Move pole, zero, evalfr, freqresp to lti module

cwrowley · cwrowley · commit 456fcaf5762c · 2015-04-26T19:16:06.000-04:00
diff --git a/control/__init__.py b/control/__init__.py
@@ -86,11 +86,10 @@
 #! of defaults from the main package.  At that point, the matlab module will
 #! allow provide compatibility with MATLAB but no package functionality.
 #!
-from .matlab import pole, zero, evalfr, freqresp, dcgain
+from .matlab import dcgain
 from .matlab import nichols, rlocus, margin
         # bode and nyquist come directly from freqplot.py
 from .matlab import step, impulse, initial, lsim
-from .matlab import ssdata, tfdata
 
 # The following is to use Numpy's testing framework
 # Tests go under directory tests/, benchmarks under directory benchmarks/
diff --git a/control/lti.py b/control/lti.py
@@ -14,6 +14,9 @@
 
 from numpy import absolute, real
 
+__all__ = ['issiso', 'timebase', 'timebaseEqual', 'isdtime', 'isctime',
+           'pole', 'zero', 'evalfr', 'freqresp']
+
 class LTI:
     """LTI is a parent class to linear time-invariant (LTI) system objects.
 
@@ -189,3 +192,164 @@ def isctime(sys, strict=False):
 
     # Got passed something we don't recognize
     return False
+
+def pole(sys):
+    """
+    Compute system poles.
+
+    Parameters
+    ----------
+    sys: StateSpace or TransferFunction
+        Linear system
+
+    Returns
+    -------
+    poles: ndarray
+        Array that contains the system's poles.
+
+    Raises
+    ------
+    NotImplementedError
+        when called on a TransferFunction object
+
+    See Also
+    --------
+    zero
+
+    Notes
+    -----
+    This function is a wrapper for StateSpace.pole and
+    TransferFunction.pole.
+
+    """
+
+    return sys.pole()
+
+
+def zero(sys):
+    """
+    Compute system zeros.
+
+    Parameters
+    ----------
+    sys: StateSpace or TransferFunction
+        Linear system
+
+    Returns
+    -------
+    zeros: ndarray
+        Array that contains the system's zeros.
+
+    Raises
+    ------
+    NotImplementedError
+        when called on a TransferFunction object or a MIMO StateSpace object
+
+    See Also
+    --------
+    pole
+
+    Notes
+    -----
+    This function is a wrapper for StateSpace.zero and
+    TransferFunction.zero.
+
+    """
+
+    return sys.zero()
+
+def evalfr(sys, x):
+    """
+    Evaluate the transfer function of an LTI system for a single complex
+    number x.
+
+    To evaluate at a frequency, enter x = omega*j, where omega is the
+    frequency in radians
+
+    Parameters
+    ----------
+    sys: StateSpace or TransferFunction
+        Linear system
+    x: scalar
+        Complex number
+
+    Returns
+    -------
+    fresp: ndarray
+
+    See Also
+    --------
+    freqresp
+    bode
+
+    Notes
+    -----
+    This function is a wrapper for StateSpace.evalfr and
+    TransferFunction.evalfr.
+
+    Examples
+    --------
+    >>> sys = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
+    >>> evalfr(sys, 1j)
+    array([[ 44.8-21.4j]])
+    >>> # This is the transfer function matrix evaluated at s = i.
+
+    .. todo:: Add example with MIMO system
+    """
+    if issiso(sys):
+        return sys.horner(x)[0][0]
+    return sys.horner(x)
+
+def freqresp(sys, omega):
+    """
+    Frequency response of an LTI system at multiple angular frequencies.
+
+    Parameters
+    ----------
+    sys: StateSpace or TransferFunction
+        Linear system
+    omega: array_like
+        List of frequencies
+
+    Returns
+    -------
+    mag: ndarray
+    phase: ndarray
+    omega: list, tuple, or ndarray
+
+    See Also
+    --------
+    evalfr
+    bode
+
+    Notes
+    -----
+    This function is a wrapper for StateSpace.freqresp and
+    TransferFunction.freqresp.  The output omega is a sorted version of the
+    input omega.
+
+    Examples
+    --------
+    >>> sys = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
+    >>> mag, phase, omega = freqresp(sys, [0.1, 1., 10.])
+    >>> mag
+    array([[[ 58.8576682 ,  49.64876635,  13.40825927]]])
+    >>> phase
+    array([[[-0.05408304, -0.44563154, -0.66837155]]])
+
+    .. todo::
+        Add example with MIMO system
+
+        #>>> sys = rss(3, 2, 2)
+        #>>> mag, phase, omega = freqresp(sys, [0.1, 1., 10.])
+        #>>> mag[0, 1, :]
+        #array([ 55.43747231,  42.47766549,   1.97225895])
+        #>>> phase[1, 0, :]
+        #array([-0.12611087, -1.14294316,  2.5764547 ])
+        #>>> # This is the magnitude of the frequency response from the 2nd
+        #>>> # input to the 1st output, and the phase (in radians) of the
+        #>>> # frequency response from the 1st input to the 2nd output, for
+        #>>> # s = 0.1i, i, 10i.
+    """
+
+    return sys.freqresp(omega)
diff --git a/control/matlab/__init__.py b/control/matlab/__init__.py
@@ -79,7 +79,7 @@
 from .. import margins
 from ..statesp import *
 from ..xferfcn import *
-from ..lti import issiso
+from ..lti import *
 from ..frdata import *
 from ..dtime import sample_system
 from ..exception import ControlArgument
@@ -387,168 +387,6 @@
 
