Dear Rooters,
My problem seems to be easy, but I lost a lot of time with it.
Let's assume I have got a histogram of integers
-
- -
- - -
- - - -
0 1 2 3
According to simple matematics fitting by y=p0+p1*x should give
p0=4 and p1=-1, errors=0.
How could I fix a range or sth other
to receive the best fiting results?
I'm using ROOT 2.00/11 RedHat 5.0.
Best wishes,
Tadeusz
root [0] TH1S *h1=new TH1S("h1","h1",4,0,4)
root [1] h1.Fill(0,4)
root [2] h1.Fill(1,3)
root [3] h1.Fill(2,2)
root [4] h1.Fill(3,1)
root [5] h1.Fit("pol1")
**********
** 1 **SET ERR 1
**********
FCN=0 FROM MIGRAD STATUS=CONVERGED 22 CALLS 23 TOTAL
EDM=8.30088e-33 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 4.50000e+00 1.83007e+00 -0.00000e+00 0.00000e+00
2 p1 -1.00000e+00 6.56532e-01 0.00000e+00 -2.77547e-16
Warning in <MakeDefCanvas>: creating a default canvas with name c1
root [6] TH1F *h2=new TH1F("h2","h2",4,-0.5,3.5)
root [7] h2.Fill(0,4)
root [8] h2.Fill(1,3)
root [9] h2.Fill(2,2)
root [10] h2.Fill(3,1)
root [11] h2.Fit("pol1")
FCN=0 FROM MIGRAD STATUS=CONVERGED 20 CALLS 21 TOTAL
EDM=1.00357e-30 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 4.00000e+00 1.53128e+00 1.20000e-03 -9.25194e-16
2 p1 -1.00000e+00 6.56532e-01 3.00000e-04 0.00000e+00
root [12] Int_t x[4]={0,1,2,3}
root [13] Int_t y[4]={4,3,2,1}
root [14] TGraph *g1=new TGraph(4,x,y)
Error: Can't call TGraph::TGraph() in current scope FILE:/tmp/19719caa
LINE:1
--
Tadeusz Pytlos
mailto:pytlos@fizwe5.fic.uni.lodz.pl
Lodz, Poland
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