Solution (source code)

= Solution

The kernel is the <Brownian bridge covariance kernel>. If $C_X\phi=\lambda\phi$, differentiating the integral equation twice gives
$$
\lambda\phi''(t)=-\phi(t),\qquad \phi(0)=\phi(1)=0.
$$
The normalized solutions and eigenvalues are therefore
$$
\boxed{\phi_k(t)=\sqrt2\sin(k\pi t),\qquad
\lambda_k=\frac1{k^2\pi^2}},\qquad k\geq1.
$$