Abstract: | By a general argument, it is shown that Herglotz wave functions are dense (with respect to the C∞(Ω)‐topology) in the space of all solutions to the reduced wave equation in Ω. This is used to provide corresponding approximation results in global spaces (eg. in L2‐Sobolev‐spaces Hm(Ω)) and for boundary data. Copyright © 2004 John Wiley & Sons, Ltd. |