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[Huadong GAO <question215444@xxxxxxxxxxxxxxxxxxxxx>]

Question #215444 on UFL changed:
https://answers.launchpad.net/ufl/+question/215444

    Status: Answered => Open

Huadong GAO is still having a problem:
First thanks Johan's help.   A simple python code is attached below. I use quadratic element
solving Poisson Equation on the UnitCircle domain, I do not know how FEniCS apply the Dirichlet boundary conditions. I mean the how to determine the value at the midpoint of the boundary edge ?

######################################
from dolfin import *

mesh = UnitCircle(5)
V = FunctionSpace(mesh, "Lagrange", degree=2)

u = TrialFunction(V)
v = TestFunction(V)

#--------------------------------------------
f = Expression("1.0")
u_e = Expression("exp(x[0]+x[1]-t)",t=0)
#--------------------------------------------

a = inner(nabla_grad(u),nabla_grad(v))*dx
v = f*v*dx

def boundary(x,on_boundary):
    return on_boundary

bc = DirichletBC(V,u_e,boundary)

A = assemble(a)
b = assemble(v)
bc.apply(A,b)
u = Function(V)
solver = KrylovSolver("gmres", "ilu")            
solver.solve(A, u.vector(), b)

plot(mesh)
plot(u)
interactive()
######################################

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