201 lines
22 KiB
HTML
201 lines
22 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::remquo, std::remquof, std::remquol</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_numeric_math_remquo skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>remquo, <span style="font-size:0.7em; line-height:130%">std::</span>remquof, <span style="font-size:0.7em; line-height:130%">std::</span>remquol</h1>
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<div id="bodyContent">
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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-math.html">math</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<td>
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<div>定义于头文件 <code><a href="cpp-header-cmath.html"><cmath></a></code></div>
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</td>
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<td></td>
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<td></td>
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<tr class="t-dcl t-since-cxx11">
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">float</span> remquo <span class="br0">(</span> <span class="kw4">float</span> x, <span class="kw4">float</span> y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">float</span> remquof<span class="br0">(</span> <span class="kw4">float</span> x, <span class="kw4">float</span> y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span> remquo <span class="br0">(</span> <span class="kw4">double</span> x, <span class="kw4">double</span> y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">double</span> remquo <span class="br0">(</span> <span class="kw4">long</span> <span class="kw4">double</span> x, <span class="kw4">long</span> <span class="kw4">double</span> y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">long</span> <span class="kw4">double</span> remquol<span class="br0">(</span> <span class="kw4">long</span> <span class="kw4">double</span> x, <span class="kw4">long</span> <span class="kw4">double</span> y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp">Promoted remquo <span class="br0">(</span> Arithmetic1 x, Arithmetic2 y, <span class="kw4">int</span><span class="sy2">*</span> quo <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<div class="t-li1"><span class="t-li">1-3)</span> 计算除法运算 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的浮点余数，如 <span class="t-lc"><a href="cpp-numeric-math-remainder.html">std::remainder()</a></span> 函数所为。另外，将存储 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的至少最低三位及符号于 <span class="t-c"><span class="mw-geshi cpp source-cpp">quo</span></span> ，这足以确定结果在周期中的八分位。</div>
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<div class="t-li1"><span class="t-li">4)</span> 1-3 所不覆盖的所有<a href="cpp-types-is_arithmetic.html">算术类型</a>参数组合的重载集或函数模板。若任何非指针参数拥有<a href="cpp-types-is_integral.html">整数类型</a>，则将它转型为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span></span></span> 。若任何非指针参数为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">double</span></span></span> ，则返回类型为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">double</span></span></span> ，否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span></span></span> 。</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>x, y</td>
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<td>-</td>
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<td>浮点值</td>
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</tr>
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<tr class="t-par">
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<td>quo</td>
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<td>-</td>
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<td>指向存储 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的符号和某些位的整数的指针</td>
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</tr>
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</table>
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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>若成功，则返回定义于 <span class="t-lc"><a href="cpp-numeric-math-remainder.html">std::remainder</a></span> 的 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的余数，并存储 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的符号和至少后三位有效数字于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>quo</span></span> （正式而言，存储的值的符号是 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的符号，而绝对值与 <span class="t-c"><span class="mw-geshi cpp source-cpp">x<span class="sy2">/</span>y</span></span> 的整数商的绝对值对于 <span class="texhtml" style="white-space: nowrap;">modulo 2<span class="t-su">n<br /></span></span> 同余，其中 <span class="texhtml" style="white-space: nowrap;">n</span> 是实现定义的大于或等于 <span class="texhtml" style="white-space: nowrap;">3</span> 的整数）。</p>
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<p>若 <code>y</code> 为零，则存储于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>quo</span></span> 的值未指定。</p>
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<p>若出现定义域错误，则返回实现定义值（受支持平台上为 NaN ）。</p>
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<p>若出现下溢所致的值域错误，则若支持非正规值则返回正确结果。</p>
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<p>若 <code>y</code> 为零，但不出现定义域错误，则返回零。</p>
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<h3><span class="mw-headline" id=".E9.94.99.E8.AF.AF.E5.A4.84.E7.90.86">错误处理</span></h3>
