英文:
Using floats for counters - Any problems?
问题
我正在查看的代码使用 golang 的 float64 作为计数器，这会在某个时候导致精度丢失的问题吗？具体来说，所有整数都能在 float64 的范围内表示吗？如果不能，我从哪里开始遇到问题？我什么时候会用完连续的整数？
如果你想知道，使用 float64 作为计数器的原因是因为它是一个包含许多不是整数的指标的 []float64 的一部分。
英文:
The code I'm looking at uses a golang float64 as a counter, does this pose a problem with loss of accuracy at some point? Specifically, are all integers represented in the range covered by float64? If not, where do I start running into problems? When do I run out of contiguous integers?
In case you're wondering, the reason for using a float64 as a counter is because it's part of a []float64 that holds many metrics that are not integers.
答案1
得分: 4
根据golang规范，"float64是所有IEEE-754 64位浮点数的集合"，通常被称为双精度数。
你可以阅读它的详细信息，如果感兴趣的话，但是为了回答你的问题，引用一下：
"...下一个范围，从2的53次方到2的54次方，每个数都乘以2..."
所以，如果你想将它用作计数器，即正整数，直到2的53次方=9,007,199,254,740,992，你不会遇到问题。
英文:
The golang specification says, "float64 is the set of all IEEE-754 64-bit floating-point numbers." which is commonly known as double precision numbers,
http://en.wikipedia.org/wiki/Double-precision_floating-point_format
You can read all of its glory details if interested, but to answer your question, quote,
"...next range, from 2<sup>53</sup> to 2<sup>54</sup>, everything is multiplied by 2..."
So if you want to use it as counters, i.e. positive integers, you won't have problem until 2<sup>53</sup>=9,007,199,254,740,992.
答案2
得分: 2
是的，float64有52位来存储您的计数器。您应该在2的53次方之前保持准确。
（附注：整个JavaScript语言只使用浮点数。）
英文:
Yes, float64 has 52 bits to store your counter. You should be accurate until 2<sup>53</sup>.
(Side note: the entire JavaScript language uses only Floating Point.)
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