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Argyris

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Orders\(k=5\)
Reference elementstriangle
Polynomial set\(\mathcal{P}_{k}\)
↓ Show polynomial set definitions ↓
DOFsOn each vertex: point evaluations,
point evaluations of derivatives in coordinate directions, and point evaluations of components of Jacobian
On each edge: point evaluations of normal derivatives at midpoints
Number of DOFstriangle: \(21\)
CategoriesScalar-valued elements

Implementations

Symfem"Argyris"
↓ Show Symfem examples ↓
UFL"Argyris"
↓ Show UFL examples ↓

Examples

triangle
order 5
  • \(R\) is the reference triangle. The following numbering of the subentities of the reference is used:
  • \(\mathcal{V}\) is spanned by: \(1\), \(x\), \(x^{2}\), \(x^{3}\), \(x^{4}\), \(x^{5}\), \(y\), \(x y\), \(x^{2} y\), \(x^{3} y\), \(x^{4} y\), \(y^{2}\), \(x y^{2}\), \(x^{2} y^{2}\), \(x^{3} y^{2}\), \(y^{3}\), \(x y^{3}\), \(x^{2} y^{3}\), \(y^{4}\), \(x y^{4}\), \(y^{5}\)
  • \(\mathcal{L}=\{l_0,...,l_{20}\}\)
  • Functionals and basis functions:
\(\displaystyle l_{0}:v\mapsto v(0,0)\)

\(\displaystyle \phi_{0} = - 6 x^{5} + 15 x^{4} + 30 x^{3} y^{2} - 10 x^{3} + 30 x^{2} y^{3} - 30 x^{2} y^{2} - 6 y^{5} + 15 y^{4} - 10 y^{3} + 1\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{1}:v\mapsto\nabla{v}(0,0)\cdot\left(\begin{array}{c}1\\0\end{array}\right)\)

\(\displaystyle \phi_{1} = x \left(- 3 x^{4} + 8 x^{3} + x^{2} y^{2} - 6 x^{2} - 10 x y^{3} + 10 x y^{2} - 8 y^{4} + 18 y^{3} - 11 y^{2} + 1\right)\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{2}:v\mapsto\nabla{v}(0,0)\cdot\left(\begin{array}{c}0\\1\end{array}\right)\)

\(\displaystyle \phi_{2} = y \left(- 8 x^{4} - 10 x^{3} y + 18 x^{3} + x^{2} y^{2} + 10 x^{2} y - 11 x^{2} - 3 y^{4} + 8 y^{3} - 6 y^{2} + 1\right)\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{3}:v\mapsto\frac{\partial^2v}{\partial x\partial x}(0,0)\)

\(\displaystyle \phi_{3} = \frac{x^{2} \left(- x^{3} + 3 x^{2} + 3 x y^{2} - 3 x + 2 y^{3} - 3 y^{2} + 1\right)}{2}\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{4}:v\mapsto\frac{\partial^2v}{\partial y\partial x}(0,0)\)

\(\displaystyle \phi_{4} = x y \left(- 2 x^{3} - 6 x^{2} y + 5 x^{2} - 6 x y^{2} + 10 x y - 4 x - 2 y^{3} + 5 y^{2} - 4 y + 1\right)\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{5}:v\mapsto\frac{\partial^2v}{\partial y\partial y}(0,0)\)

\(\displaystyle \phi_{5} = \frac{y^{2} \left(2 x^{3} + 3 x^{2} y - 3 x^{2} - y^{3} + 3 y^{2} - 3 y + 1\right)}{2}\)

This DOF is associated with vertex 0 of the reference element.
\(\displaystyle l_{6}:v\mapsto v(1,0)\)

\(\displaystyle \phi_{6} = x^{2} \left(6 x^{3} - 15 x^{2} - 15 x y^{2} + 10 x - 15 y^{3} + 15 y^{2}\right)\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{7}:v\mapsto\nabla{v}(1,0)\cdot\left(\begin{array}{c}1\\0\end{array}\right)\)

\(\displaystyle \phi_{7} = \frac{x^{2} \left(- 6 x^{3} + 14 x^{2} + 7 x y^{2} - 8 x + 7 y^{3} - 7 y^{2}\right)}{2}\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{8}:v\mapsto\nabla{v}(1,0)\cdot\left(\begin{array}{c}0\\1\end{array}\right)\)

