subroutine rdguess(ierror,il)

C
C     Reads in the parameters for density matrix approximation.
C
C     GUESS
C       DNA.dmx F
C       water1.dmx
C       water2.dmx
C     END_GUESS
C
C     the total number of atoms should be equal to the ones in divcon.dim
C     sequential numbering is assumed, i.e. DNA.dmx contains atoms 1 - x,
C     water1.dmx atoms x+1 - y, and water2.dmx contains atoms y+1 - natoms
C
C     if the filename is followed by a 'F', then the subsystems with the atoms
C     of that file in the core, will be frozen, i.e. treated by the FDM approximation.
C
C     guess
C       1-1512 dna.dmx 3-1514 F
C       1513-2931 water.dmx 1-1419
C       2932-3001 salts.dmx 4-73
C       3002-3010 dna.dmx 1515-1523 F
C     end_guess
C
C     density matrix elements for atoms 1-1512 will be filled with information
C     from atoms 3-1514 of dna.dmx and subsystems with these atoms in the core
C     will be frozen, i.e. treated by the FDM approximation
C     density matrix elements for atoms 1513-2931 will be filled with information
C     from atoms 1-1419 of water.dmx
C     density matrix elements for atoms 2932-3001 will be filled with information
C     from atoms 4-73 of salts.dmx
C
C     It is imperative that all atomtypes (H, O, C, ...) correspond with each other,
C     i.e. in the example above atom #3 of the new file should have the
C     same atom type as atom #5 of dna.dmx. Note that this is up to the user,
C     divcon does not check this.
C
C
C
C     Note that no dashes '-' are allowed in the name of the dmx files

      implicit double precision (a-h,o-z)
#include "divcon.dim"
#include "divcon.h"

      character line*80, nocapline*80
      logical int, mini, first
      data first /.true./
      save first
      dimension itmpn(2*maxsresf)

      nsresfile = 0
      minsynt = .false.
      
 5    il = il + 1
      line = (options2(il))

C 5    read (inpt,fmt='(A80)') line
      nocapline(1:80) = line(1:80)
      call upcase1(line,80)
      if (index(line,'END_GUESS').ne.0) then
         if (minsynt) then
            itmp = 2*nsresfile
            call bovsort1(itmp,itmpn,ierror)
            if (ierror.ne.0) then
C-RDC                write(iout,'(/" ERROR: NON-IDENTICAL ATOM REFERENCES "
C-RDC      &              "FOR ",
C-RDC      &              "NEW DENSITY",
C-RDC      &              /"        MATRIX IN GUESS PARAMETERS")')
               return
            endif
         endif
         return
      endif
      istart = 1
      im = index(line,'-')
      if (im.ne.0) then

         if (first) then
            minsynt = .true.
            first = .false.
         else
            if (.not.minsynt) then
C-RDC                write(iout,'(/" ERROR: MIXED SYNTAXIS IN GUESS ",
C-RDC      &              "PARAMETERS.",
C-RDC      &              /"        USE EITHER THE",
C-RDC      &              /"           ABC.DMX",
C-RDC      &              /"        OR THE",
C-RDC      &              /"           5-10 ABC.DMX 25-30",
C-RDC      &              /"        SYNTAX")')
               ierror = 1
               return
            endif
         endif
C     .  find first number
         nsresfile = nsresfile + 1
         in2 = 2*nsresfile
         in1 = in2-1
         i=1
 10      if (i.lt.80) then
            call whatis2(line(i:i),int, mini)
            if (int) then
               call iatoi(line, i, lstr, inewsres(in1), ierror)
               goto 20
            endif
            i=i+1
            goto 10
         else
C-RDC             write(iout,'(/" ERROR: WRONG SYNTAX IN GUESS PARAMETERS",
C-RDC      $           " LINE",/,1x,a20,"...")') line(1:20)
            ierror = 1
            return
         endif
 20      i=im+1
C     .  find second number
 30      if (i.lt.80) then
            call whatis2(line(i:i),int, mini)
            if (int) then
               call iatoi(line, i, lstr, inewsres(in2), ierror)
               goto 40
            endif
            i=i+1
            goto 30
         else
C-RDC             write(iout,'(/" ERROR: WRONG SYNTAX IN GUESS PARAMETERS",
C-RDC      $           " LINE",/,1x,a20,"...")') line(1:20)
            ierror = 1
            return
         endif
 40      i=lstr+1
C     .  filename
         call rdword(line,i,istop)
         if (istop.le.0) then
C-RDC             write(iout,'(/" ERROR: MISSING GUESS ENTRIES IN LINE ",
C-RDC      &           /,1X,A20)') line(1:20)
            ierror = 1
            return
         endif
         istopp = min(istop,i+59)
         sresfile(nsresfile) = nocapline(i:istopp)
         i=istop+1
C     .  find third number
 50      if (i.lt.80) then
            call whatis2(line(i:i),int, mini)
            if (int) then
               call iatoi(line, i, lstr, ioldsres(in1), ierror)
               goto 60
            endif
            i=i+1
            goto 50
         else
C-RDC             write(iout,'(/" ERROR: WRONG SYNTAX IN GUESS PARAMETERS",
C-RDC      $           " LINE",/,1x,a20,"...")') line(1:20)
            ierror = 1
            return
         endif
 60      i=lstr+1
C     .  find fourth number
 70      if (i.lt.80) then
            call whatis2(line(i:i),int, mini)
            if (int) then
               call iatoi(line, i, lstr, ioldsres(in2), ierror)
               goto 80
            endif
            i=i+1
            goto 70
         else
C-RDC             write(iout,'(/" ERROR: WRONG SYNTAX IN GUESS PARAMETERS",
C-RDC      $           " LINE",/,1x,a20,"...")') line(1:20)
            ierror = 1
            return
         endif
 80      if (index(line(lstr+1:80),'F').ne.0) then
            fdmx = .true.
            fresfile(nsresfile) = .true.
            if (stand) then
C-RDC                write(iout,'(/" ERROR: CANNOT USE THE FDM APPROXIMATION ",
C-RDC      &              "WHEN",
C-RDC      &              /"        A STANDARD CALCULATION IS DONE")')
               ierror = 1
               return
            endif
         else
            fresfile(nsresfile) = .false.
         endif

