]>
Commit | Line | Data |
---|---|---|
7c673cae FG |
1 | <html> |
2 | <head> | |
3 | <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> | |
4 | <title>gmp_rational</title> | |
5 | <link rel="stylesheet" href="../../../../../../../doc/src/boostbook.css" type="text/css"> | |
6 | <meta name="generator" content="DocBook XSL Stylesheets V1.77.1"> | |
7 | <link rel="home" href="../../../index.html" title="Chapter 1. Boost.Multiprecision"> | |
8 | <link rel="up" href="../rational.html" title="Rational Number Types"> | |
9 | <link rel="prev" href="cpp_rational.html" title="cpp_rational"> | |
10 | <link rel="next" href="tommath_rational.html" title="tommath_rational"> | |
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="cpp_rational.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../rational.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="tommath_rational.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> | |
24 | </div> | |
25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h4 class="title"> | |
27 | <a name="boost_multiprecision.tut.rational.gmp_rational"></a><a class="link" href="gmp_rational.html" title="gmp_rational">gmp_rational</a> | |
28 | </h4></div></div></div> | |
29 | <p> | |
30 | <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">gmp</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> | |
31 | </p> | |
32 | <pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">{</span> <span class="keyword">namespace</span> <span class="identifier">multiprecision</span><span class="special">{</span> | |
33 | ||
34 | <span class="keyword">class</span> <span class="identifier">gmp_rational</span><span class="special">;</span> | |
35 | ||
36 | <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_rational</span> <span class="special">></span> <span class="identifier">mpq_rational</span><span class="special">;</span> | |
37 | ||
38 | <span class="special">}}</span> <span class="comment">// namespaces</span> | |
39 | </pre> | |
40 | <p> | |
41 | The <code class="computeroutput"><span class="identifier">gmp_rational</span></code> back-end | |
42 | is used via the typedef <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">multiprecision</span><span class="special">::</span><span class="identifier">mpq_rational</span></code>. | |
43 | It acts as a thin wrapper around the <a href="http://gmplib.org" target="_top">GMP</a> | |
44 | <code class="computeroutput"><span class="identifier">mpq_t</span></code> to provide a rational | |
45 | number type that is a drop-in replacement for the native C++ number types, | |
46 | but with unlimited precision. | |
47 | </p> | |
48 | <p> | |
49 | As well as the usual conversions from arithmetic and string types, instances | |
50 | of <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_rational</span><span class="special">></span></code> | |
51 | are copy constructible and assignable from: | |
52 | </p> | |
53 | <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> | |
54 | <li class="listitem"> | |
55 | The <a href="http://gmplib.org" target="_top">GMP</a> native types: <code class="computeroutput"><span class="identifier">mpz_t</span></code>, <code class="computeroutput"><span class="identifier">mpq_t</span></code>. | |
56 | </li> | |
57 | <li class="listitem"> | |
58 | <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_int</span><span class="special">></span></code>. | |
59 | </li> | |
60 | </ul></div> | |
61 | <p> | |
62 | There is also a two-argument constructor that accepts a numerator and denominator | |
63 | (both of type <code class="computeroutput"><span class="identifier">number</span><span class="special"><</span><span class="identifier">gmp_int</span><span class="special">></span></code>). | |
64 | </p> | |
65 | <p> | |
66 | There are also non-member functions: | |
67 | </p> | |
68 | <pre class="programlisting"><span class="identifier">mpz_int</span> <span class="identifier">numerator</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">mpq_rational</span><span class="special">&);</span> | |
69 | <span class="identifier">mpz_int</span> <span class="identifier">denominator</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">mpq_rational</span><span class="special">&);</span> | |
70 | </pre> | |
71 | <p> | |
72 | which return the numerator and denominator of the number. | |
73 | </p> | |
74 | <p> | |
75 | It's also possible to access the underlying <code class="computeroutput"><span class="identifier">mpq_t</span></code> | |
76 | via the <code class="computeroutput"><span class="identifier">data</span><span class="special">()</span></code> | |
77 | member function of <code class="computeroutput"><span class="identifier">mpq_rational</span></code>. | |
78 | </p> | |
79 | <p> | |
80 | Things you should know when using this type: | |
81 | </p> | |
82 | <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> | |
83 | <li class="listitem"> | |
84 | Default constructed <code class="computeroutput"><span class="identifier">mpq_rational</span></code>s | |
85 | have the value zero (this is the <a href="http://gmplib.org" target="_top">GMP</a> | |
86 | default behavior). | |
87 | </li> | |
88 | <li class="listitem"> | |
