anchor.diff:         ang1=0.0d0
          inquire(file="cons.dat",exist=ofile)
          if(ofile) then
  -         write(*,*) "found constraint file"
  +c         write(*,*) "found constraint file"
            if(.not.util_get_io_unit(fnc)) then
                message = "no free file units"
                goto 911
  
positive.code:              ang = SUM(rd*rd1)/(d1*d)
               ocons = ang.ge.ang0
               ocons = ocons.and.(ang.le.ang1)
               write(45,*) i2,i1,ic,ang,ocons
             end if
             if(d.gt.0.01) k = int(d/dr)+1
             if(k.le.nb.and.ocons ) then
  
negative.code:        integer fnc
         logical util_get_io_unit
         external util_get_io_unit
         double precision pi
  c
         pname = "rdf_compute"
         pi = acos(-1.0)
  c
  c      ----------------------
  c      compute lattice params
  