updated sphinx documentation + changed to LinearICSystem

murrayrm · Jan 5, 2021 · Dec 29, 2020 · Jan 1, 2021 · Jan 1, 2021 · Jan 1, 2021
commit 4f04f485431cb96a00e71d3eba8ab6597c6199db
diff --git a/control/bdalg.py b/control/bdalg.py
@@ -326,6 +326,13 @@ def connect(sys, Q, inputv, outputv):
     >>> Q = [[1, 2], [2, -1]]  # negative feedback interconnection
     >>> sysc = connect(sys, Q, [2], [1, 2])
 
+    Notes
+    -----
+    The :func:`~control.interconnect` function in the
+    :ref:`input/output systems <iosys-module>` module allows the use
+    of named signals and provides an alternative method for
+    interconnecting multiple systems.
+
     """
     inputv, outputv, Q = np.asarray(inputv), np.asarray(outputv), np.asarray(Q)
     # check indices

diff --git a/control/iosys.py b/control/iosys.py
@@ -42,8 +42,8 @@
 from . import config
 
 __all__ = ['InputOutputSystem', 'LinearIOSystem', 'NonlinearIOSystem',
-           'InterconnectedSystem', 'input_output_response', 'find_eqpt',
-           'linearize', 'ss2io', 'tf2io', 'interconnect']
+           'InterconnectedSystem', 'LinearICSystem', 'input_output_response',
+           'find_eqpt', 'linearize', 'ss2io', 'tf2io', 'interconnect']
 
 # Define module default parameter values
 _iosys_defaults = {
@@ -110,8 +110,8 @@ class for a set of subclasses that are used to implement specific
 
     Notes
     -----
-    The `InputOuputSystem` class (and its subclasses) makes use of two special
-    methods for implementing much of the work of the class:
+    The :class:`~control.InputOuputSystem` class (and its subclasses) makes
+    use of two special methods for implementing much of the work of the class:
 
     * _rhs(t, x, u): compute the right hand side of the differential or
       difference equation for the system.  This must be specified by the
@@ -137,8 +137,8 @@ def __init__(self, inputs=None, outputs=None, states=None, params={},
         The InputOutputSystem contructor is used to create an input/output
         object with the core information required for all input/output
         systems.  Instances of this class are normally created by one of the
-        input/output subclasses: :class:`~control.LinearIOSystem`,
-        :class:`~control.NonlinearIOSystem`,
+        input/output subclasses: :class:`~control.LinearICSystem`,
+        :class:`~control.LinearIOSystem`, :class:`~control.NonlinearIOSystem`,
         :class:`~control.InterconnectedSystem`.
 
         Parameters
@@ -242,10 +242,10 @@ def __mul__(sys2, sys1):
               np.zeros((sys2.ninputs, sys2.noutputs))]]
         ))
 
-        # If both systems are linear, create LinearInterconnectedSystem
+        # If both systems are linear, create LinearICSystem
         if isinstance(sys1, StateSpace) and isinstance(sys2, StateSpace):
             ss_sys = StateSpace.__mul__(sys2, sys1)
-            return LinearInterconnectedSystem(newsys, ss_sys)
+            return LinearICSystem(newsys, ss_sys)
 
         # Return the newly created InterconnectedSystem
         return newsys
@@ -294,10 +294,10 @@ def __add__(sys1, sys2):
         newsys = InterconnectedSystem(
             (sys1, sys2), inplist=inplist, outlist=outlist)
 
-        # If both systems are linear, create LinearInterconnectedSystem
+        # If both systems are linear, create LinearICSystem
         if isinstance(sys1, StateSpace) and isinstance(sys2, StateSpace):
             ss_sys = StateSpace.__add__(sys2, sys1)
-            return LinearInterconnectedSystem(newsys, ss_sys)
+            return LinearICSystem(newsys, ss_sys)
 
         # Return the newly created InterconnectedSystem
         return newsys
@@ -315,10 +315,10 @@ def __neg__(sys):
         newsys = InterconnectedSystem(
             (sys,), dt=sys.dt, inplist=inplist, outlist=outlist)
 
-        # If the system is linear, create LinearInterconnectedSystem
+        # If the system is linear, create LinearICSystem
         if isinstance(sys, StateSpace):
             ss_sys = StateSpace.__neg__(sys)
-            return LinearInterconnectedSystem(newsys, ss_sys)
+            return LinearICSystem(newsys, ss_sys)
 
