Math.log2()

Math.log2() 静态方法返回数字的以 2 为底的对数。那是

¥The Math.log2() static method returns the base 2 logarithm of a number. That is

x > 0 , 𝙼𝚊𝚝𝚑.𝚕𝚘𝚐𝟸 ( 𝚡 ) = log 2 ( x ) = the unique  y  such that  2 y = x \forall x > 0,;\mathtt{\operatorname{Math.log2}(x)} = \log_2(x) = \text{the unique } y \text{ such that } 2^y = x

Try it

语法

¥Syntax

js
Math.log2(x)

参数

¥Parameters

x

大于或等于 0 的数字。

返回值

¥Return value

x 以 2 为底的对数。如果是 x < 0,则返回 NaN

¥The base 2 logarithm of x. If x < 0, returns NaN.

描述

¥Description

因为 log2()Math 的静态方法,所以你始终将其用作 Math.log2(),而不是用作你创建的 Math 对象的方法(Math 不是构造函数)。

¥Because log2() is a static method of Math, you always use it as Math.log2(), rather than as a method of a Math object you created (Math is not a constructor).

该功能相当于 Math.log(x) / Math.log(2)。对于 log2(e),使用常量 Math.LOG2E,即 1 / Math.LN2

¥This function is the equivalent of Math.log(x) / Math.log(2). For log2(e), use the constant Math.LOG2E, which is 1 / Math.LN2.

示例

¥Examples

使用 Math.log2()

¥Using Math.log2()

js
Math.log2(-2); // NaN
Math.log2(-0); // -Infinity
Math.log2(0); // -Infinity
Math.log2(1); // 0
Math.log2(2); // 1
Math.log2(3); // 1.584962500721156
Math.log2(1024); // 10
Math.log2(Infinity); // Infinity

规范

Specification
ECMAScript Language Specification
# sec-math.log2

¥Specifications

浏览器兼容性

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¥Browser compatibility

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