Fix the documentation for elementwise op in fluid layers

doc/api/v2/fluid/layers.rst

@@ -38,6 +38,16 @@ elementwise_add
 ..  autofunction:: paddle.v2.fluid.layers.elementwise_add
     :noindex:
 
+elementwise_sub
+---------------
+..  autofunction:: paddle.v2.fluid.layers.elementwise_sub
+    :noindex:
+
+elementwise_mul
+---------------
+..  autofunction:: paddle.v2.fluid.layers.elementwise_mul
+    :noindex:
+
 elementwise_div
 ---------------
 ..  autofunction:: paddle.v2.fluid.layers.elementwise_div

paddle/operators/elementwise_add_op.cc

@@ -21,7 +21,7 @@ class ElementwiseAddOpMaker : public ElementwiseOpMaker {
  public:
   ElementwiseAddOpMaker(OpProto* proto, OpAttrChecker* op_checker)
       : ElementwiseOpMaker(proto, op_checker) {
-    SetComment("Add", "$Out = X + Y$");
+    SetComment("Add", "Out = X + Y");
     AddComment(comment_);
   }
 };

paddle/operators/elementwise_div_op.cc

@@ -21,7 +21,7 @@ class ElementwiseDivOpMaker : public ElementwiseOpMaker {
  public:
   ElementwiseDivOpMaker(OpProto* proto, OpAttrChecker* op_checker)
       : ElementwiseOpMaker(proto, op_checker) {
-    SetComment("Div", "$Out = X / Y$");
+    SetComment("Div", "Out = X / Y");
     AddComment(comment_);
   }
 };

paddle/operators/elementwise_mul_op.cc

@@ -22,7 +22,7 @@ class ElementwiseMulOpMaker : public ElementwiseOpMaker {
  public:
   ElementwiseMulOpMaker(OpProto* proto, OpAttrChecker* op_checker)
       : ElementwiseOpMaker(proto, op_checker) {
-    SetComment("Mul", "$Out = X \\odot\\ Y$");
+    SetComment("Mul", "Out = X \\odot\\ Y");
     AddComment(comment_);
   }
 };

paddle/operators/elementwise_op.h

@@ -58,7 +58,8 @@ Limited Elementwise {name} Operator.
 
 The equation is:
 
-{equation}
+.. math::
+  {equation}
 
 X is a tensor of any dimension and the dimensions of tensor Y must be smaller than
 or equal to the dimensions of X. 
@@ -71,15 +72,16 @@ For case 2:
 Y will be broadcasted to match the shape of X and axis should be 
 the starting dimension index for broadcasting Y onto X.
 
-example:
-  shape(X) = (2, 3, 4, 5), shape(Y) = (,)
-  shape(X) = (2, 3, 4, 5), shape(Y) = (5,)
-  shape(X) = (2, 3, 4, 5), shape(Y) = (4, 5)
-  shape(X) = (2, 3, 4, 5), shape(Y) = (3, 4), with axis=1
-  shape(X) = (2, 3, 4, 5), shape(Y) = (2), with axis=0
+For example
+  .. code-block:: python
 
-Both the input X and Y can carry the LoD (Level of Details) information,
-or not. But the output only shares the LoD information with input X.
+    shape(X) = (2, 3, 4, 5), shape(Y) = (,)
+    shape(X) = (2, 3, 4, 5), shape(Y) = (5,)
+    shape(X) = (2, 3, 4, 5), shape(Y) = (4, 5)
+    shape(X) = (2, 3, 4, 5), shape(Y) = (3, 4), with axis=1
+    shape(X) = (2, 3, 4, 5), shape(Y) = (2), with axis=0
+
+Either of the inputs X and Y or none can carry the LoD (Level of Details) information. However, the output only shares the LoD information with input X.
 
 )DOC";
     AddComment(comment_);

paddle/operators/elementwise_sub_op.cc

@@ -21,7 +21,7 @@ class ElementwiseSubOpMaker : public ElementwiseOpMaker {
  public:
   ElementwiseSubOpMaker(OpProto* proto, OpAttrChecker* op_checker)
       : ElementwiseOpMaker(proto, op_checker) {
-    SetComment("Sub", "$Out = X - Y$");
+    SetComment("Sub", "Out = X - Y");
     AddComment(comment_);
   }
 };