I see a really strange fit behaviour, which is illustrated by the attached macro, which fits a polarization signature with a cosine.
Please play with the number of bins (NBins) of the histogram:
At NBins=100, the correct modulation is retrieved (0.20)
At NBins=1000, the modulation is somewhat smaller (0.16) but not even within errors close to the input
AT NBins=10000, the fitted cosine is almost flat, but visually the correct modulation is clearly visible (see attached image).
Any idea what might be wrong? The chi-square of the fit looks reasonable, but the result is definitely not…
Strangely, if one deactivates the normalization (UseNormalization=false) in the macro, the fit becomes acceptable again.
Any ideas what might be wrong?
OS: SuSE 9.2
ROOT: 4.04/02 (not cvs)
FitProb.C (2.41 KB)