backup dot operator changes.

src/include/migraphx/operators.hpp

@@ -807,6 +807,17 @@ struct gather
     }
 };
 
+// The dot operation is combination of the onnx GEMM and MatMul operators. 
+// For GEMM, it support the C matrix in the formula alpha * AB + beta * C, 
+// in which C is broadcastable to the shape of AB. For the transpose of A
+// and B, we add a tranpose operator if the onnx file needs. 
+// For MatMul, it has the same definition as the numpy.matmul, which means
+// A, B could be 1 to N-dims. For 1-dim input of A, it is a vector * matrix,
+// for 1-dim of B, it is a matrix * vector. Note that there is not support
+// of batch of 1-dim vector. In another word, if A or B is 1-dim, it is a 
+// vector input; if A or B is 2-dim, it is a matrix (no case of a batch of
+// vectors as input). If A or B is 3 or more dims, it is considered as a
+// stack(batch) of matrices. 
 struct dot
 {
     float alpha = 1.0;