From: Joe Van Dyk <joevandyk@...>
Date: 2006-01-15T01:55:08+09:00
Subject: Re: Duration between two days

On 1/14/06, Sky Yin <sky.yin@gmail.com> wrote:
> According to the Rdoc of Date class, operator '-(x)' is described as:
>
> If x is a Date <http://www.ruby-doc.org/core/classes/Date.html>, return the
> number of days between the two dates; or, more precisely, how many days
> later the current date is than x.
>
> However, a quick test in irb gives me a weird result:
>
> >require 'date'
> true
> >a = Date.new 2004, 1, 1
> #<Date: 4906011/2,0,2299161>
> >b = Date.new 2004, 1, 3
> #<Date: 4906015/2,0,2299161>
> >b - a
> Rational(2, 1)
>
> Basic math tells me 2/1 = 2, so what's the point of returning Rational
> instead of Fixnum here?

It's something to do with Astronomical Julian Days and fractional days.