[Boost-users] How to make is_arithmetic true for a UDT

I am facing the need to get my User Defined Type to return true from boost::is_arithmetic (This is to meet a check for autoprefixing in Boost.Units) There was some discussion on this issue before, http://lists.boost.org/boost-users/2007/10/31538.php but I am not clear if it reached a satisfactory conclusion. (Nor that I fully understand what is being proposed). A cut-down example is a Trivial UDT that does exactly same as double. (My actual example has template parameter for floating-point type of two members, a value and an uncertainty, and others). Suggestions? Paul -- - Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow@hetp.u-net.com