(a) In three-dimensional infinite space, solve 2u t2 = c 22u + g(x)e it with zero initial conditions, u(x, 0) = 0 and u t (x, 0) = 0. From your solution, show that the influence function for g(x) is an outward-propagating wave. (b) Compare with Exercise 9.5.10.

FIRST-ORDER SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS I: Introduction and Linear Systems David Levermore Department of Mathematics University of Maryland 23 April 2012 Because the presentation of this material in lecture will diﬀer from that...