Degree 1 enriched Galerkin on a triangle

• \(R\) is the reference triangle. The following numbering of the subentities of the reference is used:

• Basis functions:

\(\displaystyle \phi_{0} = - x - y + 1\)

\(\displaystyle \phi_{1} = x\)

\(\displaystyle \phi_{2} = y\)

\(\displaystyle \phi_{3} = 1\)