2018/11/22 by Karkulik, Michael
#FOS: Mathematics #Numerical Analysis (math.NA)
paper · doi:10.48550/arxiv.1811.09251
We consider the finite element discretization of an optimal Dirichlet boundary control problem for the Laplacian, where the control is considered in H1/2(Γ). To avoid computing the latter norm numerically, we realize it using the H1(Ω) norm of the harmonic extension of the control. We propose a mixed finite element discretization, where the harmonicity of the solution is included by a Lagrangian multiplier. In the case of convex polygonal domains, optimal error estimates in the H1 and L2 norm are proven. We also consider and analyze the case of control constrained problems.