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<h1>QwtSpline Class Reference</h1> </div>
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<!-- doxytag: class="QwtSpline" -->
<p>A class for spline interpolation.
<a href="#_details">More...</a></p>
<p><code>#include <<a class="el" href="qwt__spline_8h_source.html">qwt_spline.h</a>></code></p>
<p><a href="class_qwt_spline-members.html">List of all members.</a></p>
<table class="memberdecls">
<tr><td colspan="2"><h2><a name="pub-types"></a>
Public Types</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">enum  </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">SplineType</a> { <br/>
  <a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231ca506b78ec81ab6d56a4bbce891490c857">Natural</a>,
<br/>
  <a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231ca500c12cdbdef35c62e9fab86c5727acb">Periodic</a>
<br/>
}</td></tr>
<tr><td colspan="2"><h2><a name="pub-methods"></a>
Public Member Functions</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">const QVector< double > & </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#abbc5c1cf6016fc57050f379250da031e">coefficientsA</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top">const QVector< double > & </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a1de897d6cc2d0d8dac840d15d0bb603e">coefficientsB</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top">const QVector< double > & </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a27d51429a7447b18a8f05a44b3418f89">coefficientsC</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a8eb42cf7f0f81bb7b7b885466f8ebbbf">isValid</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="class_qwt_spline.html">QwtSpline</a> & </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a8a597c34477dd4b5298db2d445b4e596">operator=</a> (const <a class="el" href="class_qwt_spline.html">QwtSpline</a> &)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">QPolygonF </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a14694e61052933921eda629062554d22">points</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a5d1e0ba35c637a88c66d9e4cbaf36e93">QwtSpline</a> ()</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a2e42391f76d0b3091bf7754239f3ff0d">QwtSpline</a> (const <a class="el" href="class_qwt_spline.html">QwtSpline</a> &)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#afc52fd49e7f00d57a0336059fae299c0">reset</a> ()</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a6ed13410b1d5f6b33ba0e3c2b07932cf">setPoints</a> (const QPolygonF &points)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a222953661f01658a16042d587196aff8">setSplineType</a> (<a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">SplineType</a>)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">SplineType</a> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a36442cbb781422e5b97ae242265dd4b4">splineType</a> () const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top">double </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a1f67187eefe2959f0c902532edf64d41">value</a> (double x) const </td></tr>
<tr><td class="memItemLeft" align="right" valign="top"> </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a90805882826469c94fdc871f18261bb6">~QwtSpline</a> ()</td></tr>
<tr><td colspan="2"><h2><a name="pro-methods"></a>
Protected Member Functions</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a1cdf09e841dd6a721eb788914273c484">buildNaturalSpline</a> (const QPolygonF &)</td></tr>
<tr><td class="memItemLeft" align="right" valign="top">bool </td><td class="memItemRight" valign="bottom"><a class="el" href="class_qwt_spline.html#a8184717f8c018e69fabd1e33ac68ef19">buildPeriodicSpline</a> (const QPolygonF &)</td></tr>
</table>
<hr/><a name="_details"></a><h2>Detailed Description</h2>
<div class="textblock"><p>A class for spline interpolation. </p>
<p>The <a class="el" href="class_qwt_spline.html" title="A class for spline interpolation.">QwtSpline</a> class is used for cubical spline interpolation. Two types of splines, natural and periodic, are supported.</p>
<dl class="user"><dt><b>Usage:</b></dt><dd><ol>
<li>
First call <a class="el" href="class_qwt_spline.html#a6ed13410b1d5f6b33ba0e3c2b07932cf" title="Calculate the spline coefficients.">setPoints()</a> to determine the spline coefficients for a tabulated function y(x). </li>
