5 Oct 2000

Einar Mjølhus "WKB theory of energy-flux conserving linear systems of ordinary differential equations".

I shall speak loosely on the approximation called WKB (Wentzel, Brillouin, Kramers) and its application to the description of waves in slowly varying media. Then I present (sketchy) some new ideas taken up by me recently and leading to an application of indefinite inner product. We consider also one calculation to estimate the strength of the electric field in the so-called "caustic region" for oblique incidence of a radio wave into the ionosphere.