Are the diagonals constant values, or does each row have a separate value?
Barry
On May 6, 2011, at 4:23 PM, Xiangdong Liang wrote:
> Thanks for your response, Barry. I am going to solve A_n x = b for
> different A_n's. The difference between A_n's are only the main
> diagonal and the k-t
Dear PETSc users,
I have recently started to use PETSc in our code. As the first try, I
assemble the matrix row by row and then put each non-zero element in
each row into PETSc matrix. Then I start to solve the equation. I use
PETSc on a multi-core machine, so I will not use MPI in my program. I
ntees log-linear complexity
and no dynamic memory allocation.
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Thanks for your response, Barry. I am going to solve A_n x = b for
different A_n's. The difference between A_n's are only the main
diagonal and the k-th diagonal. I want to generate the matrix A once,
and each time modify the main and k-th diagonals to get a new A_n.
That's the reason I am asking
Hello everyone,
I am wondering whether there is some function like MatGetDiagonal to
get the k-th diagonal (above or below the main diagonal) of the matrix
A. If I have to write my own function, what built-in function should I
use to get a particular element of A? It seems that MatGetValues
return
How are you planning to use these diagonals? This might help us make
suggestions as to what is a reasonable approach. Accessing diagonals is not a
natural operation for sparse matrices stored by rows or columns.
Barry
On May 6, 2011, at 3:56 PM, Xiangdong Liang wrote:
> Hello everyone,
Danesh,
Some of the PETSc solvers (like the default ILU) require that you put
entries on all the diagonal locations of the matrix, even if they are zero. So
you should explicitly put a 0 on the diagonal locations that have 0 and the
issue will go away.
Barry
On May 6, 2011, at 1:1
> This issue of hitting worst case of quicksort came up before with
> PetscSortInt. It would be interesting to know if the pivot selection
> in PetscSortInt_Private would fix the worst-case behavior that you
> see? If so, then the same changes could be made to the other sorting
> routines.
I did
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Hi
I am using PetscSortRealWithPermutation to sort an array with around
200K elements and it causes a segfault.
STL sort is able to handle this array without any problems.
I looked at the gdb backtrace. It primarily seems to be because the
stack is exhausted because of recursive calls to
Petsc
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