.. currentmodule:: control

.. _version-0.9.4:

Version 0.9.4 Release Notes
----------------------------

* Released: date of release
* `GitHub release page
  <https://github.com/python-control/python-control/releases/tag/0.9.4>`_

This release adds functions for optimization-based estimation and
moving horizon estimation, better handling of system and signal names,
as well a number of bug fixes, small enhancements, and updated
documentation.


New classes, functions, and methods
...................................

The following new classes, functions, and methods have been added in
this release:

* Added the `optimal.OptimalEstimationProblem` class, the
  `optimal.compute_oep` function, and the
  `optimal.create_mhe_iosystem` function, which compute the optimal
  estimate for a (nonlinear) I/O system using an explicit cost
  function of a fixed window of applied inputs and measured outputs.

* Added `gaussian_likelyhood_cost` to create cost function
  corresponding to Gaussian likelihoods for use in optimal estimation.

* Added `disturbance_range_constraint` to create a range constraint on
  disturbances.

* Added `LTI.bandwidth` to compute the bandwidth of a linear system.


Bug fixes
.........

The following bugs have been fixed in this release:

* Fixed a bug in `interconnect` in which the system name was being
  clobbered internally.

* Fixed a bug in `bode_plot` where phase wrapping was not working when
  there were multiple systems.

* Fixed a bug in `root_locus_plot` in which the `ax` parameter was not
  being handled correctly.

* Fixed a bug in `create_statefbk_iosystem` that didn't proper handle
  1D gain schedules.

* Fixed a bug in `rootlocus_pid_designer` where the Bode plot was
  sometimes blank.

* Fixed a bug in which signal labels for a `StateSpace` system were
  lost when computing `forced_response`.

* Fixed a bug in which the `damp` command was assuming a
  continuous-time system when printing out pole locations (but the
  return value was correct).

* Fixed a bug in which signal names could be lost for state transfer
  functions when using the `interconnect` function.

* Fixed a bug in the block-diagonal schur matrix computation used in
  `bdschur`.


Improvements
............

The following additional improvements and changes in functionality
were implemented in this release:

* Added an `add_unused` keyword parameter to `interconnect` that
  allows unused inputs or outputs to be added as inputs or outputs of
  the interconnected system (useful for doing a "partial"
  interconnection).

* Added `control_indices` and `state_indices` to
  `create_statefbk_iosystem` to allow partial interconnection (e.g., for
  inner/outer loop construction).

* `create_mpc_iosystem` now allows system and signal names to be
  specified via appropriate keywords.

* `TransferFunction` objects can now be displayed either in polynomial
  form or in zpk form using the `display_format` parameter when
  creating the system.

* Allow discrete-time Nyquist plots for discrete-time systems with
  poles at 0 and 1.

* Generate a warning if `prewarp_frequency` is used in `sample_system`
  for a discretization type that doesn't support it.

* Converting a system from state space form to transfer function form
  (and vice versa) now updates the system name to append "$converted",
  removing an issue where two systems might have the same name.


Deprecations
............

The following functions have been newly deprecated in this release and
generate a warning message when used:

* Changed `type` keyword for `create_statefbk_iosystem` to
  `controller_type` ('linear' or 'nonlinear').

* `issys`: use ``isinstance(sys, ct.LTI)``.

The listed items are slated to be removed in future releases (usually
the next major or minor version update).


Removals
........

The following functions and capabilities have been removed in this release:

* `function`: function that was removed.

* Other functionality that has been removed.

Code that makes use of the functionality listed above will have to be
rewritten to work with this release of the python-control package.


Additional notes
................

Anything else that doesn't fit above.