add <math.h> to use floor()

source/tensor/core/arithmetic/DivDim.cpp

@@ -19,6 +19,7 @@
  * $Created by: Xu Chen (email: hello_master1954@163.com) 2018-08-15
  */
 
+#include <math.h>
 #include "Div.h"
 #include "DivDim.h"
 #include "DivDim.cuh"

source/tensor/core/arithmetic/MultiplyDim.cpp

@@ -19,6 +19,7 @@
  * $Created by: JIANG Yufan (email: jiangyufan2018@outlook.com) 2018-08-14
  */
 
+#include <math.h>
 #include "Multiply.h"
 #include "MultiplyDim.h"
 #include "MultiplyDim.cuh"

source/tensor/core/arithmetic/SubDim.cpp

@@ -19,6 +19,7 @@
 * $Created by: Lin Ye (email: linye2015@outlook.com) 2018-08-13
 */
 
+#include <math.h>
 #include "Sub.h"
 #include "SubDim.h"
 #include "SubDim.cuh"

source/tensor/core/arithmetic/SumDim.cpp

@@ -21,6 +21,7 @@
  * Add summation by broadcasting.
  */
 
+#include <math.h>
 #include "Sum.h"
 #include "SumDim.h"
 #include "SumDim.cuh"