  We study boundary determination for an inverse problem associated to the
time-harmonic Maxwell equations and another associated to the isotropic
elasticity system. We identify the electromagnetic parameters and the Lam\'e
moduli for these two systems from the corresponding boundary measurements. In a
first step we reconstruct Lipschitz magnetic permeability, electric
permittivity and conductivity on the surface from the ideal boundary
measurements. Then, we study inverse problems for Maxwell equations and the
isotropic elasticity system assuming that the data contains measurement errors.
For both systems, we provide explicit formulas to reconstruct the parameters on
the boundary as well as its rate of convergence formula.
