removing a bug

theano/sparse/basic.py

@@ -834,22 +834,22 @@ class Cast(gof.op.Op):
     def grad(self, inputs, outputs_gradients):
         gz = outputs_gradients[0]
 
-        if gz.dtype in complex_types:
+        if gz.dtype in complex_dtypes:
             raise NotImplementedError("grad not implemented for complex types")
-        if inputs[0].dtype in complex_types:
+        if inputs[0].dtype in complex_dtypes:
             raise NotImplementedError("grad not implemented for complex types")
 
-        if gz.dtype in tensor.continuous_dtypes:
-            if inputs[0].dtype in tensor.continuous_dtypes:
-                return [Cast(inputs[0].dtype)(gz)]
+        if gz.dtype in discrete_dtypes:
+            if inputs[0].dtype in discrete_dtypes:
+                return [inputs[0].zeros_like(dtype=theano.config.floatX)]
             else:
-                return [gz]
-        else:
-            if inputs[0].dtype in tensor.continuous_dtypes:
                 return [inputs[0].zeros_like()]
+        else:
+            if inputs[0].dtype in discrete_dtypes:
+                return [gz]
             else:
-                return [inputs[0].zeros_like(dtype=theano.config.floatX)]
-
+                return [Cast(inputs[0].dtype)(gz)]
+ 
     def infer_shape(self, node, ins_shapes):
         return ins_shapes