anchor.diff:       >             real(k)*dr,gr(k)
          end do
          stop
  -
  -911    continue       
  +411    continue
  +1000   format(
  +     > "NAME:",/
  +     > " rdf constructs radial density function ",
  +     > " from NWChem trajectory or xyz files",//,
  +     >  "SYNOPSIS",/,
  +     > " rdf [-help] [-v ]",
  +     > " [-frames ] [-lattice ] [-nbins ] [-rmax] [-atom1] [-atom2]",
  +     > " input file(s) outpiut file ",//,
  +     >  "DESCRIPTION",/,
  +     > " This utility builds rdf from NWChem trajectory",
  +     > " or xyz files",//,
  +     > " The required option are as follows:",/,
  +     > " -atom1   first atom id or name",/,
  +     > " -atom2   second atom id or name",/,
  +     > " -lattice lattice file or vector(3)",/,
  +     > " -rmax    maximum distance ",//,
  +     > " other options are as follows:",/,
  +     > " -help  prints out this message",/,
  +     > " -v  generate more verbose output",/,
  +     > " -frames  maximum number of frames default is all ",/,
  +     > " -nbins number of bins with default of rmax/0.1"
  +     > )
  + 911    continue       
   c      if you reach this you are in trouble
          write(*,*) "Emergency STOP"
          write(*,*) message
  
positive.code: c      -----------------
  30     FORMAT(180A1)
  20     FORMAT(A180)
         end
  
         subroutine xyz_read_natoms(n,fn_in)
  
negative.code:          read(bigbuf,*,err=10) (lat(k,i),k=1,3)
           if(i.eq.3) exit
         end do
         close(ifn)
  10     continue
         if(i.eq.0.or.i.eq.2) then
           message = "something wrong with format"
  