         # Return the newly created system
         return newsys
@@ -502,7 +502,7 @@ def feedback(self, other=1, sign=-1, params={}):
         if isinstance(self, StateSpace) and isinstance(other, StateSpace):
             # Special case: maintain linear systems structure
             ss_sys = StateSpace.feedback(self, other, sign=sign)
-            return LinearInterconnectedSystem(newsys, ss_sys)
+            return LinearICSystem(newsys, ss_sys)
 
         # Return the newly created system
         return newsys
@@ -697,10 +697,10 @@ def __init__(self, updfcn, outfcn=None, inputs=None, outputs=None,
                  name=None, **kwargs):
         """Create a nonlinear I/O system given update and output functions.
 
-        Creates an `InputOutputSystem` for a nonlinear system by specifying a
-        state update function and an output function.  The new system can be a
-        continuous or discrete time system (Note: discrete-time systems not
-        yet supported by most function.)
+        Creates an :class:`~control.InputOutputSystem` for a nonlinear system
+        by specifying a state update function and an output function.  The new
+        system can be a continuous or discrete time system (Note:
+        discrete-time systems not yet supported by most function.)
 
         Parameters
         ----------
@@ -1284,15 +1284,16 @@ def set_output_map(self, output_map):
         self.noutputs = output_map.shape[0]
 
 
-class LinearInterconnectedSystem(InterconnectedSystem, LinearIOSystem):
+class LinearICSystem(InterconnectedSystem, LinearIOSystem):
     """Interconnection of a set of linear input/output systems.
 
     This class is used to implement a system that is an interconnection of
     linear input/output systems.  It has all of the structure of an
-    :class:`InterconnectedSystem`, but also maintains the requirement elements
-    of :class:`LinearIOSystem`, including the :class:`StateSpace` class
-    structure, allowing it to be passed to functions that expect a
-    :class:`StateSpace` system.
+    :class:`~control.InterconnectedSystem`, but also maintains the requirement
+    elements of :class:`~control.LinearIOSystem`, including the
+    :class:`StateSpace` class structure, allowing it to be passed to functions
+    that expect a :class:`StateSpace` system.
+
     """
 
     def __init__(self, io_sys, ss_sys=None):
@@ -1755,7 +1756,7 @@ def linearize(sys, xeq, ueq=[], t=0, params={}, **kw):
     """Linearize an input/output system at a given state and input.
 
     This function computes the linearization of an input/output system at a
-    given state and input value and returns a :class:`control.StateSpace`
+    given state and input value and returns a :class:`~control.StateSpace`
     object.  The eavaluation point need not be an equilibrium point.
 
     Parameters
@@ -1840,10 +1841,11 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
 
     This function creates a new system that is an interconnection of a set of
     input/output systems.  If all of the input systems are linear I/O systems
-    (type `LinearIOSystem`) then the resulting system will be a linear
-    interconnected I/O system (type `LinearInterconnectedSystem`) with the
-    appropriate inputs, outputs, and states.  Otherwise, an interconnected I/O
-    system (type `InterconnectedSystem`) will be created.
+    (type :class:`~control.LinearIOSystem`) then the resulting system will be
+    a linear interconnected I/O system (type :class:`~control.LinearICSystem`)
+    with the appropriate inputs, outputs, and states.  Otherwise, an
+    interconnected I/O system (type :class:`~control.InterconnectedSystem`)
+    will be created.
 
     Parameters
     ----------
@@ -1895,8 +1897,8 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
         the system input connects to only one subsystem input, a single input
         specification can be given (without the inner list).
 
-        If omitted, the input map can be specified using the `set_input_map`
-        method.
+        If omitted, the input map can be specified using the
+        :func:`~control.InterconnectedSystem.set_input_map` method.
 
     outlist : list of output connections, optional
         List of connections for how the outputs from the subsystems are mapped
@@ -1910,8 +1912,8 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
         then those signals are added together (multiplying by the any gain
         term) to form the system output.
 
