Function lattice_qcd_rs::su3::get_sub_block_r

pub fn get_sub_block_r(m: CMatrix3) -> CMatrix2

get the CMatrix2 sub block corresponding to get_r

Example

 let m1 = CMatrix3::new(
    Complex::from(1_f64),
    Complex::from(2_f64),
    Complex::from(3_f64),
    // ---
    Complex::from(4_f64),
    Complex::from(5_f64),
    Complex::from(6_f64),
    // ---
    Complex::from(7_f64),
    Complex::from(8_f64),
    Complex::from(9_f64),
);
let m2 = CMatrix2::new(
    Complex::from(1_f64),
    Complex::from(2_f64),
    // ---
    Complex::from(4_f64),
    Complex::from(5_f64),
);
assert_eq_matrix!(get_sub_block_r(m1), m2, f64::EPSILON);