[petsc-users] Multiple points constraint in parallel

[Matthew Knepley]

On Wed, May 31, 2023 at 1:25 AM YuSh Lo <ysjosh.lo at gmail.com> wrote:

> Hi,
>
> I have some multiple points constraint input as follows,
>
> A_1 a_4
> B_2 b_5
> C_3 c_6
>
> each columns are stored in different IS.
>

So one IS lists the capital letter and one lists the lowercase?


> After dmplex distribute, they will be renumbered and distribution to
> certain processors.
>

Plex does normally renumber and send ISes, so you are doing this yourself?


> I have two questions:
>
> (1) I need both complete ISs are all the processors. Can I just do
> ISALLGather()?
>

I think so. I cannot tell what you want to do.


> (2) Although renumbered, will the original order remain(ABC and abc)?
> If the number is the node number, after distribution and I do an
> ISALLGather()
> will I have the following on each processor?
>
> A_3 a_1
> B_4 b_2
> C_6 c_5
> (I randomly renumber them)
>
>
> This is what I can come up with now. Is there any better way to do it?
>

Can you tell me what you want to use this for? Maybe there is an easier
way. For example,
if we want to impose a constraint on a mesh point, usually I mark that
point with a DMLabel.
These are propagated during distribution so you do not have to think about
it.

  Thanks,

     Matt


> Thanks,
> Josh
>


-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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