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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,548c38bb2d3e1bb6
X-Google-NewGroupId: yes
X-Google-Attributes: gida07f3367d7,domainid0,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news4.google.com!feeder1-2.proxad.net!proxad.net!feeder1-1.proxad.net!ecngs!feeder2.ecngs.de!news.netcologne.de!ramfeed1.netcologne.de!newsfeed.arcor.de!newsspool2.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: understanding floating point types
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: 
 <74406fc1-f64b-4a3e-9dd6-301f1ed467ab@w30g2000yqw.googlegroups.com>
 <mt3els2pgx78$.1dwj1p44vk16d.dlg@40tude.net>
 <7b0ca24f-4a5e-43a9-9f71-e4adffb98694@q1g2000yqg.googlegroups.com>
 <ghi6wajpwx2t.1u5g5erb7i1i6$.dlg@40tude.net>
 <37d8fbc1-fdaf-4ca9-9393-6163f2e3fa2e@s9g2000yqd.googlegroups.com>
Date: Sun, 22 Aug 2010 20:16:15 +0200
Message-ID: <toekjoyml5tx$.4xvgjm3annj4$.dlg@40tude.net>
NNTP-Posting-Date: 22 Aug 2010 20:16:13 CEST
NNTP-Posting-Host: 71b40fbd.newsspool3.arcor-online.net
X-Trace: 
 DXC=V8AXEJ6oLXOk:C4l9A;OcOMcF=Q^Z^V3H4Fo<]lROoRA8kF<OcfhCOKbTfcCacN4dB[6LHn;2LCVN[<mhadbfdUKE]K_QhhSli@>Sg_hJ48<=H
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news1.google.com comp.lang.ada:13620
Date: 2010-08-22T20:16:13+02:00
List-Id: <comp.lang.ada>

On Sun, 22 Aug 2010 10:15:24 -0700 (PDT), Ada novice wrote:

> I didn't quite get this part. In my previous example with say a = 2.33
> and b = 3.45. Does Multiplication of a with b mean converting each of
> a and b in model number first and then do the multiplication and
> afterwards approximating the result to the nearest model number? Or
> the multiplication will just be performed with the two numbers as 2.33
> X 3.45 = 8.0385 and then approximating this result to the nearest
> model number?

No, the result is 8.0385 (assuming 32-bit machine numbers). Try this:

with Ada.Text_IO; use Ada.Text_IO;
procedure Test_Float is
   type My_Float is digits 3;
   X : My_Float := 2.33;
   Y : My_Float := 3.45;
begin
   Put_Line ("Model view:" & My_Float'Image (X*Y));
   Put_Line ("The reality:" & Float'Image (Float (X*Y)));
end Test_Float;

It should print:

Model view: 8.04E+00
The reality: 8.03850E+00

When you print the number using My_Float'Image that rounds the machine
number to the nearest model number. In computations and conversions
machine numbers are left untouched.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de