[petsc-users] Row Orderings of Mat and Vec
Hui Zhang
mike.hui.zhang at hotmail.com
Wed Feb 1 09:52:17 CST 2012
>> On Feb 1, 2012, at 5:02 AM, Hui Zhang wrote:
>>
>>>
>>> On Jan 31, 2012, at 1:23 PM, Jed Brown wrote:
>>>
>>>> On Tue, Jan 31, 2012 at 04:11, Hui Zhang <mike.hui.zhang at hotmail.com> wrote:
>>>> Suppose using MatCreate() and MatSetSizes() we obtain a Mat A, and then
>>>> tion and then using local indices (e.g. MatSetValuesLocal()) during assembly. You might use AO for that setup step, but it usually doesn't make sense to use _during_ assembly.
>>>
>>> thanks, do you mean that it is faster to use LocaltoGlobalMapping & SetValuesLocal
>>> than to use AO & SetValues globally? Is there a big difference in performance?
>>
>> Yes, using the SetValuesLocal approach will be much faster for large problems than using the AO to map to global indices and calling SetValues.
>>
>> Barry
>
> Thank you! Can I use SetValuesLocal to set values beyond LocalOwnershipRange?
It is ok. I found I can.
>
>>
>>>
>>>
>>>>
>>>> with
>>>> P_1 the permutation corresponding to ao_1. In a similar way, we have that b
>>>> becomes P_2 b under the petsc ordering. I want to make sure P_1 and P_2 are
>>>> the same so arises my question.
>>>>
>>>> Thanks a lot!
>>>> Hui
>>>>
>>>>
>>>>
>>>
>>
>
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