add tf.nn.swish activation function.

Author: Oceania2018

src/TensorFlowNET.Core/APIs/tf.nn.cs

@@ -111,6 +111,7 @@ public Tensor embedding_lookup(Tensor @params,
                     name: name);
 
             public IActivation relu() => new relu();
+            public IActivation swish() => new swish();
 
             public Tensor relu(Tensor features, string name = null) => gen_nn_ops.relu(features, name);
 
@@ -206,6 +207,9 @@ public Tensor softmax_cross_entropy_with_logits(Tensor labels, Tensor logits, in
 
             public Tensor softmax_cross_entropy_with_logits_v2(Tensor labels, Tensor logits, int axis = -1, string name = null)
                 => nn_ops.softmax_cross_entropy_with_logits_v2_helper(labels, logits, axis: axis, name: name);
+
+            public Tensor sigmoid<T>(T x, string name = null)
+                => math_ops.sigmoid(x, name: name);
         }
     }
 }

src/TensorFlowNET.Core/Operations/Activation/gen_nn_ops.activations.cs

@@ -102,6 +102,14 @@ public Tensor Activate(Tensor x, string name = null)
         }
     }
 
+    public class swish : IActivation
+    {
+        public Tensor Activate(Tensor x, string name = null)
+        {
+            return tf.multiply(x, tf.nn.sigmoid(x));
+        }
+    }
+
     public class linear : IActivation
     {
         public Tensor Activate(Tensor x, string name = null)