### 12.3.1 Draw unit vectors: Ox_3d_unit_vector Oy_3d_unit_vector Oz_3d_unit_vector frame_3d

The Ox_3d_unit_vector command draws the unit vector in the x-direction on a three-dimensional graphic screen.
Input:

Ox_3d_unit_vector()

Output:

Similarly, the Oy_3d_unit_vector and Oz_3d_unit_vector commands draw the unit vector in the y and z directions, respectively.

These commands have no parameters, but can be decorated with the legend command.
Input:

Ox_3d_unit_vector(), legend(point([1,0,0]),"unit x vector",blue)

Output:

The frame_3d command draws all three vectors simultaneously.