BUG: Be explicit about allowing all integer types in matrix exponenti…

…ation Fixes gh-9506, unsigned exponentiation
numpy · charris · Aug 6, 2017 · Aug 1, 2017 · Aug 1, 2017 · Aug 1, 2017
commit 6a119c982463097aebc8d004fc731b424721a650
diff --git a/numpy/matrixlib/defmatrix.py b/numpy/matrixlib/defmatrix.py
@@ -137,7 +137,7 @@ def matrix_power(M, n):
     M = asanyarray(M)
     if M.ndim != 2 or M.shape[0] != M.shape[1]:
         raise ValueError("input must be a square array")
-    if not issubdtype(type(n), int):
+    if not issubdtype(type(n), N.integer):
         raise TypeError("exponent must be an integer")
 
     from numpy.linalg import inv

diff --git a/numpy/matrixlib/tests/test_defmatrix.py b/numpy/matrixlib/tests/test_defmatrix.py
@@ -249,6 +249,12 @@ def test_pow(self):
         assert_array_almost_equal(m4, np.dot(m2, m2))
         assert_array_almost_equal(np.dot(mi, m), np.eye(2))
 
+    def test_scalar_type_pow(self):
+        m = matrix([[1, 2], [3, 4]])
+        for scalar_t in [np.int8, np.uint8]:
+            two = scalar_t(2)
+            assert_array_almost_equal(m ** 2, m ** two)
+
     def test_notimplemented(self):
         '''Check that 'not implemented' operations produce a failure.'''
         A = matrix([[1., 2.],