On Wed, Apr 8, 2009 at 1:06 PM, John H Palmieri <jhpalmier...@gmail.com> wrote:
>
>
>
> On Apr 8, 1:03 pm, John H Palmieri <jhpalmier...@gmail.com> wrote:
>> On Apr 8, 12:56 pm, "Justin C. Walker" <jus...@mac.com> wrote:
>>
>>
>>
>> > On Apr 8, 2009, at 12:07 , gerhard wrote:
>>
>> > > Print methods for matrices with subdivisions
>>
>> > > let M be a matrix over QQ:
>> > > subdivisions are printed fine
>> > > over GF(2):
>> > > M.get_subdivisions() shows the subdivisions are defined,
>> > > but the print method does not know about them.
>>
>> > Yup. Most matrix classes seem to use a common method for printing,
>> > while the 'mod 2' matrix implementation has its own "stringify" method.
>>
>> > There may be a good explanation for this, but commenting out the mod2
>> > method seems to have the right effect without damaging anything else.
>> > At least with minimal testing.
>>
>> Another workaround: if M is a matrix over GF(2), then do this:
>>
>> sage: MS = M.sparse_matrix()
>> sage: MS.subdivide(2,3)
>>
>> The subdivisions in MS should appear: the problem is only in dense
>> matrices over GF(2).
>>
>> > > The show methods cannot handle subdivisions altogether.
>>
>> > I'm not sure I understand. For other than the mod 2 elements, show(X)
>> > produces an image of a subdivided matrix. Do you mean just in the mod
>> > 2 case?
>>
>> > > Are there any plans to enhance these printing methods?
>>
>> > I think it qualifies as a bug, and I've created a Trac report for the
>> > problem:
>> > <http://trac.sagemath.org/sage_trac/ticket/5714>
>>
>> Hi Justin,
>>
>> I also created a ticket, <http://trac.sagemath.org/sage_trac/ticket/
>> 5715>, with a patch, deleting the str method for dense mod 2
>> matrices.
>
> I'll mark mine as a duplicate. Go ahead with your patch.
>
Neither Justin nor I have a patch, and I don't think either of us are
working on one.
I posted this on your patch, which slows str down by a factor of 12
(in this example):
Needs work. There is a *very good* reason that there is a str method
for GF(2) -- it's for speed! Check this out:
{{{
BEFORE YOUR PATCH:
sage: a = random_matrix(GF(2),1000)
sage: time b = a.str()
CPU times: user 0.41 s, sys: 0.01 s, total: 0.42 s
Wall time: 0.42 s
}}}
{{{
AFTER YOUR PATCH:
sage: a = random_matrix(GF(2),1000)
sage: time b = a.str()
CPU times: user 5.02 s, sys: 0.86 s, total: 5.88 s
Wall time: 5.89 s
}}}
--~--~---------~--~----~------------~-------~--~----~
To post to this group, send email to sage-support@googlegroups.com
To unsubscribe from this group, send email to
sage-support-unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/sage-support
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
