Dear All,
I need to subtract two blocks of a BlockSparseMatrix<double> system_matrix.
I am trying to achieve this by
creating SpraseMatrix<double> tmp1, then
tmp1.copy_from(system_matrix.block(0,0));
tmp1.add(-1.0, system_matrix.block(0,1));
However, I am getting the following error message:
"When copying one sparse matrix into another, or when adding one sparse
matrix to another, both matrices need to refer to the same sparsity
pattern."
Could you please help me to overcome this problem?
system_matrix has BlockSparsityPattern sparsity_pattern;
which was obtained in the following way:
BlockDynamicSparsityPattern dsp (2, 2);
dsp.block (0, 0).reinit (n_E_re, n_E_re);
dsp.block (1, 0).reinit (n_E_im, n_E_re);
dsp.block (0, 1).reinit (n_E_re, n_E_im);
dsp.block (1, 1).reinit (n_E_im, n_E_im);
dsp.collect_sizes ();
DoFTools::make_sparsity_pattern (dof_handler, dsp, constraints,
false);
sparsity_pattern.copy_from (dsp);
I have tried various ways of declaring tmp1. Such as
SparseMatrix<double> tmp1(system_matrix.block(0,0).get_sparsity_pattern())
or creating tmp1 as BlockSparseMatrix<double> tmp1(sparsity_pattern)
Thank you in advance for your help.
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