Degree 2 enriched Galerkin on a interval

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

• Basis functions:

\(\displaystyle \phi_{0} = 2 x^{2} - 3 x + 1\)

\(\displaystyle \phi_{1} = x \left(2 x - 1\right)\)

\(\displaystyle \phi_{2} = 4 x \left(1 - x\right)\)

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