FINITE-ELEMENT APPROXIMATIONS OF AN OPTIMAL-CONTROL PROBLEM ASSOCIATED WITH THE SCALAR GINZBURG-LANDAU EQUATION

We consider finite element approximations of an optimal control problem associated with a scalar version of the Ginzburg-Landau equations of superconductivity. The control is the Neumann data on the boundary and the optimization goal is to obtain a best approximation, in the least squares sense, to some desired state. The existence of optimal solutions is proved. The use of Lagrange multipliers is justified and an optimality system of equations is derived. Then, the regularity of solutions of the optimality system is studied, and finally, finite element algorithms are defined and optimal error estimates are obtained. © 1991.