# Reference: OPCROSSMUL

v1×v2 returns the cross product of the two-dimensional real or complex vectors v1 and v2, i.e. a vector perpendicular to both v1 and v2, with norm (length) equal to |v1||v2|sin θ where θ is the angle between v1 and v2, and such that v1, v2, and v1×v2 is a right-handed system.
Example: If a plane Π ∈ R^3 is generated* by a point r and two vectors v1 and v2, the plane's normal vector is (up to a scaling factor) equal to v1×v2.
* Π = {(x, y, z) ∈ R^3: (x, y, z) = r + s v1 + t v2; s, t ∈ R}