Degree 3 bubble on a triangle

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

• \(\mathcal{V}\) is spanned by: \(x y \left(- x - y + 1\right)\)
• \(\mathcal{L}=\{l_0,...,l_{0}\}\)
• Functionals and basis functions:

\(\displaystyle l_{0}:v\mapsto v(\tfrac{1}{3},\tfrac{1}{3})\)

\(\displaystyle \phi_{0} = 27 x y \left(- x - y + 1\right)\)

This DOF is associated with face 0 of the reference element.