Check old pickled nodes for GpuMagmaSVD.

theano/gpuarray/linalg.py

@@ -407,6 +407,15 @@ class GpuMagmaSVD(COp):
                                 [GpuArrayType(A.dtype, broadcastable=[False],
                                               context_name=ctx_name)()])
 
+    def prepare_node(self, node, storage_map, compute_map, impl):
+        # Check node to prevent eventual errors with old pickled nodes.
+        if self.compute_uv:
+            A, B, C = node.outputs
+            # We expect order: S (vector), U (matrix), VT (matrix)
+            assert A.type.ndim == 1 and B.type.ndim == C.type.ndim == 2, \
+                "Due to implementation constraints, GpuMagmaSVD interface has changed and now returns (S, U, VT) " \
+                "instead of (U, S, VT). Either update your code, or use gpu_svd() to get the expected (U, S, VT) order."
+
     def get_params(self, node):
         return self.params_type.get_params(self, context=node.inputs[0].type.context)