:orphan:

:py:mod:`tlm_adjoint.tangent_linear`
====================================

.. py:module:: tlm_adjoint.tangent_linear


Module Contents
---------------

.. py:class:: TangentLinearMap(M, dM)


   
   Defines a map from forward variables to associated tangent-linear
   variables.

   The map is used via e.g.

   .. code-block:: python

       tau_x = tlm_map[x]

   where `x` is a forward variable.

       - If `x` defines a component of the control, then `tau_x` is a variable
         defining the associated component of the direction.
       - If `x` does not define a component of the control and is not
         'static', then `tau_x` is a tangent-linear variable. A new variable
         is instantiated if needed.
       - Otherwise `tau_x` is `None`, indicating that the tangent-linear
         variable is zero.

   Containment can be tested

   .. code-block:: python

       if x in tlm_map:
           [...]

   and returns `True` if `x` defines a component of the control, or a
   tangent-linear variable associated with `x` has been instantiated.

   :arg M: A variable or :class:`Sequence` of variables defining the control.
   :arg dM: A variable or :class:`Sequence` of variables defining the
       derivative direction. The tangent-linear computes directional
       derivatives with respect to the control defined by `M` and with
       direction defined by `dM`.















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   .. py:property:: id

      
      A unique :class:`int` ID associated with this
      :class:`.TangentLinearMap`.
















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   .. py:property:: M

      
      A :class:`Sequence` of variables defining the control.
















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   .. py:property:: dM

      
      A :class:`Sequence` of variables defining the derivative direction.
















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