Hot score function mysql implementation

hot_score.sql

/* hot score */
/* http://bibwild.wordpress.com/2012/05/08/reddit-story-ranking-algorithm/ */   
drop function if exists hot;       
delimiter $$
create function hot(upvotes int, downvotes int, created_time int unsigned) returns double
       begin
              declare s    int;    
              declare ord  double; 
              declare secs int;    
              declare sign int;

              set s    = upvotes - downvotes;
              set ord  = log10(greatest(abs(s), 1));
              set secs = created_time - 1134028003;
              
              if     s > 0 then set sign = 1;
              elseif s < 0 then set sign = -1;
              else              set sign = 0;
              end if;

              return round((ord * sign) + (secs / 45000), 7);
       end $$
delimiter ;

To fix later: scores even / close to even are all the same:
hot(x, x+1, y) == hot(x+1, x, y) == hot(x, x, y)