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From: Marius Vollmer <marius.vollmer@uni-dortmund.de>
Cc: guile-devel@gnu.org
Subject: Re: ratio implementation
Date: Tue, 14 Oct 2003 14:39:51 +0200	[thread overview]
Message-ID: <ljr81gyovc.fsf@troy.dt.e-technik.uni-dortmund.de> (raw)
In-Reply-To: <3F8A853D.1020708@ccrma> (Bill Schottstaedt's message of "Mon, 13 Oct 2003 03:58:05 -0700")

Bill Schottstaedt <bil@ccrma.Stanford.EDU> writes:

> I notice that Guile doesn't support "exact complex", but
> it appears that some other Schemes do -- is this a desired
> extension?
>
> guile> (exact? 2/3+i)
> #f

Yes, it would be welcome.

> Under scm_ash, the doc string:
>
> 	    "Formally, the function returns an integer equivalent to\n"
> 	    "@code{(inexact->exact (floor (* @var{n} (expt 2 @var{cnt}))))}.\n"
>
> is incorrect:
> [...]
> The scm_quotient function assumes its arguments are ints/bignums,
> so it can't be used directly in ash.

Right!  Do you have a patch? :-) I will record this in our bug
database nevertheless.

> Also: (sqrt 9/49) -> 3/7?  Seems like it should parallel:
> guile> (expt 2 -2)
> 1/4

Hmm.  We would then also need

  (sqrt 4) => 2 (exact)

I'm not sure whether exact square roots are imortant: they will only
be useful when both the numerator and denominator are squares of
integers and those pairs will be rare, I'd say.  We could use GMP for
computing bignum square roots...


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  parent reply	other threads:[~2003-10-14 12:39 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-07-28 11:24 ratio implementation Bill Schottstaedt
2003-07-28 12:08 ` Han-Wen Nienhuys
2003-07-29  0:41 ` Kevin Ryde
2003-07-29 11:57   ` Bill Schottstaedt
2003-07-30 22:42     ` Kevin Ryde
2003-09-15 10:35 ` Marius Vollmer
2003-09-15 16:19   ` Rob Browning
2003-09-15 22:06   ` Dirk Herrmann
2003-09-15 22:59     ` Kevin Ryde
2003-09-16 11:39     ` Bill Schottstaedt
2003-09-16 21:36       ` Rob Browning
2003-09-18 21:09       ` Dirk Herrmann
2003-10-07 15:26         ` Marius Vollmer
2003-10-13 10:58           ` Bill Schottstaedt
2003-10-14  8:57             ` Marius Vollmer
2004-02-18 14:25               ` fractions.test Bill Schottstaedt
2003-10-14 12:39             ` Marius Vollmer [this message]
2003-10-14 22:56               ` ratio implementation Kevin Ryde
2003-10-14 13:03             ` Marius Vollmer
2003-10-14 23:37               ` Kevin Ryde
2003-10-16 11:49                 ` Bill Schottstaedt
2003-10-17 10:09                 ` Marius Vollmer
2003-10-17 11:47                   ` Bill Schottstaedt
2003-10-17 15:04                   ` Rob Browning
2003-10-18  0:45                   ` Kevin Ryde
2003-10-15 12:57               ` Bill Schottstaedt
2003-10-17 10:20                 ` Marius Vollmer
2003-10-17 15:14                   ` Rob Browning
2003-10-17 15:42                     ` Marius Vollmer
2003-10-14 23:01             ` Kevin Ryde
2003-10-18  0:55               ` ash using shifts (was: ratio implementation) Kevin Ryde
2003-10-07 15:24       ` ratio implementation Marius Vollmer

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