Hello Matthias and Steven, following your suggestions, I've reworked my lambda.hpp (to go into, boost/units/) to cover all overloaded operators for the Boost.Units types quantity, unit, absolute, and one (I'm not sure, if the latter is necessary. I just found it while grepping for missing operators.). The open issues for lambda.hpp are: * Maybe drop specialization for quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(System),Y>? * Are the specializations for boost::units::one needed in the context of Boost.Lambda? It seems to be an implementation detail of Boost.Units. * Work out a solution for boost::lambda:bind's limitation concerning the binding of overloaded functions. The required static_cast to the function pointer (referring, e.g., a function from boost/units/cmath.hpp) is tedious. (I had no time yet to test Steven's proposal to use functors with appropriate sig template.) I also created a unit test test_lambda.cpp (to go into boost/libs/units/test), which tries to check each operator, for which a specialization of Boost.Lambda's return type traits is included in lambda.hpp. The test exposed additional issues: * Are the checks for the operations involving quantity<BOOST_UNITS_DIMENSIONLESS_UNIT(System),Y> correct? Are they needed? * All checks involving the multiplication/division of boost::units::unit and boost::units::absolute<boost::units::unit> types are not compiling. The compiler complains about ambiguous overloads for operator* and operator/ (originating from Boost.Units and Boost.Lambda). Therefore they are currently commented out. Some checks also involve the usage of Boost.Function * The check fo unit<Dim1, System1> - unit<Dim2, System2> is not compiling. The compiler finds no matching definition of operator-. * Are the checks for the operations involving absolute unit types correct? * All checks for the boost::units::one types are not compiling. The compiler complains about ambiguous overloads for operator* and operator/ (originating from Boost.Units and Boost.Lambda). Therefore they are currently commented out. * Add checks involving mathematical functions from boost/units/cmath.hpp once a solution for boost::lambda:bind's limitation concerning the binding of overloaded functions is found. I improved the example lambda.cpp (to go into, boost/libs/units/example) by adding more comments and a new thermal example demonstrating the use of absolute quantities. I developed the files inside a working copy of Boost.Units trunk. test_lambda.cpp and lambda.cpp could be compiled by bjam. However, I had to modify the Jamfile.v2 files in boost/libs/units/test and boost/libs/units/example to contain a definition of BOOST_ROOT like this: BOOST_ROOT = /opt/boost_1_35_0 ; Otherwise the other Boost libraries aren't found during compilation. How do you define this variable in Jamroot so that it becomes visible in the Jamfile.v2 files? Defining the variable as an OS environment variable doesn't help as the Boost.Build manual states. By googling for BOOST_ROOT, I found statements, which suggest to use use-project /boost : <path_to_Boost> ; instead. But this didn't help and the Boost.Build manual seems to be still incomplete about this issue. Maybe you can help me. This is how my Jamroot currently looks like: use-project /boost : /opt/boost_1_35_0 ; using gcc : 4.1 : g++-4.1 ; using xsltproc : "/usr/bin/xsltproc" ; using boostbook : "/usr/share/xml/docbook/stylesheet/nwalsh/" : "/usr/share/xml/docbook/schema/dtd/4.2" ; using doxygen : "/usr/bin/doxygen" ; using fop : "/usr/bin/fop" : "/usr/lib/jvm/java-6-sun-1.6.0.00" ; I'm looking forward to your comments! Best regards, Torsten