140 lines
8.4 KiB
HTML
140 lines
8.4 KiB
HTML
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<title>std::abs(std::complex)</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>abs<span style="font-size:0.7em; line-height:130%">(std::complex)</span></h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-numeric.html">numeric</a>‎ | <a href="cpp-numeric-complex.html">complex</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-complex.html"><complex></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T <span class="sy1">></span><br />
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T abs<span class="br0">(</span> <span class="kw4">const</span> complex<span class="sy1"><</span>T<span class="sy1">></span><span class="sy3">&</span> z <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>返回复数 <code>z</code> 的绝对值。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<td>z</td>
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<td>-</td>
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<td>复数值</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>若不出现错误，则返回 <code>z</code> 的绝对值（又称为范数、模或幅度）。</p>
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<p>错误和特殊情形按照此函数实现成 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-numeric-math-hypot.html"><span class="kw1331">std::<span class="me2">hypot</span></span></a><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">real</span><span class="br0">(</span>z<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">imag</span><span class="br0">(</span>z<span class="br0">)</span><span class="br0">)</span></span></span> 一般处理</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <complex></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-numeric-complex.html"><span class="kw1472">std::<span class="me2">complex</span></span></a><span class="sy1"><</span><span class="kw4">double</span><span class="sy1">></span> z<span class="br0">(</span><span class="nu0">1</span>, <span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> z <span class="sy1"><<</span> <span class="st0">" cartesian is rho = "</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">abs</span><span class="br0">(</span>z<span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">" theta = "</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">arg</span><span class="br0">(</span>z<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">" polar<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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<p>输出：</p>
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<div class="text source-text">
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<pre class="de1">(1,1) cartesian is rho = 1.41421 theta = 0.785398 polar</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div><a href="cpp-numeric-complex-arg.html"><span class="t-lines"><span>arg</span></span></a></div>
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<td>返回辐角<br />
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<span class="t-mark">(函数模板)</span></td>
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<div><a href="cpp-numeric-complex-polar.html"><span class="t-lines"><span>polar</span></span></a></div>
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<td>从模和辐角构造复数<br />
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<span class="t-mark">(函数模板)</span></td>
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<div><a href="cpp-numeric-math-abs.html"><span class="t-lines"><span>abs<span class="t-dsc-small">(int)</span></span><span>labs</span><span>llabs</span></span></a></div>
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<div><span class="t-lines"><span></span><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>计算整数值的绝对值（ <span class="mjax" style="display:none">\(\small{|x|}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">|x|</span> ）<br />
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<span class="t-mark">(函数)</span></td>
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<div><a href="cpp-numeric-math-fabs.html"><span class="t-lines"><span>abs<span class="t-dsc-small">(float)</span></span><span>fabs</span><span>fabsf</span><span>fabsl</span></span></a></div>
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<div><span class="t-lines"><span></span><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>浮点值的绝对值（ <span class="mjax" style="display:none">\(\small{|x|}\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;">|x|</span> ）<br />
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<span class="t-mark">(函数)</span></td>
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<div><a href="cpp-numeric-math-hypot.html"><span class="t-lines"><span>hypot</span><span>hypotf</span><span>hypotl</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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<td>计算两个给定数的平方和的平方根（ <span class="mjax" style="display:none">\(\scriptsize{\sqrt{x^2+y^2} }\)</span><span class="mjax-fallback texhtml" style="white-space: nowrap;"><span class="t-mrad"><span>√</span><span>x<span class="t-su">2<br /></span>+y<span class="t-su">2<br /></span></span></span></span> ）<br />
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<span class="t-mark">(函数)</span></td>
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<div><a href="cpp-numeric-valarray-abs.html"><span class="t-lines"><span>abs<span class="t-dsc-small">(std::valarray)</span></span></span></a></div>
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<td>应用函数 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">abs</span></span></span> 到 valarray 的每个元素<br />
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<span class="t-mark">(函数模板)</span></td>
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