frequently used to determine unknown conatants arising from boundary 

 conditions. Another common method, which is illustrated in the next 

 section on waves in beams, involves obtaining a solution like (5.6) 

 for general values of the unknown constants, and then arguing that 

 unless the constants have certain special values, a plus function will 

 have a pole somewhere in R or a minus function will have a pole some- 

 where in R . In complicated problems involving coupled elastic plate/ 

 acoustic fluid motions the plus or minus function which apparently 

 has the singularity may not be the obvious V or Y_ function, but some 

 more complicated related function. 



25 



%*£a^i^ie^~^is^^ 



