Does Python have a long floating data type please?

Tim Peters tim_one at email.msn.com
Sat Apr 1 07:29:05 CEST 2000


[David C. Ullrich, notes some examples of dubious intervals computed
 by Jurjen N.E. Bos's real.py module]

Yes, and I've posted others in the past (including cases that aren't near
0).

Jurjen used a very clever storage-efficient representation, but didn't
record correspondingly clever correctness arguments <wink>.  Sometimes it's
easy to see a bug, sometimes I have no idea what he was thinking.

This isn't unusual for these kinds of pkgs, though!  Correctness proofs can
be quite involved.  Valérie Ménissier-Morain has submitted a 59-page article
giving correctness proofs for her version of this quest, available somewhere
more-or-less obvious under

    http://pauillac.inria.fr/~menissier/


> ... - at this point I decided to give up on real.py and make my own.

Which is why there are a dozen packages like this out in the world each with
its own set of unique subtle bugs <wink>.  Since this stuff runs too slow to
use for truly large problems anyway, I never understood why pkgs try to
conserve storage at the cost of vastly subtler reasoning.  Guess it's seen
as a challenge.

personally-more-excited-by-things-that-are-obviously-right-than-by-
    things-that-aren't-obviously-wrong-ly y'rs  - tim






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