Hello List,
today I (appearantly) have a fit problem.
I try to fit a TGraph having 50 non-equidistant entries
with a Bethe-Bloch parametrization using 5 free parameters,
x[0] is \beta\gamma and all parameters are positive.
Double_t dedxfunc(Double_t *x, Double_t *par)
{
Double_t t = x[0]/sqrt(1+x[0]*x[0]);
Double_t dedx = (par[1]*log(x[0]/(x[0]+par[2]))+par[0])/(t*t)+par[3]*(t-1)+par[4]*(t-1)*(t-1);
return dedx;
}
The parameters are already known, I just want to use a fit to reproduce
their values, so I use them as start values for the fit.
The fit output tells me:
**********
** 1 **SET ERR 1
**********
PARAMETER DEFINITIONS:
NO. NAME VALUE STEP SIZE LIMITS
1 c0 1.99300e+01 5.97900e+00 no limits
2 c1 1.68400e+00 5.05200e-01 no limits
3 b 1.81400e+02 5.44200e+01 no limits
4 a1 3.00700e+00 9.02100e-01 no limits
5 a2 3.93600e+00 1.18080e+00 no limits
**********
** 2 **SET PRINT 2
**********
**********
** 3 **MIGRAD 5000 6e-05
**********
FIRST CALL TO USER FUNCTION AT NEW START POINT, WITH IFLAG=4.
Error: class,struct,union or type unknown not defined START MIGRAD
MINIMIZATION. STRATEGY 1. CONVERGENCE WHEN EDM .LT. 6.00e-08
FCN=0.0819619 FROM MIGRAD STATUS=INITIATE 20 CALLS 21
TOTAL
EDM= unknown STRATEGY= 1 NO ERROR MATRIX
EXT PARAMETER CURRENT GUESS STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.99300e+01 5.97900e+00 5.97900e+00 2.41800e+01
2 c1 1.68400e+00 5.05200e-01 5.05200e-01 -1.67969e+02
3 b 1.81400e+02 5.44200e+01 5.44200e+01 -2.24245e-01
4 a1 3.00700e+00 9.02100e-01 9.02100e-01 -6.53170e-01
5 a2 3.93600e+00 1.18080e+00 1.18080e+00 5.01446e-01
NO ERROR MATRIX
FCN=0.0137191 FROM MIGRAD STATUS=PROGRESS 38 CALLS 39
TOTAL
EDM=0.0146896 STRATEGY= 1 NO ERROR MATRIX
EXT PARAMETER CURRENT GUESS STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.99286e+01 5.97900e+00 -1.36812e-03 1.29702e+00
2 c1 1.68420e+00 5.05200e-01 2.02783e-04 -1.28832e+01
3 b 1.81547e+02 5.44200e+01 1.47200e-01 -1.21495e-02
4 a1 3.02885e+00 9.02100e-01 2.18504e-02 1.69467e-01
5 a2 3.89188e+00 1.18080e+00 -4.41213e-02 -5.72371e-02
MIGRAD MINIMIZATION HAS CONVERGED.
MIGRAD WILL VERIFY CONVERGENCE AND ERROR MATRIX.
START COVARIANCE MATRIX CALCULATION.
EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
6.0928e-06 2.1573e-03 3.4266e-02 4.2416e-01 4.5394e+00
COVARIANCE MATRIX CALCULATED SUCCESSFULLY
FCN=0.00421563 FROM HESSE STATUS=OK 31 CALLS 135
TOTAL
EDM=5.24685e-05 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.99345e+01 6.13666e+00 1.10105e-05 3.72514e-03
2 c1 1.68613e+00 9.99532e-02 1.60872e-06 -1.81193e-02
3 b 1.81062e+02 7.23261e+02 1.18468e-03 -1.37278e-05
4 a1 3.01214e+00 2.62695e+00 2.67726e-04 -9.02628e-05
5 a2 3.97725e+00 4.32249e+00 4.34197e-04 6.73886e-05
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2 3 4 5
1 0.99999 1.000 -0.803 0.998 -0.467 -0.127
2 0.99946 -0.803 1.000 -0.838 0.719 0.345
3 0.99999 0.998 -0.838 1.000 -0.500 -0.146
4 0.97807 -0.467 0.719 -0.500 1.000 0.825
5 0.97870 -0.127 0.345 -0.146 0.825 1.000
FCN=0.00421044 FROM MIGRAD STATUS=PROGRESS 146 CALLS 147
TOTAL
EDM=4.9659e-05 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.99323e+01 6.13666e+00 -2.22127e-03 1.06866e-02
2 c1 1.68616e+00 9.99532e-02 2.97770e-05 -6.58570e-02
