`prevprime`

Largest prime less than or equal to n.

Syntax

p = prevprime(n)

Returns the largest prime p <= n.

Description

If n is prime it is returned unchanged; otherwise the function walks down to the nearest smaller prime. There is no prime below 2, so prevprime(1) is an error.

Input arguments

n: Integer scalar or array, double or symbolic, at least 2.

Output arguments

p: Primes with the size of n.

Example

Previous primes

prevprime(100)
prevprime(97)
prevprime(sym(1000))

Output

ans = 97
ans = 97
ans = 997

prevprime