<html lang="en"> <head> <title>LOG - The GNU Fortran Compiler</title> <meta http-equiv="Content-Type" content="text/html"> <meta name="description" content="The GNU Fortran Compiler"> <meta name="generator" content="makeinfo 4.13"> <link title="Top" rel="start" href="index.html#Top"> <link rel="up" href="Intrinsic-Procedures.html#Intrinsic-Procedures" title="Intrinsic Procedures"> <link rel="prev" href="LOC.html#LOC" title="LOC"> <link rel="next" href="LOG10.html#LOG10" title="LOG10"> <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> <!-- Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc. 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Copies published by the Free Software Foundation raise funds for GNU development.--> <meta http-equiv="Content-Style-Type" content="text/css"> <style type="text/css"><!-- pre.display { font-family:inherit } pre.format { font-family:inherit } pre.smalldisplay { font-family:inherit; font-size:smaller } pre.smallformat { font-family:inherit; font-size:smaller } pre.smallexample { font-size:smaller } pre.smalllisp { font-size:smaller } span.sc { font-variant:small-caps } span.roman { font-family:serif; font-weight:normal; } span.sansserif { font-family:sans-serif; font-weight:normal; } --></style> </head> <body> <div class="node"> <a name="LOG"></a> <p> Next: <a rel="next" accesskey="n" href="LOG10.html#LOG10">LOG10</a>, Previous: <a rel="previous" accesskey="p" href="LOC.html#LOC">LOC</a>, Up: <a rel="up" accesskey="u" href="Intrinsic-Procedures.html#Intrinsic-Procedures">Intrinsic Procedures</a> <hr> </div> <h3 class="section">8.150 <code>LOG</code> — Natural logarithm function</h3> <p><a name="index-LOG-785"></a><a name="index-ALOG-786"></a><a name="index-DLOG-787"></a><a name="index-CLOG-788"></a><a name="index-ZLOG-789"></a><a name="index-CDLOG-790"></a><a name="index-exponential-function_002c-inverse-791"></a><a name="index-logarithm-function-792"></a><a name="index-natural-logarithm-function-793"></a> <dl> <dt><em>Description</em>:<dd><code>LOG(X)</code> computes the natural logarithm of <var>X</var>, i.e. the logarithm to the base e. <br><dt><em>Standard</em>:<dd>Fortran 77 and later <br><dt><em>Class</em>:<dd>Elemental function <br><dt><em>Syntax</em>:<dd><code>RESULT = LOG(X)</code> <br><dt><em>Arguments</em>:<dd> <p><table summary=""><tr align="left"><td valign="top" width="15%"><var>X</var> </td><td valign="top" width="70%">The type shall be <code>REAL</code> or <code>COMPLEX</code>. <br></td></tr></table> <br><dt><em>Return value</em>:<dd>The return value is of type <code>REAL</code> or <code>COMPLEX</code>. The kind type parameter is the same as <var>X</var>. If <var>X</var> is <code>COMPLEX</code>, the imaginary part \omega is in the range -\pi \leq \omega \leq \pi. <br><dt><em>Example</em>:<dd> <pre class="smallexample"> program test_log real(8) :: x = 2.7182818284590451_8 complex :: z = (1.0, 2.0) x = log(x) ! will yield (approximately) 1 z = log(z) end program test_log </pre> <br><dt><em>Specific names</em>:<dd> <p><table summary=""><tr align="left"><td valign="top" width="20%">Name </td><td valign="top" width="20%">Argument </td><td valign="top" width="20%">Return type </td><td valign="top" width="25%">Standard <br></td></tr><tr align="left"><td valign="top" width="20%"><code>ALOG(X)</code> </td><td valign="top" width="20%"><code>REAL(4) X</code> </td><td valign="top" width="20%"><code>REAL(4)</code> </td><td valign="top" width="25%">f95, gnu <br></td></tr><tr align="left"><td valign="top" width="20%"><code>DLOG(X)</code> </td><td valign="top" width="20%"><code>REAL(8) X</code> </td><td valign="top" width="20%"><code>REAL(8)</code> </td><td valign="top" width="25%">f95, gnu <br></td></tr><tr align="left"><td valign="top" width="20%"><code>CLOG(X)</code> </td><td valign="top" width="20%"><code>COMPLEX(4) X</code> </td><td valign="top" width="20%"><code>COMPLEX(4)</code> </td><td valign="top" width="25%">f95, gnu <br></td></tr><tr align="left"><td valign="top" width="20%"><code>ZLOG(X)</code> </td><td valign="top" width="20%"><code>COMPLEX(8) X</code> </td><td valign="top" width="20%"><code>COMPLEX(8)</code> </td><td valign="top" width="25%">f95, gnu <br></td></tr><tr align="left"><td valign="top" width="20%"><code>CDLOG(X)</code> </td><td valign="top" width="20%"><code>COMPLEX(8) X</code> </td><td valign="top" width="20%"><code>COMPLEX(8)</code> </td><td valign="top" width="25%">f95, gnu <br></td></tr></table> </dl> </body></html>