[Boost-users] [units] Question about user-defined value types

Hi, I am using boost units library for a project in which I need to define quantities using rational numbers. I have a rational number class but am having trouble integrating it with units library. There seems to be a lot of places where the units library implementation assumes that the conversion values are expressed as double type. Is there a good way to get around this to make units library support rational numbers? Thanks, WZ