2011/7/18 Merlin Moncure <mmoncure@xxxxxxxxx>: > 2011/7/18 Martín Marqués <martin.marques@xxxxxxxxx>: >> I'm building a table (which is a report that has to be printed) with a >> bunch of items (up to 300 in some cases) that have unitary price >> (stored in a numeric(9,2) field), how many there are, and the total >> price for each item. At the end of the table there is a total of all >> the items. >> >> The app is running on PHP and PG is the backend. >> >> The question is, how do I get the total of everything? >> >> Running it on PHP gives one value, doing a sum() on the backend gives >> another, and I'm starting to notice that even using python as a >> calculator gives me errors (big ones). Right now I'm doing the maths >> by hand to find out who has the biggest error, or if any is 100% >> accurate. > > I wouldn't even bother testing client implementations that are using > floating point numbers to do the math -- they are going to be wrong. > If you snoop around you should find math libraries that handle do a > better job handling exact numbers for most popular languages. A few > languages, like the hated COBOL, have them built in. > All my testing has suggested that Perl number addition, etc. is arbitrary precision safe. (I usually use additional libraries for finer control though). I don't know about PHP. Best Wishes, Chris Travers -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
