https://en.wikipedia.org/wiki/IEEE_floating_point#Roundings_to_nearest says that IEEE 754 provides two options for rounding to nearest: ties to even and ties away from zero.

However, under https://github.com/D-Programming-Language/phobos/blob/master/std/math.d#L4539 we have only one roundToNearest which, I presume, ties to even.

Is there a difficulty in providing the option for tieing away from zero?

Thanks.

-- 
Shriramana Sharma, Penguin #395953

On Friday, 11 December 2015 at 05:25:03 UTC, Shriramana Sharma wrote:
> https://en.wikipedia.org/wiki/IEEE_floating_point#Roundings_to_nearest says that IEEE 754 provides two options for rounding to nearest: ties to even and ties away from zero.
>
> However, under https://github.com/D-Programming-Language/phobos/blob/master/std/math.d#L4539 we have only one roundToNearest which, I presume, ties to even.
>
> Is there a difficulty in providing the option for tieing away from zero?
>
> Thanks.

Those are basically the rounding modes supported by the FPUs in hardware. Any other rounding modes would have to be emulated in software, which would require the compiler to generate completely different code instead of just changing a few bits in an FPU control register.