[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Making 'eq' == 'eql' in bignum branch

From: Herring, Davis
Subject: Re: Making 'eq' == 'eql' in bignum branch
Date: Wed, 29 Aug 2018 03:42:26 +0000

> Such a name should make clear that we're talking about a signed
> infinity, not one that makes 1/x continuous by adding a point at
> infinity to the real line.

Sure: the extended reals 
<https://en.wikipedia.org/wiki/Extended_real_number_line>, not the projective 
reals <https://en.wikipedia.org/wiki/Projectively_extended_real_line>.

> Signed infinities are convenient symbols, but they're not numbers; I
> recall the horrified reaction of a mathematician when I told her about
> IEEE infinities (she thought I was making it up about NaNs).

Of course +/-inf are numbers.  They're not real numbers, but neither are 
complex numbers, split-complex numbers, dual numbers, p-adic numbers, 
quaternions, octonions, sedenions, hyperreal numbers, or (please no) surreal 
numbers.  With all due respect to your mathematician friend, she has no 
exclusive claim over the definition (such as it is) of "number" (and I'm a bit 
surprised if she hadn't heard of at least one of the extended real lines I 

NaN, on the other hand, is of course a floating-point value that explicitly 
claims not to be a number.  I'm not sure whether to believe it; it seems very 
useful that the operations on floating-point "numbers" are closed, but that 
depends on NaN being one of them...


reply via email to

[Prev in Thread] Current Thread [Next in Thread]