[petsc-users] Global Numbering

[Matthew Knepley]

On Wed, Mar 21, 2018 at 2:18 PM, Mohammad Hassan Baghaei <
mhbaghaei at mail.sjtu.edu.cn> wrote:

> Sorry ! In fact, I am trying to construct the radius and theta coordinate
> for the circular domain I am having before going to the main local
> functions. I needed that for my local functions.
>

It sounds like you are having trouble with parallel programming. Maybe get
your stuff working in serial, and then
look at a book like Using MPI by Gropp, et.al. or Scientific Computing by
Eijkhout to understand more about parallelism.

  Thanks,

    Matt


> *From:* Matthew Knepley [mailto:knepley at gmail.com]
> *Sent:* Thursday, March 22, 2018 1:45 AM
> *To:* Mohammad Hassan Baghaei <mhbaghaei at mail.sjtu.edu.cn>
> *Cc:* PETSc <petsc-users at mcs.anl.gov>
> *Subject:* Re: [petsc-users] Global Numbering
>
>
>
> On Wed, Mar 21, 2018 at 1:28 PM, Mohammad Hassan Baghaei <
> mhbaghaei at mail.sjtu.edu.cn> wrote:
>
> I am trying to fill a vector based on global coordinate.
>
>
>
> You can see how this might be too vague for me to follow.
>
>
>
> As I am trying to use VecGetValues() on the global coordinate,
>
>
>
> Okay, this does not work for any parallel vector.
>
>
>
> I find it that argument goes out of range, since I am using global
> numbering rather than local numbering.
>
>
>
> It is not the numbering that is a problem. It is that parallel Vectors in
> PETSc are distributed. You cannot directly access
>
> data you do not own. You can send it to one process (for example using
> VecScatterCreateToZero()), but this is of course
>
> not scalable.
>
>
>
>   Thanks,
>
>
>
>     Matt
>
>
>
> *From:* Matthew Knepley [mailto:knepley at gmail.com]
> *Sent:* Wednesday, March 21, 2018 10:38 PM
> *To:* Mohammad Hassan Baghaei <mhbaghaei at mail.sjtu.edu.cn>
> *Cc:* PETSc <petsc-users at mcs.anl.gov>
> *Subject:* Re: [petsc-users] Global Numbering
>
>
>
> On Wed, Mar 21, 2018 at 8:18 AM, Mohammad Hassan Baghaei <
> mhbaghaei at mail.sjtu.edu.cn> wrote:
>
> Hello
>
> I am trying to create a global vector of coordinates based on the
> parallelized dm. I find it really hard to work with the local numbering,
> how can I manage to create a kind of numbering on global level so that I
> could easily access to the nodes based on the new numbering. Thanks for
> your time.
>
>
>
> DMGetCoordinates() gives you a global vector.
>
> DMGetCoordinatesLocal() gives you a local vector.
>
>
>
> What are you trying to do?
>
>
>
>   Thanks,
>
>
>
>      Matt
>
>
>
> Amir
>
>
>
>
>
> --
>
> 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.caam.rice.edu/~mk51/>
>
>
>
>
>
> --
>
> 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.caam.rice.edu/~mk51/>
>



-- 
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.caam.rice.edu/~mk51/>
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