python-control · bnavigator · Aug 24, 2023 · Jul 19, 2023 · Jul 19, 2023 · Jul 20, 2023
diff --git a/slycot/analysis.py b/slycot/analysis.py
@@ -1378,13 +1378,14 @@ def ab13bd(dico, jobn, n, m, p, A, B, C, D, tol = 0.0):
             denominator of `G` (see the SLICOT subroutine SB08DD).
     """
 
-    out = _wrapper.ab13bd(dico, jobn, n, m, p, A, B, C, D, tol)
-
     hidden = ' (hidden by the wrapper)'
     arg_list = ('dico', 'jobn', 'n', 'm', 'p',
                 'A', 'lda' + hidden, 'B', 'ldb' + hidden, 'C', 'ldc' + hidden,
                 'D', 'ldd' + hidden, 'nq' + hidden,'tol', 'dwork' + hidden,
                 'ldwork' + hidden, 'iwarn', 'info')
+
+    out = _wrapper.ab13bd(dico, jobn, n, m, p, A, B, C, D, tol)
+
     raise_if_slycot_error(out[-2:], arg_list, ab13bd.__doc__, locals())
     return out[0]
 

diff --git a/slycot/src/analysis.pyf b/slycot/src/analysis.pyf
@@ -305,15 +305,15 @@ function ab13bd(dico,jobn,n,m,p,a,lda,b,ldb,c,ldc,d,ldd,nq,tol,dwork,ldwork,iwar
     character intent(in) :: dico
     character intent(in) :: jobn
     integer check(n>=0) :: n
-    integer check(n>=0) :: m
-    integer check(n>=0) :: p
-    double precision dimension(n,n),depend(n) :: a
+    integer check(m>=0) :: m
+    integer check(p>=0) :: p
+    double precision intent(in,out,copy), dimension(n,n),depend(n) :: a
     integer intent(hide),depend(a) :: lda = shape(a,0)
-    double precision dimension(n,m),depend(n,m) :: b
+    double precision intent(in,out,copy), dimension(n,m),depend(n,m) :: b
     integer intent(hide),depend(b) :: ldb = shape(b,0)
-    double precision dimension(p,n),depend(n,p) :: c
+    double precision intent(in,out,copy), dimension(p,n),depend(n,p) :: c
     integer intent(hide),depend(c) :: ldc = shape(c,0)
-    double precision dimension(p,m),depend(m,p) :: d
+    double precision intent(in,out,copy), dimension(p,m),depend(m,p) :: d
     integer intent(hide),depend(d) :: ldd = shape(d,0)
     integer intent(out) :: nq
     double precision :: tol

diff --git a/slycot/tests/test_ab13bd.py b/slycot/tests/test_ab13bd.py
@@ -0,0 +1,123 @@
+# ===================================================
+# ab08n* tests
+
+import unittest
+from slycot import analysis
+import numpy as np
+
+from scipy import linalg
+from scipy import signal
+from numpy.testing import assert_equal, assert_allclose, assert_array_equal
+
+class test_ab13bd(unittest.TestCase):
+    """ Test regular pencil construction ab08nX with input parameters
+    according to example in documentation """
+
+    A = np.array([[0.0, 1.0],[-0.5, -0.1]])
+    B = np.array([[0.],[1.]])
+    C = np.eye(2)
+    D = np.zeros((2,1))
+
+    Ad, Bd, Cd, Dd, dt = signal.cont2discrete((A, B, C, D), 0.1, method='zoh')
+
+    def test_no_change_args_ccase(self):
+        """ ab13md must not change its arguments. continuous system case.
+        """
+
+        acopy = self.A.copy()
+        bcopy = self.B.copy()
+        ccopy = self.C.copy()
+        dcopy = self.D.copy()
+
+        dico = 'C'
+        jobn = 'H'
+
+        n, m = self.B.shape
+        p = self.C.shape[0]
+
+        analysis.ab13bd(dico, jobn, n, m, p, self.A, self.B, self.C, self.D)
+        assert_array_equal(self.A, acopy)
+        assert_array_equal(self.B, bcopy)
+        assert_array_equal(self.C, ccopy)
+        assert_array_equal(self.D, dcopy)
+
+    def test_no_change_args_dcase(self):
+        """ ab13md must not change its arguments. discrete system case.
+        """
+
+        acopy = self.Ad.copy()
+        bcopy = self.Bd.copy()
+        ccopy = self.Cd.copy()
+        dcopy = self.Dd.copy()
+
+        dico = 'D'
+        jobn = 'H'
+
+        n, m = self.Bd.shape
+        p = self.Cd.shape[0]
+
+        analysis.ab13bd(dico, jobn, n, m, p, self.Ad, self.Bd, self.Cd, self.Dd)
+        assert_array_equal(self.Ad, acopy)
+        assert_array_equal(self.Bd, bcopy)
+        assert_array_equal(self.Cd, ccopy)
+        assert_array_equal(self.Dd, dcopy)
+
+    def test_ab13bd_2norm_ccase(self):
+        """ Compare ab13md with scipy solution (Lyapunov Equation). 
+        continuous system case.
+        """
+
+        A = self.A
+        B = self.B
+        C = self.C
+        D = self.D
+
+        n, m = self.B.shape
+        p = self.C.shape[0]
+
+        dico = 'C'
+        jobn = 'H'
+
+        h2norm = analysis.ab13bd(dico, jobn, n, m, p, A, B, C, D)
+
+        Lc = linalg.solve_continuous_lyapunov(A, -B@B.T)    
+        h2norm_Lc = np.sqrt(np.trace(C@Lc@C.T))
+        print(h2norm_Lc, h2norm)
+        assert_allclose(h2norm_Lc, h2norm, atol=1e-5)
+
+        Lo = linalg.solve_continuous_lyapunov(A.T, -C.T@C)    
+        h2norm_Lo = np.sqrt(np.trace(B.T@Lo@B))
+        print(h2norm_Lo, h2norm)
+        assert_allclose(h2norm_Lo, h2norm, atol=1e-5)
+
+    def test_ab13bd_2norm_dcase(self):
+        """ Compare ab13md with scipy solution (Lyapunov Equation). 
+        discrete system case.
+        """
+
+        Ad = self.Ad
+        Bd = self.Bd
+        Cd = self.Cd
+        Dd = self.Dd
+
+        n, m = Bd.shape
+        p = Cd.shape[0]
+
+        dico = 'D'
+        jobn = 'H'
+
+        h2norm = analysis.ab13bd(dico, jobn, n, m, p, Ad, Bd, Cd, Dd)
+
+        Lc = linalg.solve_discrete_lyapunov(Ad, Bd@Bd.T)    
+        h2norm_Lc = np.sqrt(np.trace(Cd@Lc@Cd.T + Dd@Dd.T))
+        print(h2norm, h2norm_Lc)
+        assert_allclose(h2norm_Lc, h2norm, atol=1e-5)
+
+        Lo = linalg.solve_discrete_lyapunov(Ad.T, Cd.T@Cd)    
+        h2norm_Lo = np.sqrt(np.trace(Bd.T@Lo@Bd + Dd.T@Dd))
+        print(h2norm, h2norm_Lo)
+        assert_allclose(h2norm_Lo, h2norm, atol=1e-5)
+
+
+if __name__ == "__main__":
+    unittest.main()