Function interpolate_subgroup 

pub fn interpolate_subgroup<F, EF, Mat>(
    subgroup_evals: &Mat,
    point: EF,
) -> Vec<EF>
where
    F: TwoAdicField,
    EF: ExtensionField<F>,
    Mat: Matrix<F>,

Given evaluations of a batch of polynomials over the canonical power-of-two subgroup, evaluate the polynomials at point.

This assumes the point is not in the subgroup, otherwise the behavior is undefined.