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[python-control-discuss] SF.net SVN: python-control:[62] branches/control-0.4a/src/matlab.py
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From: <kk...@us...> - 2011-02-08 22:14:53
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Revision: 62
http://python-control.svn.sourceforge.net/python-control/?rev=62&view=rev
Author: kkchen
Date: 2011-02-08 22:14:46 +0000 (Tue, 08 Feb 2011)
Log Message:
-----------
Revised ss, tf, ss2tf, and tf2ss in matlab.py to suit our new classes.
Kevin K. Chen <kk...@pr...>
Modified Paths:
--------------
branches/control-0.4a/src/matlab.py
Modified: branches/control-0.4a/src/matlab.py
===================================================================
--- branches/control-0.4a/src/matlab.py 2011-02-08 22:14:42 UTC (rev 61)
+++ branches/control-0.4a/src/matlab.py 2011-02-08 22:14:46 UTC (rev 62)
@@ -60,8 +60,8 @@
# Control system library
import ctrlutil
import freqplot
-from statesp import StateSpace, rss_generate
-from xferfcn import TransferFunction
+from statesp import StateSpace, rss_generate, convertToStateSpace
+from xferfcn import TransferFunction, convertToTransferFunction
from exception import *
# Import MATLAB-like functions that can be used as-is
@@ -100,17 +100,17 @@
ss/getDelayModel - access internal delay model (state space only)
Conversions
- tf - conversion to transfer function
+* tf - conversion to transfer function
zpk - conversion to zero/pole/gain
- ss - conversion to state space
+* ss - conversion to state space
frd - conversion to frequency data
c2d - continuous to discrete conversion
d2c - discrete to continuous conversion
d2d - resample discrete-time model
upsample - upsample discrete-time LTI systems
- ss2tf - state space to transfer function
+* ss2tf - state space to transfer function
ss2zpk - transfer function to zero-pole-gain
- tf2ss - transfer function to state space
+* tf2ss - transfer function to state space
tf2zpk - transfer function to zero-pole-gain
zpk2ss - zero-pole-gain to state space
zpk2tf - zero-pole-gain to transfer function
@@ -257,54 +257,92 @@
* unwrap - unwrap a phase angle to give a continuous curve
"""
-# Create a state space system from appropriate matrices
-def ss(A, B, C, D):
- """Create a state space system from A, B, C, D"""
- return StateSpace(A, B, C, D)
+def ss(*args):
+ """Create a state space system.
-# Functions for creating a transfer function
-def tf(num, den):
- """Create a SISO transfer function given the numerator and denominator"""
- return TransferFunction(num, den)
+ Usage
+ =====
+ ss(A, B, C, D)
+ ss(sys)"""
+
+ if len(args) == 4:
+ return StateSpace(args[0], args[1], args[2], args[3])
+ elif len(args) == 1:
+ sys = args[0]
+ if isinstance(sys, StateSpace):
+ return sys
+ elif isinstance(sys, TransferFunction):
+ return tf2ss(sys)
+ else:
+ raise TypeError("ss(sys): sys must be a StateSpace or \
+TransferFunction object.")
+ else:
+ raise ValueError("Needs 1 or 4 arguments; received %i." % len(args))
-# Function for converting state space to transfer function
-def ss2tf(*args, **keywords):
- """Transform a state space system to a transfer function
+def tf(*args):
+ """Create a transfer function system.
+
+ Usage
+ =====
+ tf(num, den)
+ tf(sys)
+ num and den can be scalars or vectors for SISO systems, or lists of lists of
+ vectors for MIMO systems."""
+
+ if len(args) == 2:
+ return TransferFunction(args[0], args[1])
+ elif len(args) == 1:
+ sys = args[0]
+ if isinstance(sys, StateSpace):
+ return ss2tf(sys)
+ elif isinstance(sys, TransferFunction):
+ return sys
+ else:
+ raise TypeError("tf(sys): sys must be a StateSpace or \
+TransferFunction object.")
+ else:
+ raise ValueError("Needs 1 or 2 arguments; received %i." % len(args))
+
+def ss2tf(*args):
+ """Transform a state space system to a transfer function.
+
Usage
=====
ss2tf(A, B, C, D)
- ss2tf(sys) - sys should have attributes A, B, C, D
- """
- if (len(args) == 4):
+ ss2tf(sys) - sys should have attributes A, B, C, D"""
+
+ if len(args) == 4:
# Assume we were given the A, B, C, D matrix
- return TransferFunction(*args)
- elif (len(args) == 1):
- # Assume we were given a system object (lti or StateSpace)
+ return convertToTransferFunction(StateSpace(args[0], args[1], args[2],
+ args[3]))
+ elif len(args) == 1:
sys = args[0]
- return TransferFunction(sys.A, sys.B, sys.C, sys.D)
+ if not isinstance(sys, StateSpace):
+ raise TypeError("ss2tf(sys): sys must be a StateSpace object.")
+ return convertToTransferFunction(sys)
else:
- raise ValueError, "Needs 1 or 4 arguments."
+ raise ValueError("Needs 1 or 4 arguments; received %i." % len(args))
-# Function for converting transfer function to state space
-def tf2ss(*args, **keywords):
- """Transform a transfer function to a state space system
+def tf2ss(*args):
+ """Transform a transfer function to a state space system.
Usage
=====
tf2ss(num, den)
- ss2tf(sys) - sys should be a system object (lti or TransferFunction)
- """
- if (len(args) == 2):
+ tf2ss(sys) - sys should be a system object (lti or TransferFunction)"""
+
+ if len(args) == 2:
# Assume we were given the num, den
- return TransferFunction(*args)
- elif (len(args) == 1):
- # Assume we were given a system object (lti or TransferFunction)
+ return convertToStateSpace(TransferFunction(args[0], args[1]))
+ elif len(args) == 1:
sys = args[0]
- #! Should check to make sure object is a transfer function
- return StateSpace(sys.A, sys.B, sys.C, sys.D)
+ if not isinstance(sys, TransferFunction):
+ raise TypeError("tf2ss(sys): sys must be a TransferFunction \
+object.")
+ return convertToStateSpace(sys)
else:
- raise ValueError, "Needs 1 or 2 arguments."
+ raise ValueError("Needs 1 or 2 arguments; received %i." % len(args))
def rss(states=1, inputs=1, outputs=1):
"""Create a stable continuous random state space object."""
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