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=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Fun with Unbounded Rational Numbers
Date: Sun, 9 Apr 2017 10:56:29 +0200
Organization: Also freenews.netfront.net; news.tornevall.net;
 news.eternal-september.org
Message-ID: <occsq6$854$1@dont-email.me>
References: <ocaec1$a0p$1@dont-email.me> <87zifq831u.fsf@nightsong.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Sun, 9 Apr 2017 08:53:26 -0000 (UTC)
Injection-Info: mx02.eternal-september.org;
 posting-host="a97849d36a3c8ea2c5f5f919cb6231fd";
	logging-data="8356"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1/MT7o2nCe3lbwDxfOKddOFFIbmYYch/Qw="
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.8.0
In-Reply-To: <87zifq831u.fsf@nightsong.com>
Cancel-Lock: sha1:cfYLaiNqoSvC/FPWO1f5oVD4qNI=
Xref: news.eternal-september.org comp.lang.ada:46548
Date: 2017-04-09T10:56:29+02:00
List-Id: <comp.lang.ada>

On 04/09/2017 09:15 AM, Paul Rubin wrote:
>
> did you remember to recompute Y in your loop?  i.e.
>
>          M := Two * X;
>          Y = X * X - 2     -- <---- this might have been missing?
>          X := X - Y / M;

The implementation is

       X := R / Two;

       All_Iterations : for I in 1 .. 15 loop
          Y := X ** 2 - R;

          exit All_Iterations when abs Y < A;

          M := Two * X;
          X := X - Y / M;
       end loop All_Iterations;

       return X;

where R is the argument and A the accuracy.

-- 
Jeff Carter
"This trial is a travesty. It's a travesty of a mockery of a
sham of a mockery of a travesty of two mockeries of a sham. ...
Do you realize there's not a single homosexual on that jury?"
Bananas
27