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Negative zero is very, very annoying because it means that many floating point identities flies out of the window. x + 0.0 != x, x * 0.0 != 0.0, etc. It makes it much harder for the compiler to optimize arithmetic. Thus, at least some SIMD circuits do not follow ieee754 to the letter because it would result in performance degradations.

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Those identities do hold though, as long as zero and negative zero compare equal, which according to ieee754 they should. Performance degredations happen in other places such as denormals.

1/0!=1/-0

I find it so strange that IEEE-754 SQRT(-0.) is -0., even though (-0.)*(-0.) is +0.

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