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125 lines
5.5 KiB
HTML
125 lines
5.5 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- This manual documents how to install and use the Multiple Precision
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Floating-Point Reliable Library, version 3.1.4.
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Copyright 1991, 1993-2016 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document under
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the terms of the GNU Free Documentation License, Version 1.2 or any later
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version published by the Free Software Foundation; with no Invariant Sections,
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with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the
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license is included in GNU Free Documentation License. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>Introduction to MPFR (GNU MPFR 3.1.4)</title>
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<meta name="description" content="How to install and use GNU MPFR, a library for reliable multiple precision
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floating-point arithmetic, version 3.1.4.">
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<meta name="keywords" content="Introduction to MPFR (GNU MPFR 3.1.4)">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="index.html#Top" rel="up" title="Top">
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<link href="Installing-MPFR.html#Installing-MPFR" rel="next" title="Installing MPFR">
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<link href="Copying.html#Copying" rel="prev" title="Copying">
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</style>
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</head>
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<body lang="en">
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<a name="Introduction-to-MPFR"></a>
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<div class="header">
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<p>
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Next: <a href="Installing-MPFR.html#Installing-MPFR" accesskey="n" rel="next">Installing MPFR</a>, Previous: <a href="Copying.html#Copying" accesskey="p" rel="prev">Copying</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Introduction-to-MPFR-1"></a>
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<h2 class="chapter">1 Introduction to MPFR</h2>
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<p>MPFR is a portable library written in C for arbitrary precision arithmetic
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on floating-point numbers. It is based on the GNU MP library.
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It aims to provide a class of floating-point numbers with
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precise semantics. The main characteristics of MPFR, which make it differ
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from most arbitrary precision floating-point software tools, are:
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</p>
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<ul>
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<li> the MPFR code is portable, i.e., the result of any operation
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does not depend on the machine word size
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<code>mp_bits_per_limb</code> (64 on most current processors);
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</li><li> the precision in bits can be set <em>exactly</em> to any valid value
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for each variable (including very small precision);
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</li><li> MPFR provides the four rounding modes from the IEEE 754-1985
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standard, plus away-from-zero, as well as for basic operations as for other
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mathematical functions.
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</li></ul>
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<p>In particular, with a precision of 53 bits, MPFR is able to
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exactly reproduce all computations with double-precision machine
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floating-point numbers (e.g., <code>double</code> type in C, with a C
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implementation that rigorously follows Annex F of the ISO C99 standard
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and <code>FP_CONTRACT</code> pragma set to <code>OFF</code>) on the four arithmetic
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operations and the square root, except the default exponent range is much
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wider and subnormal numbers are not implemented (but can be emulated).
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</p>
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<p>This version of MPFR is released under the GNU Lesser General Public
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License, version 3 or any later version.
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It is permitted to link MPFR to most non-free programs, as long as when
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distributing them the MPFR source code and a means to re-link with a
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modified MPFR library is provided.
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</p>
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<a name="How-to-Use-This-Manual"></a>
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<h3 class="section">1.1 How to Use This Manual</h3>
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<p>Everyone should read <a href="MPFR-Basics.html#MPFR-Basics">MPFR Basics</a>. If you need to install the library
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yourself, you need to read <a href="Installing-MPFR.html#Installing-MPFR">Installing MPFR</a>, too.
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To use the library you will need to refer to <a href="MPFR-Interface.html#MPFR-Interface">MPFR Interface</a>.
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</p>
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<p>The rest of the manual can be used for later reference, although it is
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probably a good idea to glance through it.
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</p>
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<hr>
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<div class="header">
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<p>
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Next: <a href="Installing-MPFR.html#Installing-MPFR" accesskey="n" rel="next">Installing MPFR</a>, Previous: <a href="Copying.html#Copying" accesskey="p" rel="prev">Copying</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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