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<HTML>
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<TITLE>The Synthesis ToolKit in C++ (STK)</TITLE>
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<div class="navpath"><a class="el" href="namespacestk.html">stk</a>::<a class="el" href="classstk_1_1TwoZero.html">TwoZero</a>
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<h1>stk::TwoZero Class Reference</h1><!-- doxytag: class="stk::TwoZero" --><!-- doxytag: inherits="stk::Filter" -->
<p>STK two-zero filter class.
<a href="#_details">More...</a></p>
<p><code>#include <<a class="el" href="TwoZero_8h_source.html">TwoZero.h</a>></code></p>
<div class="dynheader">
Inheritance diagram for stk::TwoZero:</div>
<div class="dynsection">
<div class="center">
<img src="classstk_1_1TwoZero.png" usemap="#stk::TwoZero_map" alt=""/>
<map id="stk::TwoZero_map" name="stk::TwoZero_map">
<area href="classstk_1_1Filter.html" alt="stk::Filter" shape="rect" coords="0,56,84,80"/>
<area href="classstk_1_1Stk.html" alt="stk::Stk" shape="rect" coords="0,0,84,24"/>
</map>
</div>
</div>
<p><a href="classstk_1_1TwoZero-members.html">List of all members.</a></p>
<table border="0" cellpadding="0" cellspacing="0">
<tr><td colspan="2"><h2>Public Member Functions</h2></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a5dabe7ec659bedf76a8f8d975f36dcd9"></a><!-- doxytag: member="stk::TwoZero::TwoZero" ref="a5dabe7ec659bedf76a8f8d975f36dcd9" args="()" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a5dabe7ec659bedf76a8f8d975f36dcd9">TwoZero</a> ()</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Default constructor creates a second-order pass-through filter. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="ab9890b28f0770485494b05639a4b2140"></a><!-- doxytag: member="stk::TwoZero::~TwoZero" ref="ab9890b28f0770485494b05639a4b2140" args="()" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#ab9890b28f0770485494b05639a4b2140">~TwoZero</a> ()</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Class destructor. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="aa1a1568aae3cd3d53011b3fc344cb086"></a><!-- doxytag: member="stk::TwoZero::ignoreSampleRateChange" ref="aa1a1568aae3cd3d53011b3fc344cb086" args="(bool ignore=true)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#aa1a1568aae3cd3d53011b3fc344cb086">ignoreSampleRateChange</a> (bool ignore=true)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">A function to enable/disable the automatic updating of class data when the STK sample rate changes. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a5ac82173333659fc31ca86cd2e134413"></a><!-- doxytag: member="stk::TwoZero::setB0" ref="a5ac82173333659fc31ca86cd2e134413" args="(StkFloat b0)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a5ac82173333659fc31ca86cd2e134413">setB0</a> (StkFloat b0)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the b[0] coefficient value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a1f090992845b9c85f3de15dfba583891"></a><!-- doxytag: member="stk::TwoZero::setB1" ref="a1f090992845b9c85f3de15dfba583891" args="(StkFloat b1)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a1f090992845b9c85f3de15dfba583891">setB1</a> (StkFloat b1)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the b[1] coefficient value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a98a7d6d1615753f338f75409d850a9b4"></a><!-- doxytag: member="stk::TwoZero::setB2" ref="a98a7d6d1615753f338f75409d850a9b4" args="(StkFloat b2)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a98a7d6d1615753f338f75409d850a9b4">setB2</a> (StkFloat b2)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the b[2] coefficient value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a3c8449660561108eb1873ca6b820a939"></a><!-- doxytag: member="stk::TwoZero::setCoefficients" ref="a3c8449660561108eb1873ca6b820a939" args="(StkFloat b0, StkFloat b1, StkFloat b2, bool clearState=false)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a3c8449660561108eb1873ca6b820a939">setCoefficients</a> (StkFloat b0, StkFloat b1, StkFloat b2, bool clearState=false)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set all filter coefficients. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a3a89facd2b94bbcfc2f06d8766a46329">setNotch</a> (StkFloat frequency, StkFloat radius)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Sets the filter coefficients for a "notch" at <em>frequency</em> (in Hz). <a href="#a3a89facd2b94bbcfc2f06d8766a46329"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="ae9808b0152902d0067ea24ccfba0b4ba"></a><!-- doxytag: member="stk::TwoZero::lastOut" ref="ae9808b0152902d0067ea24ccfba0b4ba" args="(void) const " -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#ae9808b0152902d0067ea24ccfba0b4ba">lastOut</a> (void) const </td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Return the last computed output value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="acf92a66aeb2024cfcdb9d71ecadf3d82"></a><!