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
X-Received: by 10.152.45.5 with SMTP id i5mr11423630lam.2.1384196046259;
 Mon, 11 Nov 2013 10:54:06 -0800 (PST)
Path: 
 border1.nntp.dca3.giganews.com!backlog3.nntp.dca3.giganews.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!s18no770334wiv.0!news-out.google.com!ft6ni11294wib.1!nntp.google.com!proxad.net!feeder1-2.proxad.net!137.226.231.214.MISMATCH!newsfeed.fsmpi.rwth-aachen.de!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Oliver Kleinke <oliver.kleinke@c-01a.de>
Newsgroups: comp.lang.ada
Subject: Re: A curiosity about decimal fixed point types...
Date: Mon, 11 Nov 2013 19:54:05 +0100
Organization: A noiseless patient Spider
Message-ID: <20131111195405.30842cb7@PC-8N-L>
References: <7d4f2e0c-0aed-4ba3-aa5a-0c2bc0c2c5a0@googlegroups.com>
Mime-Version: 1.0
Injection-Info: mx05.eternal-september.org;
 posting-host="434901b96fa29c45bb85d71213c80cc9";
 logging-data="2948"; mail-complaints-to="abuse@eternal-september.org";
 posting-account="U2FsdGVkX1/DlPdHupXHELVQe/50cdC3iJfmiw5yx7Q="
X-Newsreader: Claws Mail 3.9.2 (GTK+ 2.24.21; x86_64-pc-linux-gnu)
Cancel-Lock: sha1:7giUNDFTTyUuN1SHHrp4GkrfVmQ=
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-Original-Bytes: 2447
Xref: number.nntp.dca.giganews.com comp.lang.ada:183821
Date: 2013-11-11T19:54:05+01:00
List-Id: <comp.lang.ada>

Am Mon, 11 Nov 2013 07:04:12 -0800 (PST)
schrieb mockturtle <framefritti@gmail.com>:

> Dear all,
> just a silly curiosity about decimal fixed point types, e.g.,
> 
>  type Euro is delta 0.01 digits 20;  
>  -- Would be 20 enough? :-)
> 
> Are they currently used? Where? Since most of the examples are about
> money (mine and RM's) included, I guess that they were thought for
> financial applications, but I am unsure if nowadays financial
> software uses this type of types or just floating point.
> 
> Best regards
> 
> Riccardo
> 

Hi Riccardo,

The type definition that you provided is a good example for using fixed
point types for accurate representation. With a fixed-point type you
can avoid the occasional precision problems that floating-point types
suffer from. (For example if I type "0.1 + 0.2" in my
Python-interpreter it yields 0.30000000000000004.)
This can be very important if you sum up/integrate a range of
measurement data obtained from a sensor -- for example a gyro.
Also, on some machines fixed-point arithmetic 'might' be faster than
floating-point arithmetic -- e.g. machines without FPU -- but I guess
that also very much depends on the operations and the compiler, &c.