anchor.diff:  c      -----------------
   30     FORMAT(180A1)
   20     FORMAT(A180)
  +       end
  +
  +       subroutine compute_default_rmax(rmax,lat)
  +       implicit none
  +       double precision rmax,lat(3,3)
  +c       
  +       double precision d(3)
  +
  +       d(1) = sqrt(SUM(lat(:,1)*lat(:,1)))
  +       d(2) = sqrt(SUM(lat(:,2)*lat(:,2)))
  +       d(3) = sqrt(SUM(lat(:,3)*lat(:,3)))
  +       rmax = 0.5*MINVAL(d)
  +       return
          end
   
          subroutine xyz_read_natoms(n,fn_in)
  
positive.code:      >             real(k)*dr,gr(k)
         end do
         stop
  
  911    continue       
  c      if you reach this you are in trouble
         write(*,*) "Emergency STOP"
         write(*,*) message
  
negative.code:        end if
  c      maximum radius
         if(rmax.lt.0) then
           message = "please provide rmax"
           goto 911
         end if
  c      number of bins
         if(nb.lt.0) then
  