Merge branch 'master' into improve-docs

Conflicts:
	control/mateqn.py

control/freqplot.py

@@ -126,27 +126,30 @@ def bode_plot(syslist, omega=None, dB=None, Hz=None, deg=None,
                 omega = default_frequency_range(syslist)
 
             # Get the magnitude and phase of the system
-            mag_tmp, phase_tmp, omega = sys.freqresp(omega)
+            mag_tmp, phase_tmp, omega_sys = sys.freqresp(omega)
             mag = np.atleast_1d(np.squeeze(mag_tmp))
             phase = np.atleast_1d(np.squeeze(phase_tmp))
             phase = unwrap(phase)
-            if Hz: omega = omega/(2*sp.pi)
+            if Hz:
+                omega_plot = omega_sys/(2*sp.pi)
+            else:
+                omega_plot = omega_sys
             if dB: mag = 20*sp.log10(mag)
             if deg: phase = phase * 180 / sp.pi
 
             mags.append(mag)
             phases.append(phase)
-            omegas.append(omega)
+            omegas.append(omega_sys)
             # Get the dimensions of the current axis, which we will divide up
             #! TODO: Not current implemented; just use subplot for now
 
             if (Plot):
                 # Magnitude plot
                 plt.subplot(211);
                 if dB:
-                    plt.semilogx(omega, mag, *args, **kwargs)
+                    plt.semilogx(omega_plot, mag, *args, **kwargs)
                 else:
-                    plt.loglog(omega, mag, *args, **kwargs)
+                    plt.loglog(omega_plot, mag, *args, **kwargs)
                 plt.hold(True);
 
                 # Add a grid to the plot + labeling
@@ -156,7 +159,7 @@ def bode_plot(syslist, omega=None, dB=None, Hz=None, deg=None,
 
                 # Phase plot
                 plt.subplot(212);
-                plt.semilogx(omega, phase, *args, **kwargs)
+                plt.semilogx(omega_plot, phase, *args, **kwargs)
                 plt.hold(True);
 
                 # Add a grid to the plot + labeling

control/mateqn.py

@@ -411,25 +411,27 @@ def dlyap(A,Q,C=None,E=None):
 #### Riccati equation solvers care and dare
 
 def care(A,B,Q,R=None,S=None,E=None):
-    """ (X,L,G) = care(A,B,Q) solves the continuous-time algebraic Riccati
+    """ (X,L,G) = care(A,B,Q,R=None) solves the continuous-time algebraic Riccati
     equation
 
-        :math:`A^T X + X A - X B B^T X + Q = 0`
+        :math:`A^T X + X A - X B R^{-1} B^T X + Q = 0`
 
-    where A and Q are square matrices of the same dimension. Further, Q
-    is a symmetric matrix. The function returns the solution X, the gain
-    matrix G = B^T X and the closed loop eigenvalues L, i.e., the eigenvalues
-    of A - B G.
+    where A and Q are square matrices of the same dimension. Further,
+    Q and R are a symmetric matrices. If R is None, it is set to the
+    identity matrix. The function returns the solution X, the gain
+    matrix G = B^T X and the closed loop eigenvalues L, i.e., the
+    eigenvalues of A - B G.
 
     (X,L,G) = care(A,B,Q,R,S,E) solves the generalized continuous-time
     algebraic Riccati equation
 
         :math:`A^T X E + E^T X A - (E^T X B + S) R^{-1} (B^T X E + S^T) + Q = 0`
 
-    where A, Q and E are square matrices of the same dimension. Further, Q and
-    R are symmetric matrices. The function returns the solution X, the gain
-    matrix G = R^-1 (B^T X E + S^T) and the closed loop eigenvalues L, i.e.,
-    the eigenvalues of A - B G , E. """
+    where A, Q and E are square matrices of the same
+    dimension. Further, Q and R are symmetric matrices. If R is None,
+    it is set to the identity matrix. The function returns the
+    solution X, the gain matrix G = R^-1 (B^T X E + S^T) and the
+    closed loop eigenvalues L, i.e., the eigenvalues of A - B G , E."""
 
     # Make sure we can import required slycot routine
     try:
@@ -531,7 +533,7 @@ def care(A,B,Q,R=None,S=None,E=None):
                 e.info = ve.info
             elif ve.info == 1:
                 e = ValueError("The matrix A is (numerically) singular in \
-                    discrete-time case.")
+                    continuous-time case.")
                 e.info = ve.info
             elif ve.info == 2:
                 e = ValueError("The Hamiltonian or symplectic matrix H cannot \