Merge pull request #174 from beckdaniel/kernel_prod_bugfix

Kernel product bugfix

GPy/testing/kernel_tests.py

@@ -401,11 +401,27 @@ class Coregionalize_weave_test(unittest.TestCase):
     GPy.util.config.config.set('weave', 'working', 'False')
 
 
+class KernelTestsProductWithZeroValues(unittest.TestCase):
+
+    def setUp(self):
+        self.X = np.array([[0,1],[1,0]])
+        self.k = GPy.kern.Linear(2) * GPy.kern.Bias(2)
+
+    def test_zero_valued_kernel_full(self):
+        self.k.update_gradients_full(1, self.X)
+        self.assertFalse(np.isnan(self.k['linear.variances'].gradient),
+                         "Gradient resulted in NaN")
+
+    def test_zero_valued_kernel_gradients_X(self):
+        target = self.k.gradients_X(1, self.X)
+        self.assertFalse(np.any(np.isnan(target)),
+                         "Gradient resulted in NaN")
 
 
 if __name__ == "__main__":
     print "Running unit tests, please be (very) patient..."
     unittest.main()
+
 #     np.random.seed(0)
 #     N0 = 3
 #     N1 = 9