Maybe you answer is different from mine because you are running Perl in another architecture.

I am running perl in a different architecture (amd64), and I get the same result as you for perl:

C:\_32>perl -e "print cos(100000000.0)"
-0.36338508935581
[download]

I'm on Win32, and that's using the Microsoft C runtime library (msvcrt.dll). If I instead use the mpfr library, then I get the correct result:

C:\_32>perl -MMath::MPFR -e "$x=Math::MPFR->new(100000000.0);print cos
+($x)"
-3.6338508935569053e-1
[download]

Cheers,
Rob