SUBROUTINE KSHCOR(IK, VERTX, P4)
 
C  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
C   Calculate the 4 vector of a shower assuming that it comes from the
C   point specified in VERTX(1-3).
C
C  IK        Integer variable (read)
C            Track # in KN list
C
C  VERTX     real array (read)
C            (x,y,z) point at which to evaluate new momentum
C
C *P4        real array (write)
C            4-vector of shower from VERTX(1-3)
C  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>