<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>powoftwo</title>
<link rel="stylesheet" type="text/css" href="csound.css" />
<link rel="stylesheet" type="text/css" href="syntax-highlighting.css" />
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" />
<link rel="home" href="index.html" title="The Canonical Csound Reference Manual" />
<link rel="up" href="OpcodesTop.html" title="Orchestra Opcodes and Operators" />
<link rel="prev" href="powershape.html" title="powershape" />
<link rel="next" href="prealloc.html" title="prealloc" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">powoftwo</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="powershape.html">Prev</a> </td>
<th width="60%" align="center">Orchestra Opcodes and Operators</th>
<td width="20%" align="right"> <a accesskey="n" href="prealloc.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="refentry">
<a id="powoftwo"></a>
<div class="titlepage"></div>
<a id="IndexPowoftwo" class="indexterm"></a>
<div class="refnamediv">
<h2>
<span class="refentrytitle">powoftwo</span>
</h2>
<p>powoftwo —
Performs a power-of-two calculation.
</p>
</div>
<div class="refsect1">
<a id="idm281472902305144"></a>
<h2>Description</h2>
<p>
Performs a power-of-two calculation.
</p>
</div>
<div class="refsect1">
<a id="idm281472902303816"></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">
<a id="idm281472902301704"></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>
</div>
<div class="refsect1">
<a id="idm281472902297176"></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="idm281472902295400"></a>
<p class="title">
<strong>Example 713. 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>
<div class="refsect1">
<a id="idm281472723061768"></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>
-odac <span class="c1">;;;realtime audio out</span>
<span class="c1">;-iadc ;;;uncomment -iadc if realtime audio input is needed too</span>
<span class="c1">; For Non-realtime ouput leave only the line below:</span>
<span class="c1">; -o poweroftwo.wav -W ;;; for file output any platform</span>
<span class="nt"></CsOptions></span>
<span class="nt"><CsInstruments></span>
<span class="vg">sr</span> <span class="o">=</span> <span class="mi">44100</span>
<span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">32</span>
<span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">2</span>
<span class="vg">0dbfs</span> <span class="o">=</span> <span class="mi">1</span>
<span class="kd">instr</span> <span class="nf">1</span> <span class="c1">; bit reduction for Lo-Fi sound</span>
i<span class="n">Bits</span> <span class="o">=</span> <span class="nb">p5</span> <span class="c1">;bit depth</span>
i<span class="n">Quantize</span> <span class="o">=</span> <span class="nb">powoftwo</span><span class="p">(</span>i<span class="n">Bits</span><span class="p">)</span> <span class="c1">;find number of discrete steps for this bit depth</span>
i<span class="n">Quantize</span> <span class="o">=</span> i<span class="n">Quantize</span><span class="o">*</span><span class="mf">0.5</span> <span class="c1">;half the number of steps for each side of a bipolar signal</span>
<span class="nb">print</span> i<span class="n">Quantize</span>
a<span class="n">sig</span> <span class="nb">soundin</span> <span class="s">"fox.wav"</span>
a<span class="n">sig</span> <span class="o">=</span> <span class="nb">round</span><span class="p">(</span>a<span class="n">sig</span> <span class="o">*</span> i<span class="n">Quantize</span><span class="p">)</span> <span class="o">/</span> i<span class="n">Quantize</span> <span class="c1">;quantize audio signal (bit reduce)</span>
<span class="nb">outs</span> a<span class="n">sig</span><span class="p">,</span> a<span class="n">sig</span>
<span class="kd">endin</span>
<span class="nt"></CsInstruments></span>
<span class="nt"><CsScore></span>
<span class="c1">; bits</span>
<span class="nb">i</span><span class="mi">1</span> <span class="mi">0</span> <span class="mi">3</span> <span class="mi">16</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">^+</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">12</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">^+</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">8</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">^+</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">4</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">^+</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">2</span>
<span class="nb">i</span><span class="mi">1</span> <span class="o">^+</span><span class="mi">3</span> <span class="o">.</span> <span class="mi">1</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" />
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">
<a id="idm281472902290184"></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">
<a id="idm281472902287144"></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>
</table>
<p>
</p>
<p>New in Csound version 3.57</p>
</div>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="powershape.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="OpcodesTop.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="prealloc.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">powershape </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> prealloc</td>
</tr>
</table>
</div>
</body>
</html>
distrib
>
Mageia
>
7
>
armv7hl
>
media
>
core-release
>
by-pkgid
>
5fcfcb7517038d1f44ab4e478e6e61fa
>
files
>
2676
