Merge pull request #6057 from bertrand-l/linspace_nonnegative_num

EHN: raise error for negative 'num' in linspace.

2 files changed, 4 insertions, 1 deletions

diff --git a/numpy/core/function_base.py b/numpy/core/function_base.py
index e50e1a505..532ef2950 100644
--- a/numpy/core/function_base.py
+++ b/numpy/core/function_base.py
@@ -25,7 +25,7 @@ def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
         evenly spaced samples, so that `stop` is excluded.  Note that the step
         size changes when `endpoint` is False.
     num : int, optional
-        Number of samples to generate. Default is 50.
+        Number of samples to generate. Default is 50. Must be non-negative.
     endpoint : bool, optional
         If True, `stop` is the last sample. Otherwise, it is not included.
         Default is True.
@@ -82,6 +82,8 @@ def linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None):
 
     """
     num = int(num)
+    if num < 0:
+        raise ValueError("Number of samples, %s, must be non-negative." % num)
     div = (num - 1) if endpoint else num
 
     # Convert float/complex array scalars to float, gh-3504
diff --git a/numpy/core/tests/test_function_base.py b/numpy/core/tests/test_function_base.py
index a64d44473..aba030f3d 100644
--- a/numpy/core/tests/test_function_base.py
+++ b/numpy/core/tests/test_function_base.py
@@ -34,6 +34,7 @@ class TestLinspace(TestCase):
         assert_(y[-1] == 10)
         y = linspace(2, 10, endpoint=0)
         assert_(y[-1] < 10)
+        assert_raises(ValueError, linspace, 0, 10, num=-1)
 
     def test_corner(self):
         y = list(linspace(0, 1, 1))