-        If omitted, the output map can be specified using the `set_output_map`
-        method.
+        If omitted, the output map can be specified using the
+        :func:`~control.InterconnectedSystem.set_output_map` method.
 
     inputs : int, list of str or None, optional
         Description of the system inputs.  This can be given as an integer
@@ -1951,17 +1953,17 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
 
     Example
     -------
-    P = control.LinearIOSystem(
-        ct.rss(2, 2, 2, strictly_proper=True), name='P')
-    C = control.LinearIOSystem(control.rss(2, 2, 2), name='C')
-    S = control.InterconnectedSystem(
-        [P, C],
-        connections = [
-          ['P.u[0]', 'C.y[0]'], ['P.u[1]', 'C.y[0]'],
-          ['C.u[0]', '-P.y[0]'], ['C.u[1]', '-P.y[1]']],
-        inplist = ['C.u[0]', 'C.u[1]'],
-        outlist = ['P.y[0]', 'P.y[1]'],
-    )
+    >>> P = control.LinearIOSystem(
+    >>>        ct.rss(2, 2, 2, strictly_proper=True), name='P')
+    >>> C = control.LinearIOSystem(control.rss(2, 2, 2), name='C')
+    >>> S = control.InterconnectedSystem(
+    >>>     [P, C],
+    >>>     connections = [
+    >>>       ['P.u[0]', 'C.y[0]'], ['P.u[1]', 'C.y[0]'],
+    >>>       ['C.u[0]', '-P.y[0]'], ['C.u[1]', '-P.y[1]']],
+    >>>     inplist = ['C.u[0]', 'C.u[1]'],
+    >>>     outlist = ['P.y[0]', 'P.y[1]'],
+    >>> )
 
     Notes
     -----
@@ -1973,10 +1975,11 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
     check your use of tuples.
 
     In addition to its use for general nonlinear I/O systems, the
-    `interconnect` function allows linear systems to be interconnected using
-    named signals (compared with the `connect` function, which uses signal
-    indicies) and to be treated as both a `StateSpace` system as well as an
-    `InputOutputSystem`.
+    :func:`~control.interconnect` function allows linear systems to be
+    interconnected using named signals (compared with the
+    :func:`~control.connect` function, which uses signal indicies) and to be
+    treated as both a :class:`~control.StateSpace` system as well as an
+    :class:`~control.InputOutputSystem`.
 
     """
     newsys = InterconnectedSystem(
@@ -1986,6 +1989,6 @@ def interconnect(syslist, connections=[], inplist=[], outlist=[],
 
     # If all subsystems are linear systems, maintain linear structure
     if all([isinstance(sys, LinearIOSystem) for sys in syslist]):
-        return LinearInterconnectedSystem(newsys, None)
+        return LinearICSystem(newsys, None)
 
     return newsys
diff --git a/control/tests/iosys_test.py b/control/tests/iosys_test.py
@@ -1293,7 +1293,7 @@ def test_linear_interconnection():
             ['sys2.y[1]'],
             ['sys2.u[1]']])
     assert isinstance(nl_connect, ios.InterconnectedSystem)
-    assert not isinstance(nl_connect, ios.LinearInterconnectedSystem)
+    assert not isinstance(nl_connect, ios.LinearICSystem)
 
     # Now take its linearization
     ss_connect = nl_connect.linearize(0, 0)
@@ -1313,7 +1313,7 @@ def test_linear_interconnection():
             ['sys2.y[1]'],
             ['sys2.u[1]']])
     assert isinstance(io_connect, ios.InterconnectedSystem)
-    assert isinstance(io_connect, ios.LinearInterconnectedSystem)
+    assert isinstance(io_connect, ios.LinearICSystem)
     assert isinstance(io_connect, ios.LinearIOSystem)
     assert isinstance(io_connect, ct.StateSpace)
 

diff --git a/control/xferfcn.py b/control/xferfcn.py
@@ -809,7 +809,7 @@ def returnScipySignalLTI(self, strict=True):
                 continuous (0) or discrete (True or > 0).
             False:
                 if `tfobject.dt` is None, continuous time
-                :class:`scipy.signal.lti`objects are returned
+                :class:`scipy.signal.lti` objects are returned
 
         Returns
         -------

diff --git a/doc/classes.rst b/doc/classes.rst
@@ -16,18 +16,17 @@ these directly.
    TransferFunction
    StateSpace
    FrequencyResponseData
-   ~iosys.InputOutputSystem
+   InputOutputSystem
 
