-# FIXME: the hyperplan equation is not correct
-pl.plot([0, -1 / w[1]], [w[0] / w[1] - 1 / w[1], -w[0] / w[1] - 1 / w[1]])
+# w[0]x + w[1]y + w[2] = 0, so y = -(w[0]x + w[2]) / w[1]
+x_start1 = -0.5
+x_start2 = 2.5
+pl.plot([x_start1, x_start2], [-(w[0] * x_start1 + w[2]) /
+ w[1], -(w[0] * x_start2 + w[2]) / w[1]])