fv_weighted_norm
================

.. py:function:: t3toolbox.backend.fv_operations.fv_weighted_norm(variations, weights, n_stack)

   .. code-block:: python

      def fv_weighted_norm(
              variations: typ.Tuple[typ.Sequence[NDArray], typ.Sequence[NDArray]],  # (V, H)
              weights:    typ.Tuple[typ.Sequence[NDArray], typ.Sequence[NDArray],
                                    typ.Sequence[NDArray], typ.Sequence[NDArray]],   # (up, down, left, right)
              n_stack:    int,                                                       # leading K+C stack axes kept
      ) -> NDArray:                                                                  # weighted norm, shape=stack


   Weighted (Grasedyck-Kramer) coordinate norm of a tangent's variations: the corewise stack-norm of
   the weight-absorbed variations. The frame (orthonormal) is not needed. Backend twin of
   ``T3Tangent.weighted_norm``.