 Input/output system subclasses
 ==============================
-.. currentmodule:: control.iosys
-
 Input/output systems are accessed primarily via a set of subclasses
 that allow for linear, nonlinear, and interconnected elements:
 
 .. autosummary::
    :toctree: generated/
 
+   InterconnectedSystem
+   LinearICSystem
    LinearIOSystem
    NonlinearIOSystem
-   InterconnectedSystem
diff --git a/doc/control.rst b/doc/control.rst
@@ -139,11 +139,12 @@ Nonlinear system support
 .. autosummary::
    :toctree: generated/
 
-   ~iosys.find_eqpt
-   ~iosys.linearize
-   ~iosys.input_output_response
-   ~iosys.ss2io
-   ~iosys.tf2io
+   find_eqpt
+   interconnect
+   linearize
+   input_output_response
+   ss2io
+   tf2io
    flatsys.point_to_point
 
 .. _utility-and-conversions:

diff --git a/doc/iosys.rst b/doc/iosys.rst
@@ -4,10 +4,6 @@
 Input/output systems
 ********************
 
-.. automodule:: control.iosys
-   :no-members:
-   :no-inherited-members:
-
 Module usage
 ============
 
@@ -40,16 +36,16 @@ equation) and and output function (computes the outputs from the state)::
   io_sys = NonlinearIOSystem(updfcn, outfcn, inputs=M, outputs=P, states=N)
 
 More complex input/output systems can be constructed by using the
-:class:`~control.InterconnectedSystem` class, which allows a collection of
-input/output subsystems to be combined with internal connections between the
-subsystems and a set of overall system inputs and outputs that link to the
-subsystems::
+:func:`~control.interconnect` function, which allows a collection of
+input/output subsystems to be combined with internal connections
+between the subsystems and a set of overall system inputs and outputs
+that link to the subsystems::
 
-    steering = ct.InterconnectedSystem(
-        (plant, controller), name='system',
-        connections=(('controller.e', '-plant.y')),
-        inplist=('controller.e'), inputs='r',
-        outlist=('plant.y'), outputs='y')
+    steering = ct.interconnect(
+        [plant, controller], name='system',
+        connections=[['controller.e', '-plant.y']],
+        inplist=['controller.e'], inputs='r',
+        outlist=['plant.y'], outputs='y')
 
 Interconnected systems can also be created using block diagram manipulations
 such as the :func:`~control.series`, :func:`~control.parallel`, and
@@ -160,19 +156,19 @@ The input to the controller is `u`, consisting of the vector of hare and lynx
 populations followed by the desired lynx population.
 
 To connect the controller to the predatory-prey model, we create an
-`InterconnectedSystem`:
+:class:`~control.InterconnectedSystem`:
 
 .. code-block:: python
 
-  io_closed = control.InterconnectedSystem(
-    (io_predprey, io_controller),	# systems
-    connections=(
-      ('predprey.u', 'control.y[0]'),
-      ('control.u1',  'predprey.H'),
-      ('control.u2',  'predprey.L')
-    ),
-    inplist=('control.Ld'),
-    outlist=('predprey.H', 'predprey.L', 'control.y[0]')
+  io_closed = control.interconnect(
+    [io_predprey, io_controller],	# systems
+    connections=[
+      ['predprey.u', 'control.y[0]'],
+      ['control.u1',  'predprey.H'],
+      ['control.u2',  'predprey.L']
+    ],
+    inplist=['control.Ld'],
+    outlist=['predprey.H', 'predprey.L', 'control.y[0]']
   )
 
 Finally, we simulate the closed loop system:
@@ -200,18 +196,20 @@ Input/output system classes
 ---------------------------
 .. autosummary::
 
-   InputOutputSystem
-   InterconnectedSystem
-   LinearIOSystem
-   NonlinearIOSystem
+   ~control.InputOutputSystem
+   ~control.InterconnectedSystem
+   ~control.LinearICSystem
+   ~control.LinearIOSystem
+   ~control.NonlinearIOSystem
 
 Input/output system functions
 -----------------------------
 .. autosummary::
 
-   find_eqpt
-   linearize
-   input_output_response
-   ss2io
-   tf2io
+   ~control.find_eqpt
+   ~control.linearize
+   ~control.input_output_response
+   ~control.interconnect
+   ~control.ss2io
+   ~control.tf2io