Minecraft wiki entry for Creating_shapes, associated text: Set the range for n as far as necessary for maximal accuracy, default is 1-20. The slope and angle chosen in the links are purposefully very close to each other, 3/17 = 0.176470588 and arctan(10 degrees) = 0.172792435, a difference small enough that won't be noticed for ~270 blocks. (Note arctan(3/17) ~= 10.007980degrees).