Bug #1496

Updated by Knödlseder Jürgen over 11 years ago

When fitting all parameters, the fit errors of the log parabola model are too large.

The problem can be reproduced using this XML file: attachment:crab_logparabola.xml.

The ctlike run produces the following output:
<pre>
2015-07-01T06:03:36: +=================================+
2015-07-01T06:03:36: | Maximum likelihood optimisation |
2015-07-01T06:03:36: +=================================+
2015-07-01T06:03:36: >Iteration 0: -logL=133492.928, Lambda=1.0e-03
2015-07-01T06:03:36: >Iteration 1: -logL=133489.599, Lambda=1.0e-03, delta=3.330, max(|grad|)=3.544902 [Index:8]
2015-07-01T06:03:36: >Iteration 2: -logL=133489.598, Lambda=1.0e-04, delta=0.000, max(|grad|)=0.013988 [Index:8]
2015-07-01T06:03:37:
2015-07-01T06:03:37: +=========================================+
2015-07-01T06:03:37: | Maximum likelihood optimization results |
2015-07-01T06:03:37: +=========================================+
2015-07-01T06:03:37: === GOptimizerLM ===
2015-07-01T06:03:37: Optimized function value ..: 133489.598
2015-07-01T06:03:37: Absolute precision ........: 0.005
2015-07-01T06:03:37: Acceptable value decrease .: 2
2015-07-01T06:03:37: Optimization status .......: converged
2015-07-01T06:03:37: Number of parameters ......: 11
2015-07-01T06:03:37: Number of free parameters .: 6
2015-07-01T06:03:37: Number of iterations ......: 2
2015-07-01T06:03:37: Lambda ....................: 1e-05
2015-07-01T06:03:37: Maximum log likelihood ....: -133489.598
2015-07-01T06:03:37: Observed events (Nobs) ...: 57339.000
2015-07-01T06:03:37: Predicted events (Npred) ..: 57337.998 (Nobs - Npred = 1.00155)
2015-07-01T06:03:37: === GModels ===
2015-07-01T06:03:37: Number of models ..........: 2
2015-07-01T06:03:37: Number of parameters ......: 11
2015-07-01T06:03:37: === GModelSky ===
2015-07-01T06:03:37: Name ......................: Crab
2015-07-01T06:03:37: Instruments ...............: all
2015-07-01T06:03:37: Instrument scale factors ..: unity
2015-07-01T06:03:37: Observation identifiers ...: all
2015-07-01T06:03:37: Model type ................: PointSource
2015-07-01T06:03:37: Model components ..........: "SkyDirFunction" * "LogParabola" * "Constant"
2015-07-01T06:03:37: Number of parameters ......: 7
2015-07-01T06:03:37: Number of spatial par's ...: 2
2015-07-01T06:03:37: RA .......................: 83.6331 [-360,360] deg (fixed,scale=1)
2015-07-01T06:03:37: DEC ......................: 22.0145 [-90,90] deg (fixed,scale=1)
2015-07-01T06:03:37: Number of spectral par's ..: 4
2015-07-01T06:03:37: Prefactor ................: 5.86089e-16 +/- 4.39833e-11 [1e-23,1e-13] ph/cm2/s/MeV (free,scale=1e-16,gradient)
2015-07-01T06:03:37: Index ....................: -2.32353 +/- 4567.39 [-0,-5] (free,scale=-1,gradient)
2015-07-01T06:03:37: Curvature ................: -0.0707068 +/- 0.00274528 [-0.01,-1000] (free,scale=-1,gradient)
2015-07-01T06:03:37: PivotEnergy ..............: 998705 +/- 3.22562e+10 [10000,1e+09] MeV (free,scale=1e+06,gradient)
2015-07-01T06:03:37: Number of temporal par's ..: 1
2015-07-01T06:03:37: Normalization ............: 1 (relative value) (fixed,scale=1,gradient)
2015-07-01T06:03:37: === GCTAModelIrfBackground ===
2015-07-01T06:03:37: Name ......................: Background model
2015-07-01T06:03:37: Instruments ...............: CTA
2015-07-01T06:03:37: Instrument scale factors ..: unity
2015-07-01T06:03:37: Observation identifiers ...: all
2015-07-01T06:03:37: Model type ................: "PowerLaw" * "Constant"
2015-07-01T06:03:37: Number of parameters ......: 4
2015-07-01T06:03:37: Number of spectral par's ..: 3
2015-07-01T06:03:37: Prefactor ................: 0.999265 +/- 0.0215484 [0.001,1000] ph/cm2/s/MeV (free,scale=1,gradient)
2015-07-01T06:03:37: Index ....................: -0.0117382 +/- 0.0123976 [-5,5] (free,scale=1,gradient)
2015-07-01T06:03:37: PivotEnergy ..............: 1e+06 [10000,1e+09] MeV (fixed,scale=1e+06,gradient)
2015-07-01T06:03:37: Number of temporal par's ..: 1
2015-07-01T06:03:37: Normalization ............: 1 (relative value) (fixed,scale=1,gradient)
</pre>

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