Re: [petsc-users] Problem with Preallocating
Am Donnerstag, 30. Oktober 2014, 09:19:38 schrieb Matthew Knepley: > On Thu, Oct 30, 2014 at 7:25 AM, Barry Smith wrote: > > > > > On Oct 30, 2014, at 3:36 AM, Florian Lindner > > wrote: > > > > > > Am Mittwoch, 29. Oktober 2014, 13:00:17 schrieb Barry Smith: > > >> > > >> MatAssembly flushes out any preallocated space that was not used. > > Hence when you try to put a diagonal entry in later it is as if you did not > > preallocate. You should set zeros in the diagonal as part of your initial > > setting values in the matrix before calling MatAssembly. > > > > > > Even with FLUSH_ASSEMBLY? > > > >No, flush assembly does not clean out any unused preallocated space. > > final assembly does > > > > Something else must be going on in your full code (as shown by the small > example). Are you running it > in serial or parallel? Of course you were right. Something else was going on, that's why I couldn't produce an example. I was not doing a FLUSH_ASSEMBLY but FULL_ASSEMBLY instead because of some bug in my petsc helper functions. I'm so sorry for having bothered you with that! Florian
Re: [petsc-users] Problem with Preallocating
On Thu, Oct 30, 2014 at 7:25 AM, Barry Smith wrote:
>
> > On Oct 30, 2014, at 3:36 AM, Florian Lindner
> wrote:
> >
> > Am Mittwoch, 29. Oktober 2014, 13:00:17 schrieb Barry Smith:
> >>
> >> MatAssembly flushes out any preallocated space that was not used.
> Hence when you try to put a diagonal entry in later it is as if you did not
> preallocate. You should set zeros in the diagonal as part of your initial
> setting values in the matrix before calling MatAssembly.
> >
> > Even with FLUSH_ASSEMBLY?
>
>No, flush assembly does not clean out any unused preallocated space.
> final assembly does
>
Something else must be going on in your full code (as shown by the small
example). Are you running it
in serial or parallel?
Thanks,
Matt
> Barry
>
> > I had this idea too, but was not able to reproduce the error I have in
> my application in a small example.
> >
> > Why does this program works? Shouldn't the MatDiagonalSet produce an
> error/warning that there were mallocs involved? Since the preallocation was
> lost?
> >
> > Thanks,
> > Florian
> >
> > #include
> > #include "petscmat.h"
> > #include "petscviewer.h"
> > #include "petscksp.h"
> >
> > using namespace std;
> >
> > // Compiling with: mpic++ -g3 -Wall -I ~/software/petsc/include -I
> ~/software/petsc/arch-linux2-c-debug/include -L
> ~/software/petsc/arch-linux2-c-debug/lib -lpetsc test.cpp
> >
> > int main(int argc, char **args)
> > {
> > PetscInitialize(&argc, &args, "", NULL);
> >
> > PetscErrorCode ierr = 0;
> > int N = 9;
> > Mat matrix;
> >
> > ierr = MatCreate(PETSC_COMM_SELF, &matrix);
> > ierr = MatSetType(matrix, MATSBAIJ); CHKERRQ(ierr);
> > ierr = MatSetSizes(matrix, PETSC_DECIDE, PETSC_DECIDE, N, N);
> CHKERRQ(ierr);
> > ierr = MatSetOption(matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
> CHKERRQ(ierr);
> >
> > PetscInt nnz[N];
> > nnz[0] = 2; nnz[1] = 1; nnz[2] = 1;
> > nnz[3] = 1; nnz[4] = 1; nnz[5] = 1;
> > nnz[6] = 1; nnz[7] = 1; nnz[8] = 1;
> >
> > for (int r = 0; r < N; r++) {
> >cout << "Preallocated row " << r << " with " << nnz[r] << "
> elements." << endl;
> > }
> > MatSeqSBAIJSetPreallocation(matrix, 1, PETSC_DEFAULT, nnz);
> >
> > MatSetValue(matrix, 0, 5, 10, INSERT_VALUES);
> >
> > ierr = MatAssemblyBegin(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
> > ierr = MatAssemblyEnd(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
> > Vec zeros;
> > MatGetVecs(matrix, NULL, &zeros);
> >
> > MatDiagonalSet(matrix, zeros, ADD_VALUES);
> > ierr = MatAssemblyBegin(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
> > ierr = MatAssemblyEnd(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
> >
> > ierr = MatView(matrix, PETSC_VIEWER_STDOUT_WORLD); CHKERRQ(ierr);
> >
> > MatDestroy(&matrix);
> > PetscFinalize();
> > return 0;
> > }
> >
> >
> >
> >
> >>
> >> Barry
> >>
> >>> On Oct 29, 2014, at 8:00 AM, Florian Lindner
> wrote:
> >>>
> >>> Hello,
> >>>
> >>> I try to preallocate a sparse matrix like it was recommended in
> another posting, but get an error which kind of surprises me. Somehow I
> think it might be related to the order of assembly calls...
