In case of a 3-D graph, it is very difficult to observe a graph from a single direction.  Since the graph is plotted three-dimensionally, it is necessary to rotate the data and observe from different angles for effective observation of the result. The rotation functions, having been made into icons, can be easily used with clicks on the mouse only. By use of these functions, you can rotate a 3-D graph without restriction and observe the result more effectively.