[petsc-dev] ASPIN and SNESSetType

[Stefano Zampini]

https://bitbucket.org/petsc/petsc/pull-requests/371/snesaspin-destroy-the-nonlinear/diff

2015-10-01 22:30 GMT+03:00 Stefano Zampini <stefano.zampini at gmail.com>:

> I'll open a pull request
> Il 01/ott/2015 10:28 PM, "Barry Smith" <bsmith at mcs.anl.gov> ha scritto:
>
>>
>>   Matt is at least partially right, having this as a SNESType is
>> questionable. It is actually a specific nonlinear preconditioner PLUS a
>> specific set of options for the NewtonLS SNES method. I also understand why
>> Peter did it this way because there is no clean "other way" to provide this
>> functionality that is not ad hoc.
>>
>>   I think the correct short term fix is to add a SNESDestroy_ASPIN() that
>> does delete the npc and then calls the SNESDestroy_NewtonLS()
>>
>>   Stefano,
>>
>>     Are you willing to make a pull request or patch to do this?
>>
>>    Thanks for letting us know about this problem
>>
>>   Barry
>>
>>
>> > On Oct 1, 2015, at 12:43 PM, Matthew Knepley <knepley at gmail.com> wrote:
>> >
>> > On Thu, Oct 1, 2015 at 7:42 AM, Stefano Zampini <
>> stefano.zampini at gmail.com> wrote:
>> > I just noticed that the behaviour of a code like this
>> >
>> > SNESSetType(snes,SNESASPIN)
>> > SNESSetFromOptions(snes)
>> >
>> > is not the same as
>> >
>> > SNESSetType(snes,SNESNEWTONLS)
>> > SNESSetFromOptions(snes)
>> >
>> > when -snes_type newtonls is specified at command line. In both cases,
>> the snes will be of type SNESNEWTONLS, but in the first case, the snes
>> object will also have a nonlinear preconditioner embedded in, since
>> SNESASPIN creates snes->pc, and there's no SNESDestroy_ASPIN.
>> >
>> > What is the correct approach to fix this? Should the nonlinear
>> preconditioner be destroyed by the SNESSetType interface or by the specific
>> implementation of ASPIN?
>> >
>> > I wish Peter had not done it this way. His reason was that a special
>> Jacobian action can be defined for
>> > Newton -L NASM, but we should just do this with a flag rather than a
>> new SNES type.
>> >
>> >    Matt
>> >
>> >
>> > --
>> > Stefano
>> >
>> >
>> >
>> > --
>> > What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
>> experiments lead.
>> > -- Norbert Wiener
>>
>>


-- 
Stefano
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20151004/25817b08/attachment.html>