Steven,

Thanks! That worked perfectly. I spent quite a bit of time trying to solve this problem and others similar to it, and could not find anything in the examples. Would it be reasonable if I were to take a bit of time to add this example to conversion.cpp (or whatever example you feel is appropriate) and add it to the documentation?

Cheers!
Andrew Hundt

-------------------------------------------------------------------------
For those who search for boost.units conversion examples, here is a working solution boostUnits.cpp:

    #include <boost/units/systems/si.hpp>
    #include <boost/units/systems/angle/revolutions.hpp>
    #include <boost/units/systems/angle/degrees.hpp>
    #include <boost/units/conversion.hpp>
    #include <boost/units/pow.hpp>
    #include <iostream>
    #include <iterator>
    #include <algorithm>

      typedef boost::units::divide_typeof_helper<
          boost::units::degree::plane_angle,
          boost::units::si::time
      >::type degrees_per_second;

    int main()
    {

      boost::units::quantity< boost::units::si::angular_velocity> m_speed((30.0*boost::units::si::radians_per_second));
      std::cout << "m_speed rad/sec: " << m_speed << std::endl;

      std::cout << " m_speed deg/sec: "<< static_cast<boost::units::quantity<degrees_per_second> >(m_speed) << std::endl;
      uint32_t result = static_cast<uint32_t>(static_cast<boost::units::quantity<degrees_per_second> >(m_speed).value());
      std::cout << " int result: "<< result << std::endl;

      return(0);
    }

-------------------------------------------------------------------------
Output:
g++ boostUnits.cpp
./a.out 
m_speed rad/sec: 30 s^-1 rad
 m_speed deg/sec: 1718.87 deg s^-1
 int result: 1718

-------------------------------------------------------------------------

Steven Watanabe <watanabesj <at> gmail.com> writes:

> 
> AMDG
> 
> On 12/1/2010 11:10 AM, Andrew Hundt wrote:
> > I have made my question more specific so it will be easier to answer.
> > I need to make a conversion from a general angular_velocity to
> > degrees/second.
> 
> There's no such thing as a general angular_velocity.
> I assume that you mean that you want to convert
> from radians/second to degrees/second.
> 
> > To illustrate this problem the example boostUnits.cpp:
> >
> >      #include<boost/units/systems/si.hpp>
> >      #include<boost/units/systems/angle/revolutions.hpp>
> >      #include<boost/units/systems/angle/degrees.hpp>
> >      #include<boost/units/conversion.hpp>
> >      #include<boost/units/pow.hpp>
> >      #include<iostream>
> >      #include<iterator>
> >      #include<algorithm>
> >
> >      int main()
> >      {
> >        boost::units::quantity<  boost::units::si::angular_velocity>
> > m_speed((30.0*boost::units::si::radians_per_second));
> >        std::cout<<  "m_speed: "<<  m_speed<<  std::endl;
> >
> >        uint32_t result =
> > static_cast<uint32_t>(boost::units::quantity<boost::units::si::angular_velocity,uint32_t>(m_speed*boost::units::degree::degrees/boost::units::si::seconds).value());
> >        std::cout<<  " result:"<<  result<<  std::endl;
> >
> >        return(0);
> >      }
> 
> Try
> 
> typedef boost::units::divide_typeof_helper<
>      boost::units::degree::plane_angle,
>      boost::units::si::time
>  >::type degrees_per_second;
> 
> static_cast<boost::units::quantity<degrees_per_second> >(m_speed);
> 
> In Christ,
> Steven Watanabe
> 


Cheers!
Andrew Hundt



On Wed, Dec 1, 2010 at 2:10 PM, Andrew Hundt <athundt@gmail.com> wrote:
I have made my question more specific so it will be easier to answer.
I need to make a conversion from a general angular_velocity to degrees/second. 

To illustrate this problem the example boostUnits.cpp:

    #include <boost/units/systems/si.hpp>
    #include <boost/units/systems/angle/revolutions.hpp>
    #include <boost/units/systems/angle/degrees.hpp>
    #include <boost/units/conversion.hpp>
    #include <boost/units/pow.hpp>
    #include <iostream>
    #include <iterator>
    #include <algorithm>

    int main()
    {
      boost::units::quantity< boost::units::si::angular_velocity> m_speed((30.0*boost::units::si::radians_per_second));
      std::cout << "m_speed: " << m_speed << std::endl;
      
      uint32_t result = static_cast<uint32_t>(boost::units::quantity<boost::units::si::angular_velocity,uint32_t>(m_speed*boost::units::degree::degrees/boost::units::si::seconds).value());
      std::cout << " result: "<< result << std::endl;

      return(0);
    }

Produces this compiler output:

