Re: convertFormat and signaling NaN
On 2011-03-13 17:24:57 -0700, Dan Zuras IEEE wrote:
While it is true that convertFormat doesn't preclude
formatOf being the same format as source, it is also
true that it does not include it.
What do you mean by "does not include it"?
The IEEE 754 standard says: "Implementations shall provide the
following formatOf conversion operations from all supported
floating-point formats to all supported floating-point formats,
as well as [...]".
So, if some format, e.g. binary64, is supported, then
binary64 convertFormat(binary64) shall be provided.
Further, is it not in keeping with the character
of C that syntax that leads to null operations are
permitted to be interpreted as removed? Thus,
-(-x) == x, or -(x - y) == y - x, et al.
No. F.8.2 says that such transformations are invalid if they
can change the result. It even mentions the case of signaling
317) Strict support for signaling NaNs -- not required by this
specification -- would invalidate these and other
transformations that remove arithmetic operators.
I recall the context is strict support for signaling NaNs.
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / Arénaire project (LIP, ENS-Lyon)