replace grad to be sit_sot sequences

theano/scan_module/scan_op.py

@@ -1405,11 +1405,18 @@ class Scan(PureOp):
                   + n_ins_mit_sot
                   + n_ins_mit_mot
                   + self.n_sit_sot )
-        n_shared_outs    = len(prev_inner_gfn_outs[offset:])
-        scan_shared_ins  = prev_inner_gfn_outs[offset:]
-        scan_shared_init = zeros_like_diff_ins[offset:]
-        scan_shared_outs = inner_gfn_outs[offset:]
-        tap_array        = mit_mot_taps
+        # Instead of shared outs use sit_sot
+        n_sitsot_outs    = len(prev_inner_gfn_outs[offset:])
+        scan_sitsot_ins  = prev_inner_gfn_outs[offset:]
+        scan_sitsot_init = []
+        for x in zeros_like_diff_ins[offset:]:
+            shapes = [x.shape[i] for i in xrange(x.ndim)]
+            empty = tensor.zeros([do_steps +1]+shapes,
+                                 dtype=x.dtype)
+            scan_sitsot_init.append(empty)
+        scan_sitsot_outs = inner_gfn_outs[offset:]
+        tap_array        = mit_mot_taps + [[-1] for k in
+                                           xrange(n_sitsot_outs)]
         info = {}
         info['n_seqs']                   = n_seqs
         info['n_mit_sot']                = 0
@@ -1422,8 +1429,8 @@ class Scan(PureOp):
         info['n_mit_mot_outs']           = n_mit_mot_outs
         info['mit_mot_out_slices']       = mit_mot_out_slices
         info['truncate_gradient']        = self.truncate_gradient
-        info['n_sit_sot']                = 0
-        info['n_shared_outs']            = n_shared_outs + self.n_shared_outs
+        info['n_sit_sot']                = n_sitsot_outs
+        info['n_shared_outs']            = self.n_shared_outs
         info['n_nit_sot']                = n_nit_sot
         info['as_while']           = self.as_while
         info['profile']            = self.profile
@@ -1447,7 +1454,7 @@ class Scan(PureOp):
         scan_inputs = ( [do_steps]                            +
                        scan_seqs                              +
                        scan_mit_mot                           +
-                       scan_shared_init                       +
+                       scan_sitsot_init                       +
                        old_scan_init                          +
                        [ args[0] for x in xrange(n_nit_sot) ] +
                        args[offset:]                          )
@@ -1461,14 +1468,13 @@ class Scan(PureOp):
         inner_other_args = self_inputs[offset:]
         inner_gfn_ins  = ( inner_seqs         +
                           inner_mit_mot       +
-                          scan_shared_ins     +
+                          scan_sitsot_ins     +
                           old_scan_shared_ins +
                           inner_other_args )
         inner_gfn_outs = ( scan_mit_mot_outs +
+                           scan_sitsot_outs  +
                            scan_nit_sot_outs +
-                           scan_shared_outs  +
                            old_scan_shared_outs )
-
         local_op = Scan( inner_gfn_ins, inner_gfn_outs, info )
         outputs = local_op(*scan_inputs)
         if type(outputs) not in (list, tuple):
@@ -1478,17 +1484,18 @@ class Scan(PureOp):
 
         offset = ( self.n_mit_mot
                   + self.n_mit_sot
-                  + self.n_sit_sot )
+                  + self.n_sit_sot
+                  + n_sitsot_outs)
         gradients += [ x[::-1] for x in outputs[offset:offset+self.n_seqs]]
 
         end = self.n_mit_mot + self.n_mit_sot + self.n_sit_sot
         gradients += [ x[::-1] for x in outputs[:end]]
         gradients += [ None for x in xrange(self.n_shared_outs)]
         gradients += [ None for x in xrange(self.n_nit_sot) ]
-        begin = end + self.n_seqs
+        begin = end
 
-        end   = begin + n_shared_outs
-        gradients += outputs[begin:end]
+        end   = begin + n_sitsot_outs
+        gradients += [x[-1] for x in outputs[begin:end]]
         return gradients
 
     def R_op(self, inputs, eval_points):