[python-control-discuss] SF.net SVN: python-control:[49] branches/control-0.4a/src

[<kk...@us...>]

Revision: 49
          http://python-control.svn.sourceforge.net/python-control/?rev=49&view=rev
Author:   kkchen
Date:     2011-02-08 22:13:44 +0000 (Tue, 08 Feb 2011)

Log Message:
-----------
Added interface for balred and modred in modelsimp.py.  Also changed * to dot in gram function.

Steven Brunton <sbr...@pr...>

Modified Paths:
--------------
    branches/control-0.4a/src/modelsimp.py
    branches/control-0.4a/src/statefbk.py

Modified: branches/control-0.4a/src/modelsimp.py
===================================================================
--- branches/control-0.4a/src/modelsimp.py	2011-02-08 22:13:40 UTC (rev 48)
+++ branches/control-0.4a/src/modelsimp.py	2011-02-08 22:13:44 UTC (rev 49)
@@ -77,6 +77,112 @@
     # Return the Hankel singular values
     return hsv
 
+def modred(sys,ELIM,method):
+    """Model reduction of sys by eliminating the states in ELIM using a given method
+
+    Usage
+    =====
+    rsys = modred(sys,ELIM,method) 
+
+    Inputs
+    ======
+    sys : original system to reduce
+    ELIM : vector of states to eliminate
+    method : method of removing states in ELIM (truncate or matchdc)
+
+    Outputs
+    =======
+    rsys : a reduced order model 
+
+    """
+
+    #Check for ss system object, need a utility for this?
+
+    #TODO: Check for continous or discrete, only continuous supported right now
+        # if isCont():
+        #    dico = 'C'
+        # elif isDisc():
+        #    dico = 'D'
+        # else:
+    dico = 'C'
+
+    #TODO: Check system is stable, perhaps a utility in ctrlutil.py
+        # or a method of the StateSpace class?
+    D,V = np.linalg.eig(sys.A)
+    for e in D:
+        if e.real >= 0:
+            raise ValueError, "Oops, the system is unstable!"
+
+    if method=='matchdc':
+        print "matchdc"
+    elif method=='truncate':
+        print "truncate"
+    else:
+        raise ValueError, "Oops, method is not supported!"
+
+    #Compute rhs using the Slycot routine XXXXXX 
+        #make sure Slycot is installed
+    #try:
+    #    from slycot import XXXXXX
+    #except ImportError:
+    #    raise ControlSlycot("can't find slycot module 'XXXXXX'")
+    rsys = 0.
+    return rsys
+
+def balred(sys,orders,elimination,method):
+    """Balanced reduced order model of sys of a given order.  States are eliminated based on Hankel singular value.
+
+    Usage
+    =====
+    rsys = balred(sys,order,elimination,method) 
+
+    Inputs
+    ======
+    sys : original system to reduce
+    orders : desired order of reduced order model (if a vector, returns a vector of systems)
+    elimination : if elimination is specified, use 'method'
+    method : method of removing states (truncate or matchdc)
+
+    Outputs
+    =======
+    rsys : a reduced order model 
+
+    """
+
+    #Check for ss system object, need a utility for this?
+
+    #TODO: Check for continous or discrete, only continuous supported right now
+        # if isCont():
+        #    dico = 'C'
+        # elif isDisc():
+        #    dico = 'D'
+        # else:
+    dico = 'C'
+
+    #TODO: Check system is stable, perhaps a utility in ctrlutil.py
+        # or a method of the StateSpace class?
+    D,V = np.linalg.eig(sys.A)
+    for e in D:
+        if e.real >= 0:
+            raise ValueError, "Oops, the system is unstable!"
+   
+    if method=='matchdc':
+        print "matchdc"
+    elif method=='truncate':
+        print "truncate"
+    else:
+        raise ValueError, "Oops, method is not supported!"
+
+    #Compute rhs using the Slycot routine XXXXXX 
+        #make sure Slycot is installed
+    #try:
+    #    from slycot import XXXXXX
+    #except ImportError:
+    #    raise ControlSlycot("can't find slycot module 'XXXXXX'")
+    rsys = 0.
+    return rsys
+
+
 def era(YY,m,n,nin,nout,r):
     """Calculate an ERA model of order r based on the impulse-response data YY
 

Modified: branches/control-0.4a/src/statefbk.py
===================================================================
--- branches/control-0.4a/src/statefbk.py	2011-02-08 22:13:40 UTC (rev 48)
+++ branches/control-0.4a/src/statefbk.py	2011-02-08 22:13:44 UTC (rev 49)
@@ -267,11 +267,11 @@
     if type=='c':
         print "controllable"
         trana = 'T'
-        C = -sys.B*sys.B.transpose()
+        C = -np.dot(sys.B,sys.B.transpose())
     elif type=='o':
         print "observable"
         trana = 'N'
-        C = -sys.C.transpose()*sys.C
+        C = -np.dot(sys.C.transpose(),sys.C)
     else:
         raise ValueError, "Oops, neither observable, nor controllable!"
 


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