CHANGELOG.md

Release 2.9

• The implementation of the Raviart-Thomas element now also includes 0th order shape functions on prisms and pyramids.

Deprecations and removals

• Deprecated many of the Lagrange headers, use lagrange(cube|prism|pyramid|simplex).hh instead.

Release 2.8

• Passing functions that support f.evaluate(x,y) to interpolate() is deprecated. Instead the functions should now provide operator(). Passing functions providing the old interface is still supported in 2.8.

  • LocalFiniteElementFunctionBase is deprecated. You can rely on duck-typing when passing functions with the new interface.
  • The virtual interface for interpolating functions in LocalFiniteElementVirtualInterface now uses std::function instead of the deprecated VirtualFunction for the passed function.
  • The virtual interface wrapper LocalFiniteElementVirtualImp now requires that the wrapped LocalFiniteElement implementation supports the new operator() based interpolation interface.

• Add an implementation of the Nédélec element of the first kind, as introduced in "Nédélec, Mixed finite elements in R^3, 1980, DOI: http://dx.doi.org/10.1007/BF01396415". Only the first-order case for triangles, tetrahedra, squares and cubes is implemented.

• Fix a bug in a shape function of the second-order Lagrange element on the three-dimensional pyramid.

• Add an implementation of the Raviart-Thomas element for tetrehedra with order 0.

• Remove deprecated GenericLocalFiniteElement::topologyId(), use type().id() instead.

• Imported the Python bindings from the 2.7 branch of dune-python.

• Replaced the combination of function arguments topologyId and dim with a single GeometryType argument. Tagged the old versions of: numLagrangePoints, equidistantLagrangePoints, RTL2InterpolationBuilder::topologyId(), VirtualMonomialBasis(topologyId), VirtualMonomialBasis::topologyId() as deprecated.

• Add a construction algorithm for high order Nédélec elements on triangles and tetrahedra.

Release 2.7

• The header lagrange.hh now includes all headers of all Lagrange implementations, not just the ones with run-time order.

• Introduce a run-time polymorphic container LocalFiniteElementVariant. Much like std::variant, it implements a type-safe union of different LocalFiniteElement implementations. Elements of type LocalFiniteElementVariant can hold one object from a list of types given as template parameters. These types must be implementations of the LocalFiniteElement interface, and the container will in turn implement this interface.

  Such a variant-based polymorphism is not as flexible as full type erasure, but it is much easier to implement. What is more, it is believed that in many situations the restriction to a fixed set of implementation types is not a problem.

• Add support for operator() syntax to interpolate(). All interpolate() implementations now support functions f that either support f.evaluate(x,y) or y = f(x).

• Add an implementation of the Crouzeix-Raviart element.

• Add an implementation of the Brezzi-Douglas-Fortin-Marini element. The coefficients and interpolation are implemented for arbitrary dimension (>1) and order (>0). The actual basis is only implemented for dim=2 and order=1,2,3.

  See !105 (merged) and !145 (merged)

• Introduce a convenience header hierarchical.hh that includes all hierarchical FE implementations.

• Introduce a new class LagrangeSimplexLocalFiniteElement, which implements Lagrange finite elements on simplices with compile-time dimension and order. It currently does not cover more general dimension/order situations than what is already available in dune-localfunctions, but it gathers the plethora of different Pk3DNodal, PkNodal, P1Nodal, etc implementations under one single name.

• Introduce new class BrezziDouglasMariniSimplexLocalFiniteElement (and the same for cubes) that subsumes all currently existing simplex BDM element implementations under a single name. Domain dimension and polynomial order are template parameters now.

• Introduce a convenience header dune/localfunctions/brezzidouglasmarini.hh that includes all BDM implementations.

Release 2.6

• The diffOrder value has disappeared from the LocalBasisTraits class. This value encoded the highest partial derivative order implemented by a local basis. Encoding this value as a compile-time parameter led to various problems related to the dynamic interface, mainly because it became part of the type of the local finite element. At the same time, it was suspected that very few people ever actually used the parameter.

  More practically, two things have disappeared: the diffOrder member of the LocalBasisTraits class, and the 8th template parameter dorder of that class. There is no replacement, and if you have used diffOrder then you currently have to find a way to live without it. As mentioned we believe that this concerns only a very small number of people.

  If you do use diffOrder and you absolutely need it or something similar, then we'd like to hear from you. One of the reasons why there is no replacement is that we couldn't really think of a good use case to begin with.

• The QkLocalFiniteElement class implements second partial derivatives of shape functions now.

• The clone() method was removed from the raw (non-virtual) LocalFiniteElement implementations. If you want to copy a LocalFiniteElement in a portable way which works for raw implementations as well as for the virtual interface class, you have to replace lfe.clone() by Dune::LocalFiniteElementCloneFactory<LFEType>::clone(lfe).