blocks|key|5166571|text|有关这种愚蠢的更多信息，请参阅这篇关于Windows计算器的优秀文章。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5166572|When+you+change+the+insides,+nobody+notices|offset|length|5166573|5166574|的内部计算-算术引擎-完全被抛弃，并从头开始重写。标准的IEEE浮点库被替换为任意精度的算术库。这是在人们一直在写哈哈文章说Calc不能正确地做十进制算术之后完成的，例如计算10.21+-+10.2会得到0.0100000000000016。|blockquote|5166575|5166576|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.msdn.com/oldnewthing/archive/2004/05/25/141253.aspx^0|0|0|17|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|Y|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

For more of this kind of silliness see this nice article pertaining to Windows calculator.

<a href="http://blogs.msdn.com/oldnewthing/archive/2004/05/25/141253.aspx" rel="nofollow noreferrer">When you change the insides, nobody notices</a>

<blockquote>
 The innards of Calc - the arithmetic
 engine - was completely thrown away
 and rewritten from scratch. The
 standard IEEE floating point library
 was replaced with an
 arbitrary-precision arithmetic
 library. This was done after people
 kept writing ha-ha articles about how
 Calc couldn't do decimal arithmetic
 correctly, that for example computing
 10.21 - 10.2 resulted in 0.0100000000000016.
</blockquote>

blocks|key|708564|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|708565|看起来像是谷歌使用了简单的32位浮点精度(这里的错误)，如果你在上面的代码中将浮点数转换为双精度，你就解决了这个问题！会是这样吗？|blockquote|708566|708567|708568|不，你只是把问题推迟了。替身仍然表现出同样的问题，只是数字更大。|708569|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|J|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|K|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|L|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|M|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|N|7|@]|8|@]|9|$]]|$1|H|3|-4|4|5|6|O|7|@]|8|@]|9|$]]]|I|$]]

<blockquote>
 It would seem like Google is using simple 32 bit floating precision (the error here), if you switch float for double in the above code, you fix the issue! Could this be it?
</blockquote>

No, you just defer the issue. doubles still exhibit the same issue, just with larger numbers.

blocks|key|5166717|text|在C#中，尝试(double.maxvalue+==+(double.maxvalue+-+100))，你会得到true+...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5166718|但这就是它应该是的样子：|5166719|http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems|offset|length|5166720|想想看，您有64位表示大于2%5E64+(double.maxvalue)的数字，因此预计会出现不准确的情况。|5166721|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|0|1P|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|R|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|S|8|@]|9|@$F|T|G|U|1|V]]|A|$]]|$1|H|3|I|5|6|7|W|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|X|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|E]]]]

in C#, try (double.maxvalue == (double.maxvalue - 100)) , you'll get true ...

but thats what it is supposed to be:

<a href="http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems" rel="nofollow noreferrer">http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems</a> 

thinking about it, you have 64 bit representing a number greater than 2^64 (double.maxvalue), so inaccuracy is expected.

blocks|key|3755923|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3755924|是真的。我没有考虑重复的编码。但实际上双打是252-1，单打是223-1。:p|blockquote|3755925|3755926|3755927|多，忘了减去无穷大了。|3755928|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|J|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|K|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|L|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|M|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|N|7|@]|8|@]|9|$]]|$1|H|3|-4|4|5|6|O|7|@]|8|@]|9|$]]]|I|$]]

<blockquote>
 True. I didn't account for duplicate encodings. There are actually 252-1 NaNs for doubles and 223-1 NaNs for singles, though. :p
</blockquote>

Doh, forgot to subtract the infinities.

blocks|key|2911598|text|我了解到的这个问题的粗略估计版本是，32位浮点数给你5位精度，64位浮点数给你15位精度。这当然会根据浮点数的编码方式而有所不同，但这是一个很好的起点。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2911599|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The rough estimate version of this issue that I learned is that 32-bit floats give you 5 digits of precision and 64-bit floats give you 15 digits of precision. This will of course vary depending on how the floats are encoded, but it's a pretty good starting point.

I did this Just for kicks (so, not exactly a question, i can see the downmodding happening already) but, in lieu of Google's newfound <a href="http://www.google.com/search?hl=en&amp;q=1999999999999999-1999999999999995&amp;btnG=Search" rel="nofollow noreferrer">inability</a> to do <a href="http://www.google.com/search?hl=en&amp;q=400000000000002-400000000000001&amp;btnG=Search" rel="nofollow noreferrer">math</a> <a href="http://www.google.com/search?hl=en&amp;q=10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001-10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000&amp;btnG=Search" rel="nofollow noreferrer">correctly</a> (check it! according to google 500,000,000,000,002 - 500,000,000,000,001 = 0), i figured i'd try the following in C to run a little theory.

<pre><code>int main()
{
 char* a = "399999999999999";
 char* b = "399999999999998";

 float da = atof(a);
 float db = atof(b);

 printf("%s - %s = %f\n", a, b, da-db);

 a = "500000000000002";
 b = "500000000000001";
 da = atof(a);
 db = atof(b);
 printf("%s - %s = %f\n", a, b, da-db);
}
</code></pre>

When you run this program, you get the following

<pre><code> 399999999999999 - 399999999999998 = 0.000000
 500000000000002 - 500000000000001 = 0.000000
</code></pre>

It would seem like Google is using simple 32 bit floating precision (the error here), if you switch float for double in the above code, you fix the issue! Could this be it?

/mp

The Google Calculator Glitch, could float vs. double be a possible reason?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我这样做只是为了好玩(所以，不完全是一个问题，我可以看到降级已经发生了)，但是，代替谷歌新发现的来做  (检查它！根据google 500,000,000,000,002 - 500,000,000,000,001 = 0)，我想我应该尝试下面的C语言来运行一些理论。int main(){   char* a = "3...

问Google Calculator故障，float vs.是可能的原因吗？
EN

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问Google Calculator故障，float vs.是可能的原因吗？EN