On Fri, Apr 20, 2018 at 4:33 PM, Junchao Zhang <[email protected]> wrote:

On Fri, Apr 20, 2018 at 3:18 PM, Matthew Knepley <[email protected]> wrote:

...

On Fri, Apr 20, 2018 at 4:10 PM, Junchao Zhang <[email protected]> wrote:

...

To pad a vector, i.e., copy a vector to a new one, I have to call VecSetValue(newb,1,&idx,...) for each element. But to be efficient, what I really needs is to set a block of values in one call. It looks PETSc does not have a routine for that(?). I looked at VecSetValuesBlocked, but it looks it is not for that purpose. Should we have something like VecSetValuesBlock(Vec <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Vec/Vec.html#Vec> v,PetscInt <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscInt.html#PetscInt> i,PetscInt cnt,PetscScalar <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscScalar.html#PetscScalar> *value, InsertMode <http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/InsertMode.html#InsertMode> mode) to set cnt values starting at index i?

Use VecGetArray().

Did you mean VecGetArray b and newb, do a memcpy from b to new and then restore them? If yes, it does not work since some of the values I want to set might be remote. E.g, I have 4 processors. b's size is 181 and is distributed as 46, 45,45,45, newb is distributed as 48,45,45,45 to match a matrix of block size 3.

If values are remote, use VecScatter or PetscSF. Matt

...

Matt

...

--Junchao Zhang

-- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>

-- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>