An algorithm that, for a given key k, yields a function f(k); this in turn yields the starting point for a hash search for the key k. The function f is called the hash function. A typical hash function is the remainder modulo p, where p is a prime,

where k is interpreted as an integer. Another hash function uses a constant A and defines f(k) as the leading bits of the least significant half of the product Ak. See also hashing.