# Copyright 1999-2007 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

# Original Author: Michael Hanselmann <hansmi@gentoo.org>
# Purpose: Functions for prime numbers

# Prints a list of primes between min and max inclusive
#
# Note: this functions gets very slow when used with large numbers.
#
# Syntax: primes <min> <max>
primes() {
	local min=${1} max=${2}
	local result= primelist=2 i p

	[[ ${min} -le 2 ]] && result="${result} 2"

	for ((i = 3; i <= max; i += 2))
	do
		for p in ${primelist}
		do
			[[ $[i % p] == 0 || $[p * p] -gt ${i} ]] && \
				break
		done
		if [[ $[i % p] != 0 ]]
		then
			primelist="${primelist} ${i}"
			[[ ${i} -ge ${min} ]] && \
				result="${result} ${i}"
		fi
	done

	echo ${result}
}

# Checks wether a number is a prime number
#
# Syntax: is_prime <number>
is_prime() {
	local number=${1} i
	for i in $(primes ${number} ${number})
	do
		[[ ${i} == ${number} ]] && return 0
	done
	return 1
}