[ntp:questions] Re: Tinker and tos configuration commands....

David L. Mills mills at udel.edu
Wed Feb 9 00:28:40 UTC 2005


Terje,

+0 == -0 == 0 == +0.0 == -0.0 == 0.0 in logical comparisons, no matter 
how you represent it, presuming of course that the integer to double 
conversions are done first before comparison. That's all I care about.

Once upon a time when checksums were expensive we did a terrible thing. 
The ones-complement Internet checksum actually does have two zeros. One 
of course is used to reprent a correct checksum, but other was used to 
disable the checksum calculation itself. Wow, that goes back a long way. 
The Univac 1100 series used ones-complement arithmetic and that drove me 
batty.

Dave

Terje Mathisen wrote:
> David L. Mills wrote:
> 
>> Brad,
>>
>> No, signs of zero disappeared with the Univac 1108 and ones complement 
>> arithmetic and notwithstanding the Internet checksum. Zero is a 
>> legitimate state variable. Twos complement arithmetic is the sole 
>> survivor. Fudge values have nothing to do with it.
> 
> 
> Actually, that's only true for binary integer operations.
> 
> FP otoh is always sign+biased_exponent+mantissa these days, since that's 
> required by the relevant IEEE standard (754?).
> 
> Terje
> 



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