Status: Accepted
Owner: asmeurer
Labels: Type-Defect Priority-Medium NeedsReview
New issue 1814 by asmeurer: Internal ODE cleanup
http://code.google.com/p/sympy/issues/detail?id=1814
Over the winter break, I started to implement an ODE solver for the
Cauchy-Euler method. I never finished the solver, partly
because of issue 1784 and partly I talked with Benhaurd on IRC and found
that he had some code that would make it easier to
implement, but I did make some internal cleanups to make my life easier.
Actually, issue 1784 is not holding it up anymore,
because I realized I can just match it to (a*x + b)**n), but I need
Benhaurd's code to solve it from there (he hasn't shared it yet).
See http://github.com/asmeurer/sympy/tree/1814
Changes:
- Fix some internal mess in classify_ode relating to nth linear ODEs.
Basically, the inhomogeneous term was in the dictionary
under 'b', when everything else was under the integer of the power of the
relevant term. So I changed it to be -1.
- Docstring and comment modification.
- Revert commit 4520e9102aba46337a6fae161b44b7c2ceae3660 "remove nth_match
from ode". This is the only change here
that actually fixes something. This commit removed a custom match function
for nth_match and replaced it with a wild match.
Unfortunately, the wild match was inferior, a fact that became painfully
obvious when I tried to implement a matcher for
Cauchy Euler ODEs (see my cauchy_euler branch if you are interested in the
WIP). Also, a test was fixed for an ODE that was
incorrectly not matched as nth_linear because of the poor wild matching.
Basically, it had a hard time getting (a + b)y''' from
ay''' + by'''.
- Cleanup gotchas.txt. All lines were changed to be under 72 characters,
and there were also some spelling fixes. I also added
information about the class Q (if there were other content changes, I
forgot what they were).
--
You received this message because you are listed in the owner
or CC fields of this issue, or because you starred this issue.
You may adjust your issue notification preferences at:
http://code.google.com/hosting/settings
--
You received this message because you are subscribed to the Google Groups
"sympy-issues" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/sympy-issues?hl=en.
