Random number generator RNG, RAN0

We can now rewrite Eq. (16) as $$\begin{equation} (aN_{i-1}) \mathrm{MOD} (M)= (aN_{i-1}-[N_{i-1}/q](aq+r))\mathrm{MOD} (M), \tag{17} \end{equation}$$ which results in $$\begin{equation} (aN_{i-1}) \mathrm{MOD} (M)= \left(a(N_{i-1}-[N_{i-1}/q]q)-[N_{i-1}/q]r)\right)\mathrm{MOD} (M), \tag{18} \end{equation}$$ yielding $$\begin{equation} (aN_{i-1}) \mathrm{MOD} (M)= \left(a(N_{i-1}\mathrm{MOD} (q)) -[N_{i-1}/q]r)\right)\mathrm{MOD} (M). \tag{19} \end{equation}$$