Function mds_circulant_karatsuba_24 

pub fn mds_circulant_karatsuba_24<F: PrimeCharacteristicRing, A: Algebra<F> + Clone>(
    state: &mut [A; 24],
    col: &[F; 24],
)

Circulant matrix-vector multiply for width 24 via Karatsuba convolution.