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  27 <a name="boost_multiprecision.ref.mpfr_ref"></a><a class="link" href="mpfr_ref.html" title="mpfr_float_backend">mpfr_float_backend</a>
  28 </h3></div></div></div>
  29 <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>
  30
  31 <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">unsigned</span> <span class="identifier">Digits10</span><span class="special">&gt;</span>
  32 <span class="keyword">class</span> <span class="identifier">mpfr_float_backend</span><span class="special">;</span>
  33
  34 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">mpfr_float_backend</span><span class="special">&lt;</span><span class="number">50</span><span class="special">&gt;</span> <span class="special">&gt;</span>    <span class="identifier">mpfr_float_50</span><span class="special">;</span>
  35 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">mpfr_float_backend</span><span class="special">&lt;</span><span class="number">100</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">mpfr_float_100</span><span class="special">;</span>
  36 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">mpfr_float_backend</span><span class="special">&lt;</span><span class="number">500</span><span class="special">&gt;</span> <span class="special">&gt;</span>   <span class="identifier">mpfr_float_500</span><span class="special">;</span>
  37 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">mpfr_float_backend</span><span class="special">&lt;</span><span class="number">1000</span><span class="special">&gt;</span> <span class="special">&gt;</span>  <span class="identifier">mpfr_float_1000</span><span class="special">;</span>
  38 <span class="keyword">typedef</span> <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">mpfr_float_backend</span><span class="special">&lt;</span><span class="number">0</span><span class="special">&gt;</span> <span class="special">&gt;</span>     <span class="identifier">mpfr_float</span><span class="special">;</span>
  39
  40 <span class="special">}}</span> <span class="comment">// namespaces</span>
  41 </pre>
  42 <p>
  43         Class template <code class="computeroutput"><span class="identifier">mpfr_float_backend</span></code>
  44         fulfils all of the requirements for a <a class="link" href="backendconc.html" title="Backend Requirements">Backend</a>
  45         type. Its members and non-member functions are deliberately not documented:
  46         these are considered implementation details that are subject to change.
  47       </p>
  48 <p>
  49         The class takes a single template parameter - <code class="computeroutput"><span class="identifier">Digits10</span></code>
  50         - which is the number of decimal digits precision the type should support.
  51         When this parameter is zero, then the precision can be set at runtime via
  52         <code class="computeroutput"><span class="identifier">number</span><span class="special">::</span><span class="identifier">default_precision</span></code> and <code class="computeroutput"><span class="identifier">number</span><span class="special">::</span><span class="identifier">precision</span></code>.
  53         Note that this type does not in any way change the GMP or MPFR library's
  54         global state (for example it does not change the default precision of the
  55         mpfr_t data type), therefore you can safely mix this type with existing code
  56         that uses GMP or MPFR, and also mix <code class="computeroutput"><span class="identifier">mpfr_float_backend</span></code>s
  57         of differing precision.
  58       </p>
  59 <p>
  60         The type of <code class="computeroutput"><span class="identifier">number_category</span><span class="special">&lt;</span><span class="identifier">cpp_int</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">...&gt;</span> <span class="special">&gt;::</span><span class="identifier">type</span></code> is <code class="computeroutput"><span class="identifier">mpl</span><span class="special">::</span><span class="identifier">int_</span><span class="special">&lt;</span><span class="identifier">number_kind_floating_point</span><span class="special">&gt;</span></code>.
  61       </p>
  62 <p>
  63         More information on this type can be found in the <a class="link" href="../tut/floats/mpfr_float.html" title="mpfr_float">tutorial</a>.
  64       </p>
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  69       and Christopher Kormanyos<p>
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