Hello, A few months ago, I created an MPL extension type for representing real numbers. The indented use is for compile-time generation of floating-point constants, although it could also be used for MPL-based graph algorithms, etc. The primary design requirement was that almost any compiler would be able to completely inline the conversion to floating-point (which means no functional recursion can be used), and I think I've achieved that. The current implementation uses a modified version of MPL's vector type (modified to add the conversion to floating point, add "overloads", and to remove the typeof-based implementation variant (which is incompatible with the floating-point conversion)). I've posted the code to the Boost vault under the "Template Metaprogramming" section; the file name is boost-mpl-cf-20100531.zip Continued fractions were chosen for the representation because the associated algorithms are simple, and simple proved important for keeping down compilation times. Even so, the compilation times might be too long for practical use. You can decrease the compilation time by using a shorter maximum cf-length by defining BOOST_MPL_LIMIT_CF_SIZE to be 10 instead of 20. The current default is 20 to allow an effective precision near that of a double. Also, continued fractions, being "based on" rational numbers, can exactly represent any rational (for example, 1/3) so the computations can be more accurate than those using a floating-point representation. If you don't know what a continued fraction is, and would like to know, you can check out the wikipedia page: http://en.wikipedia.org/wiki/Continued_fraction The current implementation supports addition, subtraction, multiplication and division, comparison ops, some constants like pi, and I've included sin()/cos() as well. I've not yet written any real documentation, but the archive has a couple of test programs; the usage is pretty simple. Each test program has many individual tests, so its compilation time will be representative of a more-complicated computation, if you just need to do a few things, it would be much faster. If there is interest, I'll add support for generating numbers using metafunctions, write some documentation, jam files, etc. Let me know what you think, and I welcome suggestions, criticisms, etc. Also, I've currently tested using only the GNU and Intel compilers, so let me know whether it does or does not work when using something else. Thanks again, Hal P.S. I know that there is a mpl_math archive on the vault from back in 2007. I did not discover this until after I had almost finished writing my mpl-cf implementation, but, the mailing-list messages from the time indicate that it was too slow to be used practically, since I think the continued fractions algorithms are simpler, mpl-cf might be better, but I've not tested it to find out.