[Python-Dev] RE: [Numpy-discussion] RE: Possible bug (was Re: numpy, overflow, inf, ieee, and rich comparison)

Tim Peters tim_one at email.msn.com
Thu Oct 12 15:33:41 CDT 2000


[Steven D. Majewski]
> ...
> I also mostly agree with Tim, except that I'm not sure that bad or
> incomplete ieee support is always better than none at all.

This is true, because having Python is better than not having Python, and in
having Python you indeed have bad *and* incomplete 754 support on every 754
platform it runs on.  Even better, it's a subset of damaged 754 support
unique to each platform whose details can't be guessed or documented in
advance of trying it exhaustively to see what happens(*), and a subset that
can change delightfully across releases, compiler upgrades, library upgrades
and seemingly irrelevant minor config changes.  So if bad or incomplete IEEE
support is good, Python is-- here as elsewhere --the King of Languages
<wink>.

Every step of this dance is thoroughly predictable.  In this case, I'm doing
my darnedest to nudge Python its very first step towards *real* 754 support,
and getting dumped on for it by a 754 fan.  Simultaneously, the "old guard"
defends their lifestyle against new-fangled ideas <wink>, asking for
protections unaware that 754 *requires* they get a better form of the
protections they seek than they've dreamed of so far.  It appears that
nobody on either side has actually read the std, and I've become the very
754 Storm Trooper I used to despise.  Computer life is great <wink>.

all-it's-missing-is-variety-ly y'rs  - tim


(*) Quiz:  *if* you can manage to trick Python into creating a NaN on your
particular 754 platform, does the Python expression NaN == 1.0 return true,
false, or raise an exception?  Answer before you try it.  Then try it on
enough 754 platforms until you give up trying to guess in advance.  NaN ==
NaN is predictable in Python, and is the one 754 feature Python guarantees
won't work correctly on any 754 platform (although I've heard that it loses
this predictability when run using NumPy's flavor of comparisons instead of
core Python's).





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