A proof of Riemann Hypothesis

Let $\Xi(t)$ be a function relating to the Riemann zeta function $\zeta (s)$ with $s = \frac{1} {2} + it$. In this paper, we construct a function $v$ containing $t$ and $\Xi(t)$, and prove that $v$ satisfies a nonadjoint boundary value problem to a nonsingular differential equation if $t$ is any nontrivial zero of $\Xi(t)$. Inspecting properties of $v$ and using known results of nontrivial zeros of $\zeta (s)$, we derive that nontrivial zeros of $\zeta (s)$ all have real part equal to $\frac{1} {2}$, which concludes that Riemann Hypothesis is true.