Figure 4.

Circular code periodicity 0 modulo 3 identified by the circular code autocorrelation function $A_{X,X}\left(i,\mathrm{t}\mathrm{R}\mathrm{N}{\mathrm{A}}_{\mathrm{A}\mathrm{l}\mathrm{a}}\right)$ in the bacterial tRNA of alanine. The abscissa represents the number $i$ of letters $N$ between $X$ and itself (i.e. $X$ and $X$), $i$ varying from 0 to $imax=20$. The ordinate gives the occurrence probability $A_{X,X}\left(i,\mathrm{t}\mathrm{R}\mathrm{N}{\mathrm{A}}_{\mathrm{A}\mathrm{l}\mathrm{a}}\right)$ (Equation (5)) of $X{N}^{i}X$ in $\mathrm{t}\mathrm{R}\mathrm{N}{\mathrm{A}}_{\mathrm{A}\mathrm{l}\mathrm{a}}$.