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[Jake Ostien <tostien@xxxxxxxxx>]

Hi,

I am trying to define a mixed element with one part linear Lagrange 
elements and one part QuadratureElement.  The error message that I get 
tells me that I can't take derivatives of a QuadratureElement, but I 
don't think that I am.  Please see the attached form.  Is this something 
that I should be able to do?

Jake

elu  = VectorElement("Lagrange", "tetrahedron", 1)
elHp = VectorQuadratureElement("tetrahedron", 1, 9)

sgp = MixedElement([elu, elHp])

(w, V) = TestFunctions(sgp)
(u, Hp) = TrialFunctions(sgp)

def Mat(A):
    return [ [A[0], A[1], A[2]],    \
             [A[3], A[4], A[5]],    \
             [A[6], A[7], A[8]] ]

def sym(v):
    return 0.5*(v + transp(v))

mu = 0.3
lmbda = 10.0

def sigma(A):
    return mult(2.0*mu,A) + mult(lmbda,mult(trace(A),Identity(3)))


a = dot(grad(w), sigma(sym(grad(u))))*dx