This week's book giveaway is in the Servlets forum. We're giving away four copies of Murach's Java Servlets and JSP and have Joel Murach on-line! See this thread for details.

To get -Infinity you have to use -0.0 as the denominator.

My interpretation of your example is as follows: -0 is done with integer arithmetic, so -0 -> -(0) -> 0 and that gets converted to 0.0 before the division is done. Therefore (+)Infinity is the result.