From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,509f8e43dc081fde
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news4.google.com!news.glorb.com!koehntopp.de!newsfeed01.sul.t-online.de!t-online.de!newsfeed.vmunix.org!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Simulation of fixed point in c WITH DIFFERENT BIT-WIDTH
Date: Thu, 03 Nov 2005 20:55:53 +0000
Organization: Pushface
Message-ID: <m2r79xa1t2.fsf@grendel.local>
References: <1130690498.388857.225170@g49g2000cwa.googlegroups.com>
 <1130690498.388857.225170@g49g2000cwa.googlegroups.com>
 <dka579$8fc$1@hudsucker.umdac.umu.se> <m2veza9s3k.fsf@grendel.local>
 <wccu0etyhar.fsf@shell01.TheWorld.com>
 <hbojdi82rqii$.1jkm8bqzmm7ik$.dlg@40tude.net>
NNTP-Posting-Host: pogner.demon.co.uk
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: news.demon.co.uk 1131051352 3207 62.49.19.209 (3 Nov 2005 20:55:52
 GMT)
X-Complaints-To: abuse@demon.net
NNTP-Posting-Date: Thu, 3 Nov 2005 20:55:52 +0000 (UTC)
Cancel-Lock: sha1:r5SmogDDeqtyTb/p+qyA/2vOPbY=
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (darwin)
Xref: g2news1.google.com comp.lang.ada:6158
Date: 2005-11-03T20:55:53+00:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> The abstraction many people mean is actually:
>
>    type Fraction is delta <> range -1.0 .. 1.0;
>    for Fraction'Size use 16*8; -- Give me as much as you can
>
> So delta isn't exactly 2.0**(-15), it is 2.0/(2.0**16 + 1.0).

When dealing with legacy software/hardware, which is the only reason
I'd expect to use fixed point, one really does mean 2.0/(2.0**16)!