// ############################## START FUNC ############################################
// This function throw away duplicate rings. With another ring calculation algorithm, where all
// coils from branches are combined, this would not be possible, but also that solution has its
// problems and the chosen algorithm resembles the algorithms for chirality and functional groups

function clear_rings(ring_list_string)
{

     var ring_list=new Array(0);
     var atoms_in_ring=new Array(0);
     var thjalp=0;
     var temp="";
     var firstval=0;

     var ring_list=ring_list_string.split("#");

// Each ring set is picked and split with respect to "  ". A number om "a->b", "b->c" now represent
// every ring. The first atom, a is picked by parseInt and its sinus value is added to a sum.
// All first atoms (=all atoms in the ring) is taken sinus of and added to the sum. Two equal sums
// indicates that the atoms that participates in those rings are identical. 

     for(n=0;n<ring_list.length;n++){
      atoms_in_ring=ring_list[n].split("  ");
      thjalp=0;
      temp="";
        for(m=0;m<atoms_in_ring.length;m++){
        firstval=parseInt(atoms_in_ring[m]);
        thjalp=thjalp+Math.sin(firstval);
        temp=temp+firstval+" ";
        }
      thjalp=Math.floor(thjalp*1000000)/100000000;
      ring_list[n]=thjalp+"#"+temp.substring(0,temp.length-1);
     }

// ring_list is sorted. If two consecutive sums ring_list[n], ring_list[n+1] are identical, (Now "#" splits each ring_list[n]
// with the sum (first) and the ring (last)) the rings are considered identical. Each new ring
// is added to the string ring_list_string.

     ring_list=ring_list.sort();
     thjalp=-1;
     ring_list_string="";
       for(n=0;n<ring_list.length;n++){
       sum_and_ring=ring_list[n].split("#");
        if(thjalp!=parseFloat(sum_and_ring[0])){
        ring_list_string=ring_list_string+sum_and_ring[1]+"#";
        thjalp=parseFloat(sum_and_ring[0]);
        }
       }

// To chop of the last "#" (again).
ring_list_string=ring_list_string.substring(0,ring_list_string.length-1);

return ring_list_string;

}
// ############################### end func ############################################