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<div class="refentry" title="statevar">
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<h2>
<span class="refentrytitle">statevar</span>
</h2>
<p>statevar —
State-variable filter.
</p>
</div>
<div class="refsect1" title="Description">
<a id="id3236801"></a>
<h2>Description</h2>
<p>
Statevar is a new digital implementation of the analogue state-variable filter.
This filter has four simultaneous outputs: high-pass, low-pass,
band-pass and band-reject. This filter uses oversampling for sharper
resonance (default: 3 times oversampling). It includes a
resonance limiter that prevents the filter from getting unstable.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="id3236817"></a>
<h2>Syntax</h2>
<pre class="synopsis">ahp,alp,abp,abr <span class="command"><strong>statevar</strong></span> ain, kcf, kq [, iosamps, istor]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="id3237031"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>iosamps</em></span> -- number of times of oversampling used in the
filtering process. This will determine the maximum sharpness
of the filter resonance (Q). More oversampling allows higher Qs,
less oversampling will limit the resonance. The default is 3
times (iosamps=0).
</p>
<p>
<span class="emphasis"><em>istor</em></span> --initial disposition of internal data space. Since
filtering incorporates a feedback loop of previous output,
the initial status of the storage space used is significant.
A zero value will clear the space; a non-zero value will allow
previous information to remain. The default value is 0.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="id3237061"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>ahp</em></span> -- high-pass output signal.
</p>
<p>
<span class="emphasis"><em>alp</em></span> -- low-pass output signal.
</p>
<p>
<span class="emphasis"><em>abp</em></span> -- band-pass signal.
</p>
<p>
<span class="emphasis"><em>abr</em></span> -- band-reject signal.
</p>
<p>
<span class="emphasis"><em>asig</em></span> -- input signal.
</p>
<p>
<span class="emphasis"><em>kcf</em></span> -- filter cutoff frequency
</p>
<p>
<span class="emphasis"><em>kq</em></span> -- filter Q. This value is limited internally depending on
the frequency and the number of times of oversampling used in
the process (3-times oversampling by default).
</p>
</div>
<div class="refsect1" title="Examples">
<a id="id3237718"></a>
<h2>Examples</h2>
<p>
</p>
<div class="example">
<a id="id3237726"></a>
<p class="title">
<b>Example 570. Example</b>
</p>
<div class="example-contents">
<pre class="programlisting">
kenv <span class="opc">linseg</span> 0, 0.1, 1, p3<span class="op">-</span>0.2, 1, 0.1, 0
asig <span class="opc">buzz</span> 16000<span class="op">*</span>kenv, 100, 100, 1;
kf <span class="opc">expseg</span> 100, p3<span class="op">/</span>2, 5000, p3<span class="op">/</span>2, 1000
ahp, alp, abp, abr <span class="opc">statevar</span> asig, kf, 200
<span class="opc">outs</span> alp, ahp</pre>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1" title="Credits">
<a id="id3237793"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Victor Lazzarini</td>
</tr>
<tr>
<td>January 2005</td>
</tr>
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<p>
</p>
<p>New plugin in version 5</p>
<p>January 2005.</p>
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