fit1.py File Reference

Namespaces
	fit1

Detailed Description

Fit example.

TFile**     py-fillrandom.root   
 TFile*     py-fillrandom.root   
  KEY: TFormula   form1;1  abs(sin(x)/x)
  KEY: TF1  sqroot;1 x*gaus(0) + [3]*form1
  KEY: TH1F h1f;1 Test random numbers
Formula based function:     sqroot 
               sqroot : x*gaus(0) + [3]*form1 Ndim= 1, Npar= 4, Number= 0 
 Formula expression: 
   x*[p0]*exp(-0.5*((x-[p1])/[p2])*((x-[p1])/[p2]))+[p3]*(abs(sin(x)/x)) 
 FCN=198.935 FROM MIGRAD    STATUS=CONVERGED     148 CALLS         149 TOTAL
                     EDM=2.98567e-07    STRATEGY= 1      ERROR MATRIX ACCURATE 
  EXT PARAMETER                                   STEP         FIRST   
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE 
   1  p0           3.31658e+01   5.45703e-01   3.00376e-03  -1.11540e-03
   2  p1           4.00667e+00   1.65304e-02   9.48491e-05  -3.06425e-02
   3  p2           9.84663e-01   1.28238e-02   6.05976e-05  -3.04244e-02
   4  p3           6.34464e+01   1.33233e+00   8.77483e-03  -3.96109e-04
fit1      : Real Time =   0.27 seconds Cpu Time =   0.27 seconds

from os import path
from ROOT import TCanvas, TFile, TPaveText
from ROOT import gROOT, gBenchmark

c1 = TCanvas( 'c1', 'The Fit Canvas', 200, 10, 700, 500 )
c1.SetGridx()
c1.SetGridy()
c1.GetFrame().SetFillColor( 21 )
c1.GetFrame().SetBorderMode(-1 )
c1.GetFrame().SetBorderSize( 5 )

gBenchmark.Start( 'fit1' )
#
# We connect the ROOT file generated in a previous tutorial
#
fill = TFile( 'py-fillrandom.root' )

#
# The function "ls()" lists the directory contents of this file
#
fill.ls()

#
# Get object "sqroot" from the file.
#

sqroot = gROOT.FindObject( 'sqroot' )
sqroot.Print()

#
# Now fit histogram h1f with the function sqroot
#
h1f = gROOT.FindObject( 'h1f' )
h1f.SetFillColor( 45 )
h1f.Fit( 'sqroot' )

# We now annotate the picture by creating a PaveText object
# and displaying the list of commands in this macro
#
fitlabel = TPaveText( 0.6, 0.3, 0.9, 0.80, 'NDC' )
fitlabel.SetTextAlign( 12 )
fitlabel.SetFillColor( 42 )
fitlabel.ReadFile(path.join(gROOT.GetTutorialsDir(), 'pyroot', 'fit1_py.py'))
fitlabel.Draw()
c1.Update()
gBenchmark.Show( 'fit1' )

Author

Wim Lavrijsen

Definition in file fit1.py.