Hi Tim,
HESSE may be called automaticalled by the MIGRAD routine
or by TH1::Fit if you have specified the option "E"
I cannot tell you more without looking at your code and being able to run it.
Could you provide a test program as short as possible?
Rene Brun
Timothy Meyer wrote:
>
> Ciao,
>
> I'm trying to understand the why one of my fits fails using
> ROOT 3.00/06 and the TMinuit/TFitter class. I have two questions:
>
> 1. Under what conditions does MIGRAD actually determine it will
> quit? (other than the call limit)
>
> 2. In the context of my situation, I'm seeing this sequence of messages
> when I call TFitter::ExecuteCommand("MIGRAD",arglist,2):
>
> //
>
> **********
> ** 3 **MIGRAD 3.8e+04 1
> **********
> START MIGRAD MINIMIZATION. STRATEGY 1. CONVERGENCE WHEN EDM .LT.
> 1.00e-03
> FCN=35111.1 FROM MIGRAD STATUS=INITIATE 76 CALLS 1037 TOTAL
> EDM=65193.8 STRATEGY= 1 ERR MATRIX NOT POS-DEF
>
> .
> .
> .
> MIGRAD MINIMIZATION HAS CONVERGED.
> MIGRAD WILL VERIFY CONVERGENCE AND ERROR MATRIX.
> EIGENVALUES OF SECOND-DERIVATIVE MATRIX:
> -5.2169e-01 9.5659e-02 1.4906e-01 1.9453e-01 2.6754e-01
> 2.7675e-01 3.2096e-01 3.6102e-01 4.4657e-01 4.8688e-01 5.2103e-01
> 7.0896e-01 7.7633e-01 8.2491e-01 8.4358e-01 9.0652e-01 9.1783e-01
> 9.3161e-01 9.3667e-01 9.6279e-01 9.8268e-01 9.8491e-01 9.9168e-01
> 1.1732e+00 1.1881e+00 1.2584e+00 1.2805e+00 1.3221e+00 1.5238e+00
> 1.5253e+00 1.6193e+00 1.7037e+00 1.7502e+00 1.7898e+00 1.8261e+00
> 1.8920e+00 2.1636e+00 2.6171e+00
> MINUIT WARNING IN HESSE
> ==============
> FCN=33792 FROM HESSE STATUS=NOT POSDEF 892 CALLS 11151 TOTAL
> EDM=0.00162124 STRATEGY= 1 ERR MATRIX NOT POS-DEF
>
> [ my parameter list, etc. ]
>
> MIGRAD FAILS TO FIND IMPROVEMENT
> MIGRAD TERMINATED WITHOUT CONVERGENCE.
> FCN=33792 FROM MIGRAD STATUS=FAILED 10450 CALLS 11411 TOTAL
> EDM=0.146157 STRATEGY= 1 ERR MATRIX NOT POS-DEF
>
> //
>
> Why does MIGRAD announce failure? I didn't ask it to call
> HESSE; does it do that normally in order to "verify convergence
> and error matrix"? I'm not used to MIGRAD doing that on its own,
> when using MINUIT outside of ROOT. Things look fine until immediately
> after the HESSE call, I get the "terminated without convergence." What
> happened?
>
> I know its hard to diagnose this without the context of my
> particular fitting problem, but I'm just asking what conditions cause
> the messages above. They don't appear to be consistent in my
> private picture of how MIGRAD does its job...
>
> Thanks,
>
> TIMeyer
> Stanford University
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