[petsc-users] how to select values from certain positions of a vec from different process to process 0.

[Barry Smith]

On Jul 31, 2013, at 7:55 AM, 丁老师 <ztdepyahoo at 163.com> wrote:

> Does the function  VecScatterCreateToZero  resolve this problem?
> 

   What problem? I told you how to do it, there is no problem. VecScatterCreateToZero() moves ALL values to process 0 which for large problems is not scalable, so if you only want some values then do what I suggest otherwise use VecScatterCreateToZero.

   Barry

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> At 2013-07-31 09:08:26,"Barry Smith" <bsmith at mcs.anl.gov> wrote:
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> >  create an IS with the global indices you want on process 0 and a seq Vec of the same size,
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> >  create an IS of size 0 on all the other processes and a seq Vec of the size zero on all other processes
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> >  create a VecScatter using these IS, the global Vec and the seq Vec.
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> >  use VecScatterBegin/End to send over the values.
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> >   Barry
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> >On Jul 30, 2013, at 6:37 PM, 丁老师 <ztdepyahoo at 163.com> wrote:
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