I'll see what I can do about getting that. To give a little more
detail, I then wrote the following function:
def manydouble(P,n):
for _ in range(n):
P = 2*P
return P
and changed the statement
if Q1 = 2**(1+len(z))*P1:
print "Hooray"
to
if Q = manydouble(P1,1+len(z)):
print "Hooray"
and then everything started working ok in the .pyx version.
On Aug 4, 3:41 am, Robert Bradshaw <rober...@math.washington.edu>
wrote:
> 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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>
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