Re: Problem in

Hello Tom!

I think is too much for roundoff error

Found funny post about it:
https://randomascii.wordpress.com/2014/10/09/intel-underestimates-error-bounds-by-1-3-quintillion/ <https://randomascii.wordpress.com/2014/10/09/intel-underestimates-error-bounds-by-1-3-quintillion/>
http://notabs.org/fpuaccuracy/index.htm <http://notabs.org/fpuaccuracy/index.htm>

> On 25 Apr 2019, at 19:56, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Max Lipsky <maxlipsky(at)gmail(dot)com> writes:
>> SELECT acos(
>> cos(radians(48.9193))
>> * cos(radians(48.9193))
>> * cos(radians(2.5431) - radians(2.5431))
>> + sin(radians(48.9193))
>> * sin(radians(48.9193))
>> ) as result;
>
>> This returned [22003] ERROR: input is out of range
>
> Not too surprising, because (at least on my machine)
>
> regression=# select cos(radians(48.9193))
> regression-# * cos(radians(48.9193)) + sin(radians(48.9193))
> regression-# * sin(radians(48.9193));
> ?column?
> --------------------
> 1.0000000000000002
> (1 row)
>
> Problems of this sort are inevitable when working with finite-precision
> math.
>
> https://en.wikipedia.org/wiki/Round-off_error
>
> regards, tom lane