    g++ boostUnits.cpp
    /usr/local/include/boost/units/detail/conversion_impl.hpp: In static member function ‘static boost::units::quantity<Unit2, T2> boost::units::conversion_helper<boost::units::quantity<Unit1, T1>, boost::units::quantity<Unit2, T2> >::convert(const boost::units::quantity<Unit1, T1>&) [with Unit1 = boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::degree_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::second_base_unit, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::radian_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> > >, boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::dimensionless_type> >, void>, T1 = double, Unit2 = boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000001l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> >, boost::units::homogeneous_system<boost::units::list<boost::units::si::meter_base_unit, boost::units::list<boost::units::scaled_base_unit<boost::units::cgs::gram_base_unit, boost::units::scale<10l, boost::units::static_rational<3l, 1l> > >, boost::units::list<boost::units::si::second_base_unit, boost::units::list<boost::units::si::ampere_base_unit, boost::units::list<boost::units::si::kelvin_base_unit, boost::units::list<boost::units::si::mole_base_unit, boost::units::list<boost::units::si::candela_base_unit, boost::units::list<boost::units::angle::radian_base_unit, boost::units::list<boost::units::angle::steradian_base_unit, boost::units::dimensionless_type> > > > > > > > > >, void>, T2 = unsigned int]’:
    /usr/local/include/boost/units/quantity.hpp:193:   instantiated from ‘boost::units::quantity<Unit, Y>::quantity(const boost::units::quantity<Unit2, YY>&, typename boost::disable_if<boost::mpl::and_<typename boost::units::is_implicitly_convertible<Unit2, Unit>::type, boost::units::detail::is_non_narrowing_conversion<YY, Y>, mpl_::bool_<true>, mpl_::bool_<true>, mpl_::bool_<true> >, typename boost::units::detail::disable_if_is_same<Unit, Unit2>::type>::type*) [with Unit2 = boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::degree_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::second_base_unit, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::radian_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> > >, boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::dimensionless_type> >, void>, YY = double, Unit = boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000001l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> >, boost::units::homogeneous_system<boost::units::list<boost::units::si::meter_base_unit, boost::units::list<boost::units::scaled_base_unit<boost::units::cgs::gram_base_unit, boost::units::scale<10l, boost::units::static_rational<3l, 1l> > >, boost::units::list<boost::units::si::second_base_unit, boost::units::list<boost::units::si::ampere_base_unit, boost::units::list<boost::units::si::kelvin_base_unit, boost::units::list<boost::units::si::mole_base_unit, boost::units::list<boost::units::si::candela_base_unit, boost::units::list<boost::units::angle::radian_base_unit, boost::units::list<boost::units::angle::steradian_base_unit, boost::units::dimensionless_type> > > > > > > > > >, void>, Y = unsigned int]’
    boostUnits.cpp:16:   instantiated from here
    /usr/local/include/boost/units/detail/conversion_impl.hpp:345: error: no matching function for call to ‘conversion_factor(boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::heterogeneous_system<boost::units::heterogeneous_system_impl<boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::degree_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::si::second_base_unit, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::heterogeneous_system_dim<boost::units::angle::radian_base_unit, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> > >, boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000002l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<2l, 1l> >, boost::units::dimensionless_type> >, boost::units::dimensionless_type> >, void>&, boost::units::unit<boost::units::list<boost::units::dim<boost::units::time_base_dimension, boost::units::static_rational<-0x000000001l, 1l> >, boost::units::list<boost::units::dim<boost::units::plane_angle_base_dimension, boost::units::static_rational<1l, 1l> >, boost::units::dimensionless_type> >, boost::units::homogeneous_system<boost::units::list<boost::units::si::meter_base_unit, boost::units::list<boost::units::scaled_base_unit<boost::units::cgs::gram_base_unit, boost::units::scale<10l, boost::units::static_rational<3l, 1l> > >, boost::units::list<boost::units::si::second_base_unit, boost::units::list<boost::units::si::ampere_base_unit, boost::units::list<boost::units::si::kelvin_base_unit, boost::units::list<boost::units::si::mole_base_unit, boost::units::list<boost::units::si::candela_base_unit, boost::units::list<boost::units::angle::radian_base_unit, boost::units::list<boost::units::angle::steradian_base_unit, boost::units::dimensionless_type> > > > > > > > > >, void>&)’

What is the syntax to achieve the desired type specification and subsequent conversion? 
Do I need to specify a degrees_per_second unit, and if so, how? 

Thank you in advance for your help.

Cheers!
Andrew Hundt



On Tue, Nov 30, 2010 at 7:29 PM, Andrew Hundt <athundt@gmail.com> wrote:
I need to make a conversion from a general angular_velocity to degrees/second. For example:

  boost::units::quantity< boost::units::si::angular_velocity> m_speed((30.0*boost::units::si::radians_per_second));
  uint32_t result = static_cast<uint32_t>(boost::units::quantity<boost::units::si::angular_velocity,uint32_t>(m_speed*boost::units::degree::degrees/boost::units::si::seconds).value());

However it fails to compile in gcc 4.4, reporting:
 error:incomplete type '[type removed]' used in nested name specifier

Could someone explain the proper syntax to achieve the desired type specification and subsequent conversion? Do I need to specify a degrees_per_second unit, and if so, how? Thank you in advance for your help.

Cheers!
Andrew Hundt