]> https://gitweb.dealii.org/ - dealii-svn.git/commitdiff
apply_boundary_values. jacobians
authorwolf <wolf@0785d39b-7218-0410-832d-ea1e28bc413d>
Wed, 17 May 2000 13:53:40 +0000 (13:53 +0000)
committerwolf <wolf@0785d39b-7218-0410-832d-ea1e28bc413d>
Wed, 17 May 2000 13:53:40 +0000 (13:53 +0000)
git-svn-id: https://svn.dealii.org/trunk@2876 0785d39b-7218-0410-832d-ea1e28bc413d

deal.II/doc/news/2000/c-3-0.html

index d647dffbdddf9178b0c76281d9bb7530ba8ece79..46b8ecf0796127de3e60f85bfa7b402d2834bae1 100644 (file)
        <br>
        (WB 2000/05/16)
        </p>
+
+  <li> <p>
+       Changed: The computation of the Jacobian matrices in the 
+       <code class="class">FEValues</code> class is now done more
+       efficiently. The speedup is in the range of a factor of 40 for
+       3D. 
+       <br>
+       (John Burnell, WB 2000/05/16)
+       </p>
+
+  <li> <p>
+       Changed: the 
+       <code class="member">MatrixTools::apply_boundary_values</code>
+       now uses a much faster algorithm when using on matrices with
+       symmetric sparsity patterns. On the other hand, it does no more
+       eliminate whole rows when a matrix has a non-symmetric sparsity
+       pattern, or if the user (through a new flag) tells the function
+       that this is not necessary, for example if the matrix itself is
+       non-symmetric. 
+       </p>
+
+       <p>
+       For symmetric sparsity patterns, the algorithm now eliminates
+       each boundary value in O(m*log(m)) steps instead of
+       O(N*log(m)), where N=number of rows of the matrix, and m=number
+       of entries per row. Note that m is roughly constant,
+       irrespective of N, so the old algorithm became slower with
+       finer grids, while the new one is O(1) for each boundary degree
+       of freedom.
+       </p>
+
+       <p>
+       (John Burnell, WB 2000/05/17)
+       </p>
 </ol>
 
 <hr>

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