ceph/src/boost/libs/math/doc/html/math_toolkit/high_precision/use_mpfr.html

   1 <html>
   2 <head>
   3 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   4 <title>Using With MPFR or GMP - High-Precision Floating-Point Library</title>
   5 <link rel="stylesheet" href="../../math.css" type="text/css">
   6 <meta name="generator" content="DocBook XSL Stylesheets V1.77.1">
   7 <link rel="home" href="../../index.html" title="Math Toolkit 2.5.1">
   8 <link rel="up" href="../high_precision.html" title="Using Boost.Math with High-Precision Floating-Point Libraries">
   9 <link rel="prev" href="float128.html" title="Using with GCC's __float128 datatype">
  10 <link rel="next" href="e_float.html" title="Using e_float Library">
  11 </head>
  12 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  13 <table cellpadding="2" width="100%"><tr>
  14 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td>
  15 <td align="center"><a href="../../../../../../index.html">Home</a></td>
  16 <td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td>
  17 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  19 <td align="center"><a href="../../../../../../more/index.htm">More</a></td>
  20 </tr></table>
  21 <hr>
  22 <div class="spirit-nav">
  23 <a accesskey="p" href="float128.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../high_precision.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="e_float.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
  24 </div>
  25 <div class="section">
  26 <div class="titlepage"><div><div><h3 class="title">
  27 <a name="math_toolkit.high_precision.use_mpfr"></a><a class="link" href="use_mpfr.html" title="Using With MPFR or GMP - High-Precision Floating-Point Library">Using With MPFR
  28       or GMP - High-Precision Floating-Point Library</a>
  29 </h3></div></div></div>
  30 <p>
  31         The special functions and tools in this library can be used with <a href="http://www.mpfr.org" target="_top">MPFR</a>
  32         (an arbitrary precision number type based on the <a href="http://gmplib.org/" target="_top">GNU
  33         Multiple Precision Arithmetic Library</a>), either via the bindings in
  34         <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpfr.hpp</a>,
  35         or via <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpreal.hpp</a>.
  36       </p>
  37 <p>
  38         <span class="bold"><strong>New projects are recommended to use <a href="../../../../../../libs/multiprecision/doc/html/index.html" target="_top">Boost.Multiprecision</a>
  39         with GMP/MPFR backend instead.</strong></span>
  40       </p>
  41 <p>
  42         In order to use these bindings you will need to have installed <a href="http://www.mpfr.org" target="_top">MPFR</a>
  43         plus its dependency the <a href="http://gmplib.org" target="_top">GMP library</a>.
  44         You will also need one of the two supported C++ wrappers for MPFR: <a href="http://math.berkeley.edu/~wilken/code/gmpfrxx/" target="_top">gmpfrxx (or mpfr_class)</a>,
  45         or <a href="http://www.holoborodko.com/pavel/mpfr/" target="_top">mpfr-C++ (mpreal)</a>.
  46       </p>
  47 <p>
  48         Unfortunately neither <code class="computeroutput"><span class="identifier">mpfr_class</span></code>
  49         nor <code class="computeroutput"><span class="identifier">mpreal</span></code> quite satisfy
  50         our conceptual requirements, so there is a very thin set of additional interfaces
  51         and some helper traits defined in <a href="../../../../../../boost/math/bindings/mpfr.hpp" target="_top">boost/math/bindings/mpfr.hpp</a>
  52         and <a href="../../../../../../boost/math/bindings/mpreal.hpp" target="_top">boost/math/bindings/mpreal.hpp</a>
  53         that you should use in place of including 'gmpfrxx.h' or 'mpreal.h' directly.