89 | Division by zero results in a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">overflow_error</span></code> | |
90 | being thrown. | |
91 | </li> | |
92 | <li class="listitem"> | |
93 | Conversion from a string results in a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">runtime_error</span></code> | |
94 | being thrown if the string can not be interpreted as a valid rational | |
95 | number. | |
96 | </li> | |
97 | <li class="listitem"> | |
98 | No changes are made to the <a href="http://gmplib.org" target="_top">GMP</a> | |
99 | library's global settings, so this type can coexist with existing | |
100 | <a href="http://gmplib.org" target="_top">GMP</a> code. | |
101 | </li> | |
102 | <li class="listitem"> | |
103 | The code can equally be used with <a href="http://mpir.org/" target="_top">MPIR</a> | |
104 | as the underlying library - indeed that is the preferred option on | |
105 | Win32. | |
106 | </li> | |
107 | </ul></div> | |
108 | <h6> | |
109 | <a name="boost_multiprecision.tut.rational.gmp_rational.h0"></a> | |
110 | <span class="phrase"><a name="boost_multiprecision.tut.rational.gmp_rational.example"></a></span><a class="link" href="gmp_rational.html#boost_multiprecision.tut.rational.gmp_rational.example">Example:</a> | |
111 | </h6> | |
112 | <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">gmp</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> | |
113 | <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">multiprecision</span><span class="special">/</span><span class="identifier">gmp</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> | |
114 | <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> | |
115 | ||
116 | <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> | |
117 | <span class="special">{</span> | |
118 | <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">multiprecision</span><span class="special">;</span> | |
119 | ||
120 | <span class="identifier">mpq_rational</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> | |
121 | ||
122 | <span class="comment">// Do some arithmetic:</span> | |
123 | <span class="keyword">for</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">1</span><span class="special">;</span> <span class="identifier">i</span> <span class="special"><=</span> <span class="number">1000</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> | |
124 | <span class="identifier">v</span> <span class="special">*=</span> <span class="identifier">i</span><span class="special">;</span> | |
125 | <span class="identifier">v</span> <span class="special">/=</span> <span class="number">10</span><span class="special">;</span> | |
126 | ||
127 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">v</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 1000! / 10</span> | |
128 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">numerator</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
129 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">denominator</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> | |
130 | ||
131 | <span class="identifier">mpq_rational</span> <span class="identifier">w</span><span class="special">(</span><span class="number">2</span><span class="special">,</span> <span class="number">3</span><span class="special">);</span> <span class="comment">// component wise constructor</span> | |
132 | <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">w</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> <span class="comment">// prints 2/3</span> | |
133 | ||
134 | <span class="comment">// Access the underlying data:</span> | |
135 | <span class="identifier">mpq_t</span> <span class="identifier">q</span><span class="special">;</span> | |
136 | <span class="identifier">mpq_init</span><span class="special">(</span><span class="identifier">q</span><span class="special">);</span> | |
137 | <span class="identifier">mpq_set</span><span class="special">(</span><span class="identifier">q</span><span class="special">,</span> <span class="identifier">v</span><span class="special">.</span><span class="identifier">backend</span><span class="special">().</span><span class="identifier">data</span><span class="special">());</span> | |
138 | <span class="identifier">mpq_clear</span><span class="special">(</span><span class="identifier">q</span><span class="special">);</span> | |
139 | <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> | |
140 | <span class="special">}</span> | |
141 | </pre> | |
142 | </div> | |
143 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
144 | <td align="left"></td> | |
145 | <td align="right"><div class="copyright-footer">Copyright © 2002-2013 John Maddock and Christopher Kormanyos<p> | |
146 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
147 | 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>) | |
148 | </p> | |
149 | </div></td> | |
150 | </tr></table> | |
151 | <hr> | |
152 | <div class="spirit-nav"> | |
153 | <a accesskey="p" href="cpp_rational.html"><img src="../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../rational.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="tommath_rational.html"><img src="../../../../../../../doc/src/images/next.png" alt="Next"></a> | |
154 | </div> | |
155 | </body> | |
156 | </html> |