[petsc-users] about DA

[Likun Tan]

Thanks,
Likun


On Wed, August 31, 2011 5:11 pm, Ethan Coon wrote:
> On Wed, 2011-08-31 at 16:23 -0400, Likun Tan wrote:
>
>> Hello,
>>
>>
>> I have a quick question about DA. When use DAVecGetArray() to set
>> values to the array and run the program with mpiexec, does
>> DAVecGetArray()
>> compute in parallel?
>>
>
> DAVecGetArray() only gives you access to the local portion (plus any
> ghost nodes) of the global vec.  The portion of the data you get is indexed
> by global numbering, so the indices into the pointer should range from
>
> xs --> xs+m
>
> where these values are given by
>
> DAGetGhostCorners() or DAGetCorners()
>
>
> http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manual
> pages/DA/DAGetGhostCorners.html#DAGetGhostCorners
>
> So yes, you should only do the local portion of the calculation to set
> set the values.
>
> Ethan
>
>
>> Thanks in advance,
>> Likun
>>
>>
>>
>>
>>
>
> --
> ------------------------------------
> Ethan Coon
> Post-Doctoral Researcher
> Applied Mathematics - T-5
> Los Alamos National Laboratory
> 505-665-8289
>
>
> http://www.ldeo.columbia.edu/~ecoon/
> ------------------------------------
>
>
>
>