Tensorflow tensor cross product shim

tensorflow.cross.shim.js

function cross(rhs) {
  const lhs = this;
  if (lhs.shape[1] !== 1 || rhs.shape[1] !== 1 || lhs.shape[0] !== 3 || rhs.shape[0] !== 3) {
    throw new Error(`cross product only implemented for vector of shape (3, 1)`);
  }
  // Cross product
  const u = lhs.dataSync();
  const v = rhs.dataSync();
  return tf.tensor([
    [u[1] * v[2] - u[2] * v[1]],
    [u[2] * v[0] - u[0] * v[2]],
    [u[0] * v[1] - u[1] * v[0]]
  ]);
}

if (tf !== undefined && tf.Tensor !== undefined) {
  if (tf.Tensor.prototype === undefined) {
    tf.Tensor.prototype = {};
  }
  tf.Tensor.prototype.cross = cross;
}