i've started to work on the variants that were brought up in a previous discussion about boost::rational<> the current code can be found at www.ccg.hu/pub/src/rat atm it is only for getting the calculations right, so no templates, optimizations, boostification, nice interface etc, and i only tested it with MSVC 7.1 there is also no implementation yet geared towards an unlimited precision representation the variants are: - legacy boost (no rounding, silently gives wrong results) - exceptions are thrown if the result overflows or cannot be represented - rounding - rounding & maintaining an exactness indicator is there anything missing from the list? there is also a simple test-bed, it runs the four basic operations 10000 times on random inputs, and collects some statistics: addition and substraction overflowed 0 times, and the result was exactly representable 44 times; the average error of the legacy code is 475%, and of the rounding code is 0.005% (the exception-throwing variant throws, so there is no error figure for that) multiplication and division overflowed once, and the result was exactly representable 79 times; the average error of the legacy code is 2025%, and of the rounding code is 0.01% it would be nice to get some advice on how the final interface should look like (and of course regarding everything else, including whether there is a point to continue the work): - any ideas for naming the variants? - how should the parameters of rational<> look like? my favourite would be rational<prec,method> where prec is the maximum absolute value allowed for numerators and denominators, and method is one of the variants from above, e.g. rational<10000,round> would be a rounding rational with four decimal digits for the numerator and denominator. of course this would cripple rational<> to be int-based, so maybe specifying the number of bits to be used instead of the maximum value is a sensible approach. (still don't know though how would user-defined types be selected based on this, so maybe the original boost approach is the only workable one.) br, andras ps: i have tried to search the archive for past discussions about rational<> to avoid repeating old stuff, but with very limited success (only the latest posts seem to be accessible) -- any hints?