Re: [Boost-users] [Units] Converting from angular_velocity to degrees_per_second

Subject: Re: [Boost-users] [Units] Converting from angular_velocity to degrees_per_second
From: Andrew Hundt (athundt_at_[hidden])
Date: 2010-12-01 14:10:34

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_at_[hidden]> 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
>
>