One does not simply calculate the absolute value

Re:One does not simply calculate the absolute value by kmm on Sunday August 22, 2021 @03:52PM (#28268918)

Naively, max(a, b) would be implemented as

    return a >= b ? a : b;

But if x is -0.0, you're back to the same problem that -0.0 >= +0.0 actually turns out to be true and not false, hence the return value will be -0.0.

Looking at the actual implementation[0], doubleToRawLongBits is used again here to take care of this edge case. So it would work, but a lot slower than the version given in the article.

0: https://github.com/openjdk/jdk/blob/36e2ddad4d2ef3ce27475af6...

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Re:One does not simply calculate the absolute value by andi999 on Sunday August 22, 2021 @04:33PM (#28269330)

Couldn't you also implement max as return a>b? a:b;

(changing greater equal to just greater). Would the problem then still persist?

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Re:One does not simply calculate the absolute value by kmm on Sunday August 22, 2021 @04:46PM (#28269452)

Positive and negative zero cannot be distinguished by normal equality checks, meaning +0.0 == -0.0. Therefore, for consistency's sake +0.0 > -0.0 ought to be false, which would yield a return value of -0.0 for max(+0.0, -(+0.0))

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Re:One does not simply calculate the absolute value by gvx on Sunday August 22, 2021 @04:50PM (#28269477)

That wouldn't solve it: max(0.0, -0.0) would be false ? 0.0 : -0.0

The problem is that 0.0 == -0.0. As long as you don't take care of signed zero, you cannot guarantee that abs(x) has no negative sign.

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