Added some comments on pi constants, and did some checking on pieni, but made no final changes.
Added some comments on pi constants, and did some checking on pieni, but made no final changes.

SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack,SixTrack/SixTrack