  54         The classes <code class="computeroutput"><span class="identifier">mpfr_class</span></code> or
  55         <code class="computeroutput"><span class="identifier">mpreal</span></code> are then usable unchanged
  56         once this header is included, so for example <code class="computeroutput"><span class="identifier">mpfr_class</span></code>'s
  57         performance-enhancing expression templates are preserved and fully supported
  58         by this library:
  59       </p>
  60 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">bindings</span><span class="special">/</span><span class="identifier">mpfr</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  61 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">special_functions</span><span class="special">/</span><span class="identifier">gamma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  62
  63 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
  64 <span class="special">{</span>
  65    <span class="identifier">mpfr_class</span><span class="special">::</span><span class="identifier">set_dprec</span><span class="special">(</span><span class="number">500</span><span class="special">);</span> <span class="comment">// 500 bit precision</span>
  66    <span class="comment">//</span>
  67    <span class="comment">// Note that the argument to tgamma is</span>
  68    <span class="comment">// an expression template - that's just fine here.</span>
  69    <span class="comment">//</span>
  70    <span class="identifier">mpfr_class</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">tgamma</span><span class="special">(</span><span class="identifier">sqrt</span><span class="special">(</span><span class="identifier">mpfr_class</span><span class="special">(</span><span class="number">2</span><span class="special">)));</span>
  71    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setprecision</span><span class="special">(</span><span class="number">50</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
  72 <span class="special">}</span>
  73 </pre>
  74 <p>
  75         Alternatively use with <code class="computeroutput"><span class="identifier">mpreal</span></code>
  76         would look like:
  77       </p>
  78 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">bindings</span><span class="special">/</span><span class="identifier">mpreal</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  79 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">math</span><span class="special">/</span><span class="identifier">special_functions</span><span class="special">/</span><span class="identifier">gamma</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  80
  81 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
  82 <span class="special">{</span>
  83    <span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span><span class="special">::</span><span class="identifier">set_precision</span><span class="special">(</span><span class="number">500</span><span class="special">);</span> <span class="comment">// 500 bit precision</span>
  84    <span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span> <span class="identifier">v</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">math</span><span class="special">::</span><span class="identifier">tgamma</span><span class="special">(</span><span class="identifier">sqrt</span><span class="special">(</span><span class="identifier">mpfr</span><span class="special">::</span><span class="identifier">mpreal</span><span class="special">(</span><span class="number">2</span><span class="special">)));</span>
  85    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">setprecision</span><span class="special">(</span><span class="number">50</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
  86 <span class="special">}</span>
  87 </pre>
  88 <p>
  89         For those functions that are based upon the <a class="link" href="../lanczos.html" title="The Lanczos Approximation">Lanczos
  90         approximation</a>, the bindings defines a series of approximations with
  91         up to 61 terms and accuracy up to approximately 3e-113. This therefore sets
  92         the upper limit for accuracy to the majority of functions defined this library
  93         when used with either <code class="computeroutput"><span class="identifier">mpfr_class</span></code>
  94         or <code class="computeroutput"><span class="identifier">mpreal</span></code>.
  95       </p>
  96 <p>
  97         There is a concept checking test program for mpfr support <a href="../../../../../../libs/math/test/mpfr_concept_check.cpp" target="_top">here</a>
  98         and <a href="../../../../../../libs/math/test/mpreal_concept_check.cpp" target="_top">here</a>.
  99       </p>
 100 </div>
 101 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 102 <td align="left"></td>
 103 <td align="right"><div class="copyright-footer">Copyright &#169; 2006-2010, 2012-2014 Nikhar Agrawal,
 104       Anton Bikineev, Paul A. Bristow, Marco Guazzone, Christopher Kormanyos, Hubert
 105       Holin, Bruno Lalande, John Maddock, Jeremy Murphy, Johan R&#229;de, Gautam Sewani,
 106       Benjamin Sobotta, Thijs van den Berg, Daryle Walker and Xiaogang Zhang<p>
 107         Distributed under the Boost Software License, Version 1.0. (See accompanying
 108         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 109       </p>
 110 </div></td>
 111 </tr></table>
 112 <hr>
 113 <div class="spirit-nav">
 114 <a accesskey="p" href="float128.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../high_precision.html"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="e_float.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
 115 </div>
 116 </body>
 117 </html>