BUG: Be explicit about allowing all integer types in matrix exponentiation

Fixes gh-9506, unsigned exponentiation

2 files changed, 7 insertions, 1 deletions

diff --git a/numpy/matrixlib/defmatrix.py b/numpy/matrixlib/defmatrix.py
index 2aed3ebde..e016b5f4c 100644
--- 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
index e4c3c49fb..77f262031 100644
--- a/numpy/matrixlib/tests/test_defmatrix.py
+++ b/numpy/matrixlib/tests/test_defmatrix.py
@@ -249,6 +249,12 @@ class TestAlgebra(object):
         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.],