# Changes in version 2016.2.0¶

FIAT 2016.2.0 was released on 2016-11-30.

## Summary of changes¶

• More elegant edge-based degrees of freedom are used for generalized Regge finite elements. This is a internal change and is not visible to other parts of FEniCS.
• The name of the mapping for generalized Regge finite element is changed to “double covariant piola” from “pullback as metric”. Geometrically, this mapping is just the pullback of covariant 2-tensor fields in terms of proxy matrix-fields. Because the mapping for 1-forms in FEniCS is currently named “covariant piola”, this mapping for symmetric tensor product of 1-forms is thus called “double covariant piola”. This change causes multiple internal changes downstream in UFL and FFC. But this change should not be visible to the end-user.
• Added support for the Hellan-Herrmann-Johnson element (symmetric matrix fields with normal-normal continuity in 2D).
• Add method FiniteElement.is_nodal() for checking element nodality
• Add NodalEnrichedElement which merges dual bases (nodes) of given elements and orthogonalizes basis for nodality
• Restructuring finite_element.py with the addition of a non-nodal class FiniteElement and a nodal class CiarletElement. FiniteElement is designed to be used to create elements where, in general, a nodal basis isn’t well-defined. CiarletElement implements the usual nodal abstraction of a finite element.
• Removing trace.py and trace_hdiv.py with a new implementation of the trace element of an HDiv-conforming element: HDivTrace. It is also mathematically equivalent to the former DiscontinuousLagrangeTrace, that is, the DG field defined only on co-dimension 1 entities.
• All nodal finite elements inherit from CiarletElement, and the non-nodal TensorProductElement, EnrichedElement and HDivTrace inherit from FiniteElement.

## Detailed changes¶

• Enable Travis CI on GitHub
• Add facet -> cell coordinate transformation