Math.random随机位数 [英] Math.random number of random bits

问题描述

是否要求生成多少随机位 Math.random ？我对Chrome和Firefox的实现进行了一些测试，将结果转换为十六进制以检查位，Firefox 27.0.1给出了结果，如

Is there any requirement on how many random bits Math.random is supposed to produce? I did some tests on Chrome and Firefox's implementations, converting the results to hex to examine the bits, and Firefox 27.0.1 gives results like

0x1.de619579d56f3p-1
0x1.ef1ada9306decp-2
0x1.df3b75e208ce6p-1

而Chrome版本33.0.1750.154 m给出

whereas Chrome Version 33.0.1750.154 m gives

0x1.1190f39c00000p-2
0x1.b959e3b600000p-1
0x1.90f614b400000p-2

相比较神奇。它似乎是一个32位的结果，而Firefox的值似乎使用了53个随机位。

which is godawful in comparison. It appears to be a 32-bit result, whereas Firefox's values seem to use 53 random bits.

推荐答案

http://www.ecma-international.org/ecma-262/5.1/# sec-15.8.2.14

15.8.2.14 random（）

15.8.2.14 random ( )

使用依赖于实现的算法或策略，返回具有正号，大于或等于0但小于1的Number值，随机或伪随机选择，在该范围内具有近似均匀的分布。这个函数没有参数。

Returns a Number value with positive sign, greater than or equal to 0 but less than 1, chosen randomly or pseudo randomly with approximately uniform distribution over that range, using an implementation-dependent algorithm or strategy. This function takes no arguments.

似乎是所有的规范说的。

Seems to be all the spec says.

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