Re: [deal.II] Sparse ILU

2018-04-02 Thread Bruno Turcksin
Phani, On Monday, April 2, 2018 at 4:59:02 PM UTC-4, Phani Motamarri wrote: > > I am trying to modify the function "SparseILU::initialize" inside > sparse_ilu.templates.h to call the mkl function "dcsrilu0" which requires > the use of some of the data like ia, ja accessed inside "initialize"

Re: [deal.II] Sparse ILU

2018-04-02 Thread Wolfgang Bangerth
On 04/02/2018 02:59 PM, Phani Motamarri wrote: I am trying to modify the function "SparseILU::initialize" inside sparse_ilu.templates.h to call the mkl function "dcsrilu0"  which requires the use of some of the data like ia, ja accessed inside "initialize" function. The tricky part is that

Re: [deal.II] Sparse ILU

2018-04-02 Thread Phani Motamarri
Dear Prof. Wolfgang, I am trying to modify the function "SparseILU::initialize" inside sparse_ilu.templates.h to call the mkl function "dcsrilu0" which requires the use of some of the data like ia, ja accessed inside "initialize" function. The tricky part is that the sparsity pattern stores the

Re: [deal.II] Overlapping decomposition using p4est and deal.ii

2018-04-02 Thread pratik . aro1
Yes, that is completely true. Information exchange is one of the main aspects that plagues the domain decomposition methods. But probably this is improved by the optimized Schwarz which introduces artificial boundary conditions to enhance the information exchange. I am not sure how this scales

Re: [deal.II] Question wrt step-3: shape functions and test functions

2018-04-02 Thread Wolfgang Bangerth
In the step-3 example (https://www.dealii.org/8.4.1/doxygen/deal.II/step_3.html), I noticed that at first the variable phi is used as a test function. It is in the same space with u, except for that the value is 0 on the boundaries. (in this problem the boundary values for u is also 0, but

Re: [deal.II] Subtle issues in time-dependent Dirichlet boundary conditions

2018-04-02 Thread Wolfgang Bangerth
Jie, I am solving time-dependent Navier-Stokes equations with varying Dirichlet boundary conditions. Although I have read the "Constraints on degrees of freedom" for many times, I am still not sure what the best way to implement changing boundary conditions is. My time scheme is fully

Re: [deal.II] Overlapping decomposition using p4est and deal.ii

2018-04-02 Thread Wolfgang Bangerth
Thank you for your reply. I understand that DD methods are not quite that popular now. But I wanted to explore the avenue keeping in mind the issue of scalability as well. For scalability, as you mention communication is probably the bottleneck. No, communication is not the issue. It's not

Re: [deal.II] Overlapping decomposition using p4est and deal.ii

2018-04-02 Thread pratik . aro1
Dear Wolfgang, Thank you for your reply. I understand that DD methods are not quite that popular now. But I wanted to explore the avenue keeping in mind the issue of scalability as well. For scalability, as you mention communication is probably the bottleneck. A few papers have worked towards

[deal.II] deal.II Newsletter #26

2018-04-02 Thread Rene Gassmoeller
Hello everyone! This is deal.II newsletter #26. It automatically reports recently merged features and discussions about the deal.II finite element library. ## Below you find a list of recently proposed or merged features: #6144: Bug fix for graph coloring/graph partitioning using Zoltan

Re: [deal.II] Overlapping decomposition using p4est and deal.ii

2018-04-02 Thread Wolfgang Bangerth
Pratik, deal.II has the parallel::distributed::Triangulation class which provides the functionality to partition and distribute the meshes using p4est's partition and adaptive space filling techniques. According to what I have understood from step-40, using the

Re: [deal.II] Sparse ILU

2018-04-02 Thread Wolfgang Bangerth
On 04/02/2018 11:48 AM, Phani Motamarri wrote: We have an ongoing research project with Caltech where we are trying to explore ways of approximating the subspace spanned by k lowest eigen values of a given positive definite matrix(FEM discretized matrix) in a sparse format using the incomplete

Re: [deal.II] Sparse ILU

2018-04-02 Thread Phani Motamarri
We have an ongoing research project with Caltech where we are trying to explore ways of approximating the subspace spanned by k lowest eigen values of a given positive definite matrix(FEM discretized matrix) in a sparse format using the incomplete Cholesky factor with reduced computational

[deal.II] Overlapping decomposition using p4est and deal.ii

2018-04-02 Thread pratik . aro1
Hello all, I wanted to know if it was possible to do overlapping decompositions using deal.II and p4est. These are my thoughts: deal.II has the parallel::distributed::Triangulation class which provides the functionality to partition and distribute the meshes using p4est's partition and