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138 lines
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HTML
138 lines
5.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Raise an arbitrary precision number to another, reduced by a specified modulus</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.bcpowmod" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">bcpowmod</h1>
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<p class="verinfo">(PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">bcpowmod</span> — <span class="dc-title">Raise an arbitrary precision number to another, reduced by a specified modulus</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.bcpowmod-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>bcpowmod</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$base</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$exponent</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$modulus</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$scale</code><span class="initializer"> = 0</span></span>
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] ) : <span class="type">string</span></div>
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<p class="para rdfs-comment">
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Use the fast-exponentiation method to raise
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<code class="parameter">base</code> to the power
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<code class="parameter">exponent</code> with respect to the modulus
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<code class="parameter">modulus</code>.
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.bcpowmod-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">base</code></dt>
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<dd>
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<p class="para">
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The base, as an integral string (i.e. the scale has to be zero).
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</p>
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</dd>
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<dt>
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<code class="parameter">exponent</code></dt>
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<dd>
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<p class="para">
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The exponent, as an non-negative, integral string (i.e. the scale has to be zero).
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</p>
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</dd>
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<dt>
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<code class="parameter">modulus</code></dt>
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<dd>
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<p class="para">
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The modulus, as an integral string (i.e. the scale has to be zero).
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</p>
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</dd>
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<dt>
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<code class="parameter">
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scale</code></dt>
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<dd>
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<p class="para">此可选参数用于设置结果中小数点后的小数位数。也可通过使用
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<span class="function"><a href="bcscale.html" class="function">bcscale()</a></span> 来设置全局默认的小数位数，用于所有函数。
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</p></dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.bcpowmod-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns the result as a string, or <strong><code>NULL</code></strong> if <code class="parameter">modulus</code>
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is <em>0</em> or <code class="parameter">exponent</code> is negative.
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.bcpowmod-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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Because this method uses the modulus operation, numbers which are not
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positive integers may give unexpected results.
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</p>
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</p></blockquote>
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</div>
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<div class="refsect1 examples" id="refsect1-function.bcpowmod-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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The following two statements are functionally identical. The
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<span class="function"><strong>bcpowmod()</strong></span> version however, executes in
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less time and can accept larger parameters.
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<div class="informalexample">
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$a </span><span style="color: #007700">= </span><span style="color: #0000BB">bcpowmod</span><span style="color: #007700">(</span><span style="color: #0000BB">$x</span><span style="color: #007700">, </span><span style="color: #0000BB">$y</span><span style="color: #007700">, </span><span style="color: #0000BB">$mod</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">$b </span><span style="color: #007700">= </span><span style="color: #0000BB">bcmod</span><span style="color: #007700">(</span><span style="color: #0000BB">bcpow</span><span style="color: #007700">(</span><span style="color: #0000BB">$x</span><span style="color: #007700">, </span><span style="color: #0000BB">$y</span><span style="color: #007700">), </span><span style="color: #0000BB">$mod</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// $a and $b are equal to each other.<br /><br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.bcpowmod-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="bcpow.html" class="function" rel="rdfs-seeAlso">bcpow()</a> - 任意精度数字的乘方</span></li>
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<li class="member"><span class="function"><a href="bcmod.html" class="function" rel="rdfs-seeAlso">bcmod()</a> - 对一个任意精度数字取模</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |