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?>
<div id="function.log" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">log</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">log</span> &mdash; <span class="dc-title">Natural logarithm</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.log-description">
  <h3 class="title">Description</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>log</strong></span>(<span class="methodparam"><span class="type"><a href="language.types.float.php" class="type float">float</a></span> <code class="parameter">$num</code></span>, <span class="methodparam"><span class="type"><a href="language.types.float.php" class="type float">float</a></span> <code class="parameter">$base</code><span class="initializer"> = <strong><code><a href="math.constants.php#constant.m-e">M_E</a></code></strong></span></span>): <span class="type"><a href="language.types.float.php" class="type float">float</a></span></div>

  <p class="para rdfs-comment">
   If the optional <code class="parameter">base</code> parameter is specified, 
   <span class="function"><strong>log()</strong></span> returns log<sub class="subscript">base</sub>
   <code class="parameter">num</code>, otherwise <span class="function"><strong>log()</strong></span> 
   returns the natural logarithm of <code class="parameter">num</code>.
  </p>
 </div>

 <div class="refsect1 parameters" id="refsect1-function.log-parameters">
  <h3 class="title">Parameters</h3>
  <p class="para">
   <dl>
    
     <dt><code class="parameter">num</code></dt>
     <dd>
      <p class="para">
       The value to calculate the logarithm for
      </p>
     </dd>
    
    
     <dt><code class="parameter">base</code></dt>
     <dd>
      <p class="para">
       The optional logarithmic base to use 
       (defaults to &#039;e&#039; and so to the natural logarithm).
      </p>
     </dd>
    
   </dl>
  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.log-returnvalues">
  <h3 class="title">Return Values</h3>
  <p class="para">
   The logarithm of <code class="parameter">num</code> to 
   <code class="parameter">base</code>, if given, or the
   natural logarithm.  
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.log-seealso">
  <h3 class="title">See Also</h3>
  <p class="para">
   <ul class="simplelist">
    <li><span class="function"><a href="function.log10.php" class="function" rel="rdfs-seeAlso">log10()</a> - Base-10 logarithm</span></li>
    <li><span class="function"><a href="function.exp.php" class="function" rel="rdfs-seeAlso">exp()</a> - Calculates the exponent of e</span></li>
    <li><span class="function"><a href="function.pow.php" class="function" rel="rdfs-seeAlso">pow()</a> - Exponential expression</span></li>
    <li><span class="function"><a href="function.error-log.php" class="function" rel="rdfs-seeAlso">error_log()</a> - Send an error message to the defined error handling routines</span></li>
   </ul>
  </p>
 </div>

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