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| <div class="titlepage"><div><div><h3 class="title"> |
| <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: |
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| <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> |
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| <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> |
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| <p> |
| The same mechanism can be used for the observers in the integrate functions. |
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| 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> |
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| <td align="right"><div class="copyright-footer">Copyright © 2009-2012 Karsten |
| Ahnert and Mario Mulansky<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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