-- doxytag: member="stk::TwoZero::tick" ref="acf92a66aeb2024cfcdb9d71ecadf3d82" args="(StkFloat input)" -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#acf92a66aeb2024cfcdb9d71ecadf3d82">tick</a> (StkFloat input)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Input one sample to the filter and return one output. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a26e2a1e21831ccb414dbede864afc63c">tick</a> (<a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &frames, unsigned int channel=0)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Take a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object as inputs to the filter and replace with corresponding outputs. <a href="#a26e2a1e21831ccb414dbede864afc63c"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1TwoZero.html#a0ef9deab4fbc7e64511d4b6d38afd185">tick</a> (<a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &iFrames, <a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Take a channel of the <code>iFrames</code> object as inputs to the filter and write outputs to the <code>oFrames</code> object. <a href="#a0ef9deab4fbc7e64511d4b6d38afd185"></a><br/></td></tr>
</table>
<hr/><a name="_details"></a><h2>Detailed Description</h2>
<p>STK two-zero filter class. </p>
<p>This class implements a two-zero digital filter. A method is provided for creating a "notch" in the frequency response while maintaining a constant filter gain.</p>
<p>by Perry R. Cook and Gary P. Scavone, 1995-2012. </p>
<hr/><h2>Member Function Documentation</h2>
<a class="anchor" id="a3a89facd2b94bbcfc2f06d8766a46329"></a><!-- doxytag: member="stk::TwoZero::setNotch" ref="a3a89facd2b94bbcfc2f06d8766a46329" args="(StkFloat frequency, StkFloat radius)" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname">void stk::TwoZero::setNotch </td>
<td>(</td>
<td class="paramtype">StkFloat </td>
<td class="paramname"> <em>frequency</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">StkFloat </td>
<td class="paramname"> <em>radius</em></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td></td>
</tr>
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<div class="memdoc">
<p>Sets the filter coefficients for a "notch" at <em>frequency</em> (in Hz). </p>
<p>This method determines the filter coefficients corresponding to two complex-conjugate zeros with the given <em>frequency</em> (in Hz) and <em>radius</em> from the z-plane origin. The coefficients are then normalized to produce a maximum filter gain of one (independent of the filter <em>gain</em> parameter). The resulting filter frequency response has a "notch" or anti-resonance at the given <em>frequency</em>. The closer the zeros are to the unit-circle (<em>radius</em> close to or equal to one), the narrower the resulting notch width. The <em>frequency</em> value should be between zero and half the sample rate. The <em>radius</em> value should be positive. </p>
</div>
</div>
<a class="anchor" id="a26e2a1e21831ccb414dbede864afc63c"></a><!-- doxytag: member="stk::TwoZero::tick" ref="a26e2a1e21831ccb414dbede864afc63c" args="(StkFrames &frames, unsigned int channel=0)" -->
<div class="memitem">
<div class="memproto">
<table class="memname">
<tr>
<td class="memname"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & stk::TwoZero::tick </td>
<td>(</td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>frames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>channel</em> = <code>0</code></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td><code> [inline, virtual]</code></td>
</tr>
</table>
</div>
<div class="memdoc">
<p>Take a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object as inputs to the filter and replace with corresponding outputs. </p>
<p>The <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument reference is returned. The <code>channel</code> argument must be less than the number of channels in the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> exception. </p>
<p>Implements <a class="el" href="classstk_1_1Filter.html#a3260a238824c4a748ac057b84b7d3f21">stk::Filter</a>.</p>
<p><div class="fragment"><pre class="fragment"><a name="l00103"></a>00103 {
<a name="l00104"></a>00104 <span class="preprocessor">#if defined(_STK_DEBUG_)</span>
<a name="l00105"></a>00105 <span class="preprocessor"></span> <span class="keywordflow">if</span> ( channel >= frames.channels() ) {
<a name="l00106"></a>00106 oStream_ << <span class="stringliteral">"TwoZero::tick(): channel and StkFrames arguments are incompatible!"</span>;
<a name="l00107"></a>00107 <a class="code" href="classstk_1_1Stk.html#a48ac73a0d8ca28445ba1a054e1f061ff" title="Static function for error reporting and handling using c-strings.">handleError</a>( StkError::FUNCTION_ARGUMENT );
<a name="l00108"></a>00108 }
