Regression test for gh-199: ab13md should not change its args

Author: roryyorke

slycot/tests/test_ab13bd.py

@@ -0,0 +1,31 @@
+import numpy as np
+from numpy.testing import assert_array_equal
+
+import pytest
+
+from slycot import ab13bd
+
+def test_no_change_args():
+    # ab13md must not change its arguments
+    # regression; see gh-199
+    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))
+
+    acopy = a.copy()
+    bcopy = b.copy()
+    ccopy = c.copy()
+    dcopy = d.copy()
+
+    dico = 'C'
+    jobn = 'H'
+
+    n, m = b.shape
+    p = c.shape[0]
+
+    ab13bd(dico, jobn, n, m, p, a, b, c, d)
+    assert_array_equal(a, acopy)
+    assert_array_equal(b, bcopy)
+    assert_array_equal(c, ccopy)
+    assert_array_equal(d, dcopy)