overload of +, -, * and /

source/tensor/XTensor.cpp

@@ -454,7 +454,7 @@ XTensor& XTensor::operator= (const XTensor&& tensor)
 }
 
 /* overloading of the plus-sign */
-XTensor XTensor::operator+ (const XTensor& tensor)
+XTensor XTensor::operator+ (const XTensor& tensor) const
 {
     return Sum(*this, tensor);
 }
@@ -466,37 +466,37 @@ XTensor XTensor::operator+ (const DTYPE shift) const
 }
 
 /* overloading of the multiply-sign */
-XTensor XTensor::operator* (const XTensor& tensor)
+XTensor XTensor::operator* (const XTensor& tensor) const
 {
     return Multiply(*this, tensor);
 }
 
 /* overloading of the multiply-sign */
-XTensor XTensor::operator* (const DTYPE scale)
+XTensor XTensor::operator* (const DTYPE scale) const
 {
     return ScaleAndShift(*this, scale, 0);
 }
 
 /* overloading of the minus-sign */
-XTensor XTensor::operator- (const XTensor& tensor)
+XTensor XTensor::operator- (const XTensor& tensor) const
 {
     return Sub(*this, tensor);
 }
 
 /* overloading of the minus-sign */
-XTensor XTensor::operator- (const DTYPE shift)
+XTensor XTensor::operator- (const DTYPE shift) const
 {
     return ScaleAndShift(*this, 1, -shift);
 }
 
 /* overloading of the division-sign */
-XTensor XTensor::operator/ (const XTensor& tensor)
+XTensor XTensor::operator/ (const XTensor& tensor) const
 {
     return Div(*this, tensor);
 }
 
 /* overloading of the division-sign */
-XTensor XTensor::operator/ (const DTYPE scale)
+XTensor XTensor::operator/ (const DTYPE scale) const
 {
     return ScaleAndShift(*this, (DTYPE)1/scale, 0);
 }
@@ -506,7 +506,7 @@ linear transformation b = a * \scale + \shift
 >> scale - the slope
 >> shift - the intercept
 */
-XTensor XTensor::Lin(DTYPE scale, DTYPE shift)
+XTensor XTensor::Lin(DTYPE scale, DTYPE shift) const
 {
     return Linear(*this, scale, shift);
 }

source/tensor/XTensor.h

@@ -222,31 +222,31 @@ public:
     #endif
 
     /* overloading of the plus-sign */
-    XTensor  operator+ (const XTensor &tensor);
+    XTensor  operator+ (const XTensor &tensor) const;
     
     /* overloading of the plus-sign */
     XTensor  operator+ (const DTYPE shift) const;
 
     /* overloading of the multiply-sign */
-    XTensor  operator* (const XTensor &tensor);
+    XTensor  operator* (const XTensor &tensor) const;
     
     /* overloading of the multiply-sign */
-    XTensor  operator* (const DTYPE scale);
+    XTensor  operator* (const DTYPE scale) const;
 
     /* overloading of the minus-sign */
-    XTensor  operator- (const XTensor &tensor);
+    XTensor  operator- (const XTensor &tensor) const;
     
     /* overloading of the minus-sign */
-    XTensor  operator- (const DTYPE shift);
+    XTensor  operator- (const DTYPE shift) const;
 
     /* overloading of the division-sign */
-    XTensor  operator/ (const XTensor &tensor);
+    XTensor  operator/ (const XTensor &tensor) const;
     
     /* overloading of the division-sign */
-    XTensor  operator/ (const DTYPE scale);
+    XTensor  operator/ (const DTYPE scale) const;
 
     /* linear transformation */
-    XTensor Lin(DTYPE scale, DTYPE shift = 0);
+    XTensor Lin(DTYPE scale, DTYPE shift = 0) const;
 
     /* judge whether the two matrices are in the same type and size */
     static