new test for connectivity matrix

theano/scan_module/tests/test_scan.py

@@ -3266,6 +3266,47 @@ class T_Scan(unittest.TestCase):
         f = theano.function([seq], results[1], updates=updates)
         assert numpy.all(exp_out == f(inp))
 
+    def test_grad_connectivity_matrix(self):
+        def inner_fn(x_tm1, y_tm1, z_tm1):
+            x_tm1.name = 'x'
+            y_tm1.name = 'y'
+            z_tm1.name = 'z'
+            return x_tm1**2, x_tm1 + y_tm1, x_tm1+1
+
+        x0 = tensor.vector('X')
+        y0 = tensor.vector('y0')
+        z0 = tensor.vector('Z')
+        [x,y,z], _ = theano.scan(inner_fn,
+                                 outputs_info=[x0,y0,z0],
+                                 n_steps=10)
+        cost = (x+y+z).sum()
+
+        #gx0 = tensor.grad(cost, x0) #defined
+        import ipdb; ipdb.set_trace()
+        gy0 = tensor.grad(cost, y0) #defined
+
+        failed = True
+        try:
+            gz0 = tensor.grad(cost, z0) #disconnected
+        except ValueError:
+            failed = False
+        if failed:
+            raise ValueError('grad should have complained about '
+                             'disconnected input')
+        cost = x.sum()
+        failed = True
+        try:
+            gy0 = tensor.grad(cost, y0) #disconnected
+        except ValueError:
+            failed = False
+        if failed:
+            raise ValueError('grad should have complained about '
+                             'disconnected input')
+
+
+
+
+
 def test_speed():
     #
     # This function prints out the speed of very simple recurrent