fixed inaccuracy in SelfGrad

gradient.py

@@ -126,10 +126,12 @@ class SelfGrad (UpdateGradient):
     This class defines update_gradient (necessary for Grad.bprop) to call a
     self.grad function like this:
 
-        if len(self.outputs) > 1:
-            self.grad(self.inputs, [grad_d[o] for o in self.outputs])
-        else
-            self.grad(self.inputs, grad_d[output[0]])
+        passed_inputs = self.inputs
+        if len(self.inputs) == 1: passed_inputs = passed_inputs[0]
+        passed_ograds = [grad_d[o] for o in self.outputs]
+        if len(self.outputs) == 1: passed_ograds = passed_ograds[0]
+        igrads = self.grad(passed_inputs, passed_ograds)
+        if len(self.inputs) == 1: igrads = [igrads]
 
     self.grad() is an Abstract function, see its documentation for the
     expected behaviour.
@@ -139,15 +141,11 @@ class SelfGrad (UpdateGradient):
     def update_gradient(self, grad_d):
         #Call self.grad(inputs, output_gradients) and add the result to grad_d
 
-        if len(self.outputs) > 1:
-            inputgs = self.grad(self.inputs, [grad_d[o] for o in self.outputs])
-        else:
-            inputgs = self.grad(self.inputs, grad_d[self.outputs[0]])
-
-        if len(self.inputs) == 1 and is_result(inputgs):
-            inputgs = [inputgs]
-        else:
-            assert len(inputgs) == len(self.inputs)
+        inputgs = gof.utils.from_return_values(
+            self.grad(gof.utils.to_return_values(self.inputs),
+                      gof.utils.to_return_values([grad_d[o] for o in self.outputs])))
+        assert len(inputgs) == len(self.inputs)
+        
         for input, inputgrad in zip(self.inputs, inputgs):
             grad_d.add(input, inputgrad)