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Su, Xiaomeng
76a5b1ee83
Reviewed-by: Pruthi, Vineet <vineet.pruthi@t-systems.com> Co-authored-by: Su, Xiaomeng <suxiaomeng1@huawei.com> Co-committed-by: Su, Xiaomeng <suxiaomeng1@huawei.com>
61 lines
6.7 KiB
HTML
61 lines
6.7 KiB
HTML
<a name="dli_spark_log"></a><a name="dli_spark_log"></a>
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<h1 class="topictitle1">log</h1>
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<div id="body8662426"><p id="dli_spark_log__en-us_topic_0000001696282273_p18471163815215">This function is used to return the natural logarithm of a given base and exponent.</p>
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<div class="section" id="dli_spark_log__en-us_topic_0000001696282273_section45291954203217"><h4 class="sectiontitle">Syntax</h4><pre class="screen" id="dli_spark_log__en-us_topic_0000001696282273_screen19928459112517">log(DOUBLE base, DOUBLE a)</pre>
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</div>
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<div class="section" id="dli_spark_log__en-us_topic_0000001696282273_section992014913317"><h4 class="sectiontitle">Parameters</h4>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="dli_spark_log__en-us_topic_0000001696282273_table1829154762513" frame="border" border="1" rules="all"><caption><b>Table 1 </b>Parameters</caption><thead align="left"><tr id="dli_spark_log__en-us_topic_0000001696282273_row8830104792517"><th align="left" class="cellrowborder" valign="top" width="19.220000000000002%" id="mcps1.3.3.2.2.5.1.1"><p id="dli_spark_log__en-us_topic_0000001696282273_p983074711252">Parameter</p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="13.44%" id="mcps1.3.3.2.2.5.1.2"><p id="dli_spark_log__en-us_topic_0000001696282273_p6830124732517">Mandatory</p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="15.57%" id="mcps1.3.3.2.2.5.1.3"><p id="dli_spark_log__en-us_topic_0000001696282273_p13318164512614">Type</p>
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</th>
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<th align="left" class="cellrowborder" valign="top" width="51.77%" id="mcps1.3.3.2.2.5.1.4"><p id="dli_spark_log__en-us_topic_0000001696282273_p08301547132513">Description</p>
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</th>
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</tr>
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</thead>
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<tbody><tr id="dli_spark_log__en-us_topic_0000001696282273_row15830184792511"><td class="cellrowborder" valign="top" width="19.220000000000002%" headers="mcps1.3.3.2.2.5.1.1 "><p id="dli_spark_log__en-us_topic_0000001696282273_p683034714250">base</p>
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</td>
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<td class="cellrowborder" valign="top" width="13.44%" headers="mcps1.3.3.2.2.5.1.2 "><p id="dli_spark_log__en-us_topic_0000001696282273_p12830184752518">Yes</p>
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</td>
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<td class="cellrowborder" valign="top" width="15.57%" headers="mcps1.3.3.2.2.5.1.3 "><p id="dli_spark_log__en-us_topic_0000001696282273_p0318545102615">DOUBLE, BIGINT, DECIMAL, or STRING</p>
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</td>
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<td class="cellrowborder" valign="top" width="51.77%" headers="mcps1.3.3.2.2.5.1.4 "><p id="dli_spark_log__en-us_topic_0000001696282273_p18653154615263">The value can be a float, integer, or string.</p>
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<p id="dli_spark_log__en-us_topic_0000001696282273_p9484232112711">If the value is not of the DOUBLE type, the system will implicitly convert it to the DOUBLE type for calculation.</p>
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</td>
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</tr>
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<tr id="dli_spark_log__en-us_topic_0000001696282273_row1526564123019"><td class="cellrowborder" valign="top" width="19.220000000000002%" headers="mcps1.3.3.2.2.5.1.1 "><p id="dli_spark_log__en-us_topic_0000001696282273_p162661340305">a</p>
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</td>
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<td class="cellrowborder" valign="top" width="13.44%" headers="mcps1.3.3.2.2.5.1.2 "><p id="dli_spark_log__en-us_topic_0000001696282273_p132664410301">Yes</p>
