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From Guillaume Melquiond Tue Dec 5 10:13:03 2006 X-Apparently-To: ahd6974-boostorg -at- yahoo.com via 68.142.206.151; Tue, 05 Dec 2006 10:13:22 -0800 X-Originating-IP: [140.77.167.16] Return-Path: <guillaume.melquiond -at- ens-lyon.fr> Authentication-Results: mta300.mail.re4.yahoo.com from=ens-lyon.fr; domainkeys=neutral (no sig) Received: from 140.77.167.16 (EHLO pilet.ens-lyon.fr) (140.77.167.16) by mta300.mail.re4.yahoo.com with SMTP; Tue, 05 Dec 2006 10:13:22 -0800 Received: from localhost (localhost [127.0.0.1]) by pilet.ens-lyon.fr (Postfix) with ESMTP id 129B515BBB3 for <ahd6974-boostorg -at- yahoo.com>; Tue, 5 Dec 2006 19:13:21 +0100 (CET) Received: from pilet.ens-lyon.fr ([127.0.0.1]) by localhost (pilet [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 23702-21 for <ahd6974-boostorg -at- yahoo.com>; Tue, 5 Dec 2006 19:13:16 +0100 (CET) Received: from [140.77.13.110] (unknown [140.77.13.110]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (Client did not present a certificate) by pilet.ens-lyon.fr (Postfix) with ESMTP id 61C6E15BB8B for <ahd6974-boostorg -at- yahoo.com>; Tue, 5 Dec 2006 19:13:16 +0100 (CET) Subject: Re: [boost] Need your permission to correct license & copyright issues From: "Guillaume Melquiond" <guillaume.melquiond -at- ens-lyon.fr> Add to Address Book Add Mobile Alert To: ahd6974-boostorg -at- yahoo.com [Edit - Delete] In-Reply-To: <20061204155943.25677.qmail@web33503.mail.mud.yahoo.com> References: <20061204155943.25677.qmail@web33503.mail.mud.yahoo.com> Content-Type: text/plain; charset=ISO-8859-1 Date: Tue, 05 Dec 2006 19:13:03 +0100 Message-Id: <1165342383.8556.52.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.6.3 Content-Transfer-Encoding: 8bit X-Virus-Scanned: by amavisd-new-20030616-p10 (Debian) at ens-lyon.fr Content-Length: 787 Le lundi 04 décembre 2006 à 07:59 -0800, Andreas Huber a écrit : > Hello Sylvain & Guillaume > > Quite a while ago it was decided that every file that goes into the > 1.34 release of the Boost distribution (www.boost.org) needs uniform > license and copyright information. For more information please see: > > <http://www.boost.org/more/license_info.html> I know about this page. But it does not seem clear to me that the license is fine for documentation files (they are the only ones missing a license statement, the code is fine). Especially as the first question of the FAQ only speaks about "source and header files". Anyway, I will let you judge of whether the license is adapted or not; and I give you permission to do the following on the files of the documentation: > 1. Replace the old license text with: > > "Distributed under the Boost Software License, Version 1.0. (See > accompanying file LICENSE_1_0.txt or copy at > http://www.boost.org/LICENSE_1_0.txt)" > > 2. (Optional) Run all html through HTML Tidy <http://tidy.sf.net> Best regards, Guillaume PS: you may want to take a look at your mail server, as your mails are categorized as spam because of the following checks: - DNS_FROM_RFC_ABUSE Envelope sender in abuse.rfc-ignorant.org - DNS_FROM_RFC_POST Envelope sender in postmaster.rfc-ignorant.org - DNS_FROM_RFC_WHOIS Envelope sender in whois.rfc-ignorant.org [SVN r36507]
123 lines
6.3 KiB
HTML
123 lines
6.3 KiB
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="Content-Language" content="en-us">
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<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
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<link rel="stylesheet" type="text/css" href="../../../../boost.css">
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<title>Choosing Your Own Interval Type</title>
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</head>
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<body lang="en">
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<h1>Choosing Your Own Interval Type</h1>
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<p>First of all, you need to select your base type. In order to obtain an
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useful interval type, the numbers should respect some requirements. Please
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refer to <a href="numbers.htm">this page</a> in order to see them. When
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your base type is robust enough, you can go to the next step: the choice of
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the policies.</p>
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<p>As you should already know if you did not come to this page by accident,
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the <code>interval</code> class expect a policies argument describing the
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<a href="rounding.htm">rounding</a> and <a href="checking.htm">checking</a>
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policies. The first thing to do is to verify if the default policies are or
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are not adapted to your case. If your base type is not <code>float</code>,
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<code>double</code>, or <code>long double</code>, the default rounding
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policy is probably not adapted. However, by specializing
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<code>interval_lib::rounded_math</code> to your base type, the default
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rounding policy will be suitable.</p>
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<p>The default policies define an interval type that performs precise
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computations (for <code>float</code>, <code>double</code>, <code>long
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double</code>), detects invalid numbers and throws exception each times an
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empty interval is created. This is a brief description and you should refer
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to the corresponding sections for a more precise description of the default
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policies. Unless you need some special behavior, this default type is
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usable in a lot of situations.</p>
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<p>After having completely defined the interval type (and its policies),
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the only thing left to do is to verify that the constants are defined and
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<code>std::numeric_limits</code> is correct (if needed). Now you can use
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your brand new interval type.</p>
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<h2>Some Examples</h2>
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<h3>Solving systems</h3>
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<p>If you use the interval library in order to solve equation and
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inequation systems by bisection, something like
