Wolfgang Korsch wrote: > > Dear ROOT team, > > I tried to do gaussian fit and got the following result on LINUX RH 5.2 > w/ EGCS1.1.1: > > FCN=3.47372 FROM MIGRAD STATUS=CONVERGED 114 CALLS 115 TOTAL > EDM=7.11533e-06 STRATEGY= 1 ERROR MATRIX ACCURATE > EXT PARAMETER STEP FIRST > NO. NAME VALUE ERROR SIZE DERIVATIVE > 1 Constant 4.57000e+01 4.66737e+00 4.66669e-03 -1.96269e-04 > 2 Mean 1.20224e+07 4.70724e+01 5.73270e+00 2.06634e-06 > 3 Sigma -4.72385e+02 1.23139e+01 1.40189e-02 3.17310e-04 > > The data is fine and even the fit looks fine when plotted on top of the > data. Running the same software on DU 4.0 gives the same Sigma with > a positive sign!! > > I use ROOT version 2.21/07 > > Any ideas? Thanks. > > Wolfgang > > Hi Wolfgang, In 2.21/08, I have introduced the constraint to be positive for "sigma". I think your histogram has a large mean value and small rms. Could you send me a Root file containing your histogram? Rene Brun
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