Does amgcl support the trillinos csrmatrix format.

[ztdepztdep]

I have a code writing with trillinos, and i want to call the amgcl routine from my trillinos code. Does amgcl supoor thtis?

[ddemidov]

There is the epetra_map adapter that should allow to use Trilinos matrices as inputs to amgcl solvers.

[ztdepztdep]

`  amgcl::mpi::init mpi();
	amgcl::mpi::communicator world(MPI_COMM_WORLD);
	amgcl::profiler<> prof("Heat Condcution");
   	typedef amgcl::backend::builtin<double> DBackend;
        typedef amgcl::mpi::make_solver<amgcl::mpi::amg<DBackend,
                                        amgcl::mpi::coarsening::smoothed_aggregation<DBackend>,
                                        amgcl::mpi::relaxation::spai0<DBackend>>,
                                        amgcl::mpi::solver::bicgstab<DBackend>> Solver;
        
   Solver solve(world, amgcl::adapter::epetra_map(EpetraA_Diffusion));
     std::vector<double> x(NumMyRows);
   std::vector<double> rhs(NumMyRows);
   std::tie(NumIters, TrueResidual) = solve(rhs, x);

`

great, it works. But it is very slow compared to the trillinos's bicgstab solver. trillinos 0.15s amgcl 1.6s

[ddemidov]

I don't have much experience with Trilinos, may be @RiccardoRossi may comment?

Also, make sure you have enabled full optimization for compilation of the amgcl test.

[RiccardoRossi]

mmm,

as i understand you have a backend in the middle, and as i understand that is making a copy of the matrix. @ddemidov am I wrong?

having said this we benchmarked against ML and it was very competitive... are u sure you properly defined the NDEBUG flag?

[ddemidov]

Yes, there is a copy being made from the adapter into amgcl distributed matrix. @ztdepztdep, if you measure the construction and the application of the solver separately, it should be clear which part takes more time (the matrix is copied inside the constructor).

[ztdepztdep]

Could you please give me some advices about how to define NDEBUG in the cmake file?

[ddemidov]

Cmake should do this for you if you set CMAKE_BUILD_TYPE=Release