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Re: [Chicken-users] From inexact to exact using the "-" procedure?


From: Jeronimo Pellegrini
Subject: Re: [Chicken-users] From inexact to exact using the "-" procedure?
Date: Sat, 24 Mar 2012 06:46:01 -0300
User-agent: Mutt/1.5.21 (2010-09-15)

On Fri, Mar 23, 2012 at 04:41:07PM -0400, John Cowan wrote:
> Jeronimo Pellegrini scripsit:
> 
> > #;5> (- a b)
> > 1.0
> 
> The imaginary part vanishes because R5RS treats 1.0+0.0i as a real number.
> However, R6RS does not and R7RS currently does not either, though that
> may change as a result of a current debate.  The rationale is that you
> don't know if the complex number is actually on the real line or just
> too close to it to discriminate.

I think it makes sense to classify a number as inexact if part
of its representation is inexact -- the same thing applies to
(/ 2 3.0), which is not the "partially exact rational 2/3.0",
using the same argument (how close is it to 2/3?)

J.




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