probe_kind
==========

.. py:function:: t3toolbox.backend.fitting.probe_kind(weight = None)

   .. code-block:: python

      def probe_kind(
              weight: typ.Optional[typ.Any] = None,  # per-mode residual weight ω, (d,) / (d,1); None = 1 (unweighted)
      ) -> SamplingKind:                             # the vector-valued `probe` kind (optionally per-mode weighted)


   The **probe** sampling kind (vector-valued: one free mode per probe), optionally **per-mode**
   weighted. Mode weighting is the order-0 special case of the same residual-weight machinery as the
   derivative kinds: the objective is ``½ Σ_i ‖ω_i z_i‖²`` over the ``d`` per-mode probe residuals ``z_i``,
   so ``ω`` (a per-mode scalar) enters ``sumsq`` (×ω) and ``transpose`` (×ω²) only. ``weight=None`` is the
   plain unweighted probe (``PROBE``). Plain probe has no order axis, so the weight is a 1-D ``(d,)``
   per-mode vector -- the frontend enforces that (rejecting a 2-D ``(d, 1)``; see
   :py:func:`t3toolbox.fitting.probe_model`).