\url{https://www.dealii.org/} and \url{https://github.com/dealii/dealii}.
The major changes of this release are:
+%
\begin{itemize}
\item Improved support for automatic and symbolic differentiation (see
Section~\ref{subsec:ad}),
as well as one new code gallery program (see
Section~\ref{subsec:steps}).
\end{itemize}
-These will all be discussed in more detail in the
-following section. There are a number of other noteworthy changes in this release:
+%
+The major changes are discussed in detail in Section~\ref{sec:major}. There
+are a number of other noteworthy changes in the current \dealii{} release
+that we briefly outline in the remainder of this section:
+%
\begin{itemize}
-\item A number of bug fixes and performance improvements to the
+\item
+ The release contains bug fixes and performance improvements of the
matrix-free framework and related geometric multigrid solvers. In
- particular, the implementation of the Chebyshev iteration, an often
- used smoother in the matrix-free context, has been revised to reduce
- vector accesses. This speeds up matrix-free
- multigrid solvers by up to 10-15\% on geometries with affine
- (parallelogram and parallelpiped) cells, and up to
- 5\% on geometries with cells bounded by curved edges and faces.
-\item Various variants of geometric multigrid solvers and matrix-free
- implementations were run on up to 304,128 cores during the acceptance phase of
- the SuperMUC-NG supercomputer, verifying the scalability of our
- implementations. Some performance bottlenecks on distributed triangulation
- with more than 100k MPI ranks have been fixed.
-\marginpar{Luca: Please expand}
-\item ParsedConvergenceTable.
-\item The \texttt{FE\_BernardiRaugel} class implements the
- non-standard Bernardi-Raugel (BR) element that can be used as one part of
- a stable velocity/pressure pair for the Stokes equation
- \cite{BR85}. The BR element can be seen as either an enriched
- version of the $Q_1^d$ element with added bubble functions on each
- edge (in 2d) or face (in 3d), or as a reduced version of the $Q_2^d$
- element. It addresses the fact that the $Q_1^d\times Q_0$
- combination is not inf-sup stable (requiring a larger velocity
- space), and that the $Q_2^d\times Q_1$ combination is stable but
- sub-optimal since the velocity space is too large relative to the
- pressure space to provide additional accuracy commensurate with the
+ particular, the implementation of the Chebyshev iteration, an often used
+ smoother in the matrix-free context, has been revised to reduce vector
+ accesses. This speeds up matrix-free multigrid solvers by up to 10-15\%
+ on geometries with affine (parallelogram and parallelpiped) cells, and up
+ to 5\% on geometries with cells bounded by curved edges and faces.
+
+\item
+ Various variants of geometric multigrid solvers and matrix-free
+ implementations were run on up to 304,128 cores during the acceptance
+ phase of the SuperMUC-NG supercomputer, verifying the scalability of our
+ implementations. Some performance bottlenecks on distributed
+ triangulation with more than 100k MPI ranks have been fixed.
+
+\item
+ A new class \texttt{ParsedConvergenceTable} has been introduced.
+ \textcolor{red}{TODO}
+ \marginpar{Luca: Please expand}
+
+\item
+ The \texttt{FE\_BernardiRaugel} class implements the non-standard
+ Bernardi-Raugel (BR) element that can be used to construct a stable
+ velocity-pressure pair for the Stokes equation \cite{BR85}. The BR
+ element is an enriched version of the $Q_1^d$ element with added bubble
+ functions on each edge (in 2d) or face (in 3d). It addresses the fact
+ that the $Q_1^d\times Q_0$ combination is not inf-sup stable (requiring a
+ larger velocity space), and that the $Q_2^d\times Q_1$ combination is
+ stable but sub-optimal since the velocity space is too large relative to
+ the pressure space to provide additional accuracy commensurate with the
cost of the large number of velocity unknowns. The BR space is
intermediate to the $Q_1^d$ and $Q_2^d$ spaces.
- The current implementation of the element only works for
- parallelogram meshes due to difficulties associated with the mapping
- of shape functions: The shape functions of the $Q_1^d$ part of the
- element need to be mapped as scalars, as is common for the vector
- components of the $Q_1^d$ element; on the other hand, the
- vector-valued edge bubble functions need to be mapped using the
- Piola transform as is common for the Raviart-Thomas
- element. \dealii{} does not currently have the ability to use
- different mappings for individual shape functions, though this
- functionality is planned for the next release.
-
-\item The \texttt{FE\_NedelecSZ} class is an alternative
- implementation of the ideas behind the N{\'e}d{\'e}elec element. It is based
- on the work of Zaglmayr \cite{Zag06} and overcomes the
- sign conflict issues present in traditional N{\'e}d{\'e}lec
- elements that arise from the edge and face parameterizations used
- in the basis functions. Therefore, this element should provide
- consistent results for general quadrilateral and hexahedral
- elements for which the relative orientations of edges and faces as
- seen from all adjacent cells are often difficult to establish.
- The way this element addresses the sign conflict problem is to assign
- local edges and faces a globally defined orientation. The
- implementation is described in \cite{Kynch2017}.
-
- \marginpar{Maybe also mention the rtree interfaces?}
+ The element is currently only implemented for parallelogram meshes due to
+ difficulties associated with the mapping of shape functions: The shape
+ functions of the $Q_1^d$ part of the element need to be mapped as
+ scalars, as is common for the vector components of the $Q_1^d$ element;
+ on the other hand, the vector-valued edge bubble functions need to be
+ mapped using the Piola transform as is common for the Raviart-Thomas
+ element. \dealii{} does not currently have the ability to use different
+ mappings for individual shape functions, though this functionality is
+ planned for the next release.
+
+\item
+ The \texttt{FE\_NedelecSZ} class is a new implementation of the
+ N{\'e}d{\'e}lec element on quadrilaterals and hexahedra. It is based on
+ the work of Zaglmayr \cite{Zag06} and overcomes the sign conflict issues
+ present in traditional N{\'e}d{\'e}lec elements that arise from the edge
+ and face parameterizations used in the basis functions. Therefore, this
+ element should provide consistent results for general quadrilateral and
+ hexahedral elements for which the relative orientations of edges and
+ faces (as seen from all adjacent cells) are often difficult to establish.
+ The \texttt{FE\_NedelecSZ} element addresses the sign conflict problem by
+ assigning a globally defined orientation to local edges and faces. A
+ detailed overview of the implementation of the \texttt{FE\_NedelecSZ}
+ element in \dealii{} can be found in \cite{Kynch2017}.
+
+\item
+ A new interface to \texttt{boost::geometry::index::rtree} has been added.
+ \textcolor{red}{TODO}
\end{itemize}
-
-Beyond these changes, the changelog lists more than 200 other features and bugfixes.
+%
+In addition to these changes, the changelog lists more than 200 other
+features and bugfixes.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\section{Significant changes to the library}
+\section{Major changes to the library}
+\label{sec:major}
This release of \dealii contains a number of large and significant changes
-that will be discussed in the following sections. It of course also contains a
+that will be discussed in this section.
+
+It of course also contains a
vast number of smaller changes and added functionality; the details of these
can be found
\href{https://dealii.org/developer/doxygen/deal.II/changes_between_9_0_1_and_9_1_0.html}{
projects / release-papers.git / commitdiff