[petsc-users] question on MatSubMatrixUpdate

[Shaohao Chen]

Dear managers and users,

I got a problem when using PETSc to make parallel codes. Could you please help me out?

Basically, I need to do is to update the values of some blocks of a large matrix (not the whole matrix), 
and I need to do it many times in a big loop. These blocks could be assembled to the same or 
different processors. If using "MatSetValues", it would spend much time for the data transfer between 
different processors. I expect "MatSubMatrixUpdate" could do the job better. Am I correct? But I can 
not find an example of using "MatSubMatrixUpdate" on the website. It is said that the 
"MatSubMatrixUpdate" is only in a "developer" level and the users should use some other functions to 
replace it. What other functions should I use? 

Thank you for your attention!

--
Shaohao Chen
Department of Physics & Astronomy, 
Louisiana State University, 
Baton Rouge, LA