> >>>
> >>> My code creates the matrix:
> >>>
> >>> MatSetType(_matrixC.matrix, MATSBAIJ);
> >>> MatSetSizes(_matrixC.matrix, PETSC_DECIDE, PETSC_DECIDE, n, n);
> >>> MatSetOption(_matrixC.matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
> >>>
> >>> Than I enter a loop to get the number of elements per row. The entire
> code is a bit too long, but right before the SetPreallocaiton I do:
> >>>
> >>> for (int r = 0; r < n; r++) {
> >>> cout << "Preallocated row " << r << " with " << nnz[r] << "
> elements." << endl;
> >>> }
> >>>
> >>> which results in the output:
> >>>
> >>> Matrix Size = 9
> >>> Preallocated row 0 with 9 elements.
> >>> Preallocated row 1 with 8 elements.
> >>> Preallocated row 2 with 7 elements.
> >>> Preallocated row 3 with 6 elements.
> >>> Preallocated row 4 with 5 elements.
> >>> Preallocated row 5 with 4 elements.
> >>> Preallocated row 6 with 1 elements.
> >>> Preallocated row 7 with 1 elements.
> >>> Preallocated row 8 with 1 elements.
> >>>
> >>> at least in rows 0 to 5 it's a dense upper triangular matrix (incl.
> main diagonal).
> >>>
> >>> ierr = MatSeqSBAIJSetPreallocation(_matrixC.matrix, 1, PETSC_DEFAULT,
> nnz);
> >>>
> >>> Now more or less the same loops as above with MatSetValues call for
> each row.
> >>>
> >>> Since the KSPSolver requires that the diagonal is set, even if it's
> merely with zeros I do:
> >>>
> >>> _matrixC.assemble(MAT_FLUSH_ASSEMBLY) // my helper function, but I'm
> sure you get the point ;-)
> >>> petsc::Vector zeros(_matrixC);
> >>> MatDiagonalSet(_matrixC.matrix, zeros.vector, ADD_VALUES);
> >>> ierr = MatAssemblyBegin(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
> CHKERRV(ierr);
> >>> [ some more code ]
> >>> ierr = MatAssemblyEnd(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
> CHKERRV(ierr);
> >>>
> >>> But when I run the code I get an error message:
> >>>
> >>> [0]PETSC ERROR: - Error Message
> ---
Re: [petsc-users] Problem with Preallocating
> On Oct 30, 2014, at 3:36 AM, Florian Lindner wrote:
>
> Am Mittwoch, 29. Oktober 2014, 13:00:17 schrieb Barry Smith:
>>
>> MatAssembly flushes out any preallocated space that was not used. Hence
>> when you try to put a diagonal entry in later it is as if you did not
>> preallocate. You should set zeros in the diagonal as part of your initial
>> setting values in the matrix before calling MatAssembly.
