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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>
52 lines
5.1 KiB
HTML
52 lines
5.1 KiB
HTML
<a name="dli_spark_log2"></a><a name="dli_spark_log2"></a>
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<h1 class="topictitle1">log2</h1>
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<div id="body8662426"><p id="dli_spark_log2__en-us_topic_0000001648161872_p18471163815215">This function is used to return the natural logarithm of a given value with a base of 2.</p>
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<div class="section" id="dli_spark_log2__en-us_topic_0000001648161872_section45291954203217"><h4 class="sectiontitle">Syntax</h4><pre class="screen" id="dli_spark_log2__en-us_topic_0000001648161872_screen19928459112517">log2(DOUBLE a)</pre>
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</div>
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<div class="section" id="dli_spark_log2__en-us_topic_0000001648161872_section992014913317"><h4 class="sectiontitle">Parameters</h4>
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" id="dli_spark_log2__en-us_topic_0000001648161872_table1829154762513" frame="border" border="1" rules="all"><caption><b>Table 1 </b>Parameter</caption><thead align="left"><tr id="dli_spark_log2__en-us_topic_0000001648161872_row8830104792517"><th align="left" class="cellrowborder" valign="top" width="19.220000000000002%" id="mcps1.3.3.2.2.5.1.1"><p id="dli_spark_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_row15830184792511"><td class="cellrowborder" valign="top" width="19.220000000000002%" headers="mcps1.3.3.2.2.5.1.1 "><p id="dli_spark_log2__en-us_topic_0000001648161872_p683034714250">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_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_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_log2__en-us_topic_0000001648161872_p18653154615263">The value can be a float, integer, or string.</p>
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<p id="dli_spark_log2__en-us_topic_0000001648161872_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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</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_log2__en-us_topic_0000001648161872_section210162513312"><h4 class="sectiontitle">Return Values</h4><p id="dli_spark_log2__en-us_topic_0000001648161872_p184124317231">The return value is of the DOUBLE type.</p>
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<div class="note" id="dli_spark_log2__en-us_topic_0000001648161872_note61422099395"><img src="public_sys-resources/note_3.0-en-us.png"><span class="notetitle"> </span><div class="notebody"><p id="dli_spark_log2__en-us_topic_0000001648161872_p4101166570">If the value of <strong id="dli_spark_log2__en-us_topic_0000001648161872_b589236699036">a</strong> is negative, <strong id="dli_spark_log2__en-us_topic_0000001648161872_b16174445789036">0</strong>, or <strong id="dli_spark_log2__en-us_topic_0000001648161872_b18641939099036">NULL</strong>, <strong id="dli_spark_log2__en-us_topic_0000001648161872_b18892848499036">NULL</strong> is returned.</p>
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</div></div>
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</div>
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<div class="section" id="dli_spark_log2__en-us_topic_0000001648161872_section13277192233920"><h4 class="sectiontitle">Example Code</h4><p id="dli_spark_log2__en-us_topic_0000001648161872_p172501262106">The value <strong id="dli_spark_log2__en-us_topic_0000001648161872_b17221741999">NULL</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log2__en-us_topic_0000001648161872_screen519616579109">select log2(null);</pre>
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<p id="dli_spark_log2__en-us_topic_0000001648161872_p480911275107">The value <strong id="dli_spark_log2__en-us_topic_0000001648161872_b19372046697">NULL</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log2__en-us_topic_0000001648161872_screen1745912616119">select log2(0);</pre>
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<p id="dli_spark_log2__en-us_topic_0000001648161872_p216623071010">The value <strong id="dli_spark_log2__en-us_topic_0000001648161872_b19347195319916">3.1699250014423126</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log2__en-us_topic_0000001648161872_screen13991215171113">select log2(9);</pre>
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<p id="dli_spark_log2__en-us_topic_0000001648161872_p1535312328107">The value <strong id="dli_spark_log2__en-us_topic_0000001648161872_b211207870423914">4</strong> is returned.</p>
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<pre class="screen" id="dli_spark_log2__en-us_topic_0000001648161872_screen17211202341120">select log2(16);</pre>
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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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