[Bug other/60843] Documentation: 4.5 Integers/C99 6.3.1.3 ("reduce modulo 2^N")
joseph at codesourcery dot com
gcc-bugzilla@gcc.gnu.org
Wed Apr 30 21:52:00 GMT 2014
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60843
--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Wed, 30 Apr 2014, kdevel at vogtner dot de wrote:
> The problem is the erroneous wording "reduction modulo 2^N". *Reduction* by
> definition results in the least *nonnegative* number out of the list of
> congruent numbers, cf. http://www.youtube.com/watch?v=SO6l6sDwEFg&t=5m50s
It's perfectly normal English usage for "X with qualifier" to be outside
what would be understood by X without the qualifier. I think the use in
the GCC manual is a perfectly ordinary and well-understood use of the
term. The GCC manual is not trying to refer to any particular set of
definitions as normative references, and it's not trying to give formal
definitions.
If anything, I'd say strictly reduction modulo 2^N is a map from Z to Z /
2^N Z, i.e. producing an equivalence class of integers rather than a
single integer (and for modulo arithmetic, integer types are interpreted
as having values that are such equivalence classes).
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