你能比较准确浮点值为零？ [英] Can you compare floating point values exactly to zero?

问题描述

我知道我们使用无法比拟2浮点值==。我们只能比较它们是彼此的一些间隔范围内。
我知道

 如果（VAL == 0.512）
  

是不对由于浮点计算和转换为二进制和
应

固有误差

 如果（VAL在（0.512-ε，0.512 +小量））
  

不过是0特殊？我们可以准确地比较花车为0？甚至可以说是不正确的？特别是在C＃和Java

 双VAL = 0的情况下？; 
 VAL = GETVAL（）; 
如果（VAL == 0）
  

解决方案

尽管0有一个精确的表示，你不能依赖于使用花车计算的结果是完全0正如你指出，这是由于浮点运算和转换的问题。

所以，你应该测试0战胜你的宽容小量。

I know we can't compare 2 floating point values using ==. We can only compare they are within some interval of each other. I know

if(val == 0.512)

is wrong due to errors inherent in floating point calculations and conversion to binary and should be

if (val in (0.512-epsilon, 0.512+epsilon))

But is 0 special? Can we compare floats exactly to 0? Or even that is incorrect? Particularly in the context of C# and Java?

double val = 0;
val = getVal();
if(val == 0)

解决方案

Even though 0 has an exact representation, you can't rely on the result of a calculation using floats to be exactly 0. As you noted, this is due to floating point calculation and conversion issues.

So, you should test for 0 against your tolerance epsilon.

这篇关于你能比较准确浮点值为零？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！