This routine tracks a particle with momentum p from v to the the distance DST. It returns the momentum (pend) and position (vend) at this point. It also returns the TKR parameters at the point.
P : Momentum of track V : Position where P is given DST : Distance to follow track from V. FIRST : TRUE if first call for this track. IPRP : true IP in R-Phi (input if FIRST = FALSE) IPZ : true IP in Z (input if FIRST = FALSE) PHI : Phi angle to perigee point in R-phi plane (input if FIRST = FALSE)
IPRP : true IP in R-Phi (output if FIRST = TRUE) IPZ : true IP in Z (output if FIRST = TRUE) PHI : Phi angle to perigee point in R-phi plane (output if FIRST = TRUE) PEND: Momentum of track (if ERROR <>0 then PEND=P) VEND : Position where PEND is given (if ERROR <>0 then VEND=V) TRACK : TKR parameters for the track. for the track ERROR : error flag : 0 - no error 1 - no intersection in barrel. 2 - track turns back. 3 - other error.
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(To track a to a PLAne given by its z)