<li>
After the coefficients have been set up, the interpolated function value for an argument x can be determined by calling <a class="el" href="class_qwt_spline.html#a1f67187eefe2959f0c902532edf64d41">QwtSpline::value()</a>. </li>
</ol>
</dd></dl>
<dl class="user"><dt><b>Example:</b></dt><dd><div class="fragment"><pre class="fragment"><span class="preprocessor">#include <qwt_spline.h></span>
QPolygonF interpolate(<span class="keyword">const</span> QPolygonF& <a class="code" href="class_qwt_spline.html#a14694e61052933921eda629062554d22">points</a>, <span class="keywordtype">int</span> numValues)
{
<a class="code" href="class_qwt_spline.html" title="A class for spline interpolation.">QwtSpline</a> spline;
<span class="keywordflow">if</span> ( !spline.<a class="code" href="class_qwt_spline.html#a6ed13410b1d5f6b33ba0e3c2b07932cf" title="Calculate the spline coefficients.">setPoints</a>(points) )
<span class="keywordflow">return</span> points;
QPolygonF interpolatedPoints(numValues);
<span class="keyword">const</span> <span class="keywordtype">double</span> delta =
(points[numPoints - 1].x() - points[0].x()) / (points.size() - 1);
<span class="keywordflow">for</span>(i = 0; i < points.size(); i++) / interpolate
{
<span class="keyword">const</span> <span class="keywordtype">double</span> x = points[0].x() + i * delta;
interpolatedPoints[i].setX(x);
interpolatedPoints[i].setY(spline.<a class="code" href="class_qwt_spline.html#a1f67187eefe2959f0c902532edf64d41">value</a>(x));
}
<span class="keywordflow">return</span> interpolatedPoints;
}
</pre></div> </dd></dl>
</div><hr/><h2>Member Enumeration Documentation</h2>
<a class="anchor" id="a2bd2bda128f82acd596348eb8d64231c"></a><!-- doxytag: member="QwtSpline::SplineType" ref="a2bd2bda128f82acd596348eb8d64231c" args="" -->
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<td class="memname">enum <a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">QwtSpline::SplineType</a></td>
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<div class="memdoc">
<p>Spline type. </p>
<dl><dt><b>Enumerator: </b></dt><dd><table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"><em><a class="anchor" id="a2bd2bda128f82acd596348eb8d64231ca506b78ec81ab6d56a4bbce891490c857"></a><!-- doxytag: member="Natural" ref="a2bd2bda128f82acd596348eb8d64231ca506b78ec81ab6d56a4bbce891490c857" args="" -->Natural</em> </td><td>
<p>A natural spline. </p>
</td></tr>
<tr><td valign="top"><em><a class="anchor" id="a2bd2bda128f82acd596348eb8d64231ca500c12cdbdef35c62e9fab86c5727acb"></a><!-- doxytag: member="Periodic" ref="a2bd2bda128f82acd596348eb8d64231ca500c12cdbdef35c62e9fab86c5727acb" args="" -->Periodic</em> </td><td>
<p>A periodic spline. </p>
</td></tr>
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</dd>
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</div>
<hr/><h2>Constructor & Destructor Documentation</h2>
<a class="anchor" id="a5d1e0ba35c637a88c66d9e4cbaf36e93"></a><!-- doxytag: member="QwtSpline::QwtSpline" ref="a5d1e0ba35c637a88c66d9e4cbaf36e93" args="()" -->
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<td class="memname">QwtSpline::QwtSpline </td>
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<p>Constructor. </p>
</div>
</div>
<a class="anchor" id="a2e42391f76d0b3091bf7754239f3ff0d"></a><!-- doxytag: member="QwtSpline::QwtSpline" ref="a2e42391f76d0b3091bf7754239f3ff0d" args="(const QwtSpline &)" -->
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<td class="memname">QwtSpline::QwtSpline </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="class_qwt_spline.html">QwtSpline</a> & </td>
<td class="paramname"><em>other</em></td><td>)</td>
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<div class="memdoc">
<p>Copy constructor </p>
<dl><dt><b>Parameters:</b></dt><dd>
<table class="params">
<tr><td class="paramname">other</td><td>Spline used for initilization </td></tr>
</table>
</dd>
</dl>
</div>
</div>
<a class="anchor" id="a90805882826469c94fdc871f18261bb6"></a><!-- doxytag: member="QwtSpline::~QwtSpline" ref="a90805882826469c94fdc871f18261bb6" args="()" -->
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<td class="memname">QwtSpline::~QwtSpline </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
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<div class="memdoc">
