Line data    Source code

       1           0 : // Distributed under the MIT License.
       2             : // See LICENSE.txt for details.
       3             : 
       4             : #pragma once
       5             : 
       6             : #include <cstddef>
       7             : 
       8             : namespace LinearSolver::Schwarz {
       9             : 
      10             : /*!
      11             :  * \brief Abstract base class for the subdomain operator, i.e. the linear
      12             :  * operator restricted to an element-centered Schwarz subdomain
      13             :  *
      14             :  * A subdomain operator must implement these member function templates
      15             :  * - `operator()`: Applies the operator to the element-centered subdomain data.
      16             :  *   It must take these arguments, in this order:
      17             :  *   - `gsl::not_null<LinearSolver::Schwarz::ElementCenteredSubdomainData*>`:
      18             :  *     The data where the result of the operator applied to the operand should
      19             :  *     be written to
      20             :  *   - `LinearSolver::Schwarz::ElementCenteredSubdomainData`: The operand data
      21             :  *     to which the operator should be applied
      22             :  *   - `db::DataBox`: The element's DataBox. Can be used to retrieve any data on
      23             :  *     the subdomain geometry and to access and mutate persistent memory
      24             :  *     buffers.
      25             :  *
      26             :  * Since the subdomain operator has access to the element's DataBox, it can
      27             :  * retrieve any background data, i.e. data that does not depend on the variables
      28             :  * it operates on. Background data on overlap regions with other elements can be
      29             :  * either initialized in advance if possible or communicated with the
      30             :  * `LinearSolver::Schwarz::Actions::SendOverlapFields` and
      31             :  * `LinearSolver::Schwarz::Actions::ReceiveOverlapFields` actions. Note that
      32             :  * such communication should not be necessary between iterations of the Schwarz
      33             :  * solve, but only between successive solves, because background data should not
      34             :  * change during the solve. The Schwarz algorithm takes care of communicating
      35             :  * all variable data that the subdomain operator operates on, whenever
      36             :  * necessary. This variable data is passed to the operator as the `operand`
      37             :  * argument (see above). It includes the data on the central element of the
      38             :  * subdomain, as well as the data on overlap regions with neighbors. Since data
      39             :  * on the entire subdomain is available, applying the subdomain operator
      40             :  * requires _no_ communication between elements. This is the strength of the
      41             :  * Schwarz algorithm: all subdomain solves are independent of each other (see
      42             :  * `LinearSolver::Schwarz::Schwarz` for details).
      43             :  *
      44             :  * Here's an example of a subdomain operator that is the restriction of an
      45             :  * explicit global matrix:
      46             :  *
      47             :  * \snippet Test_SchwarzAlgorithm.cpp subdomain_operator
      48             :  */
      49             : template <size_t Dim>
      50           1 : class SubdomainOperator {
      51             :  public:
      52           0 :   static constexpr size_t volume_dim = Dim;
      53             : 
      54           0 :   SubdomainOperator() = default;
      55             : };
      56             : 
      57             : }  // namespace LinearSolver::Schwarz