s.

In order to improve the QZ decomposition accuracy, the pencil goes
through a balancing step where the sum of absolute values of
:math:`H` and :math:`J` entries (after removing the diagonal entries of
the sum) is balanced following the recipe given in [3]_.

.. versionadded:: 0.11.0

References
----------
.. [1]  P. van Dooren , "A Generalized Eigenvalue Approach For Solving
   Riccati Equations.", SIAM Journal on Scientific and Statistical
   Computing, Vol.2(2), :doi:`10.1137/0902010`

.. [2] A.J. Laub, "A Schur Method for Solving Algebraic Riccati
   Equations.", Massachusetts Institute of Technology. Laboratory for
   Information and Decision Systems. LIDS-R ; 859. Available online :
   http://hdl.handle.net/1721.1/1301

.. [3] P. Benner, "Symplectic Balancing of Hamiltonian Matrices", 2001,
   SIAM J. Sci. Comput., 2001, Vol.22(5), :doi:`10.1137/S1064827500367993`

Examples
--------
Given `a`, `b`, `q`, and `r` solve for `x`:

>>> import numpy as np
>>> from scipy import linalg
>>> a = np.array([[4, 3], [-4.5, -3.5]])
>>> b = np.array([[1], [-1]])
>>> q = np.array([[9, 6], [6, 4.]])
>>> r = 1
>>> x = linalg.solve_continuous_are(a, b, q, r)
>>> x
array([[ 21.72792206,  14.48528137],
       [ 14.48528137,   9.65685425]])
>>> np.allclose(a.T.dot(x) + x.dot(a)-x.dot(b).dot(b.T).dot(x), -q)
True

