1.4.5

Fixed: #282, #284, #290

1.4.4

Minor fixes

1.4.3

• Fast rebuild of the MPI AMG hierarchy in case the system matrix structure has not changed.
• Support block valued backends with smoothed aggregation coarsening when user provides near nullspace components. This is implemented with help of hybrid backends, relaxation::as_block, and coarsening::as_scalar. See the "Using near null-space components" tutorial for more details.
• Implement backend::reinterpret_as_rhs() helper function for easy reinterpretation of scalar vectors as block-valued.
• Support complex types in MPI solvers.
• Minor improvements and bug fixes.

1.4.2

• Improved documentation
• Partial rebuild of the AMG hierarchy using new matrix, and reusing
  prolongation and restriction operators.
• Allow to use null-space vectors with MPI aggregation
• Implemented ILUP(k). The non-zero pattern of A^k is used to determine
  the fill-in, which may be beneficial for non-symmetric systems
• Implementation of experimental deflated solver
• prm.solver.ns_search=true ignores trivial solution for zero RHS.
  Useful in search of the null-space vectors of the system
• Published Docker image with compiled examples
• Removed SIMPLE preconditioner, which may be replaced with SchurPC
• Minor fixes and improvements.

1.4.0

• The codebase uses C++11 standard.
• amgcl::mpi::amg preconditioner is implemented! This works much better than subdomain deflation which is now considered deprecated. See examples/mpi/mpi_amg.cpp and some benchmarks in https://doi.org/10.1134/S1995080219050056 (https://arxiv.org/abs/1811.05704).
• Added wrappers for Scotch and ParMetis partitioning libraries.
• Runtime interface has been refactored. Instead of doing

  typedef amgcl::make_solver<
      amgcl::runtime::amg<Backend>,
      amgcl::runtime::iterative_solver<Backend>
      > Solver;

  one should now

  typedef amgcl::make_solver<
      amgcl::amg<
          Backend,
          amgcl::runtime::coarsening::wrapper,
          amgcl::runtime::relaxation::wrapper
          >,
      amgcl::runtime::solver::wrapper<Backend>
      > Solver;

  This allows to reuse the same amgcl::amg implementation both for compile-time and runtime interfaces and greatly reduces compilation time and memory requirements for the library.
• Got rid of as many Boost dependencies as possible in favor of C++11. Currently, only the runtime interface depends on Boost , as it uses boost::property_tree::ptree for defining runtime parameters.
  It should be possible to use the compile-time interface completely Boost-free. This also means that one should replace all uses of boost::tie and boost::make_tuple in amgcl-related code with std::tie and std::make_tuple. For example:

  Solver solve(std::tie(n, ptr, col, val));
  std::tie(iters, error) = solve(f, x);

• Provide amgcl::backend::bytes() function that returns (sometimes approximately) the amount of memory allocated for an amgcl object. std::string amgcl::backend::human_readable_memory(size_t) converts bytes to a human-readable size string (e.g. 1024 is converted to 1 K).
• Support for mixed-precision computations (where iterative solver and preconditioner use different precisions).
• MPI versions of CPR preconditioners. Support for statically-sized matrices in global preconditioners of CPR. Support for mixed-precision in global and pressure-specific parts of CPR.
• Helper functions for the computation of rigid body modes (for use as near null space vectors in structural problems) from 2D or 3D coordinates.
• Improvements for the Schur pressure correction preconditioner.
• Added Richardson and PreOnly (only apply the preconditioner once) iterative solvers. The latter is intended for use as a nested solver in composite preconditioners, such as Schur pressure correction.
• epetra_map was moved to the adapter namespace.
• Eigen backend was split into adapter and backend part.
• amgcl::make_scaling_solver has been replaced with amgcl::scaled_problem adapter.
• Added tutorials to the documentation.
• Many bug fixes and minor improvements.

