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care doc fix #47

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Merged
murrayrm merged 2 commits into from
Feb 15, 2015
+13 −11
Merged

care doc fix #47

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d0bfec7
Documentation fix: document R is None behaviour
roryyorke Feb 15, 2015
065b2cf
Exception description fix: continuous-time, not discrete-time.
roryyorke Feb 15, 2015
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24 changes: 13 additions & 11 deletions control/mateqn.py
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Original file line number Diff line number Diff line change
Expand Up @@ -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

A^T X + X A - X B B^T X + Q = 0
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

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:
Expand Down Expand Up @@ -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 \
Expand Down