 """
 
-
-def pole(sys):
-    """
-    Compute system poles.
-
-    Parameters
-    ----------
-    sys: StateSpace or TransferFunction
-        Linear system
-
-    Returns
-    -------
-    poles: ndarray
-        Array that contains the system's poles.
-
-    Raises
-    ------
-    NotImplementedError
-        when called on a TransferFunction object
-
-    See Also
-    --------
-    zero
-
-    Notes
-    -----
-    This function is a wrapper for StateSpace.pole and
-    TransferFunction.pole.
-
-    """
-
-    return sys.pole()
-
-def zero(sys):
-    """
-    Compute system zeros.
-
-    Parameters
-    ----------
-    sys: StateSpace or TransferFunction
-        Linear system
-
-    Returns
-    -------
-    zeros: ndarray
-        Array that contains the system's zeros.
-
-    Raises
-    ------
-    NotImplementedError
-        when called on a TransferFunction object or a MIMO StateSpace object
-
-    See Also
-    --------
-    pole
-
-    Notes
-    -----
-    This function is a wrapper for StateSpace.zero and
-    TransferFunction.zero.
-
-    """
-
-    return sys.zero()
-
-def evalfr(sys, x):
-    """
-    Evaluate the transfer function of an LTI system for a single complex
-    number x.
-
-    To evaluate at a frequency, enter x = omega*j, where omega is the
-    frequency in radians
-
-    Parameters
-    ----------
-    sys: StateSpace or TransferFunction
-        Linear system
-    x: scalar
-        Complex number
-
-    Returns
-    -------
-    fresp: ndarray
-
-    See Also
-    --------
-    freqresp
-    bode
-
-    Notes
-    -----
-    This function is a wrapper for StateSpace.evalfr and
-    TransferFunction.evalfr.
-
-    Examples
-    --------
-    >>> sys = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
-    >>> evalfr(sys, 1j)
-    array([[ 44.8-21.4j]])
-    >>> # This is the transfer function matrix evaluated at s = i.
-
-    .. todo:: Add example with MIMO system
-    """
-    if issiso(sys):
-        return sys.horner(x)[0][0]
-    return sys.horner(x)
-
-
-def freqresp(sys, omega):
-    """
-    Frequency response of an LTI system at multiple angular frequencies.
-
-    Parameters
-    ----------
-    sys: StateSpace or TransferFunction
-        Linear system
-    omega: array_like
-        List of frequencies
-
-    Returns
-    -------
-    mag: ndarray
-    phase: ndarray
-    omega: list, tuple, or ndarray
-
-    See Also
-    --------
-    evalfr
-    bode
-
-    Notes
-    -----
-    This function is a wrapper for StateSpace.freqresp and
-    TransferFunction.freqresp.  The output omega is a sorted version of the
-    input omega.
-
-    Examples
-    --------
-    >>> sys = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
-    >>> mag, phase, omega = freqresp(sys, [0.1, 1., 10.])
-    >>> mag
-    array([[[ 58.8576682 ,  49.64876635,  13.40825927]]])
-    >>> phase
-    array([[[-0.05408304, -0.44563154, -0.66837155]]])
-
-    .. todo::
-        Add example with MIMO system
-
-        #>>> sys = rss(3, 2, 2)
-        #>>> mag, phase, omega = freqresp(sys, [0.1, 1., 10.])
-        #>>> mag[0, 1, :]
-        #array([ 55.43747231,  42.47766549,   1.97225895])
-        #>>> phase[1, 0, :]
-        #array([-0.12611087, -1.14294316,  2.5764547 ])
-        #>>> # This is the magnitude of the frequency response from the 2nd
-        #>>> # input to the 1st output, and the phase (in radians) of the
-        #>>> # frequency response from the 1st input to the 2nd output, for
-        #>>> # s = 0.1i, i, 10i.
-    """
-
-    return sys.freqresp(omega)
-
 # Bode plots
 def bode(*args, **keywords):
     """Bode plot of the frequency response
