Negative Sigma in Gaussian Fit on Linux/egcs1.1.1

Wolfgang Korsch (wkorsch@server1.pa.uky.edu)
Mon, 15 Mar 1999 10:45:09 -0500

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