Subject Re: Wierd math???
Author Aage Johansen
Joe Martinez wrote:
I do understand the issues with floating point numbers. It's just that if
the SOURCE numbers all come out with 2 decimal places, I would expect their
SUM to also. I would just expect the database to add them together the
same way I would (line up the decemal points and add). It just seems like
a simple thing for it to do to get a "precise" sum from "precise" source

Understanding floating point ... The numbers may look precise to you, but
did you examine the binary representation?
If the numbers were to add up to exactly zero, then every one of the
numbers (and the intermediate sums) would have to be exactly represented -
not very likely.
Also, keep in mind that addition and subtraction causes larger errors than
multiplication and divison.
Then, -8.53483950180589E-16 isn't all that bas as an approximation of zero :-)

Aage J.