d = 1, n = 3: quadrature (40 and 60 Gauss points per direction); control = the same code with exponent 1
p=2  E disc_p: lattice 0.2154522 (8.9e-16), independent 0.2214099 (1.2e-15); lattice < independent: True;  control |E disc_p^p - exact|: 4.9e-17, 9.7e-17
p=4  E disc_p: lattice 0.2601443 (2.3e-14), independent 0.2681902 (1.6e-13); lattice < independent: True;  control |E disc_p^p - exact|: 4.0e-16, 2.6e-17
p=6  E disc_p: lattice 0.2885632 (1.1e-11), independent 0.2978895 (4.9e-11); lattice < independent: True;  control |E disc_p^p - exact|: 1.5e-14, 1.0e-17
p=8  E disc_p: lattice 0.3085201 (1.4e-09), independent 0.3186202 (9.2e-10); lattice < independent: True;  control |E disc_p^p - exact|: 8.4e-14, 5.4e-18
Monte Carlo d=1, n=10, p=4 (400000 samples each): lattice 0.1212 +- 0.0002, independent 0.1466 +- 0.0001
Monte Carlo d=2, n=3, p=4 (400000 samples each): lattice 0.26745 +- 0.00013, independent 0.26884 +- 0.00011
