For $a$ generator of the multiplicative group of the field $GF(p,k)$, the discrete logarithm of an element $b$ of the field to the base $a$, $b\ne 0$ is that integer $z:1\le z\le p^k-1$, $b=a^z$. The $p$-ary digits which represent $z$ can be described with extremely simple polynomial forms.