Hi Mohit,
I'm replying on the mailing list. I didn't realise we had gone
off-list in the last couple of emails.
This conversation belongs in the issue on github.
Oscar
On Tue, 10 Mar 2020 at 13:29, mohit balwani
<mohitbalwani.ic...@gmail.com> wrote:
>
> For pattern matching, I kept in mind that we can extract the elements of our
> general solution from the equation with direct matching just like
> First_linear. And for `SingleODESolver` there will be proper logic checking
> whether the given equation matches or not.
>
> I am a bit confused about how all linear solvers can be based on pattern
> because
> let's say we want to implement
> `nth_linear_constant_coeff_undetermined_coefficients`.
> its general equation is
>
> a_n f^{(n)}(x) + a_{n-1} f^{(n-1)}(x) + .. + a_1 f'(x) + a_0 f(x) = P(x)
>
> Now p(x) needs to have a finite number of linearly independent derivatives
> and in pattern matching to write general solution we should use the extracted
> elements given by wilds function.
>
> On Tue, Mar 10, 2020 at 4:18 PM Oscar Benjamin <oscar.j.benja...@gmail.com>
> wrote:
>>
>> I think the series solvers should probably have their own superclass.
>> I'd like to move them out of normal dsolve anyway.
>>
>> Of the others I think that probably all the linear ones can be based
>> on the Pattern solver. You should give a rationale for why you have
>> divided them up like this.
>>
>> On Tue, 10 Mar 2020 at 10:29, mohit balwani
>> <mohitbalwani.ic...@gmail.com> wrote:
>> >
>> > Hi,
>> > currently, there are 28 solvers in the ODE module out of which 6 solvers
>> > have been refactored already.
>> >
>> > I have classified the remaining 22 solvers on the basis of their parent
>> > class whether they should inherit SinglePatternODESolver or SingleODESolver
>> >
>> > SinglePatternODESolver
>> >
>> > separable
>> > separable_reduced
>> > linear_coefficients
>> > Liouville
>> > 2nd_linear_airy
>> > 2nd_linear_bessel
>> > 2nd_hypergeometrics
>> >
>> > SingleODESolver
>> >
>> > 1st_exact
>> > 1st_homogeneous_coeff_subs_indep_div_dep
>> > 1st_homogeneous_coeff_subs_dep_div_indep
>> > 1st_power_series
>> > 2nd_power_series_ordinary
>> > 2nd_power_series_regular
>> > nth_linear_constant_coeff_homogeneous
>> > nth_linear_euler_eq_homogeneous
>> > nth_linear_constant_coeff_undetermined_coefficients
>> > nth_linear_euler_eq_nonhomogeneous_undetermined_coefficients
>> > nth_linear_constant_coeff_variation_of_parameters
>> > nth_linear_euler_eq_nonhomogeneous_variation_of_parameters
>> > nth_order_reducible
>> > 1st_homogeneous_coeff_best ( it just gives the best result from
>> > "1st_homogeneous_coeff_subs_indep_div_dep" and
>> > "1st_homogeneous_coeff_subs_dep_div_indep")
>> > Lie_group
>> >
>> > +oscar.j.benja...@gmail.com does this classification look good?
>> > Any suggestions would be really helpful.
>> >
>> > Regards,
>> > Mohit
>> >
>> > On Sun, Mar 8, 2020 at 1:53 PM mohit balwani
>> > <mohitbalwani.ic...@gmail.com> wrote:
>> >>
>> >> Hi, oscar
>> >>
>> >> I started looking at the (Single) ODE solver closely and as suggested by
>> >> you, they are to be refactored in the form of classes. After performing
>> >> all this work it will be easier to maintain the code and whenever a new
>> >> solver is to be added it will be very easy to add it. In my GSoC proposal
>> >> what exactly I should elaborate on because refactoring different solvers
>> >> will be based on either SinglePatternODESolver
>> >> or SingleODESolver only and both of the base classes are already
>> >> implemented so we just have to inherit them. one thing I noted that there
>> >> are helper functions in ode.py so I guess they should be moved to other
>> >> file deutils.py may be.
>> >> so in my proposal should I show the code for one of the non-refactored
>> >> solvers?