3 b 1.80800e+02 7.23261e+02 -2.61838e-01 -7.90200e-05
4 a1 3.01260e+00 2.62695e+00 4.61001e-04 -3.11362e-04
5 a2 3.97746e+00 4.32249e+00 2.12923e-04 2.24200e-04
FCN=0.00413452 FROM MIGRAD STATUS=PROGRESS 271 CALLS 272
TOTAL
EDM=2.23703e-06 STRATEGY= 1 ERROR MATRIX
UNCERTAINTY 37.4 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.98878e+01 3.04062e+00 -2.56537e-03 1.73513e-01
2 c1 1.68676e+00 6.86513e-02 8.54871e-05 -1.17926e+00
3 b 1.75636e+02 3.47780e+02 -3.32747e-01 -1.65253e-03
4 a1 3.02186e+00 2.37153e+00 1.80767e-03 -5.47457e-03
5 a2 3.98166e+00 4.29384e+00 1.63272e-03 3.88712e-03
FCN=0.00410031 FROM MIGRAD STATUS=PROGRESS 405 CALLS 406
TOTAL
EDM=3.10307e-07 STRATEGY= 1 ERROR MATRIX
UNCERTAINTY 14.5 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.98444e+01 5.82550e+00 -2.36275e-03 4.70647e-02
2 c1 1.68738e+00 9.69576e-02 6.27073e-05 -3.17427e-01
3 b 1.70723e+02 6.50451e+02 -2.84847e-01 -4.62965e-04
4 a1 3.03155e+00 2.56993e+00 1.24871e-03 -1.48267e-03
5 a2 3.98627e+00 4.29325e+00 1.03513e-03 1.05285e-03
MIGRAD MINIMIZATION HAS CONVERGED.
MIGRAD WILL VERIFY CONVERGENCE AND ERROR MATRIX.
START COVARIANCE MATRIX CALCULATION.
EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
6.6936e-06 2.1837e-03 3.4262e-02 4.2440e-01 4.5391e+00
COVARIANCE MATRIX CALCULATED SUCCESSFULLY
FCN=0.00409968 FROM MIGRAD STATUS=CONVERGED 484 CALLS 485
TOTAL
EDM=1.97498e-09 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.98394e+01 5.83849e+00 1.10099e-05 2.67811e-03
2 c1 1.68745e+00 1.00900e-01 1.62314e-06 -1.79311e-02
3 b 1.70161e+02 6.49358e+02 1.11316e-03 -2.64630e-05
4 a1 3.03266e+00 2.63458e+00 2.67711e-04 -8.42569e-05
5 a2 3.98678e+00 4.32316e+00 4.34172e-04 5.97357e-05
EXTERNAL ERROR MATRIX. NDIM= 25 NPAR= 5 ERR DEF=1
3.409e+01 -4.741e-01 3.783e+03 -7.231e+00 -3.196e+00
-4.741e-01 1.018e-02 -5.512e+01 1.914e-01 1.500e-01
3.783e+03 -5.512e+01 4.217e+05 -8.622e+02 -4.130e+02
-7.231e+00 1.914e-01 -8.622e+02 6.941e+00 9.379e+00
-3.196e+00 1.500e-01 -4.130e+02 9.379e+00 1.869e+01
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2 3 4 5
1 0.99999 1.000 -0.805 0.998 -0.470 -0.127
2 0.99946 -0.805 1.000 -0.841 0.720 0.344
3 0.99999 0.998 -0.841 1.000 -0.504 -0.147
4 0.97820 -0.470 0.720 -0.504 1.000 0.823
5 0.97871 -0.127 0.344 -0.147 0.823 1.000
FCN=0.00409968 FROM MIGRAD STATUS=CONVERGED 484 CALLS 485
TOTAL
EDM=1.97498e-09 STRATEGY= 1 ERROR MATRIX
ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 c0 1.98394e+01 5.83849e+00 1.10099e-05 2.67811e-03
2 c1 1.68745e+00 1.00900e-01 1.62314e-06 -1.79311e-02
3 b 1.70161e+02 6.49358e+02 1.11316e-03 -2.64630e-05
4 a1 3.03266e+00 2.63458e+00 2.67711e-04 -8.42569e-05
5 a2 3.98678e+00 4.32316e+00 4.34172e-04 5.97357e-05
*** Break *** segmentation violation
Root >
*** Break *** segmentation violation
Root >
Any ideas what might be going wrong???
Thanks for suggestions...
Christian
----------------------------------------------------------------------
Christian Doerr
Institut fuer Experimentelle Kernphysik, Universität Karlsruhe
Wolfgang-Gaede-Str. 1, Zimmer 9-2 Tel.: +49-721-608-3586
email: doerr@ekp.physik.uni-karlsuhe.de www.christiandoerr.de
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