Dear all,

Maple gives me the complete solution to the attached PDE. This solution is expressed in terms of KummerU and KummerM. What I want is to obtain the solution for real numbers only, i.e. I want to get rid of the possible imaginary numbers in the solution. This implies that the separation constant, _c1, must be less or equal to 2r. 

How can I do this?

Furthermore, the four arbitrary constants will need to be determined through boundary conditions....