\(\displaystyle \phi_{8} = \frac{x^{2} y \left(- 16 x^{2} - 37 x y + 28 x - 27 y^{2} + 37 y - 10\right)}{2}\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{9}:v\mapsto\frac{\partial^2v}{\partial x\partial x}(1,0)\)

\(\displaystyle \phi_{9} = \frac{x^{2} \left(2 x^{3} - 4 x^{2} - x y^{2} + 2 x - y^{3} + y^{2}\right)}{4}\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{10}:v\mapsto\frac{\partial^2v}{\partial y\partial x}(1,0)\)

\(\displaystyle \phi_{10} = \frac{x^{2} y \left(4 x^{2} + 7 x y - 6 x + 5 y^{2} - 7 y + 2\right)}{2}\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{11}:v\mapsto\frac{\partial^2v}{\partial y\partial y}(1,0)\)

\(\displaystyle \phi_{11} = \frac{x^{2} y^{2} \left(- 3 x - 5 y + 5\right)}{4}\)

This DOF is associated with vertex 1 of the reference element.
\(\displaystyle l_{12}:v\mapsto v(0,1)\)

\(\displaystyle \phi_{12} = y^{2} \left(- 15 x^{3} - 15 x^{2} y + 15 x^{2} + 6 y^{3} - 15 y^{2} + 10 y\right)\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{13}:v\mapsto\nabla{v}(0,1)\cdot\left(\begin{array}{c}1\\0\end{array}\right)\)

\(\displaystyle \phi_{13} = \frac{x y^{2} \left(- 27 x^{2} - 37 x y + 37 x - 16 y^{2} + 28 y - 10\right)}{2}\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{14}:v\mapsto\nabla{v}(0,1)\cdot\left(\begin{array}{c}0\\1\end{array}\right)\)

\(\displaystyle \phi_{14} = \frac{y^{2} \left(7 x^{3} + 7 x^{2} y - 7 x^{2} - 6 y^{3} + 14 y^{2} - 8 y\right)}{2}\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{15}:v\mapsto\frac{\partial^2v}{\partial x\partial x}(0,1)\)

\(\displaystyle \phi_{15} = \frac{x^{2} y^{2} \left(- 5 x - 3 y + 5\right)}{4}\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{16}:v\mapsto\frac{\partial^2v}{\partial y\partial x}(0,1)\)

\(\displaystyle \phi_{16} = \frac{x y^{2} \left(5 x^{2} + 7 x y - 7 x + 4 y^{2} - 6 y + 2\right)}{2}\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{17}:v\mapsto\frac{\partial^2v}{\partial y\partial y}(0,1)\)

\(\displaystyle \phi_{17} = \frac{y^{2} \left(- x^{3} - x^{2} y + x^{2} + 2 y^{3} - 4 y^{2} + 2 y\right)}{4}\)

This DOF is associated with vertex 2 of the reference element.
\(\displaystyle l_{18}:v\mapsto\nabla{v}(\tfrac{1}{2},\tfrac{1}{2})\cdot\hat{\boldsymbol{n}}_{0}\)
where \(\hat{\boldsymbol{n}}_{0}\) is the normal to facet 0.

\(\displaystyle \phi_{18} = 8 \sqrt{2} x^{2} y^{2} \left(- x - y + 1\right)\)

This DOF is associated with edge 0 of the reference element.
\(\displaystyle l_{19}:v\mapsto\nabla{v}(0,\tfrac{1}{2})\cdot\hat{\boldsymbol{n}}_{1}\)
where \(\hat{\boldsymbol{n}}_{1}\) is the normal to facet 1.

\(\displaystyle \phi_{19} = 16 x y^{2} \left(- x^{2} - 2 x y + 2 x - y^{2} + 2 y - 1\right)\)

This DOF is associated with edge 1 of the reference element.
\(\displaystyle l_{20}:v\mapsto\nabla{v}(\tfrac{1}{2},0)\cdot\hat{\boldsymbol{n}}_{2}\)
where \(\hat{\boldsymbol{n}}_{2}\) is the normal to facet 2.

\(\displaystyle \phi_{20} = 16 x^{2} y \left(x^{2} + 2 x y - 2 x + y^{2} - 2 y + 1\right)\)

This DOF is associated with edge 2 of the reference element.

References

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Element added09 January 2021
Element last updated05 June 2021