The type of Tag is object but the Split method is on String.  You need to cast Tag back to String in order to call Split

string[] someStuff = ((string)Tag).Split(';');


Convert a String[] into an object and back into a String[]?
Expectation values of $(x,y,z)$ in the $| n\ell m\rangle$ state of hydrogen?

Does anyone know of a quick way of finding this (if there is even one)? Can I somehow use the relation that:

$$\langle r\rangle ~=~ \frac{a_0}{2}(3n^2 - \ell(\ell+1)),$$ 

or do I just have to brute force and use properties of Laguerre polynomials and spherical harmonics and what not?