>
> Even with FLUSH_ASSEMBLY?
No, flush assembly does not clean out any unused preallocated space. final
assembly does
Barry
> I had this idea too, but was not able to reproduce the error I have in my
> application in a small example.
>
> Why does this program works? Shouldn't the MatDiagonalSet produce an
> error/warning that there were mallocs involved? Since the preallocation was
> lost?
>
> Thanks,
> Florian
>
> #include
> #include "petscmat.h"
> #include "petscviewer.h"
> #include "petscksp.h"
>
> using namespace std;
>
> // Compiling with: mpic++ -g3 -Wall -I ~/software/petsc/include -I
> ~/software/petsc/arch-linux2-c-debug/include -L
> ~/software/petsc/arch-linux2-c-debug/lib -lpetsc test.cpp
>
> int main(int argc, char **args)
> {
> PetscInitialize(&argc, &args, "", NULL);
>
> PetscErrorCode ierr = 0;
> int N = 9;
> Mat matrix;
>
> ierr = MatCreate(PETSC_COMM_SELF, &matrix);
> ierr = MatSetType(matrix, MATSBAIJ); CHKERRQ(ierr);
> ierr = MatSetSizes(matrix, PETSC_DECIDE, PETSC_DECIDE, N, N); CHKERRQ(ierr);
> ierr = MatSetOption(matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE); CHKERRQ(ierr);
>
> PetscInt nnz[N];
> nnz[0] = 2; nnz[1] = 1; nnz[2] = 1;
> nnz[3] = 1; nnz[4] = 1; nnz[5] = 1;
> nnz[6] = 1; nnz[7] = 1; nnz[8] = 1;
>
> for (int r = 0; r < N; r++) {
>cout << "Preallocated row " << r << " with " << nnz[r] << " elements." <<
> endl;
> }
> MatSeqSBAIJSetPreallocation(matrix, 1, PETSC_DEFAULT, nnz);
>
> MatSetValue(matrix, 0, 5, 10, INSERT_VALUES);
>
> ierr = MatAssemblyBegin(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
> ierr = MatAssemblyEnd(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
> Vec zeros;
> MatGetVecs(matrix, NULL, &zeros);
>
> MatDiagonalSet(matrix, zeros, ADD_VALUES);
> ierr = MatAssemblyBegin(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
> ierr = MatAssemblyEnd(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
>
> ierr = MatView(matrix, PETSC_VIEWER_STDOUT_WORLD); CHKERRQ(ierr);
>
> MatDestroy(&matrix);
> PetscFinalize();
> return 0;
> }
>
>
>
>
>>
>> Barry
>>
>>> On Oct 29, 2014, at 8:00 AM, Florian Lindner wrote:
>>>
>>> Hello,
>>>
>>> I try to preallocate a sparse matrix like it was recommended in another
>>> posting, but get an error which kind of surprises me. Somehow I think it
>>> might be related to the order of assembly calls...
>>>
>>> My code creates the matrix:
>>>
>>> MatSetType(_matrixC.matrix, MATSBAIJ);
>>> MatSetSizes(_matrixC.matrix, PETSC_DECIDE, PETSC_DECIDE, n, n);
>>> MatSetOption(_matrixC.matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
>>>
>>> Than I enter a loop to get the number of elements per row. The entire code
>>> is a bit too long, but right before the SetPreallocaiton I do:
>>>
>>> for (int r = 0; r < n; r++) {
>>> cout << "Preallocated row " << r << " with " << nnz[r] << " elements."
>>> << endl;
>>> }
>>>
>>> which results in the output:
>>>
>>> Matrix Size = 9
>>> Preallocated row 0 with 9 elements.
>>> Preallocated row 1 with 8 elements.
>>> Preallocated row 2 with 7 elements.
>>> Preallocated row 3 with 6 elements.
