BUG: fix #786, bad exception for wrong order for linalg.norm.

3 files changed, 9 insertions, 6 deletions

diff --git a/numpy/linalg/linalg.py b/numpy/linalg/linalg.py
index 583ab2f71..1570407ff 100644
--- a/numpy/linalg/linalg.py
+++ b/numpy/linalg/linalg.py
@@ -1378,6 +1378,10 @@ def norm(x, ord=None):
         elif ord == 2:
             return sqrt(((x.conj()*x).real).sum()) # special case for speedup
         else:
+            try:
+                ord + 1
+            except TypeError:
+                raise ValueError, "Invalid norm order for vectors."
             return ((abs(x)**ord).sum())**(1.0/ord)
     elif nd == 2:
         if ord == 2:
diff --git a/numpy/linalg/tests/test_linalg.py b/numpy/linalg/tests/test_linalg.py
index 1a5edc5bc..3330db2a3 100644
--- a/numpy/linalg/tests/test_linalg.py
+++ b/numpy/linalg/tests/test_linalg.py
@@ -290,12 +290,6 @@ class _TestNorm(TestCase):
                   array(c, dtype=self.dt)):
             _test(v)
 
-    @np.testing.dec.knownfailureif(True, "#786: FIXME")
-    def test_vector_badarg(self):
-        """Regression for #786: Froebenius norm for vectors raises
-        TypeError."""
-        self.assertRaises(ValueError, norm, array([1., 2., 3.]), 'fro')
-
     def test_matrix(self):
         A = matrix([[1.,3.],[5.,7.]], dtype=self.dt)
         A = matrix([[1.,3.],[5.,7.]], dtype=self.dt)
diff --git a/numpy/linalg/tests/test_regression.py b/numpy/linalg/tests/test_regression.py
index ab101b7d0..ab31d9960 100644
--- a/numpy/linalg/tests/test_regression.py
+++ b/numpy/linalg/tests/test_regression.py
@@ -52,6 +52,11 @@ class TestRegression(TestCase):
 
         assert_array_almost_equal(b, np.zeros((2, 2)))
 
+    def test_norm_vector_badarg(self):
+        """Regression for #786: Froebenius norm for vectors raises
+        TypeError."""
+        self.assertRaises(ValueError, linalg.norm, array([1., 2., 3.]), 'fro')
+
 
 if __name__ == '__main__':
     run_module_suite()