Yikes ! Sorry to put you through the trouble. The translation is from German --> English . You should correct the english version to see which parts were misunderstood. I neglected to mention that. (8P . I am going to give the results to Nils or James or whoever is responsible to put it on the page linking to the original german. -- John Lapeyre <lapeyre@physics.arizona.edu> Tucson,AZ http://www.physics.arizona.edu/~lapeyre