>>> Preallocated row 4 with 5 elements.
>>> Preallocated row 5 with 4 elements.
>>> Preallocated row 6 with 1 elements.
>>> Preallocated row 7 with 1 elements.
>>> Preallocated row 8 with 1 elements.
>>>
>>> at least in rows 0 to 5 it's a dense upper triangular matrix (incl. main
>>> diagonal).
>>>
>>> ierr = MatSeqSBAIJSetPreallocation(_matrixC.matrix, 1, PETSC_DEFAULT, nnz);
>>>
>>> Now more or less the same loops as above with MatSetValues call for each
>>> row.
>>>
>>> Since the KSPSolver requires that the diagonal is set, even if it's merely
>>> with zeros I do:
>>>
>>> _matrixC.assemble(MAT_FLUSH_ASSEMBLY) // my helper function, but I'm sure
>>> you get the point ;-)
>>> petsc::Vector zeros(_matrixC);
>>> MatDiagonalSet(_matrixC.matrix, zeros.vector, ADD_VALUES);
>>> ierr = MatAssemblyBegin(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
>>> CHKERRV(ierr);
>>> [ some more code ]
>>> ierr = MatAssemblyEnd(_matrixC.matrix, MAT_FINAL_ASSEMBLY); CHKERRV(ierr);
>>>
>>> But when I run the code I get an error message:
>>>
>>> [0]PETSC ERROR: - Error Message
>>> --
>>> [0]PETSC ERROR: Argument out of range
>>> [0]PETSC ERROR: New nonzero at (0,0) caused a malloc
>>> Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn
>>> off this check
>>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for
>>> trouble shooting.
>>>
Re: [petsc-users] Problem with Preallocating
Am Mittwoch, 29. Oktober 2014, 13:00:17 schrieb Barry Smith:
>
>MatAssembly flushes out any preallocated space that was not used. Hence
> when you try to put a diagonal entry in later it is as if you did not
> preallocate. You should set zeros in the diagonal as part of your initial
> setting values in the matrix before calling MatAssembly.
Even with FLUSH_ASSEMBLY? I had this idea too, but was not able to reproduce
the error I have in my application in a small example.
Why does this program works? Shouldn't the MatDiagonalSet produce an
error/warning that there were mallocs involved? Since the preallocation was
lost?
Thanks,
Florian
#include
#include "petscmat.h"
#include "petscviewer.h"
#include "petscksp.h"
using namespace std;
// Compiling with: mpic++ -g3 -Wall -I ~/software/petsc/include -I
~/software/petsc/arch-linux2-c-debug/include -L
~/software/petsc/arch-linux2-c-debug/lib -lpetsc test.cpp
int main(int argc, char **args)
{
PetscInitialize(&argc, &args, "", NULL);
PetscErrorCode ierr = 0;
int N = 9;
Mat matrix;
ierr = MatCreate(PETSC_COMM_SELF, &matrix);
ierr = MatSetType(matrix, MATSBAIJ); CHKERRQ(ierr);
ierr = MatSetSizes(matrix, PETSC_DECIDE, PETSC_DECIDE, N, N); CHKERRQ(ierr);
ierr = MatSetOption(matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE); CHKERRQ(ierr);
PetscInt nnz[N];
nnz[0] = 2; nnz[1] = 1; nnz[2] = 1;
nnz[3] = 1; nnz[4] = 1; nnz[5] = 1;
nnz[6] = 1; nnz[7] = 1; nnz[8] = 1;
for (int r = 0; r < N; r++) {
cout << "Preallocated row " << r << " with " << nnz[r] << " elements." <<
endl;
}
MatSeqSBAIJSetPreallocation(matrix, 1, PETSC_DEFAULT, nnz);
MatSetValue(matrix, 0, 5, 10, INSERT_VALUES);
ierr = MatAssemblyBegin(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
ierr = MatAssemblyEnd(matrix, MAT_FLUSH_ASSEMBLY); CHKERRQ(ierr);
Vec zeros;
MatGetVecs(matrix, NULL, &zeros);
MatDiagonalSet(matrix, zeros, ADD_VALUES);
ierr = MatAssemblyBegin(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
ierr = MatAssemblyEnd(matrix, MAT_FINAL_ASSEMBLY); CHKERRQ(ierr);
ierr = MatView(matrix, PETSC_VIEWER_STDOUT_WORLD); CHKERRQ(ierr);
MatDestroy(&matrix);
PetscFinalize();
return 0;
}
>
> Barry
>
> > On Oct 29, 2014, at 8:00 AM, Florian Lindner wrote:
> >
> > Hello,
> >
> > I try to preallocate a sparse matrix like it was recommended in another
> > posting, but get an error which kind of surprises me. Somehow I think it
> > might be related to the order of assembly calls...
