On Fri, Apr 20, 2018 at 3:18 PM, Matthew Knepley <knepley@gmail.com> wrote:

On Fri, Apr 20, 2018 at 4:10 PM, Junchao Zhang <jczhang@mcs.anl.gov> 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 v,PetscInt i,PetscInt cnt,PetscScalar *value, 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.

 

  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.
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https://www.cse.buffalo.edu/~knepley/