<a name="l00109"></a>00109 <span class="preprocessor">#endif</span>
<a name="l00110"></a>00110 <span class="preprocessor"></span>
<a name="l00111"></a>00111 StkFloat *samples = &frames[channel];
<a name="l00112"></a>00112 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> hop = frames.channels();
<a name="l00113"></a>00113 <span class="keywordflow">for</span> ( <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<frames.frames(); i++, samples += hop ) {
<a name="l00114"></a>00114 inputs_[0] = gain_ * *samples;
<a name="l00115"></a>00115 *samples = b_[2] * inputs_[2] + b_[1] * inputs_[1] + b_[0] * inputs_[0];
<a name="l00116"></a>00116 inputs_[2] = inputs_[1];
<a name="l00117"></a>00117 inputs_[1] = inputs_[0];
<a name="l00118"></a>00118 }
<a name="l00119"></a>00119
<a name="l00120"></a>00120 lastFrame_[0] = *(samples-hop);
<a name="l00121"></a>00121 <span class="keywordflow">return</span> frames;
<a name="l00122"></a>00122 }
</pre></div></p>
</div>
</div>
<a class="anchor" id="a0ef9deab4fbc7e64511d4b6d38afd185"></a><!-- doxytag: member="stk::TwoZero::tick" ref="a0ef9deab4fbc7e64511d4b6d38afd185" args="(StkFrames &iFrames, StkFrames &oFrames, unsigned int iChannel=0, unsigned int oChannel=0)" -->
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<table class="memname">
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<td class="memname"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & stk::TwoZero::tick </td>
<td>(</td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>iFrames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & </td>
<td class="paramname"> <em>oFrames</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>iChannel</em> = <code>0</code>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">unsigned int </td>
<td class="paramname"> <em>oChannel</em> = <code>0</code></td><td> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td><td><code> [inline]</code></td>
</tr>
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</div>
<div class="memdoc">
<p>Take a channel of the <code>iFrames</code> object as inputs to the filter and write outputs to the <code>oFrames</code> object. </p>
<p>The <code>iFrames</code> object reference is returned. Each channel argument must be less than the number of channels in the corresponding <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> argument (the first channel is specified by 0). However, range checking is only performed if _STK_DEBUG_ is defined during compilation, in which case an out-of-range value will trigger an <a class="el" href="classstk_1_1StkError.html" title="STK error handling class.">StkError</a> exception. </p>
<p><div class="fragment"><pre class="fragment"><a name="l00125"></a>00125 {
<a name="l00126"></a>00126 <span class="preprocessor">#if defined(_STK_DEBUG_)</span>
<a name="l00127"></a>00127 <span class="preprocessor"></span> <span class="keywordflow">if</span> ( iChannel >= iFrames.channels() || oChannel >= oFrames.channels() ) {
<a name="l00128"></a>00128 oStream_ << <span class="stringliteral">"TwoZero::tick(): channel and StkFrames arguments are incompatible!"</span>;
<a name="l00129"></a>00129 <a class="code" href="classstk_1_1Stk.html#a48ac73a0d8ca28445ba1a054e1f061ff" title="Static function for error reporting and handling using c-strings.">handleError</a>( StkError::FUNCTION_ARGUMENT );
<a name="l00130"></a>00130 }
<a name="l00131"></a>00131 <span class="preprocessor">#endif</span>
<a name="l00132"></a>00132 <span class="preprocessor"></span>
<a name="l00133"></a>00133 StkFloat *iSamples = &iFrames[iChannel];
<a name="l00134"></a>00134 StkFloat *oSamples = &oFrames[oChannel];
<a name="l00135"></a>00135 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> iHop = iFrames.channels(), oHop = oFrames.channels();
<a name="l00136"></a>00136 <span class="keywordflow">for</span> ( <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<iFrames.frames(); i++, iSamples += iHop, oSamples += oHop ) {
<a name="l00137"></a>00137 inputs_[0] = gain_ * *iSamples;
<a name="l00138"></a>00138 *oSamples = b_[2] * inputs_[2] + b_[1] * inputs_[1] + b_[0] * inputs_[0];
<a name="l00139"></a>00139 inputs_[2] = inputs_[1];
<a name="l00140"></a>00140 inputs_[1] = inputs_[0];
<a name="l00141"></a>00141 }
<a name="l00142"></a>00142
<a name="l00143"></a>00143 lastFrame_[0] = *(oSamples-oHop);
<a name="l00144"></a>00144 <span class="keywordflow">return</span> iFrames;
<a name="l00145"></a>00145 }
</pre></div></p>
</div>
</div>
<hr/>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="TwoZero_8h_source.html">TwoZero.h</a></li>
</ul>
</div>
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<table>
<tr><td><A HREF="http://ccrma.stanford.edu/software/stk/"><I>The Synthesis ToolKit in C++ (STK)</I></A></td></tr>
<tr><td>©1995-2012 Perry R. Cook and Gary P. Scavone. All Rights Reserved.</td></tr>
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