> >
> > My code creates the matrix:
> >
> > MatSetType(_matrixC.matrix, MATSBAIJ);
> > MatSetSizes(_matrixC.matrix, PETSC_DECIDE, PETSC_DECIDE, n, n);
> > MatSetOption(_matrixC.matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
> >
> > Than I enter a loop to get the number of elements per row. The entire code
> > is a bit too long, but right before the SetPreallocaiton I do:
> >
> > for (int r = 0; r < n; r++) {
> >cout << "Preallocated row " << r << " with " << nnz[r] << " elements."
> > << endl;
> > }
> >
> > which results in the output:
> >
> > Matrix Size = 9
> > Preallocated row 0 with 9 elements.
> > Preallocated row 1 with 8 elements.
> > Preallocated row 2 with 7 elements.
> > Preallocated row 3 with 6 elements.
> > Preallocated row 4 with 5 elements.
> > Preallocated row 5 with 4 elements.
> > Preallocated row 6 with 1 elements.
> > Preallocated row 7 with 1 elements.
> > Preallocated row 8 with 1 elements.
> >
> > at least in rows 0 to 5 it's a dense upper triangular matrix (incl. main
> > diagonal).
> >
> > ierr = MatSeqSBAIJSetPreallocation(_matrixC.matrix, 1, PETSC_DEFAULT, nnz);
> >
> > Now more or less the same loops as above with MatSetValues call for each
> > row.
> >
> > Since the KSPSolver requires that the diagonal is set, even if it's merely
> > with zeros I do:
> >
> > _matrixC.assemble(MAT_FLUSH_ASSEMBLY) // my helper function, but I'm sure
> > you get the point ;-)
> > petsc::Vector zeros(_matrixC);
> > MatDiagonalSet(_matrixC.matrix, zeros.vector, ADD_VALUES);
> > ierr = MatAssemblyBegin(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
> > CHKERRV(ierr);
> > [ some more code ]
> > ierr = MatAssemblyEnd(_matrixC.matrix, MAT_FINAL_ASSEMBLY); CHKERRV(ierr);
> >
> > But when I run the code I get an error message:
> >
> > [0]PETSC ERROR: - Error Message
> > --
> > [0]PETSC ERROR: Argument out of range
> > [0]PETSC ERROR: New nonzero at (0,0) caused a malloc
> > Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn
> > off this check
> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for
> > trouble shooting.
> > [0]PETSC ERROR: Petsc Release Version 3.5.2, unknown
> > [0]PETSC ERROR: ./petBench on a arch-linux2-c-debug named helium by
> > lindnefn Wed Oct 29 13:48:49 2014
> > [0]PETSC ERROR: Configure options --with-debugging=1
> > [0]PETSC ERROR: #1 MatSetValues_SeqSB
Re: [petsc-users] Problem with Preallocating
MatAssembly flushes out any preallocated space that was not used. Hence when
you try to put a diagonal entry in later it is as if you did not preallocate.
