Boost logo

Boost :

From: Deane Yang (deane_yang_at_[hidden])
Date: 2006-08-26 10:55:47

Andy Little wrote:

>> Can the dimension checking part of the library be used without the SI
>> unit system? For most other unit systems I use, I mainly need
>> dimension checking and not conversions between different units, such
>> as km or m? Thus just a quantity with dimensions would be useful to
>> catch programming errors.
> Yes. In the signature fixed_quantity<Unit, ValueType>, the Unit parameter can
> be so modelled that it only allows base units to be used, and in this case there
> is no conversion overhead BTW, a multiply is simply a multiply of the numeric
> values for example). By default Quan wont work across Unit models (IOW the
> class template names of units must match), which means that attempting to do
> calculations between Units with different class template names will fail at
> compile time. By this means you can guarantee that you can prevent any
> conversions. (FWIW there is also the option to allow unit conversions but make
> them explicit, prompted by Deane Yang easrlier in this thread.)

I guess I wasn't particularly clear earlier in this thread, because
fixed_quantity appears to be what I want. I'm sorry for not RTFM (I did
try to read the documentation once, but my memory is not what it used to
be), but I have two quick questions:

1) Does operator*(fixed_quantity<Unit1, ValueType1> x,
fixed_quantity<Unit2, ValueType2> y) work and, if so, what is the result
type, assuming that operator*(ValueType1 v, ValueType2 w) returns a

2) Can you raise a fixed_quantity to a rational power (I personally only
need the power 1/2)?


Boost list run by bdawes at, gregod at, cpdaniel at, john at