On Wed, Aug 3, 2011 at 2:52 PM, Victor Miller <victorsmil...@gmail.com> wrote:
> Good news (so far) -- I tracked down the source of the bug. I had a long
> calculation (the details of which are irrelevant) which produced a pair of
> points on an elliptic curve, say P1 and P2, over a finite field of the form
> GF(2^n). In order to check the calculation I needed to check
>
> Q1 == 2**(1+m)*P1 and
> Q2 == 2**(1+m)*P2
>
> where Q1,Q2 were another pair of points, and m was some integer (actually
> calculated as len(x) where x was some list). I put in tracing in both the
> .py and .pyx version and saw that P1,P2, Q1,Q2 were the same in each
> version, but the comparisons weren't!
Interesting. To clarify, the string representations that were printed
out were identical, but the == operator returned False? Could you
pickle these points and send them?
> I should say that in this case n was
> 251 and m 200. So far I can't get an isolated case like this where I choose
> P1 to be a random point, but according to the traces everything computed up
> to that point was the same.
>
> Victor
>
> On Aug 3, 8:38 am, VictorMiller <victorsmil...@gmail.com> wrote:
>> Robert, I'll see what I can do. As you suspected, the files are not
>> disclosable :-(.
>>
>> Victor
>>
>> On Aug 3, 3:03 am, Robert Bradshaw <rober...@math.washington.edu>
>> wrote:
>>
>> > This is exactly the kind if thing we try to avoid. I'd like to see the
>> > files (if they're disclosable of course), or perhaps you could come up
>> > with a whittled-down example.
>>
>> > On Tue, Aug 2, 2011 at 7:22 PM, VictorMiller <victorsmil...@gmail.com>
>> > wrote:
>> > > Robert, The .py and .pyx files are identical. I copied one to the
>> > > other, and just in case I checked with diff. It's very puzzling.
>>
>> > > Victor
>>
>> > > On Aug 2, 8:19 pm, Robert Bradshaw <rober...@math.washington.edu>
>> > > wrote:
>> > >> On Tue, Aug 2, 2011 at 11:29 AM, William Stein <wst...@gmail.com>
>> > >> wrote:
>> > >> > On Tue, Aug 2, 2011 at 11:09 AM, VictorMiller
>> > >> > <victorsmil...@gmail.com> wrote:
>> > >> >> I've written a bunch of functions (some organized in classes) to
>> > >> >> do
>> > >> >> some large computations in a particular finite field (always
>> > >> >> GF(2^n)
>> > >> >> for some odd n). This seems to work fine. I'd like the
>> > >> >> computation
>> > >> >> to be as fast as possible, so the first thing I did was to copy
>> > >> >> the .py file to a .pyx file. The good news is that the compiled
>> > >> >> cython is at least 30% faster (sometimes more) than the
>> > >> >> interpreted .py version. The bad news is that it gives different
>> > >> >> results! In trying to track down where things go awry, I made the
>> > >> >> following declaration in each
>>
>> > >> >> from sage.misc.decorators import sage_wrap
>> > >> >> from string import join
>> > >> >> def logged(func):
>> > >> >> @sage_wrap(func)
>> > >> >> def with_logging(*args, **kwds):
>> > >> >> print func.__name__ + '(' + join([str(_) for _ in
>> > >> >> args],',')
>> > >> >> + ')'
>> > >> >> return func(*args,**kwds)
>> > >> >> return with_logging
>>
>> > >> >> I then put
>> > >> >> @logged
>>
>> > >> >> in from of the defs of a bunch of functions.
>>
>> > >> >> This works as expected with .py version, but when I try to compile
>> > >> >> the .pyx version I get the message:
>>
>> > >> >> .... in update_wrapper
>> > >> >> setattr(wrapper, attr, getattr(wrapped, attr))
>> > >> >> AttributeError: attribute '__doc__' of
>> > >> >> 'builtin_function_or_method'
>> > >> >> objects not writable
>>
>> > >> >> I think that I understand what's going on here, but are there any
>>
>> > >> > You often can't use decorators with Cython code,
>>
>> > >> yet...
>>
>> > >> > since it is compiled (not dynamic).
>>
>> > >> >> suggestions as to how to get to the bottom of the differences
>> > >> >> between
>> > >> >> the cython compiled version and the interpreted version?
>>
>> > >> > Put in print statements?
>>
>> > >> You could also write your own with_logging that doesn't try to access
>> > >> __name__ or __doc__ and decorate with that.
>>
>> > >> I'm very curious what goes awry. Did you make any changes other than
>> > >> changing the file from .py to .pyx and compiling it?
>>
>> > >> - Robert
>>
>> > > --
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>> > > URL:http://www.sagemath.org
>>
>>
>
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