# Math.atan()

## 概述

Math.atan() 函数返回一个数值的反正切（以弧度为单位），即：

$Math.atan ( x ) = arctan ( x ) = the unique y ∊ [ - π 2 ; π 2 ] such that tan ( y ) = x \mathtt{\operatorname{Math.atan}(x)} = \arctan(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \tan(y) = x$

## 语法

Math.atan(x)

### 参数

x

## 描述

atan 返回一个  $-\frac\left\{\pi\right\}\left\{2\right\}$ 到  $\frac\left\{\pi\right\}\left\{2\right\}$ 弧度之间的数值。

## 示例

### 例子：使用 Math.atan

Math.atan(1);  // 0.7853981633974483
Math.atan(0);  // 0


## 规范

ECMAScript 1st Edition. Implemented in JavaScript 1.0 Standard Initial definition.
ECMAScript 5.1 (ECMA-262)
Math.atan
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
Math.atan
Standard

## 浏览器兼容性

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Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
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Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
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