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<code>boost::interval<double></code> is probably what you need. The
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computations are precise, and they may be fast if enclosed in a protected
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rounding mode block (see the <a href="rounding.htm#perf">performance</a>
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section). The comparison are "certain"; it is probably the most used type
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of comparison, and the other comparisons are still accessible by the
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explicit comparison functions. The checking forbid empty interval; they are
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not needed since there would be an empty interval at end of the computation
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if an empty interval is created during the computation, and no root would
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be inside. The checking also forbid invalid numbers (NaN for floating-point
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numbers). It can be a minor performance hit if you only use exact
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floating-point constants (which are clearly not NaNs); however, if
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performance really does matter, you will probably use a good compiler which
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knows how to inline functions and all these annoying little tests will
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magically disappear (if not, it is time to upgrade your compiler).</p>
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<h3>Manipulating wide intervals</h3>
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<p>You may want to use the library on intervals with imprecise bounds or on
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inexact numbers. In particular, it may be an existing algorithm that you
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want to rewrite and simplify by using the library. In that case, you are
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not really interested by the inclusion property; you are only interested by
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the computation algorithms the library provides. So you do not need to use
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any rounding; the checking also may not be useful. Use an "exact
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computation" rounding (you are allowed to think the name stangely applies
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to the situation) and a checking that never tests for any invalid numbers
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or empty intervals. By doing that, you will obtain library functions
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reduced to their minimum (an addition of two intervals will only be two
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additions of numbers).</p>
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<h3>Computing ranges</h3>
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<p>The inputs of your program may be empty intervals or invalid values (for
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example, a database can allow undefined values in some field) and the core
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of your program could also do some non-arithmetic computations that do not
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always propagate empty intervals. For example, in the library, the
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<code>hull</code> function can happily receive an empty interval but not
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generate an empty interval if the other input is valid. The
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<code>intersect</code> function is also able to produce empty intervals if
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the intervals do not overlap. In that case, it is not really interesting if
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an exception is thrown each time an empty interval is produced or an
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invalid value is used; it would be better to generate and propagate empty
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intervals. So you need to change the checking policy to something like
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<code>interval_lib::checking_base<T></code>.</p>
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<h3>Switching interval types</h3>
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<p>This example does not deal with a full case, but with a situation that
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can occur often. Sometimes, it can be useful to change the policies of an
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interval by converting it to another type. For example, this happens when
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you use an unprotected version of the interval type in order to speed up
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the computations; it is a change of the rounding policy. It also happens
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when you want to temporarily allow empty intervals to be created; it is a
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change of the checking policy. These changes should not be prohibited: they
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can greatly enhance a program (lisibility, interest, performance).</p>
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<hr>
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<p><a href="http://validator.w3.org/check?uri=referer"><img border="0" src=
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"http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional"
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height="31" width="88"></a></p>
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<p>Revised
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<!--webbot bot="Timestamp" s-type="EDITED" s-format="%Y-%m-%d" startspan -->2006-12-24<!--webbot bot="Timestamp" endspan i-checksum="12172" --></p>
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<p><i>Copyright © 2002 Guillaume Melquiond, Sylvain Pion, Hervé
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Brönnimann, Polytechnic University</i></p>
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<p><i>Distributed under the Boost Software License, Version 1.0. (See
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accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
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or copy at <a href=
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"http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</a>)</i></p>
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</body>
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</html>
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