From: Yusuke Endoh <mame@...>
Date: 2011-10-31T23:24:08+09:00
Subject: [ruby-core:40563] Re: [ruby-trunk - Feature #5321] Introducing Numeric#exact? and Numeric#inexact?

Hello,

2011/10/31 Kenta Murata <muraken@gmail.com>:
> I want to create a mathematical function which behaves like 1/x.
> This function is defined over real numbers except for zero,
> because lim_{x -> +0} 1/x = +inf while lim_{x -> -0} 1/x = -inf.
> So I want to raise Math::DomainError for the function with exact zero.
> But I don't want to raise the error for inexact zeros, such as 0.0, -0.0,
> BigDecimal("0"), and others which are instances of classes I don't know.
>
> If Numeric#inexact? and Numeric#exact? are given,
> I can realize the function more easily.


Thank you for the explanation.

You expect that 1/x does never raise any exception if x is an
inexact number, right?  I wonder if the expectation is valid.

But anyway, your use case is certainly convincing for me.
Thank you.

-- 
Yusuke Endoh <mame@tsg.ne.jp>