You should set zeros in the diagonal as part of your initial setting values in
the matrix before calling MatAssembly.
Barry
> On Oct 29, 2014, at 8:00 AM, Florian Lindner wrote:
>
> Hello,
>
> I try to preallocate a sparse matrix like it was recommended in another
> posting, but get an error which kind of surprises me. Somehow I think it
> might be related to the order of assembly calls...
>
> My code creates the matrix:
>
> MatSetType(_matrixC.matrix, MATSBAIJ);
> MatSetSizes(_matrixC.matrix, PETSC_DECIDE, PETSC_DECIDE, n, n);
> MatSetOption(_matrixC.matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
>
> Than I enter a loop to get the number of elements per row. The entire code
> is a bit too long, but right before the SetPreallocaiton I do:
>
> for (int r = 0; r < n; r++) {
>cout << "Preallocated row " << r << " with " << nnz[r] << " elements." <<
> endl;
> }
>
> which results in the output:
>
> Matrix Size = 9
> Preallocated row 0 with 9 elements.
> Preallocated row 1 with 8 elements.
> Preallocated row 2 with 7 elements.
> Preallocated row 3 with 6 elements.
> Preallocated row 4 with 5 elements.
> Preallocated row 5 with 4 elements.
> Preallocated row 6 with 1 elements.
> Preallocated row 7 with 1 elements.
> Preallocated row 8 with 1 elements.
>
> at least in rows 0 to 5 it's a dense upper triangular matrix (incl. main
> diagonal).
>
> ierr = MatSeqSBAIJSetPreallocation(_matrixC.matrix, 1, PETSC_DEFAULT, nnz);
>
> Now more or less the same loops as above with MatSetValues call for each row.
>
> Since the KSPSolver requires that the diagonal is set, even if it's merely
> with zeros I do:
>
> _matrixC.assemble(MAT_FLUSH_ASSEMBLY) // my helper function, but I'm sure
> you get the point ;-)
> petsc::Vector zeros(_matrixC);
> MatDiagonalSet(_matrixC.matrix, zeros.vector, ADD_VALUES);
> ierr = MatAssemblyBegin(_matrixC.matrix, MAT_FINAL_ASSEMBLY); CHKERRV(ierr);
> [ some more code ]
> ierr = MatAssemblyEnd(_matrixC.matrix, MAT_FINAL_ASSEMBLY); CHKERRV(ierr);
>
> But when I run the code I get an error message:
>
> [0]PETSC ERROR: - Error Message
> --
> [0]PETSC ERROR: Argument out of range
> [0]PETSC ERROR: New nonzero at (0,0) caused a malloc
> Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn off
> this check
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html for
> trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.5.2, unknown
> [0]PETSC ERROR: ./petBench on a arch-linux2-c-debug named helium by lindnefn
> Wed Oct 29 13:48:49 2014
> [0]PETSC ERROR: Configure options --with-debugging=1
> [0]PETSC ERROR: #1 MatSetValues_SeqSBAIJ() line 977 in
> /data2/scratch/lindner/petsc/src/mat/impls/sbaij/seq/sbaij.c
> [0]PETSC ERROR: #2 MatSetValues() line 1135 in
> /data2/scratch/lindner/petsc/src/mat/interface/matrix.c
> [0]PETSC ERROR: #3 MatDiagonalSet_Default() line 203 in
> /data2/scratch/lindner/petsc/src/mat/utils/axpy.c
> [0]PETSC ERROR: #4 MatDiagonalSet() line 241 in
> /data2/scratch/lindner/petsc/src/mat/utils/axpy.c
>
> I'm surprised that I get this error message since I do have preallocated 9
> elements and I do not understand why inserting an element at (0, 0) could be
> a problem / needing a malloc. Has the preallocation got lost somewhere?
>
> Thanks once again
>
> Florian
Re: [petsc-users] Problem with Preallocating
Can you send a small example? This looks like it should work.
