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<div class="navpath"><a class="el" href="namespacestk.html">stk</a>::<a class="el" href="classstk_1_1Asymp.html">Asymp</a>
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<h1>stk::Asymp Class Reference</h1><!-- doxytag: class="stk::Asymp" --><!-- doxytag: inherits="stk::Generator" -->
<p>STK asymptotic curve envelope class.
<a href="#_details">More...</a></p>
<p><code>#include <<a class="el" href="Asymp_8h_source.html">Asymp.h</a>></code></p>
<div class="dynheader">
Inheritance diagram for stk::Asymp:</div>
<div class="dynsection">
<div class="center">
<img src="classstk_1_1Asymp.png" usemap="#stk::Asymp_map" alt=""/>
<map id="stk::Asymp_map" name="stk::Asymp_map">
<area href="classstk_1_1Generator.html" alt="stk::Generator" shape="rect" coords="0,56,90,80"/>
<area href="classstk_1_1Stk.html" alt="stk::Stk" shape="rect" coords="0,0,90,24"/>
</map>
</div>
</div>
<p><a href="classstk_1_1Asymp-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="ad8ea9fc5621a1d8b81001d459de265a0"></a><!-- doxytag: member="stk::Asymp::Asymp" ref="ad8ea9fc5621a1d8b81001d459de265a0" args="(void)" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#ad8ea9fc5621a1d8b81001d459de265a0">Asymp</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Default constructor. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="ad869abbd938c263a2c177de636f5a57c"></a><!-- doxytag: member="stk::Asymp::~Asymp" ref="ad869abbd938c263a2c177de636f5a57c" args="(void)" -->
</td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#ad869abbd938c263a2c177de636f5a57c">~Asymp</a> (void)</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="a51f0aad846eb6bda4c20eb63534786e2"></a><!-- doxytag: member="stk::Asymp::keyOn" ref="a51f0aad846eb6bda4c20eb63534786e2" args="(void)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#a51f0aad846eb6bda4c20eb63534786e2">keyOn</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set target = 1. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a082e765dc3bd6b452e92b602af7a1042"></a><!-- doxytag: member="stk::Asymp::keyOff" ref="a082e765dc3bd6b452e92b602af7a1042" args="(void)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#a082e765dc3bd6b452e92b602af7a1042">keyOff</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set target = 0. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top">void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#aebd8ebaf6f6c9570d3ee78e1bcbbcbd2">setTau</a> (StkFloat tau)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the asymptotic rate via the time factor <em>tau</em> (must be > 0). <a href="#aebd8ebaf6f6c9570d3ee78e1bcbbcbd2"></a><br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="aca998e9c4ae86b4958da59fc9433268c"></a><!-- doxytag: member="stk::Asymp::setTime" ref="aca998e9c4ae86b4958da59fc9433268c" args="(StkFloat time)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#aca998e9c4ae86b4958da59fc9433268c">setTime</a> (StkFloat time)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the asymptotic rate based on a time duration (must be > 0). <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="afa6fcf4bf3060c0c6092701e409d5fbf"></a><!-- doxytag: member="stk::Asymp::setT60" ref="afa6fcf4bf3060c0c6092701e409d5fbf" args="(StkFloat t60)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#afa6fcf4bf3060c0c6092701e409d5fbf">setT60</a> (StkFloat t60)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the asymptotic rate such that the target value is perceptually reached (to within -60dB of the target) in <em>t60</em> seconds. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a7b0f7025ba5f268f1e5ce097b209f0ec"></a><!-- doxytag: member="stk::Asymp::setTarget" ref="a7b0f7025ba5f268f1e5ce097b209f0ec" args="(StkFloat target)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#a7b0f7025ba5f268f1e5ce097b209f0ec">setTarget</a> (StkFloat target)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set the target value. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="a81881bb8aca615f69bbbfd56267f971c"></a><!-- doxytag: member="stk::Asymp::setValue" ref="a81881bb8aca615f69bbbfd56267f971c" args="(StkFloat value)" -->
void </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#a81881bb8aca615f69bbbfd56267f971c">setValue</a> (StkFloat value)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Set current and target values to <em>value</em>. <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="aaba01ef0ac1a493a14a73c3b29259bde"></a><!-- doxytag: member="stk::Asymp::getState" ref="aaba01ef0ac1a493a14a73c3b29259bde" args="(void) const " -->
int </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#aaba01ef0ac1a493a14a73c3b29259bde">getState</a> (void) const </td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Return the current envelope <em>state</em> (0 = at target, 1 otherwise). <br/></td></tr>
