galois.prev_prime

galois.prev_prime(n)

Returns the nearest prime \(p\), such that \(p \le n\).

Parameters

n (int) – An integer.

Returns

The nearest prime \(p \le n\). If \(n < 2\), the function returns None.

Return type

int

Examples

In [1]: galois.prev_prime(13)
Out[1]: 13

In [2]: galois.prev_prime(15)
Out[2]: 13