\set ECHO none
SELECT to_days('0001-01-01');
 to_days 
---------
     366
(1 row)

SELECT from_days(1);
   from_days   
---------------
 01-02-0001 BC
(1 row)

SELECT to_days('2011-08-15');
 to_days 
---------
  734729
(1 row)

SELECT from_days(734729);
 from_days  
------------
 08-15-2011
(1 row)

SELECT from_days(to_days(now()::date)) = now()::date;
 ?column? 
----------
 t
(1 row)

ROLLBACK;