Given the following problem

$-\frac{1}{2}y''(x)+-\frac{1}{2}[x^2+\sin^2{(\frac{2 k \pi x}{L}})]y(x)=E y(x), \quad x \in [-L,L]$

$y(-L)=y(L)=0$ where L=30 and k=2. We want to calculate the first ten eigenvalues and the 5 first eigenfunctions. Using the command NDEigensystem.

As the following notebook shows, I have defined my equation and my Dirichlet conditions. Then I used the NDEigensystem command and calculate the first ten eigenvalues. But I cannot figure out how I could plot only the first five eigenfunctions. Any suggestions