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116 lines
5.9 KiB
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116 lines
5.9 KiB
HTML
<article id="wikiArticle">
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<div></div>
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<p><strong><code>Math.atanh()</code></strong> 函数返回一个数值反双曲正切值, 即：</p>
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<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>∊</mo><mrow><mo>(</mo><mrow><mo>-</mo><mn>1</mn><mo>,</mo><mn>1</mn></mrow><mo>)</mo></mrow><mo>,</mo><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.atanh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="thinmathspace">arctanh</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mspace width="thickmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">tanh</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\forall x \in \left( -1, 1 \right), \mathtt{\operatorname{Math.atanh}(x)} = \operatorname{arctanh}(x) = \text{ the unique } \; y \; \text{such that} \; \tanh(y) = x</annotation></semantics></math></p>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript"><code>Math.atanh(<var>x</var>)</code></code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt><code>x</code></dt>
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<dd>一个数值</dd>
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</dl>
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<h2 id="描述">描述</h2>
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<p>由于 <code>atanh()</code> 是 <code>Math 的静态方法</code>,所以应该像这样使用：<code>Math.atanh()</code>，而不是作为你创建的 <code>Math</code> 实例的方法（<code>Math 不是一个构造函数</code>）。 </p>
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<h2 id="示例">示例</h2>
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<h3 id="使用_Math.atanh()"><code>使用 Math.atanh()</code></h3>
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<pre><code class="language-javascript">Math.atanh(-2); // NaN
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Math.atanh(-1); // -Infinity
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Math.atanh(0); // 0
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Math.atanh(0.5); // 0.5493061443340548
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Math.atanh(1); // Infinity
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Math.atanh(2); // NaN
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</code></pre>
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<p>对于大于1或是小于－1的值，函数返回 <a href="Reference/Global_Objects/NaN" title="全局属性 NaN 的值表示不是一个数字（Not-A-Number）。"><code>NaN</code></a> 。</p>
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<h2 id="Polyfill">Polyfill</h2>
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<p>For \left|x\right| < 1, we have \operatorname {artanh} (x) = \frac{1}{2}\ln \left( \frac{1 + x}{1 - x} \right) so this can be emulated by the following function:</p>
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<pre><code class="language-javascript">Math.atanh = Math.atanh || function(x) {
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return Math.log((1+x)/(1-x)) / 2;
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};
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</code></pre>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-math.atanh" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Math.atanh</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-math.atanh" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Math.atanh</small></a></td>
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<td><span class="spec-Draft">Draft</span></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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<h2 id="浏览器兼容性">浏览器兼容性</h2>
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<div><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
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This compatibility table still uses the old format,
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because we haven't yet converted the data it contains.
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<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<div class="htab">
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<ul>
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<li class="selected"><a>Desktop</a></li>
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<li><a>Mobile</a></li>
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</ul>
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</div></div>
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<div id="compat-desktop">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Chrome</th>
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<th>Firefox (Gecko)</th>
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<th>Internet Explorer</th>
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<th>Opera</th>
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<th>Safari</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td>38</td>
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<td><a href="/en-US/Firefox/Releases/25" title="Released on 2013-10-29.">25</a> (25)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>25</td>
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<td>7.1</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 id="compat-mobile">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Android</th>
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<th>Chrome for Android</th>
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<th>Firefox Mobile (Gecko)</th>
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<th>IE Mobile</th>
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<th>Opera Mobile</th>
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<th>Safari Mobile</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>25.0 (25)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>8</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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<h2 id="相关链接">相关链接</h2>
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<ul>
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<li><a class="new" href="Reference/Global_Objects/Math/acosh" rel="nofollow" title="此页面仍未被本地化, 期待您的翻译!"><code>Math.acosh()</code></a></li>
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<li><a href="Reference/Global_Objects/Math/asinh" title="Math.asinh() 函数返回给定数字的反双曲正弦值, 即："><code>Math.asinh()</code></a></li>
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<li><a href="Reference/Global_Objects/Math/cosh" title="Math.cosh() 函数返回数值的双曲余弦函数, 可用 constant e 表示:"><code>Math.cosh()</code></a></li>
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<li><a href="Reference/Global_Objects/Math/sinh" title="Math.sinh() 函数返回一个数字(单位为角度)的双曲正弦值."><code>Math.sinh()</code></a></li>
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<li><a href="Reference/Global_Objects/Math/tanh" title="Math.tanh() 函数将会返回一个数的双曲正切函数值，计算如下:"><code>Math.tanh()</code></a></li>
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</ul>
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</article> |