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<div class="titlepage"><div><div><h3 class="title">
<a name="boost_numeric_odeint.concepts.controlled_stepper"></a><a class="link" href="controlled_stepper.html" title="Controlled Stepper">Controlled
      Stepper</a>
</h3></div></div></div>
<p>
        This concept specifies the interface a controlled stepper has to fulfill
        to be used within <a class="link" href="../odeint_in_detail/integrate_functions.html" title="Integrate functions">integrate
        functions</a>.
      </p>
<h5>
<a name="boost_numeric_odeint.concepts.controlled_stepper.h0"></a>
        <span class="phrase"><a name="boost_numeric_odeint.concepts.controlled_stepper.description"></a></span><a class="link" href="controlled_stepper.html#boost_numeric_odeint.concepts.controlled_stepper.description">Description</a>
      </h5>
<p>
        A controlled stepper following this Controlled Stepper concept provides the
        possibility to perform one step of the solution <span class="emphasis"><em>x(t)</em></span>
        of an ODE with step-size <span class="emphasis"><em>dt</em></span> to obtain <span class="emphasis"><em>x(t+dt)</em></span>
        with a given step-size <span class="emphasis"><em>dt</em></span>. Depending on an error estimate
        of the solution the step might be rejected and a smaller step-size is suggested.
      </p>
<h5>
<a name="boost_numeric_odeint.concepts.controlled_stepper.h1"></a>
        <span class="phrase"><a name="boost_numeric_odeint.concepts.controlled_stepper.associated_types"></a></span><a class="link" href="controlled_stepper.html#boost_numeric_odeint.concepts.controlled_stepper.associated_types">Associated
        types</a>
      </h5>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
            <p><span class="bold"><strong>state_type</strong></span></p>
<p><code class="computeroutput"><span class="identifier">Stepper</span><span class="special">::</span><span class="identifier">state_type</span></code></p>
<p>The
            type characterizing the state of the ODE, hence <span class="emphasis"><em>x</em></span>.</p>
          </li>
<li class="listitem">
            <p><span class="bold"><strong>deriv_type</strong></span></p>
<p><code class="computeroutput"><span class="identifier">Stepper</span><span class="special">::</span><span class="identifier">deriv_type</span></code></p>
<p>The
            type characterizing the derivative of the ODE, hence <span class="emphasis"><em>d x/dt</em></span>.</p>
          </li>
<li class="listitem">
            <p><span class="bold"><strong>time_type</strong></span></p>
<p><code class="computeroutput"><span class="identifier">Stepper</span><span class="special">::</span><span class="identifier">time_type</span></code></p>
<p>The
            type characterizing the dependent variable of the ODE, hence the time
            <span class="emphasis"><em>t</em></span>.</p>
          </li>
<li class="listitem">
            <p><span class="bold"><strong>value_type</strong></span></p>
<p><code class="computeroutput"><span class="identifier">Stepper</span><span class="special">::</span><span class="identifier">value_type</span></code></p>
<p>The
            numerical data type which is used within the stepper, something like
            <code class="computeroutput"><span class="keyword">float</span></code>, <code class="computeroutput"><span class="keyword">double</span></code>,
            <code class="computeroutput"><span class="identifier">complex</span><span class="special">&amp;</span><span class="identifier">lt</span><span class="special">;</span> <span class="keyword">double</span> <span class="special">&amp;</span><span class="identifier">gt</span><span class="special">;</span></code>.</p>
          </li>
<li class="listitem">
            <p><span class="bold"><strong>stepper_category</strong></span></p>
<p><code class="computeroutput"><span class="identifier">Stepper</span><span class="special">::</span><span class="identifier">stepper_category</span></code></p>
<p>A
            tag type characterizing the category of the stepper. This type must be
            convertible to <code class="computeroutput"><span class="identifier">controlled_stepper_tag</span></code>.</p>
          </li>
</ul></div>
<h5>
<a name="boost_numeric_odeint.concepts.controlled_stepper.h2"></a>
        <span class="phrase"><a name="boost_numeric_odeint.concepts.controlled_stepper.notation"></a></span><a class="link" href="controlled_stepper.html#boost_numeric_odeint.concepts.controlled_stepper.notation">Notation</a>
      </h5>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term"><code class="computeroutput"><span class="identifier">ControlledStepper</span></code></span></dt>
<dd><p>
              A type that is a model of Controlled Stepper
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">State</span></code></span></dt>
<dd><p>
              A type representing the state <span class="emphasis"><em>x</em></span> of the ODE
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">Time</span></code></span></dt>
<dd><p>
              A type representing the time <span class="emphasis"><em>t</em></span> of the ODE
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">stepper</span></code></span></dt>
<dd><p>
              An object of type <code class="computeroutput"><span class="identifier">ControlledStepper</span></code>
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">x</span></code></span></dt>
<dd><p>
              Object of type <code class="computeroutput"><span class="identifier">State</span></code>
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">t</span></code>, <code class="computeroutput"><span class="identifier">dt</span></code></span></dt>
<dd><p>
              Objects of type <code class="computeroutput"><span class="identifier">Time</span></code>
            </p></dd>
<dt><span class="term"><code class="computeroutput"><span class="identifier">sys</span></code></span></dt>
<dd><p>
              An object defining the ODE, should be a model of <a class="link" href="system.html" title="System">System</a>,
              <a class="link" href="symplectic_system.html" title="Symplectic System">Symplectic
              System</a>, <a class="link" href="simple_symplectic_system.html" title="Simple Symplectic System">Simple
              Symplectic System</a> or <a class="link" href="implicit_system.html" title="Implicit System">Implicit
              System</a>.
