[petsc-users] AOCreateBasic & AOCreateBasicIS

[Hui Zhang]

On Apr 15, 2013, at 5:26 PM, Jed Brown wrote:

> Hui Zhang <mike.hui.zhang at hotmail.com> writes:
> 
>> Maybe my question was unclear.  From the manual
>> 
>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/AO/AOCreateBasicIS.html#AOCreateBasicIS
>> 
>> AOCreateBasicIS(IS isapp,IS ispetsc,AO *aoout)
>> 
>> is collective on IS so the parallel IS's must already conceptually
>> contain all the indices from all the processors in the 'comm' of IS.
>> Is this also what you meant?
> 
> No, "collective" means that all processes in the communicator must call
> the function together.  Usually (not always, documentation should
> explain), PETSc makes collective interfaces memory scalable so that each
> process provides only its local part.

Ok, I see. Thanks very much!