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[meg@xxxxxxxxx]

> Is there anything telling how the bubble functions are defined?
>
> For example with the Mini example:
>
> P1 = VectorElement("Lagrange", "triangle", 1)
> B = VectorElement("Bubble", "triangle", 3)
> Q = FiniteElement("Lagrange", "triangle", 1)
> Mini = (P1 + B) * Q
>
> Does B consist of 3 bubble functions in some symmetric pattern in the
> element?
>

The bubble functions are the bubble functions ;)

In the above example, B is the span of the piecewise continuous
cubic functions that are zero on the boundary of each triangle.
(1 per triangle for a FiniteElement and hence 2 per triangle for a
VectorElement of value dimension 2.)

In general, the bubble finite element of degree k is the span of the interior
basis functions of CG_k.

--
Marie