Re: [COMMITTERS] pgsql: Add trigonometric functions that work in degrees.

Noah Misch <noah@leadboat.com> writes:
> On Mon, Apr 18, 2016 at 10:22:59PM -0400, Tom Lane wrote:
>> We could alternatively set extra_float_digits to its max value and hope
>> that off-by-one-in-the-last-place values would get printed as something
>> visibly different from the exact result.  I'm not sure I want to trust
>> that that works reliably; but maybe it would be worth printing the
>> result both ways, just to provide additional info when there's a failure.

> We'd have an independent problem if extra_float_digits=3 prints the same
> digits for distinguishable float values, so I wouldn't mind relying on it not
> to do that.  But can we expect the extra_float_digits=3 representation of
> those particular values to be the same for every implementation?

Hm?  The expected answer is exact (30, 45, or whatever) in each case.
If we get some residual low-order digits then it's a failure, so we don't
need to worry about whether it's the same failure everywhere.
        regards, tom lane