#18600: Fix several methods for sparse polynomials
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Reporter: bruno | Owner:
Type: defect | Status: needs_info
Priority: major | Milestone: sage-6.9
Component: commutative | Resolution:
algebra | Merged in:
Keywords: sparse polynomial | Reviewers: Vincent Delecroix
Authors: Bruno Grenet | Work issues:
Report Upstream: N/A | Commit:
Branch: public/18600 | 29331f254d9255c23c673393c6fd0121c04d9d6c
Dependencies: | Stopgaps:
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Comment (by bruno):
The coercion model is really something I do not understand yet in Sage, so
I trust what you wrote. Simply, in the following change, isn't it faster
(and cleaner to some extent) to first define the underlying list of
coefficients rather than defining the zero polynomial before adding
monomials to it?
{{{#!diff
- coeffs = self.list()
- v = [0] + [coeffs[n]/(n+1) for n from 0 <= n <= degree]
- return S(v)
+ p = S.zero()
+ for n in range(degree+1):
+ if self[n]:
+ p += cm.bin_op(Q(self[n]), n+1, operator.div) *
S.gen()**(n+1)
+ return p
}}}
What about something as the following?
{{{#!python
coeffs = [self.zero()] * (degree + 2)
for n in range(degree+1):
if self[n]:
coeffs[n+1] = cm.bin_op(Q(self[n]), n+1, operator.div)
return S(coeffs)
}}}
''Note. I'm going in vacations and won't be able to interact much until
August 24.''
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Ticket URL: <http://trac.sagemath.org/ticket/18600#comment:7>
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