile = ROOT.TFile("ntpData.root","RECREATE")

# Create an instance of a TNtuple object
ntuple = ROOT.TNtuple("ntp1", "My First Ntuple", "x:y" )

# define plotting limits and step size
xMin = 0.0
xMax =  5.0
deltaX = 0.01


for x in np.arange( xMin, xMax, deltaX ):
	# Fill the TNtuple with values for x & y
	ntuple.Fill( x, func(x) )

# Save the ROOT TFile containing ROOT objects
rootFile.Write()