The transverse wave equation and boundary condition (dirichlet or
neumann) are an *eigenvalue problem*. We can see two things right
away. First of all:

(10.70) |

(10.71) |

To proceed further in our understanding, we need to look at an actual example - we'll find that only certain for will permit the boundary conditions to be solved, and we'll learn some important things about the propagating solutions at the same time.

Robert G. Brown 2015-08-23