e are given by</p>
$$ \phi_k = \lambda_i \nabla^{\bot} \lambda_j - \lambda_j \nabla^{\bot} \lambda_i. $$<p>For BDM1, one more basis is added on this edge</p>
$$ \psi_k = \lambda_i \nabla^{\bot} \lambda_j + \lambda_j \nabla^{\bot} \lambda_i. $$<p>For RT1, two more bases are added to the triangle. Suppose $i,j,k$ are the vertices of the triangle and $i&lt;j&lt;k$. The two bases are</p>
$$ \chi_1 = \lambda_j\phi _{ik} = \lambda_j(\lambda_i\nabla^{\bot} \lambda_k -
\lambda_k\nabla^{\bot}\lambda_i),\quad
   \chi