dsalgo 0.3.10

A package for Datastructures and Algorithms.
Documentation 
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pub fn jacobi_symbol_recurse(
    n: u64,
    mut a: u64,
) -> i8 {
    assert!(a < n && n & 1 == 1);

    if a == 0 {
        return if n != 1 { 0 } else { 1 };
    }

    let mut symbol = 1;

    let ctz = a.trailing_zeros();

    if ctz & 1 == 1 && (n & 7 == 3 || n & 7 == 5) {
        symbol = -symbol;
    }

    a >>= ctz;

    if a & 3 == 3 && n & 3 == 3 {
        symbol = -symbol;
    }

    jacobi_symbol_recurse(a, n % a) * symbol
}

#[cfg(test)]

mod tests {

    #[test]

    fn test() {
        use super::*;
        use crate::jacobi_symbol::jacobi_symbol;

        for n in (1..100).step_by(2) {
            for a in 0..n {
                assert_eq!(jacobi_symbol_recurse(n, a), jacobi_symbol(n, a),);
            }
        }
    }
}