PsiValue and Chi2Value to investigate statistical significance
of observations in counting experiments.
06-oct-2007 NvE Memberfunctions Chi2Value of class AliMath extended with ndf determination.
+09-oct-2007 NvE Memberfunctions ResetSignals and DeleteSignals of class AliSignal
+ extended with options to preserve the waveform histo contents.
+ These new options are now also used in the SetSignal and SetSignalError
+ memberfunctions of class AliSignal.