Example: f1(x,y)= 5-x2-y2
Click the "Graph" button (this button also refreshes the graph).
Rotate the graph by clicking and dragging the mouse on the graph.
To see two functions graphed simultaneously:
Enter the second function f2(x,y) in the text input field marked "f2(x,y)=".
Click (to its "on" state) the check box next to this input field.
Click the "Graph" button
Up to three functions can be graphed simultaneously.
To remove a function from the graph, click (to its "off" state) the check box next to the associated text input field and click the "Graph" button to refresh.
To erase the graph and all input fields, click the "Clear" button.
The graphs of the functions are color-coded, corresponding to the colors of the labels marking the text input fields: the graph of f1(x,y) is blue, f2(x,y) is red, and f3(x,y) is green.