Draw the graph of the function

Using

Most computer programs and calculators will draw this function as shown below with the two extraneous vertical lines.

> plot(1/(1-x^2),x=-3..3, y=-10..10);

You can prevent this from happening when you use Maple by adding by adding the term discont=true:

> plot(1/(1-x^2),x=-3..3, y=-10..10, discont=true);