Hello,
I am attempting to fit a graph in the form of TGraphErrors with a user defined fit function. My fit is listed as “FAILED”. I tried moving around the fit parameters and parameter initial values but does not seem to help.
Attached is the sample code with the fit that fails.
The output of the macro is as follows:
[localhost:~/analysis_code/asym_code] jawalkar% root -l
root [0] .L testfit.C+
root [1] testfit();
Info in TCanvas::MakeDefCanvas: created default TCanvas with name c1
** 1 **SET PRINT 2
** 2 **SET NOGRAD
PARAMETER DEFINITIONS:
NO. NAME VALUE STEP SIZE LIMITS
1 Constant 0.00000e+00 2.00000e-02 -1.00000e-01 1.00000e-01
2 sin #phi moment 2.00000e-02 4.00000e-02 -2.00000e-01 2.00000e-01
** 3 **SET ERR 1
** 4 **SET PRINT 2
** 5 **MIGRAD 1220 0.0001
FIRST CALL TO USER FUNCTION AT NEW START POINT, WITH IFLAG=4.
START MIGRAD MINIMIZATION. STRATEGY 1. CONVERGENCE WHEN EDM .LT. 1.00e-07
FCN=31.6206 FROM MIGRAD STATUS=INITIATE 8 CALLS 9 TOTAL
EDM= unknown STRATEGY= 1 NO ERROR MATRIX
EXT PARAMETER CURRENT GUESS STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant 0.00000e+00 2.00000e-02 2.01358e-01 5.55525e+01
2 sin #phi moment 2.00000e-02 4.00000e-02 2.02430e-01 -4.62530e+02
NO ERROR MATRIX
FCN=17.9128 FROM MIGRAD STATUS=PROGRESS 13 CALLS 14 TOTAL
EDM=0.00494594 STRATEGY= 1 NO ERROR MATRIX
EXT PARAMETER CURRENT GUESS STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant -1.29868e-03 2.00000e-02 -1.29872e-02 -2.04075e+00
2 sin #phi moment 3.14090e-02 4.00000e-02 5.75302e-02 -3.47195e+00
MIGRAD FAILS TO FIND IMPROVEMENT
MACHINE ACCURACY LIMITS FURTHER IMPROVEMENT.
MIGRAD MINIMIZATION HAS CONVERGED.
MIGRAD WILL VERIFY CONVERGENCE AND ERROR MATRIX.
START COVARIANCE MATRIX CALCULATION.
EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
7.2417e-01 1.2758e+00
COVARIANCE MATRIX CALCULATED SUCCESSFULLY
FCN=17.9115 FROM HESSE STATUS=OK 14 CALLS 67 TOTAL
EDM=1.37217e-06 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant -1.25013e-03 1.72304e-03 4.01103e-05 -7.88189e-02
2 sin #phi moment 3.14974e-02 2.61690e-03 2.80496e-05 1.75086e-01
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2
1 0.27583 1.000 0.276
2 0.27583 0.276 1.000
FCN=17.9115 FROM MIGRAD STATUS=PROGRESS 82 CALLS 83 TOTAL
EDM=4.48205e-07 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant -1.25013e-03 1.72304e-03 3.97862e-08 6.13381e-02
2 sin #phi moment 3.14974e-02 2.61690e-03 -8.28420e-08 4.38133e-02
MIGRAD FAILS TO FIND IMPROVEMENT
MACHINE ACCURACY LIMITS FURTHER IMPROVEMENT.
MIGRAD MINIMIZATION HAS CONVERGED.
MIGRAD WILL VERIFY CONVERGENCE AND ERROR MATRIX.
START COVARIANCE MATRIX CALCULATION.
EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
6.1811e-01 1.3819e+00
COVARIANCE MATRIX CALCULATED SUCCESSFULLY
MIGRAD TERMINATED WITHOUT CONVERGENCE.
FCN=17.9115 FROM MIGRAD STATUS=FAILED 100 CALLS 101 TOTAL
EDM=5.52975e-05 STRATEGY= 1 ERR MATRIX APPROXIMATE
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant -1.25013e-03 1.84212e-03 3.51723e-05 -5.00349e-01
2 sin #phi moment 3.14974e-02 2.01532e-03 1.65724e-05 -2.59206e-01
EXTERNAL ERROR MATRIX. NDIM= 25 NPAR= 2 ERR DEF=1
3.394e-06 1.418e-06
1.418e-06 4.062e-06
ERR MATRIX APPROXIMATE
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2
1 0.38189 1.000 0.382
2 0.38189 0.382 1.000
ERR MATRIX APPROXIMATE
Info in : Finished to run MIGRAD - status 4
Warning in : Abnormal termination of minimization.
FCN=17.9115 FROM MIGRAD STATUS=FAILED 100 CALLS 101 TOTAL
EDM=5.52975e-05 STRATEGY= 1 ERR MATRIX APPROXIMATE
EXT PARAMETER PARABOLIC MINOS ERRORS
NO. NAME VALUE ERROR NEGATIVE POSITIVE
1 Constant -1.25013e-03 1.84212e-03
2 sin #phi moment 3.14974e-02 2.01532e-03
root [2]
Thanks,
Sucheta.
Attachment: testfit.C (1.33 KB)