Function primecount::pi

pub fn pi(x: i64) -> i64

Counts the number of primes <= x using Xavier Gourdon’s algorithm. Uses all CPU cores by default.

Returns -1 if an error occurs.

Examples

// The primes are: 2, 3, 5 and 7.
assert_eq!(primecount::pi(10), 4);

// The primes are: 2, 3, 5, 7 and 11.
assert_eq!(primecount::pi(11), 5);

assert_eq!(primecount::pi(10i64.pow(12)), 37607912018);

• Run time complexity: O(x^(2/3) / (log x)^2)
• Memory usage: O(x^(1/3) * (log x)^3)