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</td>
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<td class="cellrowborder" valign="top" width="15.57%" headers="mcps1.3.3.2.2.5.1.3 "><p id="dli_spark_log__en-us_topic_0000001696282273_p172665410309">DOUBLE, BIGINT, DECIMAL, or STRING</p>
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</td>
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<td class="cellrowborder" valign="top" width="51.77%" headers="mcps1.3.3.2.2.5.1.4 "><p id="dli_spark_log__en-us_topic_0000001696282273_p1066913503720">The value can be a float, integer, or string.</p>
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<p id="dli_spark_log__en-us_topic_0000001696282273_p126695516372">If the value is not of the DOUBLE type, the system will implicitly convert it to the DOUBLE type for calculation.</p>
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</td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="section" id="dli_spark_log__en-us_topic_0000001696282273_section210162513312"><h4 class="sectiontitle">Return Values</h4><p id="dli_spark_log__en-us_topic_0000001696282273_p184124317231">The return value is of the DOUBLE type.</p>
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<div class="note" id="dli_spark_log__en-us_topic_0000001696282273_note61422099395"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><ul id="dli_spark_log__en-us_topic_0000001696282273_ul3323533203716"><li id="dli_spark_log__en-us_topic_0000001696282273_li41401840113718">If the value of <strong id="dli_spark_log__en-us_topic_0000001696282273_b1692415581805">base</strong> or <strong id="dli_spark_log__en-us_topic_0000001696282273_b792405811011">a</strong> is <strong id="dli_spark_log__en-us_topic_0000001696282273_b189240585013">NULL</strong>, <strong id="dli_spark_log__en-us_topic_0000001696282273_b09251583011">NULL</strong> is returned.</li><li id="dli_spark_log__en-us_topic_0000001696282273_li64954513371">If the value of <strong id="dli_spark_log__en-us_topic_0000001696282273_b2281183517117">base</strong> or <strong id="dli_spark_log__en-us_topic_0000001696282273_b1933712201917">a</strong> is negative or <strong id="dli_spark_log__en-us_topic_0000001696282273_b1233782012117">0</strong>, <strong id="dli_spark_log__en-us_topic_0000001696282273_b163381620716">NULL</strong> is returned.</li><li id="dli_spark_log__en-us_topic_0000001696282273_li5324133133720">If the value of <strong id="dli_spark_log__en-us_topic_0000001696282273_b1067719493117">base</strong> is <strong id="dli_spark_log__en-us_topic_0000001696282273_b106251352412">1</strong> (would cause a division by zero), <strong id="dli_spark_log__en-us_topic_0000001696282273_b1977610591410">NULL</strong> is returned.</li></ul>
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</div></div>
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</div>
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<div class="section" id="dli_spark_log__en-us_topic_0000001696282273_section13277192233920"><h4 class="sectiontitle">Example Code</h4><p id="dli_spark_log__en-us_topic_0000001696282273_p61291833105817">The value <strong id="dli_spark_log__en-us_topic_0000001696282273_b847409115114013">2</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log__en-us_topic_0000001696282273_screen975051918593">select log(2, 4);</pre>
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<p id="dli_spark_log__en-us_topic_0000001696282273_p33221434185818">The value <strong id="dli_spark_log__en-us_topic_0000001696282273_b522895814212">NULL</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log__en-us_topic_0000001696282273_screen1535872614596">select log(2, null);</pre>
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<p id="dli_spark_log__en-us_topic_0000001696282273_p1589083510584">The value <strong id="dli_spark_log__en-us_topic_0000001696282273_b14923511317">NULL</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log__en-us_topic_0000001696282273_screen1952213515915">select log(null, 4);</pre>
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<p id="dli_spark_log__en-us_topic_0000001696282273_p015152716585"></p>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="dli_08_0473.html">Mathematical Functions</a></div>
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</div>
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</div>
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