Dylan Thurston writes: | Any such system would probably not be able to type (^), since the | output type depends on the exponent. I think that is acceptable. In other words, the first argument to (^) would have to be dimensionless? I agree. So would the arguments to trig functions, etc. Ashley Yakeley writes: | Very occasionally non-integer or 'fractal' exponents of dimensions | are useful. For instance, geographic coastlines can be measured in | km ^ n, where 1 <= n < 2. This doesn't stop the CIA world factbook | listing all coastline lengths in straight kilometres, however. David Barton writes: | Even without fractals, there are cases where weird dimensions come | up (I ran across this in my old MHDL (microwave) days). Square | root volts is the example that was constantly thrown in my face. In both of those cases, the apparent non-integer dimension is accompanied by a particular unit (km, V). So, could they equally well be handled by stripping away the units and exponentiating a dimensionless number? For example: (x / 1V) ^ y Regards, Tom