Function ewald 

pub(super) fn ewald<const N: usize>(
    wave: Family,
    lattice: &BlochLattice,
    inputs: Inputs<N>,
    eta: Complex,
    evaluation: Evaluation,
    shared: Option<&SphericalCache<N>>,
) -> Result<Jet<N>>

The Ewald parts selected by evaluation with split eta. Both sums run over shells of reduced bases, and the reciprocal sum over the Bloch vector reduced into a cell of the reduced reciprocal basis, so their results do not depend on the given basis or on the Bloch vector’s cell.