There are also platforms,such as IBM mainframes, which don't define an "infinity." Perl uses the math library of the compiler with which it's built on a given platform. I would suspect that most Linux platforms use the gcc compiler, most commercial Unix-oid systems (such as Solaris or AIX) use their vendor's proprietary compiler, Windows usually uses Microsoft's compiler, etc.

If you're getting "infinities" as the result of a computational process, I would suggest that some rather careful code revisions are required. Numerical programming is rather an arcane speciality, and poking around Netlib, NA-Net, and NCSA may be profitable. Some CS programs are less than thorough in this area, which is something I find quite disturbing.