Math.atanh()

Math.atanh() 函数返回一个数值反双曲正切值, 即:

x ( - 1 , 1 ) , Math.atanh ( x ) = arctanh ( x ) = the unique y such that tanh ( y ) = x \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

语法

Math.atanh(x)

参数

x
一个数值

描述

由于 atanh() 是 Math 的静态方法,所以应该像这样使用:Math.atanh(),而不是作为你创建的 Math 实例的方法(Math 不是一个构造函数)。 

示例

使用 Math.atanh()

Math.atanh(-2);  // NaN
Math.atanh(-1);  // -Infinity
Math.atanh(0);   // 0
Math.atanh(0.5); // 0.5493061443340548
Math.atanh(1);   // Infinity
Math.atanh(2);   // NaN

对于大于1或是小于-1的值,函数返回 NaN

Polyfill

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:

Math.atanh = Math.atanh || function(x) {
  return Math.log((1+x)/(1-x)) / 2;
};

规范

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
Math.atanh
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
Math.atanh
Draft  

浏览器兼容性

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Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 38 25 (25) 未实现 25 7.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 未实现 未实现 25.0 (25) 未实现 未实现 8

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