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| <h3 class="section">8.153 <code>LOG</code> — Natural logarithm function</h3> |
| |
| <p><a name="index-LOG-815"></a><a name="index-ALOG-816"></a><a name="index-DLOG-817"></a><a name="index-CLOG-818"></a><a name="index-ZLOG-819"></a><a name="index-CDLOG-820"></a><a name="index-exponential-function_002c-inverse-821"></a><a name="index-logarithm-function-822"></a><a name="index-natural-logarithm-function-823"></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> |
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