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<div class="refentry" title="powoftwo">
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<h2>
<span class="refentrytitle">powoftwo</span>
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<p>powoftwo —
Performs a power-of-two calculation.
</p>
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<div class="refsect1" title="Description">
<a id="idp37013448"></a>
<h2>Description</h2>
<p>
Performs a power-of-two calculation.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp37000384"></a>
<h2>Syntax</h2>
<pre class="synopsis"><span class="command"><strong>powoftwo</strong></span>(x) (init-rate or control-rate args only)</pre>
</div>
<div class="refsect1" title="Performance">
<a id="idp37001384"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>powoftwo</em></span>() function returns 2<sup><span class="emphasis"><em>x</em></span></sup> and allows positive and negatives numbers as argument. The range of values admitted in <span class="emphasis"><em>powoftwo</em></span>() is -5 to +5 allowing a precision more fine than one cent in a range of ten octaves. If a greater range of values is required, use the slower opcode <a class="link" href="pow.html" title="pow"><em class="citetitle">pow</em></a>.
</p>
<p>
These functions are fast, because they read values stored in tables. Also they are very useful when working with tuning ratios. They work at i- and k-rate.
</p>
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<div class="refsect1" title="Examples">
<a id="idp37049984"></a>
<h2>Examples</h2>
<p>
Here is an example of the powoftwo opcode. It uses the file <a class="ulink" href="examples/powoftwo.csd" target="_top"><em class="citetitle">powoftwo.csd</em></a>.
</p>
<div class="example">
<a id="idp37050952"></a>
<p class="title">
<strong>Example 611. Example of the powoftwo 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>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
-odac <span class="comment">;;;realtime audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o poweroftwo.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 32
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1
<span class="oblock">instr</span> 1 <span class="comment">; bit reduction for Lo-Fi sound</span>
iBits <span class="op">=</span> p5 <span class="comment">;bit depth</span>
iQuantize <span class="op">=</span> <span class="opc">powoftwo</span>(iBits) <span class="comment">;find number of discrete steps for this bit depth</span>
iQuantize <span class="op">=</span> iQuantize<span class="op">*</span>0.5 <span class="comment">;half the number of steps for each side of a bipolar signal</span>
<span class="opc">print</span> iQuantize
asig <span class="opc">soundin</span> "fox.wav"
asig <span class="op">=</span> <span class="opc">round</span>(asig <span class="op">*</span> iQuantize) <span class="op">/</span> iQuantize <span class="comment">;quantize audio signal (bit reduce)</span>
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="comment">; bits</span>
<span class="stamnt">i</span>1 0 3 16
<span class="stamnt">i</span>1 ^+3 . 12
<span class="stamnt">i</span>1 ^+3 . 8
<span class="stamnt">i</span>1 ^+3 . 4
<span class="stamnt">i</span>1 ^+3 . 2
<span class="stamnt">i</span>1 ^+3 . 1
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
</div>
</div>
<p><br class="example-break" />
Its output should include a line like this:
</p>
<pre class="screen">
instr 1: iQuantize = 32768.000
instr 1: iQuantize = 2048.000
instr 1: iQuantize = 128.000
instr 1: iQuantize = 8.000
instr 1: iQuantize = 2.000
instr 1: iQuantize = 1.000
</pre>
<p>
</p>
</div>
<div class="refsect1" title="See Also">
<a id="idp37053928"></a>
<h2>See Also</h2>
<p>
<a class="link" href="logbtwo.html" title="logbtwo"><em class="citetitle">logbtwo</em></a>,
<a class="link" href="pow.html" title="pow"><em class="citetitle">pow</em></a>
</p>
</div>
<div class="refsect1" title="Credits">
<a id="idp37055456"></a>
<h2>Credits</h2>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: Gabriel Maldonado</td>
</tr>
<tr>
<td>Italy</td>
</tr>
<tr>
<td>June 1998</td>
</tr>
</table>
<p>
</p>
<p>
</p>
<table border="0" summary="Simple list" class="simplelist">
<tr>
<td>Author: John ffitch</td>
</tr>
<tr>
<td>University of Bath, Codemist, Ltd.</td>
</tr>
<tr>
<td>Bath, UK</td>
</tr>
<tr>
<td>July 1999</td>
</tr>
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<p>
</p>
<p>New in Csound version 3.57</p>
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