斯卡拉。浮点数的奇怪结果 [英] Scala. Strange result with floating point numbers

问题描述

为什么从 3 中减去 2.99999 ... 时会得到奇怪的结果？

Why do I get strange results when subtracting 2.99999... from 3?

scala> math.sqrt(3)
res0: Double = 1.7320508075688772

scala> math.pow(res0, 2)
res1: Double = 2.9999999999999996

scala> 3 - res1
res2: Double = 4.440892098500626E-16

推荐答案

这是由于浮点精度;详细记录在
16-，32-和64-中可以表示的数字范围位IEEE-754系统？

This is due to floating point precision; well documented in What range of numbers can be represented in a 16-, 32- and 64-bit IEEE-754 systems?

此外，值得注意的是，完美的计算机无法用十进制表示sqrt（3），因为它是不合理的！

Also, its worth noting here that there is no way the perfect computer could represent sqrt(3) in decimal as it's irrational!

你真的认为sqrt（3）等于正好 1.7320508075688772吗？

Did you really think that sqrt(3) equals exactly 1.7320508075688772?

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