Let's say I'm am given the Sturm-Lioville problem

$\displaystyle \[{y}''+\lambda y=0\]$

with a particular set of boundary conditions.

From this I can determine the set of eigenvalues ($\displaystyle \[\lambda _{n}\]

$) and eigenfunctions ($\displaystyle \[\phi _{n}\]$) which satisfy the equation.

The part I am stuck at is determing the normalization constant needed to no to normalize the eigenfunctions. Any suggestions. Thanks.