<p>Destructor. </p>
</div>
</div>
<hr/><h2>Member Function Documentation</h2>
<a class="anchor" id="a1cdf09e841dd6a721eb788914273c484"></a><!-- doxytag: member="QwtSpline::buildNaturalSpline" ref="a1cdf09e841dd6a721eb788914273c484" args="(const QPolygonF &)" -->
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<td class="memname">bool QwtSpline::buildNaturalSpline </td>
<td>(</td>
<td class="paramtype">const QPolygonF & </td>
<td class="paramname"><em>points</em></td><td>)</td>
<td><code> [protected]</code></td>
</tr>
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<div class="memdoc">
<p>Determines the coefficients for a natural spline. </p>
<dl class="return"><dt><b>Returns:</b></dt><dd>true if successful </dd></dl>
</div>
</div>
<a class="anchor" id="a8184717f8c018e69fabd1e33ac68ef19"></a><!-- doxytag: member="QwtSpline::buildPeriodicSpline" ref="a8184717f8c018e69fabd1e33ac68ef19" args="(const QPolygonF &)" -->
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<td class="memname">bool QwtSpline::buildPeriodicSpline </td>
<td>(</td>
<td class="paramtype">const QPolygonF & </td>
<td class="paramname"><em>points</em></td><td>)</td>
<td><code> [protected]</code></td>
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<div class="memdoc">
<p>Determines the coefficients for a periodic spline. </p>
<dl class="return"><dt><b>Returns:</b></dt><dd>true if successful </dd></dl>
</div>
</div>
<a class="anchor" id="abbc5c1cf6016fc57050f379250da031e"></a><!-- doxytag: member="QwtSpline::coefficientsA" ref="abbc5c1cf6016fc57050f379250da031e" args="() const " -->
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<td class="memname">const QVector< double > & QwtSpline::coefficientsA </td>
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<td> const</td>
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<dl class="return"><dt><b>Returns:</b></dt><dd>A coefficients </dd></dl>
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</div>
<a class="anchor" id="a1de897d6cc2d0d8dac840d15d0bb603e"></a><!-- doxytag: member="QwtSpline::coefficientsB" ref="a1de897d6cc2d0d8dac840d15d0bb603e" args="() const " -->
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<td class="memname">const QVector< double > & QwtSpline::coefficientsB </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
<td> const</td>
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<dl class="return"><dt><b>Returns:</b></dt><dd>B coefficients </dd></dl>
</div>
</div>
<a class="anchor" id="a27d51429a7447b18a8f05a44b3418f89"></a><!-- doxytag: member="QwtSpline::coefficientsC" ref="a27d51429a7447b18a8f05a44b3418f89" args="() const " -->
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<td class="memname">const QVector< double > & QwtSpline::coefficientsC </td>
<td>(</td>
<td class="paramname"></td><td>)</td>
<td> const</td>
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<dl class="return"><dt><b>Returns:</b></dt><dd>C coefficients </dd></dl>
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<a class="anchor" id="a8eb42cf7f0f81bb7b7b885466f8ebbbf"></a><!-- doxytag: member="QwtSpline::isValid" ref="a8eb42cf7f0f81bb7b7b885466f8ebbbf" args="() const " -->
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<td class="memname">bool QwtSpline::isValid </td>
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<p>True if valid. </p>
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<a class="anchor" id="a8a597c34477dd4b5298db2d445b4e596"></a><!-- doxytag: member="QwtSpline::operator=" ref="a8a597c34477dd4b5298db2d445b4e596" args="(const QwtSpline &)" -->
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<td class="memname"><a class="el" href="class_qwt_spline.html">QwtSpline</a> & QwtSpline::operator= </td>
<td>(</td>
<td class="paramtype">const <a class="el" href="class_qwt_spline.html">QwtSpline</a> & </td>
<td class="paramname"><em>other</em></td><td>)</td>
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<p>Assignment operator </p>
<dl><dt><b>Parameters:</b></dt><dd>
<table class="params">
<tr><td class="paramname">other</td><td>Spline used for initilization </td></tr>
</table>
</dd>
</dl>
</div>
</div>
<a class="anchor" id="a14694e61052933921eda629062554d22"></a><!-- doxytag: member="QwtSpline::points" ref="a14694e61052933921eda629062554d22" args="() const " -->
