Macro sieve_segment

macro_rules! sieve_segment {
    ($n:expr; < $lim:expr) => { ... };
    ($n:expr; >= $lim:expr) => { ... };
}

Call sieve_geq or sieve_lt, and automatically compute the memory requirement of the sieve.

Sieve the N smallest numbers larger than or equal to some limit as sieve_segment!(N; >= LIMIT), and the N largest numbers smaller than some limit as sieve_segment!(N; < LIMIT).

Computes the sieve size as isqrt(upper_limit) + 1 for sieve_lt and as isqrt(lower_limit) + 1 + N for sieve_geq. This may overestimate the memory requirement for sieve_geq.

Examples

const PRIME_STATUS_LT: Result<[bool; 5], SieveError> = sieve_segment!(5; < 100_005);
const PRIME_STATUS_GEQ: Result<[bool; 7], SieveError> = sieve_segment!(7; >= 615);
assert_eq!(
    PRIME_STATUS_LT,
//      100_000  100_101  100_102  100_103  100_104
    Ok([false,   false,   false,   true,    false])
);
assert_eq!(
    PRIME_STATUS_GEQ,
//      615    616    617   618    619   620    621
    Ok([false, false, true, false, true, false, false])
);

Errors

Has the same error behaviour as sieve_geq and sieve_lt, with the exception that it sets MEM such that the sieve doesn’t run out of memory.