Dear Prof. Bangerth,
Thank you for your reply. I tried as you suggested. However, I am getting
the following error -
/home/animesh/Documents/dealii/dealii-9.2.0/examples/Quasi_Static_Finite_Strain_Beam_Buckling_Analysis/Quasi_Static_Finite_Strain_Beam_Buckling_Analysis.cc:873:20:
error: ‘BlockSparseMatrix’ in namespace ‘dealii::PETScWrappers’ does not
name a type
PETScWrappers::BlockSparseMatrix tangent_matrix;
For vectors, the documentation
<https://www.dealii.org/8.4.1/doxygen/deal.II/classPETScWrappers_1_1BlockVector.html>
says that "This class is deprecated, use PETScWrappers::MPI::BlockVector
<https://www.dealii.org/8.4.1/doxygen/deal.II/classPETScWrappers_1_1MPI_1_1BlockVector.html>".
So I used as suggested in the documentation and am getting the following
error related to that.
/home/animesh/Documents/dealii/dealii-9.2.0/examples/Quasi_Static_Finite_Strain_Beam_Buckling_Analysis/Quasi_Static_Finite_Strain_Beam_Buckling_Analysis.cc:1288:37:
error: no matching function for call to
‘dealii::PETScWrappers::MPI::BlockVector::reinit(std::vector<unsigned
int>&)’
system_rhs.reinit(dofs_per_block);
Also, I wish to use a Direct solver by PETSc and could not find any related
to the PETSc block vector. In my current code, I am using SparseDirectUMFPACK.
Do I need to convert my entire code to be using non-blocked vectors and
matrices to use the Direct Solver by PETSc? (Although the system is
"blocked", it only has one block that contains the displacement degree of
freedom).
Thanks!
Animesh
On Friday, January 15, 2021 at 2:51:30 PM UTC-6 Wolfgang Bangerth wrote:
> On 1/15/21 10:46 AM, Animesh Rastogi IIT Gandhinagar wrote:
> >
> > I am using a modified version of Code Gallery Quasi Static
> Compressibility
> > <
> https://nam01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdealii.org%2Fdeveloper%2Fdoxygen%2Fdeal.II%2Fcode_gallery_Quasi_static_Finite_strain_Compressible_Elasticity.html&data=04%7C01%7CWolfgang.Bangerth%40colostate.edu%7C3f03e1b7a92342c0331e08d8b97d7f35%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C637463295948040000%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=wukJxVr%2BMJ0%2BGymh3b5cYRkeUH%2BFCzH2qsBBiujG2h8%3D&reserved=0>
>
>
> > program to compute eigenvalues and eigenvectors of my system matrix. I
> have
> > used ARPACK solver, however, I did not get the expected results. Bruno
> > suggested me to go for PETSc/Slepsc solver to compute the eigenvalues.
> For
> > this, I would need to convert the dealii data structures to the PETSc
> data
> > structures using PETSc wrappers.
>
> All objects that relate to the linear system you are solving (or to the
> eigenvalue problem you are solving). So, matrices and vectors.
>
>
> > I looked at the Step-17 and Step-36 for this. However, I am unable to
> > understand how I can change my current dealii data structures to the one
> using
> > PETSc wrappers. I am also confused regarding what all variables do I
> need to
> > convert using PETScWrappers. Also, for the system matrix, do I need to
> use
> > PETScWrappers::MPI::BlockSparseMatrix or
> PETScWrappers::BlockSparseMatrix.
>
> That depends on whether you want to run your problem on multiple machines
> using MPI. If you've been using ARPACK, then I suspect that you're not
> using
> MPI. So then PETScWrappers::BlockSparseMatrix.
>
>
> > This finite strain code already assembles the system matrix in parallel
> using
> > multi-threading. What changes do I need to do in the assembly if I go on
> to
> > use PETSc data structures.
>
> None, really. The functions filling matrices should work on PETSc data
> structures just fine.
>
> Best
> W.
>
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth email: bang...@colostate.edu
> www: http://www.math.colostate.edu/~bangerth/
>
>
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