java中双精度乘法的精度？ [英] Accuracy of double precision multiplication in java?

问题描述

java中double值的乘法运算符的保证精度是多少？

例如，2.2 * 100是220.00000000000003，但是220是一个双数。 220.00000000000003是220后的下一个double。

解决方案

乘法工作正常，但 2.2 不能完全表示为双精度。最接近的双打是：

• 2.199999999999999733（0x4001999999999999）
  
• 2.200000000000000177（0x400199999999999a）



有些软件会把后面的值打印成 2.2 ，但这并不意味着它是准确的。这只是意味着它被视为足够接近。



What is the guaranteed accuracy of multiplication operator for double values in java?

For example, 2.2 * 100 is 220.00000000000003, but 220 is a double number. 220.00000000000003 is the next double after 220.

解决方案

The multiplication is working fine, but 2.2 cannot be represented exactly as a double. The closest doubles are:

• 2.199999999999999733 (0x4001999999999999)
• 2.200000000000000177 (0x400199999999999a)

Some software will print the latter value as 2.2, but that doesn't mean it's exact. It just means it's treated as "close enough".

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