From: Nobuyoshi Nakada <nobu@...>
Date: 2009-05-11T19:03:59+09:00
Subject: [ruby-core:23423] Re: [Bug #1363] Wrong value for Hash of NaN

Hi,

At Wed, 8 Apr 2009 14:38:31 +0900,
Heesob Park wrote in [ruby-core:23154]:
> Ruby cannot handle NaN as a unique key of Hash.

It's easy to make them unique as key, I'm not sure which is
"correct" behavior though.

> I think this is related with the NaN comparing problem:
> 
> irb(main):001:0> 0/0.0 == 0/0.0
> => false
> irb(main):002:0> a = 0/0.0
> => NaN
> irb(main):003:0> a == a
> => false
> irb(main):004:0> a <=> a
> => nil

I think it's mathematically correct behavior, and different
thing from Hash.


Index: numeric.c
===================================================================
--- numeric.c	(revision 23390)
+++ numeric.c	(working copy)
@@ -1127,7 +1127,6 @@ flo_eql(VALUE x, VALUE y)
 	double a = RFLOAT_VALUE(x);
 	double b = RFLOAT_VALUE(y);
-#if defined(_MSC_VER) && _MSC_VER < 1300
-	if (isnan(a) || isnan(b)) return Qfalse;
-#endif
+	if (isnan(a) && isnan(b))
+	    return memcmp(&a, &b, sizeof(a)) ? Qfalse : Qtrue;
 	if (a == b)
 	    return Qtrue;


-- 
Nobu Nakada