            </p></dd>
</dl>
</div>
<h5>
<a name="boost_numeric_odeint.concepts.controlled_stepper.h3"></a>
        <span class="phrase"><a name="boost_numeric_odeint.concepts.controlled_stepper.valid_expressions"></a></span><a class="link" href="controlled_stepper.html#boost_numeric_odeint.concepts.controlled_stepper.valid_expressions">Valid
        Expressions</a>
      </h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
                <p>
                  Name
                </p>
              </th>
<th>
                <p>
                  Expression
                </p>
              </th>
<th>
                <p>
                  Type
                </p>
              </th>
<th>
                <p>
                  Semantics
                </p>
              </th>
</tr></thead>
<tbody><tr>
<td>
                <p>
                  Do step
                </p>
              </td>
<td>
                <p>
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">stepper</span><span class="special">.</span><span class="identifier">try_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></pre>
<p>
                </p>
              </td>
<td>
                <p>
                  <code class="computeroutput"><span class="identifier">controlled_step_result</span></code>
                </p>
              </td>
<td>
                <p>
                  Tries one step of step size <code class="computeroutput"><span class="identifier">dt</span></code>.
                  If the step was successful, <code class="computeroutput"><span class="identifier">success</span></code>
                  is returned, the resulting state is written to <code class="computeroutput"><span class="identifier">x</span></code>,
                  the new time is stored in <code class="computeroutput"><span class="identifier">t</span></code>
                  and <code class="computeroutput"><span class="identifier">dt</span></code> now contains
                  a new (possibly larger) step-size for the next step. If the error
                  was too big, <code class="computeroutput"><span class="identifier">rejected</span></code>
                  is returned and the results are neglected - <code class="computeroutput"><span class="identifier">x</span></code>
                  and <code class="computeroutput"><span class="identifier">t</span></code> are unchanged
                  and <code class="computeroutput"><span class="identifier">dt</span></code> now contains
                  a reduced step-size to be used for the next try.
                </p>
              </td>
</tr></tbody>
</table></div>
<h5>
<a name="boost_numeric_odeint.concepts.controlled_stepper.h4"></a>
        <span class="phrase"><a name="boost_numeric_odeint.concepts.controlled_stepper.models"></a></span><a class="link" href="controlled_stepper.html#boost_numeric_odeint.concepts.controlled_stepper.models">Models</a>
      </h5>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
            <code class="computeroutput"><span class="identifier">controlled_error_stepper</span><span class="special">&lt;</span> <span class="identifier">runge_kutta_cash_karp54</span>
            <span class="special">&gt;</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">controlled_error_stepper_fsal</span><span class="special">&lt;</span> <span class="identifier">runge_kutta_dopri5</span>
            <span class="special">&gt;</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">controlled_error_stepper</span><span class="special">&lt;</span> <span class="identifier">runge_kutta_fehlberg78</span>
            <span class="special">&gt;</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">rosenbrock4_controller</span></code>
          </li>
<li class="listitem">
            <code class="computeroutput"><span class="identifier">bulirsch_stoer</span></code>
          </li>
</ul></div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2009-2015 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>)
      </p>
</div></td>
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