#10053: Equality testing instead of comparisons in differential forms code
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Reporter: jvkersch | Owner: burcin
Type: defect | Status: needs_review
Priority: major | Milestone:
Component: symbolics | Keywords: forms, comparison, equality
Author: Joris Vankerschaver | Upstream: N/A
Reviewer: Niles Johnson | Merged:
Work_issues: |
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Changes (by jvkersch):
* status: needs_info => needs_review
Comment:
Replying to [comment:5 niles]:
>
> Note:
>
> {{{
> sage: g.__dict__
> {'_components': {(1, 2): 2*x, (0, 2): y}, '_degree': 2}
> sage: f.__dict__
> {'_components': {(1, 2): x}, '_degree': 2}
> sage: type(g.__dict__['_components'][(0,2)])
> <type 'sage.symbolic.expression.Expression'>
> }}}
Thanks for noting this -- I agree that this code would give the same kind
of problems as before. I've uploaded a new patch, where `__eq__`
essentially iterates over the underlying dictionary, converts the values
to strings and does the comparison on the strings. Secondly, in the
internal function `_cleanup()` there was some code `if fun == 0`, which
I've replaced by `if fun.is_zero()`. I think this addresses all cases of
symbolic expressions appearing in equalities. One downside however is
that the current implementation is somewhat slower than the previous one.
I have a few ideas of how to address this, but I feel this issue is better
left to a different patch.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10053#comment:6>
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