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<h2>
<span class="refentrytitle">logcurve</span>
</h2>
<p>logcurve —
This opcode implements a formula for generating a normalised logarithmic curve in range 0 - 1. It is based on the Max / MSP work of Eric Singer (c) 1994.
</p>
</div>
<div class="refsect1">
<a id="idm281472919223592"></a>
<h2>Description</h2>
<p>
Generates a logarithmic curve in range 0 to 1 of arbitrary steepness.
Steepness index equal to or lower than 1.0 will result in Not-a-Number
errors and cause unstable behavior.
</p>
<p>
The formula used to calculate the curve is:
</p>
<pre class="programlisting">log(x * (y-1)+1) / (log(y)</pre>
<p>
where x is equal to <span class="emphasis"><em>kindex</em></span> and y is equal to <span class="emphasis"><em>ksteepness</em></span>.
</p>
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<div class="refsect1">
<a id="idm281472919219848"></a>
<h2>Syntax</h2>
<pre class="synopsis">kout <span class="command"><strong>logcurve</strong></span> kindex, ksteepness</pre>
</div>
<div class="refsect1">
<a id="idm281472919217608"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>kindex</em></span> -- Index value. Expected range 0 to 1.
</p>
<p>
<span class="emphasis"><em>ksteepness</em></span> -- Steepness of the generated curve. Values
closer to 1.0 result in a straighter line while larger values steepen the
curve.
</p>
<p>
<span class="emphasis"><em>kout</em></span> -- Scaled output.
</p>
</div>
<div class="refsect1">
<a id="idm281472919213928"></a>
<h2>Examples</h2>
<p>
Here is an example of the logcurve opcode. It uses the file <a class="ulink" href="examples/logcurve.csd" target="_top"><em class="citetitle">logcurve.csd</em></a>.
</p>
<div class="example">
<a id="idm281472919212152"></a>
<p class="title">
<strong>Example 480. Example of the logcurve opcode.</strong>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<div class="refsect1">
<a id="idm281472745904088"></a>
<pre class="programlisting">
<span class="nt"><CsoundSynthesizer></span>
<span class="nt"><CsOptions></span>
<span class="c1">; Select audio/midi flags here according to platform</span>
<span class="c1">; Audio out Audio in Silent</span>
-odac -iadc -d <span class="c1">;;;realtime output</span>
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="vg">sr</span> <span class="o">=</span> <span class="mi">48000</span>
<span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">100</span>
<span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">2</span>
<span class="kd">instr</span> <span class="nf">1</span> <span class="c1">; logcurve test</span>
k<span class="n">mod</span> <span class="nb">phasor</span> <span class="mi">1</span><span class="o">/</span><span class="nb">p3</span>
k<span class="n">out</span> <span class="nb">logcurve</span> k<span class="n">mod</span><span class="p">,</span> <span class="nb">p4</span>
<span class="nb">printks</span> <span class="s">"kmod = %f kout = %f</span><span class="se">\\</span><span class="s">n"</span><span class="p">,</span> <span class="mf">0.1</span><span class="p">,</span> k<span class="n">mod</span><span class="p">,</span> k<span class="n">out</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">10</span> <span class="mi">2</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">10</span> <span class="mi">10</span> <span class="mi">30</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">20</span> <span class="mi">10</span> <span class="mf">0.5</span>
<span class="nb">e</span>
<span class="nt"></CsScore></span>
<span class="nt"></CsoundSynthesizer></span>
</pre>
</div>
</div>
</div>
<p><br class="example-break" />
</p>
</div>
<div class="refsect1">
<a id="idm281472919207928"></a>
<h2>See Also</h2>
<p>
<a class="link" href="scale.html" title="scale"><em class="citetitle">scale</em></a>,
<a class="link" href="gainslider.html" title="gainslider"><em class="citetitle">gainslider</em></a>,
<a class="link" href="expcurve.html" title="expcurve"><em class="citetitle">expcurve</em></a>
</p>
</div>
<div class="refsect1">
<a id="idm281472919203896"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: David Akbari</td>
</tr>
<tr>
<td>October</td>
</tr>
<tr>
<td>2006</td>
</tr>
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</p>
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