1.3.99

• The code base uses C++11 standard.
• amgcl::mpi::amg preconditioner is implemented! This works much better than subdomain deflation which is now considered deprecated. See examples/mpi/mpi_amg.cpp and some benchmarks in https://doi.org/10.1134/S1995080219050056 (https://arxiv.org/abs/1811.05704).
• Added wrappers for Scotch and ParMetis partitioning libraries.
• Runtime interface has been refactored. Instead of doing

  typedef amgcl::make_solver<
      amgcl::runtime::amg<Backend>,
      amgcl::runtime::iterative_solver<Backend>
      > Solver;

  one should now

  typedef amgcl::make_solver<
      amgcl::amg<
          Backend,
          amgcl::runtime::coarsening::wrapper,
          amgcl::runtime::relaxation::wrapper
          >,
      amgcl::runtime::solver::wrapper<Backend>
      > Solver;

  This allows to reuse the same amgcl::amg implementation both for compile-time and runtime interfaces, and greately reduces compilation time and memory requirements for the library.
• Got rid of as many Boost dependencies as possible in favor of C++11. Currently , only the runtime interface depends on Boost , as it uses boost::property_tree::ptree for defining runtime parameters.
  It should be possible to use the compile-time interface completely Boost-free. This also means that one should replace all uses of boost::tie and boost::make_tuple in amgcl-related code with std::tie and std::make_tuple. For example:

  Solver solve(std::tie(n, ptr, col, val));
  std::tie(iters, error) = solve(f, x);

• Provide amgcl::backend::bytes() function that returns (sometimes approximately) the amount of memory allocated for an amgcl object. std::string amgcl::backend::human_readable_memory(size_t) converts bytes to a human-readable size string (e.g. 1024 is converted to 1 K).
• Initial support for mixed-precision computations (where iterative solver and preconditioner use different precisions).
• MPI versions of CPR preconditioners. Support for statically-sized matrices in global preconditioners of CPR. Support for mixed precision in global and pressure-specific parts of CPR.
• epetra_map was moved to adapter namespace.
• Eigen backend was split into adapter and backend part.
• amgcl::make_scaling_solver has been replaced with amgcl::scaled_problem adapter.

This is marked as pre-release, because the documentation still needs to be updated.

1.2.0

• Change default value of smoothed_aggregation.aggr.eps_strong
  from 0 to 0.08. This should work better for anisotropic cases.
• Pressure mask may be set with a pattern in Schur pressure correction
  preconditioner.
• When using async_setup, allow to exit initialization thread early in
  case the solution has already converged.
• Stable implementation of inner product in OpenMP backend. This makes
  the solution deterministic for a fixed number of OpenMP threads.
• Support non-zero initial condition in BiCGStab(L).
• Switch implementation of BiCGStab(L) to Fokkema's version [1].
• Support both left and right preconditioning in BiCGStab, BiCGStab(L),
  GMGES, CG.
• Improve performance/scalability of mpi::subdomain_deflation.
• Minor bug fixes and improvements.

[1] Fokkema, Diederik R. Enhanced implementation of BiCGstab (l) for
solving linear systems of equations. Universiteit Utrecht.
Mathematisch Instituut, 1996.

1.1.0

• Improve profiling: allow users to configure profiling operations.
• Implement adapter::reorder for matrices and vectors. Allows to
  transparently apply Cuthill-McKee reordering to the system matrix and
  RHS before solution.
• Improve performance of Schur pressure correction preconditioner by
  (optionally) approximating inverse of Kuu matrix with its inverted
  diagonal.
• Use power iteration to estimate spectral radius in smoothed_aggregation.
  This improves convergence rate at the cost of setup time.
  The total time is usually improved, but may suffer on GPGPU backends.
• Adding IDR(s) iterative solver (http://ta.twi.tudelft.nl/nw/users/gijzen/IDR.html).
• Improve performance and scalability of mpi::subdomain_deflation
  preconditioner.
• Support matrix-free solution with mpi::subdomain_deflation.
• Provide amgcl::put(ptree p, string s) where s has key=value format.
  This makes parsing of command line parameters easier.
• Add shared and distributed memory benchmarks to the documentation.
• Add Clang and OSX tests on Travis-CI.
• Minor bug fixes and improvements.

1.0.0

• Implemented OpenMP versions of incomplete LU smoothers (ilu0, iluk, ilut), and got rid of now obsolete parallel_ilu0 smoother. Parallel algorithm is based on level scheduling approach and is automatically selected when there are four or more OpenMP threads.
• Reimplemented multicolor Gauss-Seidel smoother, merged the new implementation with gauss_seidel, and got rid of obsolete multicolor_gauss_seidel smoother. Parallel algorithm is based on level scheduling approach and is automatically selected when there are four or more OpenMP threads.
• Code cleanup, minor improvements and bug fixes.

0.9.1

Mostly a bug fix release.

• Fixed a bug in matrix-matrix product.
• Allow to disable selected components from runtime interface to reduce compilation overhead (see #45).