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- <a name="boost_numeric_odeint.odeint_in_detail.using_boost__ref"></a><a class="link" href="using_boost__ref.html" title="Using boost::ref">Using
- boost::ref</a>
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- <p>
- In odeint all system functions and observers are passed by value. For example,
- if you call a <code class="computeroutput"><span class="identifier">do_step</span></code> method
- of a particular stepper or the integration functions, your system and your
- stepper will be passed by value:
- </p>
- <p>
- </p>
- <pre class="programlisting"><span class="identifier">rk4</span><span class="special">.</span><span class="identifier">do_step</span><span class="special">(</span> <span class="identifier">sys</span> <span class="special">,</span> <span class="identifier">x</span> <span class="special">,</span> <span class="identifier">t</span> <span class="special">,</span> <span class="identifier">dt</span> <span class="special">);</span> <span class="comment">// pass sys by value</span>
- </pre>
- <p>
- </p>
- <p>
- This behavior is suitable for most systems, especially if your system does
- not contain any data or only a few parameters. However, in some cases you
- might contain some large amount of data with you system function and passing
- them by value is not desired since the data would be copied.
- </p>
- <p>
- In such cases you can easily use <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span></code> (and
- its relative <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">cref</span></code>) which passes its argument by reference
- (or constant reference). odeint will unpack the arguments and no copying
- at all of your system object will take place:
- </p>
- <p>
- </p>
- <pre class="programlisting"><span class="identifier">rk4</span><span class="special">.</span><span class="identifier">do_step</span><span class="special">(</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span><span class="special">(</span> <span class="identifier">sys</span> <span class="special">)</span> <span class="special">,</span> <span class="identifier">x</span> <span class="special">,</span> <span class="identifier">t</span> <span class="special">,</span> <span class="identifier">dt</span> <span class="special">);</span> <span class="comment">// pass sys as references</span>
- </pre>
- <p>
- </p>
- <p>
- The same mechanism can be used for the observers in the integrate functions.
- </p>
- <div class="tip"><table border="0" summary="Tip">
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- <th align="left">Tip</th>
- </tr>
- <tr><td align="left" valign="top"><p>
- If you are using C++11 you can also use <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">ref</span></code>
- and <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">cref</span></code>
- </p></td></tr>
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- <td align="right"><div class="copyright-footer">Copyright © 2009-2015 Karsten Ahnert and Mario Mulansky<p>
- Distributed under the Boost Software License, Version 1.0. (See accompanying
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