定义　Riemann函数：
$$R\left( x \right) = \left\{ \begin{array}{l} \frac{1}{q},当x=\frac{p}{q}\left( p,q \in N_+,\frac{p}{q}为即约真分数 \right)\\ 0,当x=0,1和\left( 0,1 \right)内的无理数\end{array} \right.$$