shared variables become sit_sot if are of tensor type

theano/scan_module/scan.py

@@ -843,17 +843,31 @@ def scan(fn,
     shared_scan_inputs = []
     shared_inner_inputs = []
     shared_inner_outputs = []
+    sit_sot_shared = []
     for input in dummy_f.maker.expanded_inputs:
         if isinstance(input.variable, SharedVariable) and input.update:
             new_var = safe_new(input.variable)
             if getattr(input.variable, 'name', None) is not None:
                 new_var.name = input.variable.name + '_copy'
-            shared_inner_inputs.append(new_var)
-            shared_scan_inputs.append(input.variable)
-            shared_inner_outputs.append(input.update)
-            givens[input.variable] = new_var
-            n_shared_outs += 1
+            if isinstance(new_var.type, tensor.TensorType):
+                sit_sot_inner_inputs.append(new_var)
+                sit_sot_scan_inputs.append(
+                    scan_utils.expand(
+                        tensor.unbroadcast(
+                            tensor.shape_padleft(input.variable), 0),
+                        actual_n_steps))
+                sit_sot_inner_outputs.append(input.update)
+                sit_sot_rightOrder.append(-1 - len(sit_sot_shared))
+                sit_sot_shared.append(input.variable)
+                givens[input.variable] = new_var
 
+            else:
+                shared_inner_inputs.append(new_var)
+                shared_scan_inputs.append(input.variable)
+                shared_inner_outputs.append(input.update)
+                givens[input.variable] = new_var
+                n_shared_outs += 1
+    n_sit_sot = len(sit_sot_inner_inputs)
     ## Step 5.4 Outputs with no taps used in the input
     n_nit_sot = 0
     nit_sot_inner_outputs = []
@@ -1041,10 +1055,13 @@ def scan(fn,
                   nit_sot_rightOrder)
     scan_out_list = [None] * len(rightOrder)
     for idx, pos in enumerate(rightOrder):
-        scan_out_list[pos] = _scan_out_list[idx]
+        if pos >= 0:
+            scan_out_list[pos] = _scan_out_list[idx]
+        else:
+            update_map[sit_sot_shared[abs(pos)-1]] = _scan_out_list[idx][-1]
+    scan_out_list = [x for x in scan_out_list if x is not None]
     if len(scan_out_list) == 1:
         scan_out_list = scan_out_list[0]
     elif len(scan_out_list) == 0:
         scan_out_list = None
-
     return (scan_out_list, update_map)