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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