j=0: |A(Xi) - det(Xi) Lam2(conj(Xi) Xi^-1)| / |A| = 1.0e-15 ; |coeffs - c@vec(A)|/|coeffs| = 2.3e-15
j=1: det(Xi) = 8.5e-16 ; |A| = 1.10e+02 (nonzero), rank A = 2 ; |coeffs - c@vec(A)|/|coeffs| = 2.0e-15
j=2: det(Xi) = 8.0e-33 ; |A| = 2.10e+02 (nonzero), rank A = 1 ; |coeffs - c@vec(A)|/|coeffs| = 1.8e-15
rank of c_0..c_15: 16  rank of c_0..c_16: 17
