Feature #8994: add methods for Float to get if an NaN is quiet or not, also add class methods for Float to "generate" an quiet NaN and an loud NaN

• Status: Open
• Assignee: -
• Target version: -

[Hanmac (Hans Mackowiak)]

Currently its not easy possible to know of an NaN in ruby is silent or not

like Float::NAN.quiet?

there should also methods to make an new NaN like Float::quiet_nan, maybe with the possibility to set user data

also there is

[Float::NAN].pack("g") #=> "\x7F\xC0\x00\x00"
[0.0/0.0].pack("g") #=> "\xFF\xC0\x00\x00"

and

[-(0.0/0.0)].pack("g") #=> "\x7F\xC0\x00\x00"

so it seems that - can turn an quiet NaN into an loud one? (i am not 100% clear about that)
specially when using two different NaN in one operation like

[(0.0/0.0) + Float::NAN].pack("g") #=> "\xFF\xC0\x00\x00"
[Float::NAN + (0.0/0.0)].pack("g") #=> "\x7F\xC0\x00\x00"

Wikipedia says:
For example, a bit-wise IEEE floating-point standard single precision (32-bit) NaN would be: s111 1111 1axx xxxx xxxx xxxx xxxx xxxx where s is the sign (most often ignored in applications), a determines the type of NaN, and x is an extra payload (most often ignored in applications). If a = 1, it is a quiet NaN; if a is zero and the payload is nonzero, then it is a signaling NaN.

so it seems that the negation does it a bit wrong? i mean -@ should not change the value like that?

[jeremyevans0 (Jeremy Evans)]

• Tracker changed from Bug to Feature
• ruby -v deleted (ruby 2.1.0dev (2013-10-01) [x86_64-darwin12.5.0])
• Backport deleted (1.9.3: UNKNOWN, 2.0.0: UNKNOWN)