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| <h2><span class="refentrytitle">Struct template dim</span></h2> |
| <p>boost::units::dim — Dimension tag/exponent pair for a single fundamental dimension. </p> |
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| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../boost_units/Reference.html#header.boost.units.dim_hpp" title="Header <boost/units/dim.hpp>">boost/units/dim.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">,</span> <span class="keyword">typename</span> V<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="dim.html" title="Struct template dim">dim</a> <span class="special">{</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <a class="link" href="dim.html" title="Struct template dim">dim</a> <a name="boost.units.dim.type"></a><span class="identifier">type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="emphasis"><em><span class="identifier">unspecified</span></em></span> <a name="boost.units.dim.tag"></a><span class="identifier">tag</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">T</span> <a name="boost.units.dim.tag_type"></a><span class="identifier">tag_type</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">V</span> <a name="boost.units.dim.value_type"></a><span class="identifier">value_type</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2832489"></a><h2>Description</h2> |
| <p>The dim class represents a single dimension tag/dimension exponent pair. That is, <code class="computeroutput">dim<tag_type,value_type></code> is a pair where <code class="computeroutput">tag_type</code> represents the fundamental dimension being represented and <code class="computeroutput">value_type</code> represents the exponent of that fundamental dimension as a <code class="computeroutput">static_rational</code>. <code class="computeroutput">tag_type</code> must be a derived from a specialization of <code class="computeroutput">base_dimension</code>. Specialization of the following Boost.MPL metafunctions are provided</p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p><code class="computeroutput">mpl::plus</code> for two <code class="computeroutput">dims</code> </p></li> |
| <li class="listitem"><p><code class="computeroutput">mpl::minus</code> for two <code class="computeroutput">dims</code> </p></li> |
| <li class="listitem"><p><code class="computeroutput">mpl::negate</code> for a <code class="computeroutput">dim</code> </p></li> |
| </ul></div> |
| <p> |
| </p> |
| <p>These metafunctions all operate on the exponent, and require that the <code class="computeroutput">dim</code> operands have the same base dimension tag. In addition, multiplication and division by <code class="computeroutput">static_rational</code> is supported.</p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p><code class="computeroutput">mpl::times</code> for a <code class="computeroutput">static_rational</code> and a <code class="computeroutput">dim</code> in either order</p></li> |
| <li class="listitem"><p><code class="computeroutput">mpl::divides</code> for a <code class="computeroutput">static_rational</code> and a <code class="computeroutput">dim</code> in either order</p></li> |
| </ul></div> |
| <p> |
| </p> |
| <p>These metafunctions likewise operate on the exponent only. </p> |
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| <td align="right"><div class="copyright-footer">Copyright © 2003 -2008 Matthias Christian Schabel, 2007-2010 Steven |
| Watanabe<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| 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>) |
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