Notation for a continious function represented as a list of numbers in discrete steps


If we have some function, let’s say
$$f(t) = cos{(omega_{0} t)} text{,}$$
but I want to represent it for discrete steps of $t$, i.e. $Delta t$. Is there a notation for this? I want to say a list of numbers from $f(t)$ in steps of $Delta t$. Or that using $f(t)$ I generate a list of numbers for every $Delta t$.

Perhaps
$$ f(Delta t) = { cos{(omega_{0} Delta t)} }$$
?