Getting unbinned fitting to work

ROOT
1

Hello,

I am trying to fit unbinned data using ROOT::Fit::UnBinData, however, I am unable to get it to work. When I exchange it with ROOT::Fit::BinData it works without problems. Is there some additional option which I am missing?

Here is a simplified example:
UnbinnedFit.C (1.5 KB)

Any help is appreciated.

Thanks,
Andreas

ROOT Version: 6.12.06
Platform: Ubuntu 16.04
Compiler: gcc

2

Yes I see that MIGRAD says:

 CALL LIMIT EXCEEDED IN MIGRAD.
 MIGRAD TERMINATED WITHOUT CONVERGENCE.

May be the initial value of your parameters are not appropriate ?
@moneta can surely give you some hints.

3

Hi Olivier,

Even with the correct values as start parameters I get:

 **********
 **    1 **SET PRINT           0
 **********
 **********
 **    2 **SET NOGRAD
 **********
 PARAMETER DEFINITIONS:
    NO.   NAME         VALUE      STEP SIZE      LIMITS
     1 Offset       0.00000e+00  3.00000e-01     no limits
     2 Height       2.41000e+02  7.23000e+01     no limits
     3 Mean         0.00000e+00  3.00000e-01     no limits
     4 Sigma        1.00000e+00  3.00000e-01     no limits
 **********
 **    3 **SET ERR         0.5
 **********
 **********
 **    4 **SET PRINT           0
 **********
 **********
 **    5 **SET STR           1
 **********
 **********
 **    6 **MIGRAD        1480        0.01
 **********
 CALL LIMIT EXCEEDED IN MIGRAD.
 MIGRAD TERMINATED WITHOUT CONVERGENCE.
 FCN=-2.63795e+06 FROM MIGRAD    STATUS=CALL LIMIT   1489 CALLS        1490 TOTAL
                     EDM=0.466804    STRATEGY= 1  ERROR MATRIX UNCERTAINTY  49.9 per cent
  EXT PARAMETER                APPROXIMATE        STEP         FIRST   
  NO.   NAME      VALUE            ERROR          SIZE      DERIVATIVE 
   1  Offset      1.09546e+111  2.00301e+108  1.05884e+111 -2.09850e-111
   2  Height      3.66968e+114  6.70987e+111  3.54699e+114 -2.72441e-111
   3  Mean        7.91346e+109  1.44695e+107  7.64889e+109  2.46194e-110
   4  Sigma       4.95495e+111  9.05994e+108  4.78929e+111 -3.93191e-112
                               ERR DEF= 0.5

Thanks,
Andreas

4

Ok, I think @moneta can help you with that.

5

Hi all,

Since nobody can figure out what’s wrong with my example, has anybody a simple reference example on how to use the unbinned fitting routines in ROOT?

Thanks a lot,
Andreas

6

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