How to use

cross

function

in

Array

/**
  * @param  {Array} vectorA         angle from
  * @param  {Array} vectorB         angle to
  * @param  {Array} referenceVector angle to set 0 degree from. coplanar with vecA and vecB
  * @return {number}                 description
  * @example angleBetween([1,0,0],[0,1,0],[0,0,1]) // PI/2
  */
 static angleBetween(vectorA, vectorB, referenceVector) {
  // angle = atan2(norm(cross(a, b)), dot(a, b))

  const norm = Kinematics.length3(Kinematics.cross(vectorA, vectorB))

  const angle = Math.atan2(norm, (this.dot(vectorA, vectorB)))

  const tmp = referenceVector[0] * vectorA[0] + referenceVector[1] * vectorA[1] + referenceVector[2] * vectorA[2]

  const sign = (tmp > 0) ? 1.0 : -1.0

  return angle * sign
 }

const J4J5_J4J3_normal_vector = Kinematics.cross(J4J5_vector, J4J3_vector)
const XZ_parallel_aligned_vector = [
 10 * Math.cos(R[0] + (Math.PI / 2)),
const reference = Kinematics.cross(XZ_parallel_aligned_vector, J4J3_vector)
const referenceVector = Kinematics.cross(J4J3_vector, J4J5_J4J3_normal_vector)
R[5] -= Kinematics.angleBetween(J4J5_J4J3_normal_vector, targetVectorY, Kinematics.cross(targetVectorY, targetVectorX))