how many uniform hash function I can create when I want to hash elements from $U$ where $|U|=m \cdot r$ , $m,r$ are integers.
a hash function $h:U \rightarrow T $ , $|T|=n$ is uniform if $Prob(h(x)=i)=1/n$ for $i=0,1,...n-1$
I know that functions like $h(x)=a \cdot x +b \space mod \space n$ are uniform and the number of such functions are $|U|* (|U|-1)$ . but are there any other functions? how many?