Hi Mohit,
You don't need to resend the previous emails. This discussion is
becoming too detailed though and belongs on the Github issue for
refactoring the ODE module:
https://github.com/sympy/sympy/issues/18348
Oscar
On Tue, 10 Mar 2020 at 15:26, mohit balwani
<mohitbalwani.ic...@gmail.com> wrote:
>
> hello,
>
> so should I resend the previous mail to the mailing list?
>
> On Tue, Mar 10, 2020 at 6:59 PM 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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