We consider absorbing layers that are extensions of the PML of Berenge
r (1994). These will be constructed both for time problems and for Hel
mholtz-like equations. We shall consider applications to electricity a
nd magnetism and acoustics (with a mean flow) in both physical space a
nd in the time Fourier space (Helmholtz equation). Numerical results a
re presented showing the efficiency of this condition for the time dep
endent Maxwell equations. (C) 1998 Elsevier Science B.V. and IMACS. Al
l rights reserved.