Some software packages like MATALB, GNU Octave, Maple, and Mathematica know how to treat Infinity as a special number.
If you want to know how to check for a singularity (infinity) in a general function without specialized mathematical programs, you need to break the function down into the pieces that cause it to spike to infinity and check the components individually.
For example, the function f(x)
Has two singularities, at X=-2 and X=-1. As x approaches these values, f(x) approaches -infinity or +infinity, depending on the direction.
Hope this is of some help.
[ October 12, 2004: Message edited by: M. O'Brien ]
[ October 12, 2004: Message edited by: M. O'Brien ]