#10053: Equality testing instead of comparisons in differential forms code
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Reporter: jvkersch | Owner: burcin
Type: defect | Status: needs_info
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 niles):
* status: needs_review => needs_info
* reviewer: => Niles Johnson
Old description:
> This patch replaces the comparison member function in `CoordinatePatch`
> and `DifferentialForms` by equality checking (`__eq__` instead
> `__cmp__`), as there is generally no canonical way of making sense of the
> comparison between instances of those classes.
>
> This is related to #10041.
New description:
This patch replaces the comparison member function in `CoordinatePatch`
and `DifferentialForms` by equality checking (`__eq__` instead `__cmp__`),
as there is generally no canonical way of making sense of the comparison
between instances of those classes.
This is related to #10041.
== Apply ==
* patch from #10041
* [attachment:trac_10053_equality_testing_forms.patch]
--
Comment:
With this patch and the one at #10041, sage passes all (`-long`) doctests
(linux, Red Hat Enterprise).
At #10041, jason
[http://trac.sagemath.org/sage_trac/ticket/10041#comment:3 commented] that
comparison of tuples of symbolic variables is not well-defined, and
suggested using strings instead. That has been done in
`coordinate_patch.py` and `differential_forms.py`, but not in
`differential_form_element.py` -- there, comparison uses `__dict__`. So
is the following expected to work on all systems?
{{{
sage: F = DifferentialForms(); F
Algebra of differential forms in the variables x, y, z
sage: var('x,y,z')
(x, y, z)
sage: f = DifferentialForm(F, 2)
sage: f[1,2] = x; f
x*dy/\dz
sage: g = DifferentialForm(F, 2)
sage: g[0, 2] = y
sage: g[1, 2] = 2*x; g
2*x*dy/\dz + y*dx/\dz
sage: f == g
False
sage: g == g
True
}}}
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'>
}}}
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/10053#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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