From: Heesob Park Date: 2009-04-08T14:38:31+09:00 Subject: [ruby-core:23154] [Bug #1363] Wrong value for Hash of NaN Bug #1363: Wrong value for Hash of NaN http://redmine.ruby-lang.org/issues/show/1363 Author: Heesob Park Status: Open, Priority: Normal ruby -v: ruby 1.9.1p0 (2009-01-30 revision 21907) [i686-linux] Ruby cannot handle NaN as a unique key of Hash. Here is an example: irb(main):001:0> h = {} => {} irb(main):002:0> h[0/0.0]=1 => 1 irb(main):003:0> h[0/0.0]=2 => 2 irb(main):004:0> h[0/0.0]=3 => 3 irb(main):005:0> h => {NaN=>1, NaN=>2, NaN=>3} irb(main):006:0> h[0/0.0] => nil 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 ---------------------------------------- http://redmine.ruby-lang.org