Commented on why local_1msigmoid is not registered. Modified 1msigmoid test to not run

theano/tensor/nnet/sigm.py

@@ -294,9 +294,8 @@ def local_inv_1_plus_exp(node):
                                 sigmoid(tensor.neg(nonconsts[0].owner.inputs[0])),
                                 scalar_inputs)
 
-              
-#@opt.register_canonicalize
-@gof.local_optimizer([tensor.inv])
+# Registration is below, and conditional.
+@gof.local_optimizer([tensor.sub])
 def local_1msigmoid(node):
     """
     1-sigm(x) -> sigm(-x)
@@ -313,3 +312,13 @@ def local_1msigmoid(node):
             if numpy.allclose(numpy.sum(val_l), 1):
                 return [sigmoid(-sub_r.owner.inputs[0])]
 
+register_local_1msigmoid = False
+# This is False because the Stabilize pattern above 
+# is looking for 1-sigm.  Also Canonizer turns neg into *(-1) and so 
+# this optimization might set off an unwanted chain of things.
+# OTH - this transformation can be seen as pushing normal arithmetic either  below or above the
+# sigmoidal nonlinearity... so if the canonicalized form had anything to say about that then it
+# would be a consideration... anyway leaving False for now.
+              
+if register_local_1msigmoid:
+    opt.register_canonicalize(local_1msigmoid)

theano/tensor/nnet/tests/test_sigm.py

@@ -7,6 +7,7 @@ from theano.tests import unittest_tools as utt
 from theano.tensor.tests import test_basic as TT
 
 from theano.tensor.nnet import *
+from theano.tensor.nnet.sigm import register_local_1msigmoid
 
 
 class T_sigmoid(unittest.TestCase):
@@ -21,7 +22,6 @@ class T_softplus(unittest.TestCase):
     def test_elemwise(self):
         utt.verify_grad(softplus, [numpy.random.rand(3,4)])
 
-
 class T_sigmoid_opts(unittest.TestCase):
     def test_exp_over_1_plus_exp(self):
         m = theano.config.mode
@@ -53,6 +53,9 @@ class T_sigmoid_opts(unittest.TestCase):
                 T.mul]
 
     def test_1msigmoid(self):
+        if not register_local_1msigmoid:
+            return
+
         m = theano.config.mode
         if m == 'FAST_COMPILE':
             m = 'FAST_RUN'
@@ -70,6 +73,3 @@ class T_sigmoid_opts(unittest.TestCase):
         assert [node.op for node in f.maker.env.toposort()] == [tensor.neg, 
                 sigmoid_inplace]
 
-
-
-