When I ask my students to give the magnitude and direction of a vector and
the magnitude turns out to be zero, I'd rather they tell me the direction
is "UNDETERMINED" rather than "NONE" (but I accept "NONE").
(Using components and vector addition in 2-d, the angle measured from the
x-axis toward the y-axis is arctan 0/0--undetermined.)
Can one determine the direction of nothing?
Tom Sandin