<?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>log</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="locsig.html" title="locsig" /> <link rel="next" href="log10.html" title="log10" /> </head> <body> <div class="navheader"> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">log</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="locsig.html">Prev</a> </td> <th width="60%" align="center">Orchestra Opcodes and Operators</th> <td width="20%" align="right"> <a accesskey="n" href="log10.html">Next</a></td> </tr> </table> <hr /> </div> <div class="refentry"> <a id="log"></a> <div class="titlepage"></div> <a id="IndexLog" class="indexterm"></a> <div class="refnamediv"> <h2> <span class="refentrytitle">log</span> </h2> <p>log — Returns a natural log of a number, or an array (with optional arbitrary base). </p> </div> <div class="refsect1"> <a id="idm281472919510648"></a> <h2>Description</h2> <p> Returns the natural log of <span class="emphasis"><em>x</em></span> (<span class="emphasis"><em>x</em></span> positive only). In the case of an array input, the operation can have an optional arbitrary base. </p> <p> The argument value is restricted for <span class="emphasis"><em>log</em></span>, <a class="link" href="log10.html" title="log10"><em class="citetitle">log10</em></a>, and <a class="link" href="sqrt.html" title="sqrt"><em class="citetitle">sqrt</em></a>. </p> </div> <div class="refsect1"> <a id="idm281472919463160"></a> <h2>Syntax</h2> <pre class="synopsis"><span class="command"><strong>log</strong></span>(x) (no rate restriction)</pre> <pre class="synopsis"><span class="command"><strong>log</strong></span>(k/i[]) (k- or i-arrays )</pre> <pre class="synopsis">kout[]<span class="command"><strong>log</strong></span> kin[],ibas</pre> <p> where the argument within the parentheses may be an expression. Value converters perform arithmetic translation from units of one kind to units of another. The result can then be a term in a further expression. In the case of an array input, ibas is the optional arbitrary base, which defaults to e (natural log base). </p> </div> <div class="refsect1"> <a id="idm281472919457400"></a> <h2>Examples</h2> <p> Here is an example of the log opcode. It uses the file <a class="ulink" href="examples/log.csd" target="_top"><em class="citetitle">log.csd</em></a>. </p> <div class="example"> <a id="idm281472919455624"></a> <p class="title"> <strong>Example 476. Example of the log 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="idm281472746698040"></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 log.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">log</span><span class="p">(</span><span class="mi">8</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 = 2.079</pre> <p> </p> </div> <div class="refsect1"> <a id="idm281472919450664"></a> <h2>See Also</h2> <p> <a class="link" href="abs.html" title="abs"><em class="citetitle">abs</em></a>, <a class="link" href="exp.html" title="exp"><em class="citetitle">exp</em></a>, <a class="link" href="frac.html" title="frac"><em class="citetitle">frac</em></a>, <a class="link" href="int.html" title="int"><em class="citetitle">int</em></a>, <a class="link" href="log10.html" title="log10"><em class="citetitle">log10</em></a>, <a class="link" href="opi.html" title="i"><em class="citetitle">i</em></a>, <a class="link" href="sqrt.html" title="sqrt"><em class="citetitle">sqrt</em></a> </p> </div> <div class="refsect1"> <a id="idm281472919443016"></a> <h2>Credits</h2> <p>Written by John ffitch.</p> <p>New in version 3.47</p> <p>Example written by Kevin Conder.</p> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="locsig.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="log10.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">locsig </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> log10</td> </tr> </table> </div> </body> </html>