<tr><td class="memItemLeft" align="right" valign="top"><a class="anchor" id="aeb868c171e07206e2d5d30f8ce8f4436"></a><!-- doxytag: member="stk::Asymp::lastOut" ref="aeb868c171e07206e2d5d30f8ce8f4436" args="(void) const " -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#aeb868c171e07206e2d5d30f8ce8f4436">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="a64df3b44aa1033b642d7a8a93659580e"></a><!-- doxytag: member="stk::Asymp::tick" ref="a64df3b44aa1033b642d7a8a93659580e" args="(void)" -->
StkFloat </td><td class="memItemRight" valign="bottom"><a class="el" href="classstk_1_1Asymp.html#a64df3b44aa1033b642d7a8a93659580e">tick</a> (void)</td></tr>
<tr><td class="mdescLeft"> </td><td class="mdescRight">Compute and return one output sample. <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_1Asymp.html#a2647bc013816f026915b1e92ddd6a322">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">Fill a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object with computed outputs. <a href="#a2647bc013816f026915b1e92ddd6a322"></a><br/></td></tr>
</table>
<hr/><a name="_details"></a><h2>Detailed Description</h2>
<p>STK asymptotic curve envelope class. </p>
<p>This class implements a simple envelope generator which asymptotically approaches a target value. The algorithm used is of the form:</p>
<p>y[n] = a y[n-1] + (1-a) target,</p>
<p>where a = exp(-T/tau), T is the sample period, and tau is a time constant. The user can set the time constant (default value = 0.3) and target value. Theoretically, this recursion never reaches its target, though the calculations in this class are stopped when the current value gets within a small threshold value of the target (at which time the current value is set to the target). It responds to <em>keyOn</em> and <em>keyOff</em> messages by ramping to 1.0 on keyOn and to 0.0 on keyOff.</p>
<p>by Perry R. Cook and Gary P. Scavone, 1995-2012. </p>
<hr/><h2>Member Function Documentation</h2>
<a class="anchor" id="aebd8ebaf6f6c9570d3ee78e1bcbbcbd2"></a><!-- doxytag: member="stk::Asymp::setTau" ref="aebd8ebaf6f6c9570d3ee78e1bcbbcbd2" args="(StkFloat tau)" -->
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<td class="memname">void stk::Asymp::setTau </td>
<td>(</td>
<td class="paramtype">StkFloat </td>
<td class="paramname"> <em>tau</em></td>
<td> ) </td>
<td></td>
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<div class="memdoc">
<p>Set the asymptotic rate via the time factor <em>tau</em> (must be > 0). </p>
<p>The rate is computed as described above. The value of <em>tau</em> must be greater than zero. Values of <em>tau</em> close to zero produce fast approach rates, while values greater than 1.0 produce rather slow rates. </p>
</div>
</div>
<a class="anchor" id="a2647bc013816f026915b1e92ddd6a322"></a><!-- doxytag: member="stk::Asymp::tick" ref="a2647bc013816f026915b1e92ddd6a322" args="(StkFrames &frames, unsigned int channel=0)" -->
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<td class="memname"><a class="el" href="classstk_1_1StkFrames.html">StkFrames</a> & stk::Asymp::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>
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<td></td>
<td>)</td>
<td></td><td></td><td><code> [inline, virtual]</code></td>
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<div class="memdoc">
<p>Fill a channel of the <a class="el" href="classstk_1_1StkFrames.html" title="An STK class to handle vectorized audio data.">StkFrames</a> object with computed outputs. </p>
<p>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_1Generator.html#a86bb0421223cf27e25704d5f27b97425">stk::Generator</a>.</p>
<p><div class="fragment"><pre class="fragment"><a name="l00128"></a>00128 {
<a name="l00129"></a>00129 <span class="preprocessor">#if defined(_STK_DEBUG_)</span>
<a name="l00130"></a>00130 <span class="preprocessor"></span> <span class="keywordflow">if</span> ( channel >= frames.channels() ) {
<a name="l00131"></a>00131 oStream_ << <span class="stringliteral">"Asymp::tick(): channel and StkFrames arguments are incompatible!"</span>;
<a name="l00132"></a>00132 <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="l00133"></a>00133 }
<a name="l00134"></a>00134 <span class="preprocessor">#endif</span>
<a name="l00135"></a>00135 <span class="preprocessor"></span>
<a name="l00136"></a>00136 StkFloat *samples = &frames[channel];
<a name="l00137"></a>00137 <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> hop = frames.channels();
<a name="l00138"></a>00138 <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="l00139"></a>00139 *samples = <a class="code" href="classstk_1_1Asymp.html#a64df3b44aa1033b642d7a8a93659580e" title="Compute and return one output sample.">Asymp::tick</a>();
<a name="l00140"></a>00140
<a name="l00141"></a>00141 <span class="keywordflow">return</span> frames;
<a name="l00142"></a>00142 }
</pre></div></p>
</div>
</div>
<hr/>The documentation for this class was generated from the following file:<ul>
<li><a class="el" href="Asymp_8h_source.html">Asymp.h</a></li>
</ul>
</div>
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<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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