C
C $Id: rcalc.F,v 1.4 1998/07/16 16:40:25 jjv5 Exp arjan $
C
C------------------------------------------------------------------------
      SUBROUTINE RCALC(IERROR)
C
C     COMPUTES AND STORES INTERATOMIC DISTANCES RPAIR FOR ALL ATOMS.
C     DON'T USE IF 'DIRECT' KEYWORD HAS BEEN SPECIFIED.
C
C     RETURNS WITH AN ERROR IF ANY TWO ATOMS ARE SEPARATED BY LESS
C     THAN 0.5 ANGSTROMS.
C
      IMPLICIT DOUBLE PRECISION (A-H,O-Z)
#include "divcon.dim"
#include "divcon.h"
C
C	
      IERROR = 0
      rminimr = 6.0E6
      rmaximr = 0.0
      IF(NATOMS.LT.2) RETURN
      IJ = 0
      iri = 1
      irie = irpnt(2)-1
      DO 100 I=2,NATOMS
         IAI = IATNUM(I)
         IF(IAI.EQ.0) GO TO 100
C     .  find out to what residue atom i belongs
         if (i.gt.irie) then
            iri = iri + 1
            irie = irpnt(iri+1)-1
         endif
         XI = XYZ(1,I)
         YI = XYZ(2,I)
         ZI = XYZ(3,I)
         irj = 1
         irje = irpnt(2)-1
         DO 50 J=1,I-1
            IAJ = IATNUM(J)
            IF(IAJ.EQ.0) GO TO 50
C     .     find out to what residue atom j belongs
            if (j.gt.irje) then
               irj = irj + 1
               irje = irpnt(irj+1)-1
            endif
            IF(PBC)THEN
               CALL PBCXYZ(I,J,XJ,YJ,ZJ)
            ELSE
               XJ = XYZ(1,J)
               YJ = XYZ(2,J)
               ZJ = XYZ(3,J)
            ENDIF
            RIJ = DSQRT((XI-XJ)**2 + (YI-YJ)**2 + (ZI-ZJ)**2)
C     .     save minimum/maximum distances between atoms of different residue
            if (iri.ne.irj) then
               rminimr = min(rminimr,rij)
               rmaximr = max(rmaximr,rij)
            endif
            IF(RIJ.LT.rijmin)THEN
               IERROR = 1
C-RDC                if (nmc.le.1) WRITE(IOUT,
C-RDC      .              '(/" ATOMS ",I4," AND ",I4," ARE SEPARATED BY",
C-RDC      .              " ONLY ",F12.5," ANGSTROMS")') I,J,RIJMIN
               RETURN
            ENDIF
            IJ = IJ + 1
            RPAIR(IJ) = RIJ
 50      CONTINUE
 100  CONTINUE
      RETURN
      END