Yes, that is exactly what I am trying to do.
In the documentation it says that MatGetRow cannot be used to alter the
entries, it is only for examining them. So if I understand correctly, do
you suggest:
1:MatGetRow, get the row
2:MatSetValues, set the values
3:Do not call assembly, instead call matRestoreRow, because the next
MatGetRow will not need assembly (will it really not after matsetvalues
on line 2?) (note: next MatGetRow will not need to reach these newly set
values, it will work on a different row)
4:go to step 1 for the next row
Also, I can spare memory for 1 additional matrix. Should I just generate
a new identical matrix with same values, using either MatCopy or
MatConvert , and use MatGetValues on the old matrix and MatSetValues on
the new matrix, hence no need for assembly on the new matrix until
everything is done? If you think this is possible, how expensive would
this be? Which function do you suggest (Copy or Convert)?
Thank you for your answers and attention so far
Ali
On 29-01-2018 02:16, Smith, Barry F. wrote:
From your code it looks like you are accessing values in a single row,
changing them and then putting them back in the same row at the same index
locations?
If this is the case you should use MatGetRow() to process the values,
change the numerical entries in that row as needed and then call
MatRestoreRow(). No need to call MatSetValues() and hence no business about
unassembled matrices.
Will this work for you?
Barry
On Jan 28, 2018, at 2:16 PM, Ali Berk Kahraman <[email protected]>
wrote:
Dear Barry,
I see what you are talking about, I have oversimplified my problem. The problem is that I
will have to call MatGetValues on Wavelets matrix for every row in a loop. Thus, if I do
not call assembly routine in the child function, it starts to give "not for
unassembled matrix" error after the first loop. The relevant part of the code is
appended on this e-mail. You can see the matgetvalues calls on line 81, and it is also in
line 94's function GetWaveletPolyFit2DSingleRow_x1.
Ali
On 28-01-2018 22:24, Smith, Barry F. wrote:
In your code there is NO reason to call the MatAssemblyBegin/End where you
do. Just pull it out and call it once. I submit this is the same for any other
code. Please explain enough about your code (or send it) that has to call the
assembly routines a different number of times. You just pull it above all the
calls to MatSetValues().
Barry
On Jan 28, 2018, at 1:15 PM, Ali Berk Kahraman <[email protected]>
wrote:
Hello All,
My apologies, I have closed this e-mail window and the first thing I read on the manual
is "ALL processes that share a matrix MUST call MatAssemblyBegin() and
MatAssemblyEnd() the SAME NUMBER of times". So I understand that petsc simply does
not support unequal number of assembly calls.
My question evolves then. I have a problem at hand where I do not know how many
calls each process will make to MatAssembly routines. Any suggestions to make
this work?
On 28-01-2018 22:09, Ali Berk Kahraman wrote:
Hello All,
The code takes a parallel matrix and calls a function using that matrix. That
function fills the specified row of that matrix with the id of the process that
part of the matrix belongs in. You can see the short code in the attachment, it
is about 80 lines.
The problem is that the code gets into a deadlock at some point, usually at the last row
of each process except for the last process (greatest pid). I use petsc with configure
options "--with-cc=gcc --with-cxx=g++ --with-fc=gfortran --download-mpich
--download-fblaslapack".
I am a beginner with MPI, so I do not know what may be causing this. My
apologies in advance if this is a very trivial problem.
Best Regards to All,
Ali Berk Kahraman
M.Sc. Student, Mechanical Eng.
Bogazici Uni., Istanbul, Turkey
<PetscRealProblem.c>
