in reply to Re^4: Spaceship Zero
in thread Spaceship Zero

The OP didn't say sign function, he said sign of a number. In floating point numbers, every number including zero has a sign. -0 is a different number than 0. It's not a visual representation. It's used in underflows. n = 0 means 0 ≤ n < {smallest positive}. n = -0 means {smallest negative} < n ≤ 0

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Re^6: Spaceship Zero (real)
by tye (Sage) on Nov 10, 2008 at 17:16 UTC
    The OP didn't say sign function, he said sign of a number.

    Actually, he said sgn($x) three times.

    In real numbers, 0 is neither positive nor negative. The fiction of "negative zero" in some floating point implementations can be interesting but doesn't trump the existence of the Real number system.

    And that the OP wanted 0 returned for the "sign" of zero is quite clearly stated in multiple ways, despite your misinterpretting "sign of a number" to mean "sign of a floating point number (in an implementation that implements negative zero and 'treats negative zero consistently in arithmetic operations')". The ability to get -1 from "negative zero" on some systems is surely useful in some cases. But it is certainly not the only useful result.

    - tye        

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[d/l]
      I agree, by the way. Like I stated, I was just answering what I thought the anonymous monk meant.
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