From: Simon Strandgaard <neoneye@...>
Date: 2004-02-16T20:04:56+09:00
Subject: Re: Math.sqrt(-1) doesn't raise ArgumentError

On Mon, 16 Feb 2004 19:10:37 +0900, Yukihiro Matsumoto wrote:

> Hi,
> 
> In message "Math.sqrt(-1) doesn't raise ArgumentError"
>     on 04/02/16, Simon Strandgaard <neoneye@adslhome.dk> writes:
> 
> |server> irb
> |irb(main):001:0> Math.sqrt(-1)
> |=> NaN
> |irb(main):002:0>
> |
> |NaN == Not a Number
> |
> |Why has sqrt behavier changed, when it hasn't for divisionbyzero?
> 
> Because sqrt is a float operation.
> 
>   p 3.0 / 0
>   => Infinity
> 
> 							matz.

I want to do an assert_equal in rubicon, like this

	Version.less_than("1.8.1") do
		assert_raise(ArgumentError) { Math.sqrt(-1) }
	end
	Version.greater_or_equal("1.8.1") do
		assert_equal(NaN, Math.sqrt(-1))
	end 

However How do I make an Float instance of NaN?


irb(main):001:0> Math.sqrt(-1)
=> NaN
irb(main):002:0> v = NaN
NameError: uninitialized constant NaN
        from (irb):2
irb(main):003:0> v = Math::NaN
NameError: uninitialized constant Math::NaN
        from (irb):3
irb(main):004:0> v = Math.NaN
NoMethodError: undefined method `NaN' for Math:Module
        from (irb):4
irb(main):005:0> v = Math.NaN
NoMethodError: undefined method `NaN' for Math:Module
        from (irb):5
irb(main):006:0> v = Math.sqrt(-1)
=> NaN
irb(main):007:0> v.class
=> Float
irb(main):008:0> x = Float::NaN
NameError: uninitialized constant Float::NaN
        from (irb):8
irb(main):009:0> x = Float.NaN
NoMethodError: undefined method `NaN' for Float:Class
        from (irb):9
irb(main):010:0> x = Float.new(NaN)
NameError: uninitialized constant NaN
        from (irb):10
irb(main):011:0>


--
Simon Strandgaard