Example

> a = [0,0,1]
 a =
        0          0          1  
> b = [1;0;0]
 b =
        1  
        0  
        0  
> c = cross(a,b)
 c =
        0          1          0  
> d = cross(a,c)
 d =
       -1         -0          0  
> d = cross(c,a)
 d =
        1         -0          0  
> e = [1,1,1]
 e =
        1          1          1  
> cross(a,e)
       -1          1          0  
> cross(c,e)
        1         -0         -1