Re: [Boost-users] [units] inconvent printing of composite scaled units

Subject: Re: [Boost-users] [units] inconvent printing of composite scaled units
From: Matthias Schabel (boost_at_[hidden])
Date: 2010-07-24 22:23:08

You might want to take a look at the implementation of the CGS system - I believe centimeters are treated in the way you want...

Matthais

> In the following program,
> a quantity of fempto*second unit is printed as
> 0 fs (correctly)
> but a quantity of composed units composed meter over femptosecond  is
> printed as
> P( m s^-1)
> I was expecting:
> m fs^-1
> 
> At first I though it was a bug, where the P is coming from? where the
> parenthesis is coming from?, but then I realized  that P stands for
> Peta (10e15).
> 
> is there any workaround? For example an easy way to define fs_unit in
> some other way such that the f (fempto) keeps attached to the s
> (second).
> 
> Below is the example code
> 
> #include<boost/units/systems/si.hpp>
> #include<boost/units/make_scaled_unit.hpp>
> #include<iostream>
> using namespace boost::units;
> using namespace std;
> int main(){
> 	typedef make_scaled_unit<si::time, scale<10, static_rational<-15> >
>> ::type fs_unit;
> 	quantity<fs_unit> t(1.*si::second);
> 	quantity<si::length> l(1.*si::meter);
> 	quantity<divide_typeof_helper<si::length, fs_unit>::type > v = l/t;
> 	cout << t << endl; // prints  1e+15 fs
> 	cout << l << endl; // prints 1 m
> 	cout << v << endl; //prints 1e-15 P(m s^-1), notice the P
> 	return 0;
> }
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