>> 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 >>>> >>>> >>>> >>> >> >