>> >>
>> >> Thanks,
>> >> Mohit
>> >>
>> >> On Sat, Mar 7, 2020 at 2:22 AM Oscar Benjamin
>> >> <oscar.j.benja...@gmail.com> wrote:
>> >>>
>> >>> Hi Mohit,
>> >>>
>> >>> That's plenty enough for a GSOC project. You should try to go into
>> >>> more detail in your proposal about exactly what you think should
>> >>> happen though. Perhaps review all of the (single) ODE solvers that are
>> >>> there now and how they can be refactored and simplified or improved in
>> >>> the process.
>> >>>
>> >>> Refactoring the tests so that they can be reused will make it possible
>> >>> to run all solvers on all of the tested ODEs which will expose many
>> >>> bugs in the individual solvers. You don't need to worry about having
>> >>> enough to do if you start thinking about fixing those bugs! If I was
>> >>> doing this work myself I would begin with refactoring the tests so
>> >>> that I can use them to compare before/after performance while
>> >>> refactoring the solving code.
>> >>>
>> >>> I think this would be too much for one GSOC project but the ultimate
>> >>> goal I would like is to see the ODE code organised more like
>> >>> integral_steps with rules leading to other rules and so on so that we
>> >>> can have step-by-step solutions and better debugging output. Many of
>> >>> the solvers are actually using substitutions so we should make it
>> >>> possible for a solver to simply match the ODE and say "use this
>> >>> substitution". We can't even begin to implement a rule-based system
>> >>> until dsolve is refactored though.
>> >>>
>> >>> Oscar
>> >>>
>> >>> On Fri, 6 Mar 2020 at 19:34, mohit balwani
>> >>> <mohitbalwani.ic...@gmail.com> wrote:
>> >>> >
>> >>> > I am planning to take Refactoring ODE module as a GSoC project.
>> >>> >
>> >>> > For every solver we need to make it as a separate class so that
>> >>> > classify_ode() can easily match the ode and return the solution right
>> >>> > away. After that the test_ode.py also needs to be refactored as there
>> >>> > are lot of redundant test and we can use data structures for
>> >>> > maintaining and testing each and every part of test_ode.py.This will
>> >>> > provide uniformity as there are some blocks which are not tested.
>> >>> >
>> >>> > So will this be enough for GSoC'20?
>> >>> >
>> >>> > On Fri, Jan 24, 2020, 12:14 AM Oscar Benjamin
>> >>> > <oscar.j.benja...@gmail.com> wrote:
>> >>> >>
>> >>> >> Those might be able to speed things up but not until the ODE module is
>> >>> >> refactored. The reason the module needs to be refactored is that right
>> >>> >> now it runs the whole of classify_ode including the matching code for
>> >>> >> every single solver.
>> >>> >>
>> >>> >> If it just returned the first match straight away and computed the
>> >>> >> result it would be much faster. Then adding new fast methods that are
>> >>> >> tried first can speed things up. As it stands though each method that
>> >>> >> you add will probably just slow it down more. There needs to be a
>> >>> >> refactor first so that classify_ode still works as expected even if
>> >>> >> dsolve does something different.
>> >>> >>
>> >>> >>
>> >>> >> On Thu, 23 Jan 2020 at 16:04, mohit balwani
>> >>> >> <mohitbalwani.ic...@gmail.com> wrote:
>> >>> >> >
>> >>> >> >
>> >>> >> >
>> >>> >> > On Thursday, January 9, 2020 at 10:00:33 PM UTC+5:30, mohit balwani
>> >>> >> > wrote:
>> >>> >> >>
>> >>> >> >> I have ideas of implementing functionalities in ODE mentioned in
>> >>> >> >> wiki page. with whom should I discuss it?
>> >>> >> >
>> >>> >> >
>> >>> >> >
>> >>> >> > I have attached a pdf file in which there are shortcut tricks to
>> >>> >> > solve linear ode, i don't know whether these methods are already
>> >>> >> > implemented indirectly or will enhance the speed.But In my opinion
>> >>> >> > if they are implemented then lot of work could be saved. For
>> >>> >> > example if we look at method of undetermined coefficients, to find
>> >>> >> > a particular integral of ode it solves for coefficient by comparing
>> >>> >> > them and call solve which has matrix as argument. Now with the help
>> >>> >> > of these tricks we do not need to call solve as it will directly
>> >>> >> > find out the coefficients of particular integral. This pdf is
>> >>> >> > handwritten notes and i have tried to write them as neat and
>> >>> >> > understandable as possible and with each case i have also written 1
>> >>> >> > example so that it becomes easy to go through.
>> >>> >> >
>> >>> >> > --
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