(vec(a) "," vec(b) "," vec(c)) = (vec(a) ^^ vec(b)) . vec(c)
<=>
{:(+,a_x,,b_x,,c_x,-),(,,xx,,xx,,),(+,a_y,,b_y,,c_y,-),(,,xx,,xx,,),(+,a_z,,b_z,,c_z,-),(,,xx,,xx,,),(,a_x,,b_x,,c_x,),(,,xx,,xx,,),(,a_y,,b_y,,c_y,):}
"avec"
vec(a) ((a_x),(a_y),(a_z))
vec(b) ((b_x),(b_y),(b_z))
vec(c) ((c_x),(c_y),(c_z))