Updates:
Labels: NeedsBetterPatch
Comment #10 on issue 1644 by asmeurer: Coeff() with derivatives and
functions
http://code.google.com/p/sympy/issues/detail?id=1644
I get
error: patch failed: sympy/core/basic.py:1844
error: sympy/core/basic.py: patch does not apply
error: patch failed: sympy/core/tests/test_numbers.py:127
error: sympy/core/tests/test_numbers.py: patch does not apply
on the current master. Could you maybe push to a branch? At any rate,
just based on the code in the patch file, here are
some comments:
1) Thanks for fixing my typos. :)
2) There's this:
- if r['b']:
+ if r.get('b', 0):
I can't tell for sure just from the code, but does this mean that if there
is not b part, then the dictionary doesn't have the
key b? I think it should always have the key b, and set it to 0 if there
is no non-function part.
3) I'm assuming this change relates to the same thing:
- if r and all([not r[i].has(x) for i in range(order + 1)]):
+ if r and not any(r[i].has(x) for i in r if i != 'b'):
I just realized that every other key is an int. Maybe we should use -1
instead of b, (like you did in your code block on IRC a
while ago).
4)
- - dsolve always returns an Equality class. If possible, it
+ - dsolve always returns an Equality class (except for the case
+ when the hint is "all" or "all_Integral"). If possible, it
OK, 'technically' it doesn't *always* return an Equality class. Maybe it
should be, "The solutions returned by dsolve are
always in the form of an Equality class.", which is still correct but less
confusing.
5)
+ # f must be func or one of its derivatives in only var x
+ dargs = f.args[1:]
+ if not (f.is_Function and
+ f == func or
+ isinstance(f, Derivative) and
+ all(w == x for w in dargs)):
Good, though f.args[1:] will have no effect for f(x). I think dsolve
should already be checking to see that f(x) is a function
of one variable, so you should only need to look at the derivatives, for
which you can just use Derivative.symbols.
I don't know how the other code works (though there is my comment on the
as_numer_denom stuff above. Maybe that
should be clearer that it is a commented out block), so I will assume it is
right if the tests pass. But please fix the patch so
that it applies!
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