Function cross2

cross2(v, u): number
Parameters
- v: [number, number] | [number, number, number]
  one 2D vector
- u: [number, number] | [number, number, number]
  one 2D vector
Returns number
one scalar; the determinant; the magnitude of the 2D cross product vector.

Description
the determinant of the matrix of the 2 vectors (possible bad name, 2D cross product is undefined)
- Defined in src/math/vector.js:311