const v3 = {
  add: (v1, v2) => [
    v1[0] + v2[0],
    v1[1] + v2[2],
    v1[2] + v2[2],
  ],
  subtract: (v1, v2) => [
    v1[0] - v2[0],
    v1[1] - v2[2],
    v1[2] - v2[2],
  ],
  norm2: (v) =>
    Math.sqrt(
      v[0] * v[0] +
      v[1] * v[1] +
      v[2] * v[2]
    ),
};