9. @Jesse: the argument goes that if you include math.h, then you know you're dropping a heap of junk in your global namespace. If you include cmath then you may or may not be dropping a heap of junk in your global namespace.. @Jesse: the argument goes that if you include math.h, then you know you're dropping a heap of junk in your global namespace. If you include cmath then you may or may not be dropping a heap of junk in your global namespace.