Always false float comparisons

[Timon Gehr via Digitalmars-d]

On 17.05.2016 21:31, deadalnix wrote:
> On Tuesday, 17 May 2016 at 18:08:47 UTC, Timon Gehr wrote:
>> Right. Hence, the 80-bit CTFE results have to be converted to the
>> final precision at some point in order to commence the runtime
>> computation. This means that additional rounding happens, which was
>> not present in the original program. The additional total roundoff
>> error this introduces can exceed the roundoff error you would have
>> suffered by using the lower precision in the first place, sometimes
>> completely defeating precision-enhancing improvements to an algorithm.
>>
>
> WAT ? Is that really possible ?
>

Yes, I'm sorry, but this can and does happen.
Consider http://forum.dlang.org/post/nhi7m4$css$1@digitalmars.com

You can build similar examples involving only CTFE. Refer to 
http://forum.dlang.org/post/nhi9gh$fa4$1@digitalmars.com for an 
explanation of one case where this can happen. (I had actually written 
that post three days ago, and assumed that it had been posted to the 
newsgroup, but something went wrong, apparently.)