Matt
On Wed, Oct 29, 2014 at 8:00 AM, Florian Lindner
wrote:
> Hello,
>
> I try to preallocate a sparse matrix like it was recommended in another
> posting, but get an error which kind of surprises me. Somehow I think it
> might be related to the order of assembly calls...
>
> My code creates the matrix:
>
> MatSetType(_matrixC.matrix, MATSBAIJ);
> MatSetSizes(_matrixC.matrix, PETSC_DECIDE, PETSC_DECIDE, n, n);
> MatSetOption(_matrixC.matrix, MAT_SYMMETRY_ETERNAL, PETSC_TRUE);
>
> Than I enter a loop to get the number of elements per row. The entire
> code is a bit too long, but right before the SetPreallocaiton I do:
>
> for (int r = 0; r < n; r++) {
> cout << "Preallocated row " << r << " with " << nnz[r] << "
> elements." << endl;
> }
>
> which results in the output:
>
> Matrix Size = 9
> Preallocated row 0 with 9 elements.
> Preallocated row 1 with 8 elements.
> Preallocated row 2 with 7 elements.
> Preallocated row 3 with 6 elements.
> Preallocated row 4 with 5 elements.
> Preallocated row 5 with 4 elements.
> Preallocated row 6 with 1 elements.
> Preallocated row 7 with 1 elements.
> Preallocated row 8 with 1 elements.
>
> at least in rows 0 to 5 it's a dense upper triangular matrix (incl. main
> diagonal).
>
> ierr = MatSeqSBAIJSetPreallocation(_matrixC.matrix, 1, PETSC_DEFAULT,
> nnz);
>
> Now more or less the same loops as above with MatSetValues call for each
> row.
>
> Since the KSPSolver requires that the diagonal is set, even if it's merely
> with zeros I do:
>
> _matrixC.assemble(MAT_FLUSH_ASSEMBLY) // my helper function, but I'm
> sure you get the point ;-)
> petsc::Vector zeros(_matrixC);
> MatDiagonalSet(_matrixC.matrix, zeros.vector, ADD_VALUES);
> ierr = MatAssemblyBegin(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
> CHKERRV(ierr);
> [ some more code ]
> ierr = MatAssemblyEnd(_matrixC.matrix, MAT_FINAL_ASSEMBLY);
> CHKERRV(ierr);
>
> But when I run the code I get an error message:
>
> [0]PETSC ERROR: - Error Message
> --
> [0]PETSC ERROR: Argument out of range
> [0]PETSC ERROR: New nonzero at (0,0) caused a malloc
> Use MatSetOption(A, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE) to turn
> off this check
> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
> [0]PETSC ERROR: Petsc Release Version 3.5.2, unknown
> [0]PETSC ERROR: ./petBench on a arch-linux2-c-debug named helium by
> lindnefn Wed Oct 29 13:48:49 2014
> [0]PETSC ERROR: Configure options --with-debugging=1
> [0]PETSC ERROR: #1 MatSetValues_SeqSBAIJ() line 977 in
> /data2/scratch/lindner/petsc/src/mat/impls/sbaij/seq/sbaij.c
> [0]PETSC ERROR: #2 MatSetValues() line 1135 in
> /data2/scratch/lindner/petsc/src/mat/interface/matrix.c
> [0]PETSC ERROR: #3 MatDiagonalSet_Default() line 203 in
> /data2/scratch/lindner/petsc/src/mat/utils/axpy.c
> [0]PETSC ERROR: #4 MatDiagonalSet() line 241 in
> /data2/scratch/lindner/petsc/src/mat/utils/axpy.c
>
> I'm surprised that I get this error message since I do have preallocated 9
> elements and I do not understand why inserting an element at (0, 0) could
> be a problem / needing a malloc. Has the preallocation got lost somewhere?
>
> Thanks once again
>
> Florian
>
--
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
