BUG: Check for NaN parameter in random.zipf.

Avoids infinite loop.

2 files changed, 12 insertions, 6 deletions

diff --git a/numpy/random/mtrand/mtrand.pyx b/numpy/random/mtrand/mtrand.pyx
index 9e8a79804..adf820f0d 100644
--- a/numpy/random/mtrand/mtrand.pyx
+++ b/numpy/random/mtrand/mtrand.pyx
@@ -4076,13 +4076,15 @@ cdef class RandomState:
         if oa.shape == ():
             fa = PyFloat_AsDouble(a)
 
-            if fa <= 1.0:
-                raise ValueError("a <= 1.0")
+            # use logic that ensures NaN is rejected.
+            if not fa > 1.0:
+                raise ValueError("'a' must be a valid float > 1.0")
             return discd_array_sc(self.internal_state, rk_zipf, size, fa,
                                   self.lock)
 
-        if np.any(np.less_equal(oa, 1.0)):
-            raise ValueError("a <= 1.0")
+        # use logic that ensures NaN is rejected.
+        if not np.all(np.greater(oa, 1.0)):
+            raise ValueError("'a' must contain valid floats > 1.0")
         return discd_array(self.internal_state, rk_zipf, size, oa, self.lock)
 
     def geometric(self, p, size=None):
diff --git a/numpy/random/tests/test_random.py b/numpy/random/tests/test_random.py
index a530b9e13..e9c9bc492 100644
--- a/numpy/random/tests/test_random.py
+++ b/numpy/random/tests/test_random.py
@@ -1106,13 +1106,13 @@ class TestBroadcast(object):
         assert_raises(ValueError, nonc_f, bad_dfnum, dfden, nonc * 3)
         assert_raises(ValueError, nonc_f, dfnum, bad_dfden, nonc * 3)
         assert_raises(ValueError, nonc_f, dfnum, dfden, bad_nonc * 3)
-    
+
     def test_noncentral_f_small_df(self):
         self.setSeed()
         desired = np.array([6.869638627492048, 0.785880199263955])
         actual = np.random.noncentral_f(0.9, 0.9, 2, size=2)
         assert_array_almost_equal(actual, desired, decimal=14)
-        
+
     def test_chisquare(self):
         df = [1]
         bad_df = [-1]
@@ -1434,6 +1434,10 @@ class TestBroadcast(object):
         actual = zipf(a * 3)
         assert_array_equal(actual, desired)
         assert_raises(ValueError, zipf, bad_a * 3)
+        with np.errstate(invalid='ignore'):
+            assert_raises(ValueError, zipf, np.nan)
+            assert_raises(ValueError, zipf, [0, 0, np.nan])
+
 
     def test_geometric(self):
         p = [0.5]