x1 <- c(-0.6, -4.6, -0.4, -1.3, 1, 4.1, 1.7, -0.3, 0.6, -0.3, -2.3,
-0.7, -3.3, 0.8, -3.6, -0.1, -0.8, -3.5, -1.5, -3.5, 2.2, 3.6, 3.5, 0.1,
-2.4)

x2 <- c(-1.9, -2.8, -1.7, 2.8, 0.6, 1.3, -3.5, 1.2, -0.9, 1.1, 1.7,
-3.3, 0.4, -0.6, 1.9, -0.5, -5, 3.6, -1.2, -1.1, 1.3, -2.1, 0.1, -3.2,
0.3)

y <- c(-2.2, -10.9, -0.7, -0.2, 2.1, 5.1, 2.1, 0.1, 1, -0.1, -1, -5.4,
15, -1.6, -5.8, 2.5, -6.7, 3.7, -2, -3.5, 0.2, -0.7, 2, 1.4, -1.4)