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<p>报告 <span class="t-lc"><a href="cpp-numeric-math-math_errhandling.html">math_errhandling</a></span> 中指定的错误。</p>
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<p>若 <code>y</code> 为零则可能出现定义域错误。</p>
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<p>若实现支持 IEEE 浮点算术（ IEC 60559 ），则</p>
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<ul>
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<li>当前<a href="cpp-numeric-fenv-FE_round.html">舍入模式</a>无效。</li>
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<li>决不引发 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_INEXACT</a></span> 。</li>
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<li>若 <code>x</code> 为 ±∞ 且 <code>y</code> 非 NaN ，则返回 NaN 并引发 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span> 。</li>
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<li>若 <code>y</code> 为 ±0 且 <code>x</code> 非 NaN ，则返回 NaN 并引发 <span class="t-lc"><a href="cpp-numeric-fenv-FE_exceptions.html">FE_INVALID</a></span> 。</li>
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<li>若 <code>x</code> 或 <code>y</code> 为 NaN ，则返回 NaN 。</li>
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</ul>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p><a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/remquo.html">POSIX 要求</a>若 <code>x</code> 为无穷大或 <code>y</code> 为零则出现定义域错误。</p>
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<p>此函数在实现周期可准确表示为浮点值的周期函数时有用：对非常大的 <code>x</code> 计算 <span class="texhtml" style="white-space: nowrap;">sin(πx)</span> 时，直接调用 <span class="t-lc"><a href="cpp-numeric-math-sin.html">std::sin</a></span> 可能导致巨大误差，但若首先以 <code>std::remquo</code> 减小参数，则商的低位可用来确定结果在周期中的八分位，同时余数可用来计算拥有高精度的值。</p>
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<p>某些平台上硬件支持此运算（而例如在 Intel CPU 上， <code>FPREM1</code> 在完成时于商中准确保留 3 位精度）。</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="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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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 <cmath></span>
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<span class="co2">#include <cfenv></span>
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<span class="co2">#pragma STDC FENV_ACCESS ON</span>
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<span class="kw4">const</span> <span class="kw4">double</span> pi <span class="sy1">=</span> <a href="cpp-numeric-math-acos.html"><span class="kw1336">std::<span class="me2">acos</span></span></a><span class="br0">(</span><span class="sy2">-</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">double</span> cos_pi_x_naive<span class="br0">(</span><span class="kw4">double</span> x<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> <a href="cpp-numeric-math-cos.html"><span class="kw1333">std::<span class="me2">cos</span></span></a><span class="br0">(</span>pi <span class="sy2">*</span> x<span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span>
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<span class="co1">// 周期为 2 ，值为 (0;0.5) 正， (0.5;1.5) 负， (1.5,2) 正</span>
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<span class="kw4">double</span> cos_pi_x_smart<span class="br0">(</span><span class="kw4">double</span> x<span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">int</span> quadrant<span class="sy4">;</span>
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<span class="kw4">double</span> rem <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">remquo</span><span class="br0">(</span>x, <span class="nu0">1</span>, <span class="sy3">&</span>quadrant<span class="br0">)</span><span class="sy4">;</span>
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quadrant <span class="sy1">=</span> <span class="br0">(</span><span class="kw4">unsigned</span><span class="br0">)</span>quadrant <span class="sy2">%</span> <span class="nu0">2</span><span class="sy4">;</span> <span class="co1">// 周期为 2 。</span>
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<span class="kw1">switch</span><span class="br0">(</span>quadrant<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">case</span> <span class="nu0">0</span><span class="sy4">:</span> <span class="kw1">return</span> <a href="cpp-numeric-math-cos.html"><span class="kw1333">std::<span class="me2">cos</span></span></a><span class="br0">(</span>pi <span class="sy2">*</span> rem<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">case</span> <span class="nu0">1</span><span class="sy4">:</span> <span class="kw1">return</span> <span class="sy2">-</span><a href="cpp-numeric-math-cos.html"><span class="kw1333">std::<span class="me2">cos</span></span></a><span class="br0">(</span>pi <span class="sy2">*</span> rem<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span><span class="sy4">;</span>
