Centrality is organized via the StEStructCentrality singleton class which simply maps an array of floats to a centrality binning.

• The idea is to fill the definitions within a macro so that any of the code can access the definition.
• Currently, Duncan has QA histograms that histogram the definitions within the macro - I am adding this to a general in-code QA histogramming object .
• The mapping is currently only from number-of-tracks for real data but includes impact parameter for hijing. May later include something else for pythia.

The code currently evaluates the number-of-tracks count dependent upon the track-selection cuts - including the pt and eta ranges. This wasn't the case before and I'm tempted to change it back - i.e. we should be able change the pt,eta ranges subjected to the analysis without altering this counting. But I'll discuss with Duncan - perhaps there is some effect via cannonical suppression on the fluctuations measurements that he is adressing with this coding.

Update: In the StEStructMuDstReader class - I've added a "isGoodTrackToUse(track)" method which calls "isGoodTrack(track)" + track kinematic cuts. Previously, the counting and the use of track selection were done with the same "isGoodTrack" method. Now counting is done via "isGoodTrack" while use of track is the combination that plus kinematic selection. This coding builds in the distinction; We still may need to examine its utility. Also, it's not yet checked into cvs.