使用Python的max（）时的浮点精度 [英] Floating point precision while using Python's max()

问题描述

 >>> max（2，2.01）
 2.0099999999999998 
  

解决方案

以二进制表示的数字为2.01：

  b10.00000010100011111100001010001111110000101000111111000010100011111100 ... 
  

计算机仅使用有限数量的数字来存储浮点值，但二进制表示2.01需要无限多个数字;结果，它是最接近的可表示的值：

  b10.000000101000111111000010100011111100001010001111110 
  

用十进制表示，这个数字正是：

  2.0099999999999997868371792719699442386627197265625 
  

打印出来时，时间到十七位数字，给：

  2.0099999999999998 
  

Why so?

>>> max(2, 2.01)
2.0099999999999998

解决方案

The number 2.01 represented in binary is:

b10.00000010100011111100001010001111110000101000111111000010100011111100...

The computer uses only a finite number of digits to store floating-point values, but the binary representation of 2.01 requires infinitely many digits; as a result, it is rounded to the closest representable value:

b10.000000101000111111000010100011111100001010001111110

Expressed in decimal, this number is exactly:

2.0099999999999997868371792719699442386627197265625

When you print it out, it is rounded a second time to seventeen decimal digits, giving:

2.0099999999999998

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