Gauche:NaNの扱い

ちゃんとやろうとすると厄介だなあ。とりあえず情報集め。

Discussions

http://www.cs.berkeley.edu/~wkahan/ieee754status/IEEE754.PDF "Lecture notes on the status of IEEE 754"; pp. 7--9 に詳細な説明あり。
http://mail.gnu.org/archive/html/guile-devel/2002-05/msg00018.html Guileでの実装の議論
http://archive.develooper.com/perl6-language@perl.org/msg08468.html Perl 6での実装の議論
http://groups.google.com/groups?threadm=m23cgapvhn.fsf%40aubrey.jaffer "Infinities in Scheme" by Aubrey Jaffer

Implementations

External Representation

	Chez	Guile	PLT Scheme	Gambit	Chicken	SCM	Bigloo	Kawa
NaN	+nan.0	+nan.0	+nan.0	+nan.	nan.	#.#	#.#	#i0/0
+Inf	+inf.0	+inf.0	+inf.0	+inf.	+inf.	+#.#	+#.#	#i1/0
-Inf	-inf.0	-inf.0	-inf.0	-inf.	-inf.	-#.#	-#.#	#i-1/0

Features

	Chez	Guile	PLT Scheme	Gambit	Chicken	SCM	Bigloo	Kawa
-0	O	O	O	O	O	X	X	O
readable?	O	X	O	O	O	X	X	O

NaN Reflexivity

(pred NaN NaN)

	Chez	Guile	PLT Scheme	Gambit	Chicken	SCM	Bigloo	Kawa
eq?		#t	#t	#t	#t	#t	#t	#t
=		#f	#f	#f	#f	#f	#f	#f
eqv?		#t	#t	#t	#t	#t	#f	#t
equal?		#t	#t	#t	#t	#t	#t	#t