how to generate an initial direction for a set of random points?

I'm simulating a kind of molecules'motion. The molecules are demonstrated by a large amount of point. But firstly, I have to give an initial direction for the large of points. What commands could be used in my situation? any ideas？

[Geoff Hayes]

junwei - does each point have a different direction? What are the units for each direction (radians, degrees, or...)? Can the directions be random and so can you use randn?

Answer 1

[John BG]

you have, for each particle: direction=[direction_x direction_y direction_z] position=[position_x position_y position_z]

you generate movement by modifying position

for i=1:1:N for each particle position=position+direction.*i end end