mathtools/internal/lib/sieve/common.go

/*
Copyright © 2025 filifa

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package sieve

func updateMultiples(sieve []uint, p uint, n uint, additive bool) {
	for q := p; ; q *= p {
		// sieve[a*b] = sieve[a] * sieve[b] if gcd(a,b) = 1
		for i := 2 * q; i < n; i += q {
			if i%(p*q) != 0 {
				if additive {
					sieve[i] += sieve[q]
				} else {
					sieve[i] *= sieve[q]
				}
			}
		}

		if p*q >= n {
			break
		}
	}
}