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| 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> | |
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