<?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>logbtwo</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="log2.html" title="log2" /> <link rel="next" href="logcurve.html" title="logcurve" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">logbtwo</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="log2.html">Prev</a> </td> <th width="60%" align="center">Orchestra Opcodes and Operators</th> <td width="20%" align="right"> <a accesskey="n" href="logcurve.html">Next</a></td> </tr> </table> <hr /> </div> <div class="refentry"> <a id="logbtwo"></a> <div class="titlepage"></div> <a id="IndexLogbtwo" class="indexterm"></a> <div class="refnamediv"> <h2> <span class="refentrytitle">logbtwo</span> </h2> <p>logbtwo — Performs a logarithmic base two calculation. </p> </div> <div class="refsect1"> <a id="idm281472919341288"></a> <h2>Description</h2> <p> Performs a logarithmic base two calculation. </p> </div> <div class="refsect1"> <a id="idm281472919339944"></a> <h2>Syntax</h2> <pre class="synopsis"><span class="command"><strong>logbtwo</strong></span>(x) (init-rate or control-rate args only)</pre> </div> <div class="refsect1"> <a id="idm281472919337832"></a> <h2>Performance</h2> <p> <span class="emphasis"><em>logbtwo</em></span>() returns the logarithm base two of <span class="emphasis"><em>x</em></span>. The range of values admitted as argument is .25 to 4 (i.e. from -2 octave to +2 octave response). This function is the inverse of <span class="emphasis"><em>powoftwo</em></span>(). </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="idm281472919273144"></a> <h2>Examples</h2> <p> Here is an example of the logbtwo opcode. It uses the file <a class="ulink" href="examples/logbtwo.csd" target="_top"><em class="citetitle">logbtwo.csd</em></a>. </p> <div class="example"> <a id="idm281472919271368"></a> <p class="title"> <strong>Example 479. Example of the logbtwo 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="idm281472746063464"></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</span> -odac -iadc <span class="c1">;;;RT audio I/O</span> <span class="c1">; For Non-realtime ouput leave only the line below:</span> <span class="c1">; -o logbtwo.wav -W ;;; for file output any platform</span> <span class="nt"></CsOptions></span> <span class="nt"><CsInstruments></span> <span class="c1">; Initialize the global variables.</span> <span class="vg">sr</span> <span class="o">=</span> <span class="mi">44100</span> <span class="vg">kr</span> <span class="o">=</span> <span class="mi">4410</span> <span class="vg">ksmps</span> <span class="o">=</span> <span class="mi">10</span> <span class="vg">nchnls</span> <span class="o">=</span> <span class="mi">1</span> <span class="c1">; Instrument #1.</span> <span class="kd">instr</span> <span class="nf">1</span> i<span class="n">1</span> <span class="o">=</span> <span class="nb">logbtwo</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span> <span class="nb">print</span> i<span class="n">1</span> <span class="kd">endin</span> <span class="nt"></CsInstruments></span> <span class="nt"><CsScore></span> <span class="c1">; Play Instrument #1 for one second.</span> <span class="nb">i</span> <span class="mi">1</span> <span class="mi">0</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: i1 = 1.585</pre> <p> </p> </div> <div class="refsect1"> <a id="idm281472919266408"></a> <h2>See Also</h2> <p> <a class="link" href="powoftwo.html" title="powoftwo"><em class="citetitle">powoftwo</em></a> </p> </div> <div class="refsect1"> <a id="idm281472919264264"></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>Example written by Kevin Conder.</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="log2.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="logcurve.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">log2 </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> logcurve</td> </tr> </table> </div> </body> </html>