Re: [BUGS] BUG #4660: float functions return -0

Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:
>> I'm of the opinion that minus zero was put into the IEEE floating point
>> standard by people who know a great deal more about the topic than
>> anyone on this list does, and that we do not have the expertise to be
>> second-guessing how it should work. Not long ago we took out code that
>> was interfering with spec-compliant treatment of IEEE infinity; I think
>> we should take out this code too.

> If the original complaint was that it looked ugly in query results then the
> right way to fix it would surely in float4out and float8out. Interfering with
> IEEE floating points may be a bad idea but surely it's up to us how we want to
> represent those values in text.

> But without a convenient and widely used binary format that kind of restricts
> our options. If we squash -0 on float[48]out then dumps will lose information.

The point I'm trying to make is that we should deliver IEEE-compliant
results if we are on a platform that complies with the spec. Right down
to the minus sign. If that surprises people who are unfamiliar with the
spec, well, there are a lot of things about floating point arithmetic
that surprise people who aren't familiar with it.

regards, tom lane