[petsc-dev] sor smoothers

[Mark F. Adams]

OK, so its ground hog day.  The plan?:

1) I should add a residual method to Mat, make a MatResidualDefault, and have all (yuck) SetUp_MatXXX set this default.  I guess there is no base class SetUp ….  then make a MatResidual_SeqAIJ that just does a dumb residual for now, with testing logic if Jed's stuff is available.

2) Have PCMGResidualDefault call MatResidual instead MatMult & VecAYPX.  Or do we want to nuke PCMGResidualDefault?  Jed's defect correction argument might sound like a typical Jed, e.g., what if a Martian gets hepatitis during mardi gras, but defect correction is really useful and I would like to see its support supported ...

3) Add fields in Mat: mat_res_state, vec_res_state, vec_res_id.  I need to know the types but I can do this in the next phase.

Mark

On Sep 9, 2013, at 5:35 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

> 
> On Sep 9, 2013, at 4:32 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> 
>> Barry Smith <bsmith at mcs.anl.gov> writes:
>>>  I don't care if PCMGSetResidual stays around for now but I do not
>>>  think we should "point to it" as a standard way for people to do
>>>  things; I think we should improve how the two slots are used with
>>>  PCMG, it really has never been thought about at all and whenever
>>>  possible I think using the two slots appropriately is better than
>>>  PCMGSetResidual and will solve most of the "use" cases.
>> 
>> Fine, I was just not eager to _delete_ PCMGSetResidual until we had
>> established a complete replacement, and even then, it might be enough to
>> leave it as "advanced" and suggest the preferred alternative in the man
>> page.  It just doesn't seem expensive to support and I don't think it
>> causes people to tangle themselves up in bad design.
> 
>  It doesn't have its own object which is kind of limiting.
> 
> 
>