> -----Original Message----- > From: Paul Tillotson [mailto:pntil@shentel.net] > Sent: Monday, April 26, 2004 4:41 PM > To: pgsql-general@postgresql.org > Subject: Re: Arbitrary precision modulo operation > > > I see there are a few misconceptions about numeric and > modulus on here: > > (1) A modulus operation on a numeric type should NOT have > rounding errors. The whole point of numeric is that it is an > arbitrary precision BASE 10 representation of your number. This is true > The modulus returns the (whole > number) remainder as a result of a division. This is true if the numeric values are integers. When the values are not integral, some non-integral results can be returned. 2.50 % 2.50 is 0 But 13.89 modulo 3.50 is 3.39 If you work it out on paper, you will see that 3.39 is the correct remainder. > (2) the modulus operator/function is, AFAIK, supposed to > return the modulus with the SAME SIGN as the divisor, so I > think this is a bug. That's what every other modulus operator > that I have ever seen does. Would you mind doing I would agree that a positive modulus is preferable. However, the negative result is also mathematically correct. > foodb=> SELECT version(); > > (3) MySQL just rounds large numbers to the highest value that > the type will support, and apparently, no arbitrary precision > types are listed on this page: > > http://dev.mysql.com/doc/mysql/en/Numberic_type_overview.html > > You can't expect to get a modulus from an out-of-range number. Should it not (therefore) throw an error of some sort? ---------------------------(end of broadcast)--------------------------- TIP 2: you can get off all lists at once with the unregister command (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
