Hi Daniel,
thanks for your kind reply. I apologize for not giving more details about
my code.
In the file where the global matrix (m33) and its sparsity pattern is
created, I also include the declaration and initialization of the new
matrix (m22). After that, the new matrix is of size 2x2 blocks. Then, I
simply copy the sparsity pattern of each block of matrix m33 to the blocks
of matrix m22 as:
for (int i = 0; i < dim; i++)
{
for (int j = 0; j < dim; j++)
{
m22.block(i,j).reinit(m33.block(i+1,j+1).get_sparsity_pattern());
m22.block(i,j).copy_from(m33.block(i+1,j+1));
}
}
The error appears on the next step, when I try to initialize the
preconditioner with matrix m22:
SparseDirectUMFPACK preconditioner;
preconditioner.initialize (A_mat, SparseDirectUMFPACK::AdditionalData());
The exact error message that I get in debug mode is the following:
--------------------------------------------------------
An error occurred in line <272> of file
</home/alex/Git/openfcst/openfcst/Build/contrib/deal.II/src/source/lac/sparse_direct.cc>
in function
void dealii::SparseDirectUMFPACK::factorize(const Matrix&) [with Matrix
= dealii::BlockSparseMatrix<double>]
The violated condition was:
row_pointers[i] == Ap[i+1]
The name and call sequence of the exception was:
ExcInternalError()
Additional Information:
This exception -- which is used in many places in the library -- usually
indicates that some condition which the author of the code thought must be
satisfied at a certain point in an algorithm, is not fulfilled. An example
would be that the first part of an algorithm sorts elements of an array in
ascending order, and a second part of the algorithm later encounters an an
element that is not larger than the previous one.
There is usually not very much you can do if you encounter such an
exception since it indicates an error in deal.II, not in your own program.
Try to come up with the smallest possible program that still demonstrates
the error and contact the deal.II mailing lists with it to obtain help.
--------------------------------------------------------
I cannot understand why the initialization of the blocks of matrix m22 is
not working properly..
Thanks for your help.
Cheers,
Alex
On Monday, October 16, 2017 at 9:03:05 AM UTC-6, Daniel Arndt wrote:
>
> Alex,
>
> Hi all,
>>
>> I am having a similar problem. I want to take a 3x3 BlockSparseMatrix m33
>> and copy four of its blocks into a 2x2 BlockSparseMatrix m22. For instance:
>>
>> m33 = [ A B C
>> D E F
>> G H I ]
>>
>> From this matrix, I would like to obtain the following:
>>
>> m22 = [ E F
>> H I ]
>>
>> Timo, I have tried the solutions that you suggest, but none of them work,
>> I keep getting a segmentation fault error. Could you please give me an
>> alternative option?
>>
> What exactly are you doing and what is the exact error message you are
> getting in debug mode?
> Do the sparsity patterns already match before copying?
>
> Best,
> Daniel
>
>
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