Rich Shepard wrote:
In the early and mid-1980s we used a procedure for business
applications
involving money that worked regardless of programming language or
platform.
To each (float, real) monetary amount we added 0.005 and truncated the
result
to two digits on the right of the decimal point. In almost all cases,
this
allowed financial calculations to be correct to the nearest penny.
Financial calculations are still imperfect. Now and then I see this in
both my business and personal bank statements when reconciliation is
off by
a penny or two. The transaction amounts (debits and credits) match,
but the
bank comes out with a different total than do I. This is usually only
for a
month or two before we are once again in agreement.
Rich
Rich what causes the difference you are referring to is method used to
round, bankers rounding aka (round to even) vs basic rounding we are
taught in school aka (round half up).
http://en.wikipedia.org/wiki/Rounding
General what i do is leave more digits in the number than is needed then
round after all the calculations are done... A common problem
applications/databases suffer from is inconsistent precision. In one
place the database is using 4 digits another 6 in another 0 and in
another 2 digits. Be consistent in the use of precision if not, be
prepared to untangle a nightmare.
The money type i have found is absolutely worthless when doing math but
using it to simplify formating great.
select 123456789::text::money;
set session lc_monetary to 'fr_FR.UTF-8';
select 123456789::text::money
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