import random
import ROOT

class Event:
    def __init__(self, m, s):
        self.mean = m
        self.width = s


evt1 = Event(0,1)
evt2 = Event(1,2)

chain = []
for  i in range(0,10):
    chain.append(Event( random.gauss(150,10), random.gammavariate(10, 1)  ) )


for iev in chain:
    print( iev.mean, iev.width)

def my_function(x) : 
  gaus_tot = 0.
  for iev in chain: 
      gaus_tot += ROOT.TMath.Gaus(x[0], iev.mean, iev.width, True)
      
  print (x[0], gaus_tot)
  return gaus_tot

f1 = ROOT.TF1('f1',my_function, 100, 200 , 0)
f1.Draw()
y = f1.Eval(3)
print(y)