]> https://gitweb.dealii.org/ - dealii.git/commit
When eliminating boundary values from a matrix, we only have to eliminate the respect...
authorWolfgang Bangerth <bangerth@math.tamu.edu>
Wed, 17 May 2000 12:22:49 +0000 (12:22 +0000)
committerWolfgang Bangerth <bangerth@math.tamu.edu>
Wed, 17 May 2000 12:22:49 +0000 (12:22 +0000)
commitb1c3137fc6acb5479e8b4cd74b6e8dbadbe33aac
tree92ccf76ec27893d76347391f4509444397d1feca
parent3f2637fb4edc8358e3f5acf5236ac3be866cac1e
When eliminating boundary values from a matrix, we only have to eliminate the respective element from the other rows for which we know that they have a nonzero element in that column. Previously, we searched all rows for this, but if the sparsity pattern is symmetric then we can do better than that by checking the nonzero elements of the present row and only visiting the respective columns. This reduces the complexity from N*log(m) to m*log(m), where N=size of the matrix and m=number of elements per row, i.e. from O(N) to O(1). In the case of non-symmetric sparsity patterns, it might not be worth to eliminate the respective row, since we have to use a solver for nonsymmetric problems anyway, and that can then eliminate the respective column iteratively.

git-svn-id: https://svn.dealii.org/trunk@2874 0785d39b-7218-0410-832d-ea1e28bc413d
deal.II/deal.II/include/dofs/dof_tools.h
deal.II/deal.II/include/numerics/matrices.h
deal.II/deal.II/source/numerics/base.cc
deal.II/deal.II/source/numerics/matrices.cc
deal.II/deal.II/source/numerics/vectors.cc

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