Product consist only of one element, this method returns this element. Another example: if Sum is empty, method returns zero. By default, this method returns this.
@see Product#equivalent()
@see Sum#equivalent()
@return simplified equivalent of this tensor
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  | 
|  |  |