C     .  do some checking
         if ((inewsres(in2).lt.inewsres(in1)).or.
     &        (ioldsres(in2).lt.ioldsres(in1))) then
C-RDC             write(iout,'(/" ERROR: INVALID ATOM REFERENCING IN GUESS ",
C-RDC      $           "PARAMETERS LINE",
C-RDC      $           /,1X,a20,"...")') line(1:20)
            ierror = 1
            return
         else
            do i=in1,in2
               if (((inewsres(i).le.0).or.(inewsres(i).gt.natoms))
     &              .or.
     &              (ioldsres(i).le.0))
     &              then
C-RDC                   write(iout,'(/" ERROR: OUT OF RANGE ERROR IN ",
C-RDC      &                 "GUESS LINE ",
C-RDC      &                 /,1X,A20,"...")') line(1:20)
                  ierror = 1
                  return
               endif
               itmpn(i) = inewsres(i)
            enddo
         endif
         k1 = inewsres(in2)-inewsres(in1)
         k2 = ioldsres(in2)-ioldsres(in1)
         if (k1.ne.k2) then
C-RDC             write(iout,'(/" ERROR: DIFFERENT RANGES IN LINE ",
C-RDC      &           A20,"... OF ",
C-RDC      $           /"        GUESS PARAMETERS")') line(1:20)
            ierror = 1
            return
         endif

      else

         if (first) then
            minsynt = .false.
            first = .false.
         else
            if (minsynt) then
C-RDC                write(iout,'(/" ERROR: MIXED SYNTAXIS IN GUESS ",
C-RDC      &              "PARAMETERS.",
C-RDC      &              /"        USE EITHER THE",
C-RDC      &              /"           ABC.DMX",
C-RDC      &              /"        OR THE",
C-RDC      &              /"           5-10 ABC.DMX 25-30",
C-RDC      &              /"        SYNTAX")')
               ierror = 1
               return
            endif
         endif
         istart=1
         call rdword(line,istart,istop)
         nsresfile = nsresfile + 1
         if (stand.and.(nsresfile.gt.1)) then
C-RDC             write(iout,'(/" ERROR: ONLY ONE DMX FILE IS ALLOWED WHEN ",
C-RDC      &           /"        DOING A STANDARD CALCULATION")')
            ierror = 1
            return
         endif
         if (nsresfile.gt.maxsresf) then
C-RDC             write(iout,'(/" ERROR: TOO MANY DENSITY MATRIX FILES ",
C-RDC      &           "SPECIFIED",
C-RDC      &           /"        INCREASE MAXSRESF IN divcon.dim AND ",
C-RDC      &           "RECOMPILE")')
            ierror = 1
            return
         endif
         istopp = min(istop,istart+59)
         sresfile(nsresfile) = nocapline(istart:istopp)
         if (index(line(istop+1:80),'F').ne.0) then
            fdmx = .true.
            fresfile(nsresfile) = .true.
            if (stand) then
C-RDC                write(iout,'(/" ERROR: CANNOT USE THE FDM APPROXIMATION ",
C-RDC      &              "WHEN",
C-RDC      &              /"        A STANDARD CALCULATION IS DONE")')
               ierror = 1
               return
            endif
         else
            fresfile(nsresfile) = .false.
         endif
      endif

      goto 5

      end