4. MATLAB
a) Referring to Exercise 3 of Section 7.1, plot the graphs of the functions
$y_n = e^{x^2/2}H_n(x)$,
$n = 0, 1, 2, 3$,
where $H_n$ is the $n$-degree Hermite polynomial from the previous
exercise.
b) Use BVP4C to solve the problem
$y'' + (\lambda - x^2)y = 0$,
$-L \le x \le L$,
$y(-L) = y(L) = 0$,
for various large values of $L$, and compare the first four eigenfunctions with the functions in part (a).
