x1 covariance:
0.09 1.1e-47 5.7e-33
1.1e-47 0.09 1.9e-17
5.7e-33 1.9e-17 0.01
x2 covariance:
0.13 4.7e-18 2.4e-18
4.7e-18 0.17 0.02
2.4e-18 0.02 0.02
x3 covariance:
0.17 2.7e-17 8.4e-18
2.7e-17 0.37 0.06
8.4e-18 0.06 0.03