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<refentry id="resonx">
<indexterm id="IndexResonx"><primary>resonx</primary></indexterm>
<refentryinfo><title>Signal Modifiers:Standard Filters:Resonant</title></refentryinfo>
<refmeta>
<refentrytitle>resonx</refentrytitle>
</refmeta>
<refnamediv>
<refname>resonx</refname>
<refpurpose>
Emulates a stack of filters using the reson opcode.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
<emphasis>resonx</emphasis> is equivalent to a filters consisting of more layers of <link linkend="reson"><citetitle>reson</citetitle></link> with the same arguments, serially connected. Using a stack of a larger number of filters allows a sharper cutoff. They are faster than using a larger number instances in a Csound orchestra of the old opcodes, because only one initialization and k- cycle are needed at time and the audio loop falls entirely inside the cache memory of processor.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>ares <command>resonx</command> asig, xcf, xbw [, inumlayer] [, iscl] [, iskip]</synopsis>
</refsect1>
<refsect1>
<title>Initialization</title>
<para>
<emphasis>inumlayer</emphasis> (optional) -- number of elements in the filter stack. Default value is 4.
</para>
<para>
<emphasis>iscl</emphasis> (optional, default=0) -- coded scaling factor for resonators. A value of 1 signifies a peak response factor of 1, i.e. all frequencies other than kcf are attenuated in accordance with the (normalized) response curve. A value of 2 raises the response factor so that its overall RMS value equals 1. (This intended equalization of input and output power assumes all frequencies are physically present; hence it is most applicable to white noise.) A zero value signifies no scaling of the signal, leaving that to some later adjustment (see <link linkend="balance"><citetitle>balance</citetitle></link>). The default value is 0.
</para>
<para>
<emphasis>iskip</emphasis> (optional, default=0) -- 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.
</para>
</refsect1>
<refsect1>
<title>Performance</title>
<para>
<emphasis>asig</emphasis> -- input signal
</para>
<para>
<emphasis>xcf</emphasis> -- the center frequency of the filter, or frequency position of the peak response.
</para>
<para>
<emphasis>xbw</emphasis> -- bandwidth of the filter (the Hz difference between the upper and lower half-power points)
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Here is an example of the resonx opcodes. It uses the file <ulink url="examples/resonx.csd"><citetitle>resonx.csd</citetitle></ulink>.
<example>
<title>Example of the resonx opcodes.</title>
<para>See the sections <link linkend="UsingRealTime"><citetitle>Real-time Audio</citetitle></link> and <link linkend="CommandFlags"><citetitle>Command Line Flags</citetitle></link> for more information on using command line flags.</para>
<xi:include href="examples-xml/resonx.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
</example>
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<link linkend="atonex"><citetitle>atonex</citetitle></link>,
<link linkend="tonex"><citetitle>tonex</citetitle></link>
</para>
</refsect1>
<refsect1>
<title>Credits</title>
<para>
<simplelist>
<member>Author: &namegabriel; (adapted by &namejohn;)</member>
<member>Italy</member>
</simplelist>
</para>
<para>New in Csound version 3.49</para>
<para>Audio rate parameters introduced in version 6.02</para>
<para>November 2013.</para>
</refsect1>
</refentry>
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