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<td class="memname">QPolygonF QwtSpline::points </td>
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<td class="paramname"></td><td>)</td>
<td> const</td>
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<p>Return points passed by setPoints </p>
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<a class="anchor" id="afc52fd49e7f00d57a0336059fae299c0"></a><!-- doxytag: member="QwtSpline::reset" ref="afc52fd49e7f00d57a0336059fae299c0" args="()" -->
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<td class="memname">void QwtSpline::reset </td>
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<p>Free allocated memory and set size to 0. </p>
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<a class="anchor" id="a6ed13410b1d5f6b33ba0e3c2b07932cf"></a><!-- doxytag: member="QwtSpline::setPoints" ref="a6ed13410b1d5f6b33ba0e3c2b07932cf" args="(const QPolygonF &points)" -->
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<td class="memname">bool QwtSpline::setPoints </td>
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<td class="paramtype">const QPolygonF & </td>
<td class="paramname"><em>points</em></td><td>)</td>
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<p>Calculate the spline coefficients. </p>
<p>Depending on the value of <em>periodic</em>, this function will determine the coefficients for a natural or a periodic spline and store them internally.</p>
<dl><dt><b>Parameters:</b></dt><dd>
<table class="params">
<tr><td class="paramname">points</td><td>Points </td></tr>
</table>
</dd>
</dl>
<dl class="return"><dt><b>Returns:</b></dt><dd>true if successful </dd></dl>
<dl class="warning"><dt><b>Warning:</b></dt><dd>The sequence of x (but not y) values has to be strictly monotone increasing, which means <code>points[i].x() < points[i+1].x()</code>. If this is not the case, the function will return false </dd></dl>
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<a class="anchor" id="a222953661f01658a16042d587196aff8"></a><!-- doxytag: member="QwtSpline::setSplineType" ref="a222953661f01658a16042d587196aff8" args="(SplineType)" -->
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<td class="memname">void QwtSpline::setSplineType </td>
<td>(</td>
<td class="paramtype"><a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">SplineType</a> </td>
<td class="paramname"><em>splineType</em></td><td>)</td>
<td></td>
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<p>Select the algorithm used for calculating the spline</p>
<dl><dt><b>Parameters:</b></dt><dd>
<table class="params">
<tr><td class="paramname">splineType</td><td>Spline type </td></tr>
</table>
</dd>
</dl>
<dl class="see"><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_spline.html#a36442cbb781422e5b97ae242265dd4b4">splineType()</a> </dd></dl>
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</div>
<a class="anchor" id="a36442cbb781422e5b97ae242265dd4b4"></a><!-- doxytag: member="QwtSpline::splineType" ref="a36442cbb781422e5b97ae242265dd4b4" args="() const " -->
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<td class="memname"><a class="el" href="class_qwt_spline.html#a2bd2bda128f82acd596348eb8d64231c">QwtSpline::SplineType</a> QwtSpline::splineType </td>
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<td class="paramname"></td><td>)</td>
<td> const</td>
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<dl class="return"><dt><b>Returns:</b></dt><dd>the spline type </dd></dl>
<dl class="see"><dt><b>See also:</b></dt><dd><a class="el" href="class_qwt_spline.html#a222953661f01658a16042d587196aff8">setSplineType()</a> </dd></dl>
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<a class="anchor" id="a1f67187eefe2959f0c902532edf64d41"></a><!-- doxytag: member="QwtSpline::value" ref="a1f67187eefe2959f0c902532edf64d41" args="(double x) const " -->
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<td class="memname">double QwtSpline::value </td>
<td>(</td>
<td class="paramtype">double </td>
<td class="paramname"><em>x</em></td><td>)</td>
<td> const</td>
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<p>Calculate the interpolated function value corresponding to a given argument x. </p>
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