Hi everyone,
I just came across a big "zero" problem on my patch and I was
wondering where it was coming from.
Here is what I have
sage: A = AbstractPolynomialRing(QQ)
sage: m = A.monomial_basis()
sage: (0 * m[1,2]) == 0
False
By comparing sage versions (because, it was working before), it seems
to come from the dict_linear_combination function in
sage.combinat.dict_addition import
Here is the code that is causing issues :
if D != {}:
a = iter(D).next()
if hasattr(a,'parent') and hasattr(a.parent(),'zero'):
zero = a.parent().zero()
else:
zero = 0
for_removal = [key for key in D if D[key] == zero]
for key in for_removal:
del D[key]
This is the part removing the zeros, it used to be only :
for_removal = [ key for key, value in D.iteritems() if value == 0 ]
for key in for_removal:
del D[key]
It seems to me that you're not testing the right 0, when I was looking
for the error, my D was as follow :
sage: D
{[1, 2]: 0}
sage: a =iter(D).next()
sage: a
[1, 2]
so the a is the key, not the value, so the test makes zero equals to
the key zero and not the ring zero :
sage: zero = a.parent().zero()
sage: zero
[0, 0]
sage: D[key]
0
sage: D[key] == zero
False
Obviously, there is something wrong, and it's breaking my program ...
Regards
Viviane
--
You received this message because you are subscribed to the Google Groups
"sage-combinat-devel" group.
To post to this group, send email to sage-combinat-devel@googlegroups.com.
To unsubscribe from this group, send email to
sage-combinat-devel+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sage-combinat-devel?hl=en.
