I've posted v0.5 of mcs::units along with updated documentation in the Vault/Units directory. This version has only been tested under gcc 4.0.1. I have attempted to put #define guards in appropriate places to accommodate compilers that don't support typeof, but some examples may not compile without it. There have been a number of changes and improvements since the previous version: 1) The biggest change is in the syntax for quantities. Rather than hiding quantity typedefs within a class templated on value type like the previous version (e.g. SI<double>::length), quantities are now in the open : quantity<double,SI::length>, with the unit definitions for each system being declared in a namespace. This significantly simplifies some things and, if anything, makes the code more self- documenting, IMO. Very little of the underlying code has changed appreciably. 2) Implementation of rational and integer powers and roots have been streamlined and now work in most test cases. 3) An example of interoperability of mcs::units with boost::math::quaternion has been added. 4) A partial reimplementation of std::complex that supports heterogeneous operators, and allows complex to be a value type of quantity or quantity to be a value type of complex, has been added as an example. This example demonstrates the implementation steps necessary to make a user-defined type that is completely interoperable with mcs::units. Both quantity<complex<Y>,Unit> and complex<quantity<Y,Unit> > function, and all operators including rational powers and roots behave as expected. 5) A number of physical constants from the CODATA tables have been added (currently only function with typeof). As always, feedback is welcomed. Matthias ---------------------------------------------------------------- Matthias Schabel, Ph.D. Assistant Professor, Department of Radiology Utah Center for Advanced Imaging Research 729 Arapeen Drive Salt Lake City, UT 84108 801-587-9413 (work) 801-585-3592 (fax) 801-706-5760 (cell) 801-484-0811 (home) matthias at stanfordalumni dot org ----------------------------------------------------------------