FEMDocumentation`
FEMDocumentation`

represents n linear quad elements ek with incidents {ik1,ik2,ik3,ik4}.

represents n quad elements ek and n integer markers mk.

# Details

• QuadElement can be used as an input to ToElementMesh or ToBoundaryMesh.
• Incidents ikj are integers that index an array of spatial coordinates. The coordinates referenced by ek={ik1,} are the nodes of the k quad.
• The first four incidents ik1, ik2, ik3, and ik4 are always vertices.
• For quadratic quad elements, the next four incidents are mid-side nodes of possibly curved edges.
• Linear elements are order 1 elements and quadratic elements are order 2 elements.
• In QuadElement[{e1,,en}], all elements ek need to be of the same order.
• The quads in QuadElement[{e1,,en}] will share common nodes and edges but cannot intersect with each other or with themselves.
• The nodes for a linear and a quadratic quad are shown:
• • The incidents {i1,i2,i3,i4} must be ordered so that going from the coordinates referenced by i1 to i2 to i3 to i4 is in the counterclockwise direction.
• Typically, QuadElement is used for two-dimensional regions, but may be embedded in three dimensions, for example, as a part of a boundary mesh.
• The quad element is known in the finite element method as a Lagrange element.

# Examples

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## Basic Examples(1)

 In:= Create a mesh with one quad element:

 In:= Out= 