C
C $Id: pbcxyz.F,v 1.4 1999/04/06 20:54:50 arjan Exp arjan $
C
C------------------------------------------------------------------------
      SUBROUTINE PBCXYZ(I,J,XJ,YJ,ZJ)
C
C     RETURNS MINIMUM IMAGE COORDINATES FOR ATOM J BASED ON ITS
C     LOCATION RELATIVE TO ATOM I (ATOMWISE)
C
C     note that in case of push, the values of gcres correspond to the
C     original (non-pushed) configuration. This way, the correct geometry
C     will be taken (since else dxij would always be larger than dhalf)
C
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
#include "divcon.dim"
#include "divcon.h"
C
      XJ = XYZ(1,J)
      YJ = XYZ(2,J)
      ZJ = XYZ(3,J)
C
C     CENTER-OF-RESIDUE COORDINATE DIFFERENCES:
C

c      DXIJ = XYZ(1,I) - XYZ(1,J)
c      DYIJ = XYZ(2,I) - XYZ(2,J)
c      DZIJ = XYZ(3,I) - XYZ(3,J)

      DXIJ = gcres(1,I) - gcres(1,J)
      DYIJ = gcres(2,I) - gcres(2,J)
      DZIJ = gcres(3,I) - gcres(3,J)
C
C     USE MINIMUM IMAGE FOR J IF THE RESIDUE CENTERS ARE SEPARATED
C     BY MORE THAN HALF THE BOX DIMENSION.
C
      IF(ABS(DXIJ).GT.DHALF(1)) XJ = XJ + SIGN(DBOX(1),DXIJ)
      IF(ABS(DYIJ).GT.DHALF(2)) YJ = YJ + SIGN(DBOX(2),DYIJ)
      IF(ABS(DZIJ).GT.DHALF(3)) ZJ = ZJ + SIGN(DBOX(3),DZIJ)
C
      RETURN
      END