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: 103376,560b069fa82486f6
X-Google-Attributes: gid103376,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news3.google.com!news.germany.com!newsfeed.utanet.at!newsfeed01.chello.at!newsfeed.arcor.de!newsspool1.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Rounding with decimal 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: <fic4q7$1p6$1@nemesis.news.tpi.pl>
 <13kjevsjmhujaa3@corp.supernews.com> <fidva6$pkd$1@nemesis.news.tpi.pl>
Date: Mon, 26 Nov 2007 14:47:09 +0100
Message-ID: <1k7nof3469gt2.144br30askbb5.dlg@40tude.net>
NNTP-Posting-Date: 26 Nov 2007 14:39:48 CET
NNTP-Posting-Host: a89c8d73.newsspool3.arcor-online.net
X-Trace: 
 DXC=3h;Gjc@aX]4i6K;>iZ]763McF=Q^Z^V384Fo<]lROoR14nDHegD_]R5foo<?4_66Q7DNcfSJ;bb[5FCTGGVUmh?4LK[5LiR>kg2E=5^kAV?J]2
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news1.google.com comp.lang.ada:18627
Date: 2007-11-26T14:39:48+01:00
List-Id: <comp.lang.ada>

On Mon, 26 Nov 2007 08:15:02 +0000 (UTC), Wiktor Moskwa wrote:

> I'd like to know if there is "round up" and "unbiased rounding"
> implemented for decimal types in Ada and if not, how "is it usually done"?

Yep, this is a problem, I faced it too but for floating-point numbers when
implemented interval computations. There one needs rounding up and down as
well.

I would suggest something as clumsy as:

   -- Up-rounding multiplication
function "*" (Left, Right : My_Decimal) return My_Decimal is
   type Impl is new My_Decimal;
begin
   if Left = 0.0 then
      return 0.0;
   else
      declare
         Result : Impl := Impl'(Impl (Left) * Impl (Right));
      begin
         if Result / Left /= Right then
            return My_Decimal'Succ (My_Decimal (Result));
         else
            return My_Decimal (Result);
         end if;
      end;
   end if;
end "*";

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