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<span class="br0">}</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-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"cos(pi * 0.25) = "</span> <span class="sy1"><<</span> cos_pi_x_naive<span class="br0">(</span><span class="nu16">0.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1.25) = "</span> <span class="sy1"><<</span> cos_pi_x_naive<span class="br0">(</span><span class="nu16">1.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 2.25) = "</span> <span class="sy1"><<</span> cos_pi_x_naive<span class="br0">(</span><span class="nu16">2.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 0.25) = "</span> <span class="sy1"><<</span> cos_pi_x_smart<span class="br0">(</span><span class="nu16">0.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1.25) = "</span> <span class="sy1"><<</span> cos_pi_x_smart<span class="br0">(</span><span class="nu16">1.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 2.25) = "</span> <span class="sy1"><<</span> cos_pi_x_smart<span class="br0">(</span><span class="nu16">2.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1000000000000.25) = "</span>
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<span class="sy1"><<</span> cos_pi_x_naive<span class="br0">(</span><span class="nu16">1000000000000.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1000000000001.25) = "</span>
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<span class="sy1"><<</span> cos_pi_x_naive<span class="br0">(</span><span class="nu16">1000000000001.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1000000000000.25) = "</span>
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<span class="sy1"><<</span> cos_pi_x_smart<span class="br0">(</span><span class="nu16">1000000000000.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span>
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<span class="sy1"><<</span> <span class="st0">"cos(pi * 1000000000001.25) = "</span>
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<span class="sy1"><<</span> cos_pi_x_smart<span class="br0">(</span><span class="nu16">1000000000001.25</span><span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="co1">// 错误处理</span>
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<a href="cpp-numeric-fenv-feclearexcept.html"><span class="kw1449">std::<span class="me2">feclearexcept</span></span></a><span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1460">FE_ALL_EXCEPT</span></a><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">int</span> quo<span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"remquo(+Inf, 1) = "</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">remquo</span><span class="br0">(</span><a href="cpp-numeric-math-INFINITY.html"><span class="kw1376">INFINITY</span></a>, <span class="nu0">1</span>, <span class="sy3">&</span>quo<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>fetestexcept<span class="br0">(</span><a href="cpp-numeric-fenv-FE_exceptions.html"><span class="kw1463">FE_INVALID</span></a><span class="br0">)</span><span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1757">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">" FE_INVALID raised<span class="es1">\n</span>"</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">cos(pi * 0.25) = 0.707107
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cos(pi * 1.25) = -0.707107
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cos(pi * 2.25) = 0.707107
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cos(pi * 0.25) = 0.707107
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cos(pi * 1.25) = -0.707107
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cos(pi * 2.25) = 0.707107
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cos(pi * 1000000000000.25) = 0.707123
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cos(pi * 1000000000001.25) = -0.707117
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cos(pi * 1000000000000.25) = 0.707107
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cos(pi * 1000000000001.25) = -0.707107
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remquo(+Inf, 1) = -nan
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FE_INVALID raised</pre></div>
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</div>
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</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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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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|
<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-math-div.html"><span class="t-lines"><span>div<span class="t-dsc-small">(int)</span></span><span>ldiv</span><span>lldiv</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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</div>
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</td>
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<td>计算整数除法的商和余数<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-numeric-math-fmod.html"><span class="t-lines"><span>fmod</span><span>fmodf</span><span>fmodl</span></span></a></div>
|
|
<div><span class="t-lines"><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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|
</div>
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</td>
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|
<td>浮点除法运算的余数<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
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|
<div><a href="cpp-numeric-math-remainder.html"><span class="t-lines"><span>remainder</span><span>remainderf</span><span>remainderl</span></span></a></div>
|
|
<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>
|
|
</div>
|
|
</td>
|
|
<td>除法运算的有符号余数<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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