Update

Week8/Solution_8.py

+#!/usr/bin/env python2
+
+# -*- coding: utf-8 -*-
+
+"""
+
+Created on Sat Dec 12 00:00:00 2021
+
+
+@author: vitz
+
+"""
+
+
+
+
+from array import array
+from numpy import sqrt,exp,pi
+
+import ctypes 
+import numpy as np
+
+from ROOT import gROOT,gStyle,TMinuit,TH1F,TF1,TCanvas,TLegend,TLatex,TMarker,TArrow,TGraph
+
+########################################################################
+
+def f1(			x					,\
+				par					):
+
+   val		=	0;
+
+   m		=	x[0];
+   
+   A		=	par[0];
+   x0		=	par[1];
+   sigma	=	par[2];
+   b		=	par[3];
+   
+   arg		=	( m - x0 ) / sigma;
+
+   val 		= 	A / ( sqrt(2*pi) * sigma ) * exp( -0.5 * arg**2 ) + b;
+
+   return val 
+
+########################################################################
+
+def go(		nevents	= 	10000 				,\
+			nbins	= 	100					,\
+			b		= 	1					):
+
+  npar				=	4
+  mmin				=	0 
+  mmax				=	2
+  
+  A 				= 	3
+  x0 				= 	1
+  sigma 			=	0.1
+
+# Create a 1-Dim histogram with fix bins of type float.
+
+  h1 = TH1F( 			"h1" 				,\
+						"" 					,\
+						nbins 				,\
+						mmin				,\
+						mmax				);
+  
+  h1.SetXTitle( 		"x"					);
+  h1.SetYTitle( 		"nb. of events" 	);   
+
+  gStyle.SetOptFit(		111111				);
+
+# A TF1 object is a 1-Dim function defined between a lower and upper limit.
+
+  ff1 = TF1(			"ff1"				,\
+						f1					,\
+						mmin				,\
+						mmax				,\
+						npar				)
+
+
+  ff1.SetParameter( 	0, 		A		  	)
+  ff1.SetParameter( 	1, 		x0		  	)
+  ff1.SetParameter( 	2, 		sigma	  	)
+  ff1.SetParameter( 	3, 		b		  	)
+
+  ff1.SetMinimum(		0					)
+
+  h1.FillRandom(		"ff1"				,\
+						int((A+2*b)*nevents ))
+
+# Create a new canvas with a predefined size form.
+
+  c1 = TCanvas(			"c1"				,\
+						"" 					,\
+						1000				,\
+						400					)
+
+  ff1.SetParameter( 	0, 		A 	 * 0.7 	)
+  ff1.SetParameter( 	1, 		x0 	 * 1.1 	)
+  ff1.SetParameter( 	2, 		sigma* 1.5 	)
+  ff1.SetParameter( 	3, 		0 		   	)  
+
+  h1.SetMinimum(		0					)
+
+  ff1.FixParameter(		0					,\
+						500					)
+
+  h1.Fit(				"ff1"				)
+
+  ff1.ReleaseParameter(	0					)  
+
+  h1.Fit(				"ff1"				)  
+
+  print('Espected number of signal events: ', h1.GetBinWidth(1)*A*nevents)
+
+########################################################################
+
+  bgd	=	np.array(	[	0.0				,\
+							0.5				,\
+							1.0				,\
+							2.0				,\
+							5.0				,\
+							10				,\
+							30				,\
+							50				])
+
+  bgd	=	array(			"d"				,\
+							bgd				)
+
+  errA 	= 	np.array(	[	3.49543e+00		,\
+							3.71073e+00		,\
+							3.91263e+00 	,\
+							4.28512e+00		,\
+							5.20164e+00 	,\
+							6.46264e+00		,\
+							1.01335e+01		,\
+							1.26267e+01		])
+  
+  errA	=	array(			"d"				,\
+							errA			) 
+
+# Create a new canvas with a predefined size form.
+
+  c2 	= 	TCanvas(		"c2"			,\
+							""				,\
+							1000			,\
+							400				)  
+
+# A TGraph is an object made of two arrays X and Y with npoints each. 
+
+  gr1	=	TGraph(			len(bgd)		,\
+							bgd				,\
+							errA			)
+							
+  gr1.SetMarkerStyle(		20				)
+
+  gr1.Draw(					"ap"			)
+
+  input(					"Hit to return"	)
+
+########################################################################
+
+def main():
+
+   go()
+
+
+if __name__ == "__main__":
+
+    main()