Hello, I haven't looked much at the math toolkit yet but I was interested in how it handled errors so I peeked at common_error_handling.hpp I see it explicitly qualifies each all to isfinite with (boost::math::isfinite)( value ). I assume this is to prevent macro expansion however this means that if a UDT is passed in the user is required to add their isfinite to the boost::math namespace instead of having it be reachable through ADL. Is this intentional? I think the following would work if it's not. using boost::math::isfinite; isfinite BOOST_PREVENT_MACRO_SUBSTITUTION( value ); I'm not sure if UDT support for this library has been considered in its design but I'm working to provide a fixed-point math library that I hope can be used as a real type just like float and double. I would like to be able to keep as much as possible in the library's namespace. Thanks, Michael Marcin