On Thu, 23 Feb 2017 22:01:25 -0800, [email protected] wrote:
> Somewhat offtopic:
Feels like a bad place for offtopic discussions. You can ask questions in the
same IRC channel you evaled your example.
> toolforger: p6: say Inf cmp Inf
> camelia: rakudo-moar 320c2f: OUTPUT: «Same»
>
> I.e. Inf compares equal to itself - is this intentional?
Yes, and we didn't invent this concept. This area is governed by IEEE 2008-753
standard, section 6.1 of which has this to say on infinities:
"The behavior of infinity in floating-point arithmetic is derived from the
limiting cases of real arithmetic
with operands of arbitrarily large magnitude, when such a limit exists.
Infinities shall be interpreted in
the affine sense, that is: −∞ < {every finite number} < +∞"
It's not the only departure from mathematical result for the sake more
practically useful results. Division by zero has well-defined behaviour in
floating point math, and Rationals in Num view preserve it:
<Zoffix> m: say <1/0> == Inf
<camelia> rakudo-moar 320c2f: OUTPUT: «True»
<Zoffix> m: say <-1/0> == -Inf
<camelia> rakudo-moar 320c2f: OUTPUT: «True»
<Zoffix> m: say <0/0>.Num === NaN
<camelia> rakudo-moar 320c2f: OUTPUT: «True»
On Thu, 23 Feb 2017 22:22:22 -0800, [email protected] wrote:
> I would have a serious problem with any programming language where it
> isn't the
> case that asking "is $x the same thing as $x in every possible way"
> doesn't
> result in TRUE for all possible values of $x.
Then I'd hate to tell you, but such a value exists in most languages: a NaN:
<Zoffix> m: say NaN == NaN
<camelia> rakudo-moar 320c2f: OUTPUT: «False»
