On Thu, Feb 24, 2011 at 7:31 PM, Merlin Moncure <mmonc...@gmail.com> wrote: > the root issue I think here is that the string version of the double > precision math is approximated:
No, it's simpler than that, all double precision math is approximated. The root issue is that 2183.67 is not representable in a floating point binary number. Just like 1/3 isn't representable in base 10 (decimal) numbers many fractions aren't representable in base 2 (binary) numbers. The result are repeated decimals like 0.3333... if you multiply that by three you get 0.99999 and if you truncate that you get 0 insted of 1. It's the trunc() that's exposing the imprecision because like "=" it depends on the precise value of the number down to the last digit. Though depending on the arithmetic you can always make the precision expand beyond the last digit anyways -- when you multiply by 100 you magnify that imprecision too. -- greg -- Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-bugs
