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Phalanx Documentation

Index

Overview

Phalanx is a local graph-based field evaluation toolkit. While the intended use case is for solving general partial differential equations (PDEs), there is NO specific code implemented for PDEs in Phalanx. It can be applied to any system that requires function evaluation. In terms of PDE discretization schemes it can be used for finite element, finite difference and finite volume.

Phalanx is a local node evaluation tool. Phalanx relies on the Kokkos package for performance portability and provides a simple performant interface to multicore and manycore architectures. While its main use is for large scale parallel high performance computing, the MPI communication (possibly required for ghosting) must be handled by other packages in the toolchain (separation of concerns). Users can handle this manually as Phalanx places no requirements on this but we recomend the Tpetra package in Trilinos be leveraged.

The main goal of Phalanx is to decompose a complex problem into a number of simpler problems with managed dependencies to support rapid development and extensibility. Through the use of template metaprogramming concepts, Phalanx supports arbitrary user defined data types and evaluation types. This allows for extreme flexibility in integration with user applications and provides extensive support for embedded technology such as automatic differentiation for sensitivity analysis, optimization, and uncertainty quantification. This approach, coupled with the template capabilities of C++ offers a number of unique and powerful capabilities:

Phalanx is a hammer. It's use should be carefully considered. We recommend its use when writing a general PDE framework where one needs support for flexibility in equation sets, discretizations, and material models. It should not be used for a fixed set of equations and a single discretization that never changes (Although the template metaprogramming support could still be leveraged). There are some drawbacks to using Phalanx that should be considered:

Managing these trade-offs can result in application code that both performs well and supports rapid development and extensibility.

News

Phalanx has just completed the transition from shards::Array to the Kokkos::View. Leveraging Kokkos, Phalanx is now performance portable to GPUs. The examples and user guide, however, have not been updated to reflect the transition. Please look at the MultiDimensionalArray example and the unit tests for examples on how to use Phalanx. We will update the user guide and other examples asap.

Reporting Bugs and Making Enhancement Requests

To reports bugs or make enhancement requests, visit the Trilinos Bugzilla (Bug Tracking) Database, and use the following instructions.

History

Phalanx grew out of the Variable Manger in the Charon code and the Expression Manager in the Aria code at Sandia National Laboratires. It is an attempt at merging the two capabilities.

Authors and Contributors

The following have contributed to the design through ideas, discussions, and/or code development of Phalanx:

Copyright

// @HEADER
// ************************************************************************
//
//        Phalanx: A Partial Differential Equation Field Evaluation 
//       Kernel for Flexible Management of Complex Dependency Chains
//                    Copyright 2008 Sandia Corporation
//
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
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For All Questions and Comments...

Please contact Roger Pawlowski (rppaw.nosp@m.lo@s.nosp@m.andia.nosp@m..gov).