subroutine kvir_add_nofit(ntrk, list_trk, vertex, kput, error)
*
* begin_doc
*
*  Build a new particle with a covariance matrix by adding the 4-momenta
*  of several particles at the point of closest approach to a
*  specified vertex. No constraints are applied and the final particle
*  is placed at the vertex.
*
*  Note: For now the covariance matrix is calculated as the sum of the
*        covariance matrices of the individual particles.
*
*  Input Parameters:
*  ntrk         integer variable
*               # of input tracks
*
*  list_trk(*)  integer variable
*               List of KWFIT tracks.
*
*  vertex(3)    double precision array
*               (x,y,z) point at which to evaluate the 4-vectors
*
*  kput         integer variable
*               KWFIT track number to write the fitted particle
*
*  Output Parameters:
*  error        integer variable
*               = 0  All OK
*               > 0  Bad track number
*
*  Other routines:
*
*  Notes:
*
*  Author:   Paul Avery      Created:  Wed Aug 20 00:34:38 EDT 1997
*
*  Major revisions:
*
*
* end_doc