Dear StephanH @StephanH :
Thanks. Good news: after using the verbose mode “V”, it returns to me some EXTERNAL ERROR MATRIX, which seems to be the covariance matrix that I always want (see the terminal report below).
But still the MIGRAD thing didn’t converge, I’m not sure how that happened when everything “seems” to be fine (the fit result seems to agree with my data; and it actually get some reasonable covariance matrix, and just doesn’t want to share it with me, when I print it.).
Now I’m not sure if it’s legitimate to use the EXTERNAL MATRIX as my covariance matrix after all its error-report on MIGRAD divergence.
The following is the terminal report, starting from the second last fit status report:
FCN=38.2639 FROM MIGRAD STATUS=PROGRESS 1604 CALLS 1605 TOTAL
EDM=0.00628792 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 20.7 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 2.96631e-01 9.40791e-02 3.91372e-03 -1.12405e+02
2 p1 3.70289e-01 2.53365e-02 -1.98576e-03 -2.65629e+01
3 p2 8.30575e-03 1.00820e-02 -1.95435e-02 -3.06363e+00
4 p3 1.23265e+00 3.75070e-02 -3.36459e-03 -1.39326e+02
5 p4 1.43869e+01 1.01233e-01 -1.43233e-03 9.98044e+01
CALL LIMIT EXCEEDED IN MIGRAD.
MIGRAD TERMINATED WITHOUT CONVERGENCE.
FCN=38.2478 FROM MIGRAD STATUS=CALL LIMIT 1630 CALLS 1631 TOTAL
EDM=0.00988881 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 14.5 per cent
EXT PARAMETER APPROXIMATE STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 p0 3.02999e-01 1.08434e-01 1.31306e-03 -2.14674e+02
2 p1 3.72073e-01 3.38375e-02 1.20516e-03 -3.40276e+01
3 p2 8.84789e-03 1.12145e-02 -5.94815e-03 3.18160e+00
4 p3 1.22696e+00 6.50898e-02 -1.64670e-03 -3.91608e+02
5 p4 1.43640e+01 2.63856e-01 -8.94469e-04 3.39474e+02
EXTERNAL ERROR MATRIX. NDIM= 25 NPAR= 5 ERR DEF=1
1.176e-02 -1.636e-03 -1.213e-03 -6.063e-03 -1.414e-02
-1.636e-03 1.145e-03 2.077e-04 -1.446e-04 -4.736e-03
-1.213e-03 2.077e-04 1.270e-04 5.821e-04 1.162e-03
-6.063e-03 -1.446e-04 5.821e-04 4.238e-03 1.493e-02
-1.414e-02 -4.736e-03 1.162e-03 1.493e-02 6.963e-02
ERR MATRIX APPROXIMATE
PARAMETER CORRELATION COEFFICIENTS
NO. GLOBAL 1 2 3 4 5
1 1.00000 1.000 -0.446 -0.993 -0.859 -0.494
2 0.99984 -0.446 1.000 0.545 -0.066 -0.530
3 0.99989 -0.993 0.545 1.000 0.793 0.391
4 1.00000 -0.859 -0.066 0.793 1.000 0.869
5 0.99999 -0.494 -0.530 0.391 0.869 1.000
ERR MATRIX APPROXIMATE
Info in <TMinuitMinimizer::Minimize>: Finished to run MIGRAD - status 4
Warning in <Fit>: Abnormal termination of minimization.
FCN=38.2478 FROM MIGRAD STATUS=CALL LIMIT 1630 CALLS 1631 TOTAL
EDM=0.00988881 STRATEGY= 1 ERROR MATRIX UNCERTAINTY 14.5 per cent
EXT PARAMETER PARABOLIC MINOS ERRORS
NO. NAME VALUE ERROR NEGATIVE POSITIVE
1 p0 3.02999e-01 1.08434e-01
2 p1 3.72073e-01 3.38375e-02
3 p2 8.84789e-03 1.12145e-02
4 p3 1.22696e+00 6.50898e-02
5 p4 1.43640e+01 2.63856e-01
i=0 (ERR, ERR^2)=(0.108434,0.011758).
i=1 (ERR, ERR^2)=(0.0338375,0.00114498).
i=2 (ERR, ERR^2)=(0.0112145,0.000125764).
i=3 (ERR, ERR^2)=(0.0650898,0.00423668).
i=4 (ERR, ERR^2)=(0.263856,0.0696199).
covariance matrix is
5x5 matrix is as follows
| 0 | 1 | 2 | 3 | 4 |
----------------------------------------------------------------------
0 | 0 0 0 0 0
1 | 0 0 0 0 0
2 | 0 0 0 0 0
3 | 0 0 0 0 0
4 | 0 0 0 0 0
correlaton matrix is:
5x5 matrix is as follows
| 0 | 1 | 2 | 3 | 4 |
----------------------------------------------------------------------
0 | 0 0 0 0 0
1 | 0 0 0 0 0
2 | 0 0 0 0 0
3 | 0 0 0 0 0
4 | 0 0 0 0 0