What does $R \rightarrow R$ means in functions? I have a function.
The function is:
$$ f:R \rightarrow R $$
$$ f(x) = x^3$$
What does $R \rightarrow R$ means?
I don't know what types of questions should I ask here. If it is not ok, the I will delete.

Intuitively, it means that for every $x \in R$, the function f will give back a value $f(x) \in R$.
For example, a function $f(x)=1/x$ is only defined for those $x \in R$ Real Numbers $R$ that are different from $0$, so you should write $f: R/\{ 0 \} \rightarrow R$.
