是通过BOOST.UNITS支持尺寸分析的Boost Odeint

Is boost odeint supporting dimensional analysis via Boost.Units?

本文关键字：Boost Odeint BOOST UNITS 支持      更新时间：2023-10-16

我试图实现一个简单的ode来测试boost.dodeint是否支持boost.units的使用。但是，我的示例是在编译时失败。是我的代码，还是不升级。DODEINT支持BOOST.UNITS用于维数分析？

#include<boost/units/systems/si.hpp>
#include<boost/numeric/odeint.hpp>
typedef boost::units::quantity<boost::units::si::length,double> state_type;
typedef boost::units::quantity<velocity,double> dev_type;
typedef boost::units::quantity<boost::units::si::time,double> time_type;

using namespace boost::units::si;
void exponential_decay(const state_type &x, dev_type &dxdt, time_type t){
    dxdt = -0.0001*x/second;
}
int main(){
    state_type startValue = 10*meter;
    using namespace boost::numeric::odeint;
    auto steps = integrate(exponential_decay, startValue, 0.0*second,
            10.0*second, 0.1*second);
    return 0;
}

因此，最初未能找到一组state_type，代数和操作的工作集 @arash提供了缺失的链接。

但是，为了完整性，您需要不是需要带上重型机械(fusion_algebra.hpp(。这些是针对更一般的情况，例如状态类型不是单个值。

在这种简单的情况下，真正需要的就是指定代数，而不是使用默认值。这涉及声明stepper_type，例如：

using stepper_type = runge_kutta4<length_type, double, velocity_type,
                            time_type, vector_space_algebra>;

接下来，我们选择一种迭代算法超载，使我们能够提供该步骤：

活在coliru 

#include <boost/numeric/odeint.hpp>
#include <boost/units/systems/si.hpp>
typedef boost::units::quantity<boost::units::si::length, double> length_type;
typedef boost::units::quantity<boost::units::si::velocity, double> velocity_type;
typedef boost::units::quantity<boost::units::si::time, double> time_type;
namespace si = boost::units::si;
void exponential_decay(const length_type &x, velocity_type &dxdt, time_type /*t*/) { dxdt = -0.0001 * x / si::second; }
int main() {
    using stepper_type = boost::numeric::odeint::runge_kutta4<
        length_type, double, velocity_type, time_type, boost::numeric::odeint::vector_space_algebra>;
    length_type startValue = 10 * si::meter;
    auto steps = integrate_const(
            stepper_type{}, exponential_decay,
            startValue, 0.0 * si::second, 10.0 * si::second,
            0.1 * si::second);
    std::cout << "Steps: " << steps << "n";
}

打印

Steps: 100

¹从http://www.boost.org/doc/libs/1_66_0/libs/numeric/numeric/odeint/doc/doc/doc/html/boost_numereric_ode_odeint/odeint/odeint_in_in_in_in_indet_in_detet_in_detail/state_tate_types_types_types_types_algebras_and_and_operations.htperations.htperations.htpperations and and Htperations.htpperations.htp.org/doc/libs/1_66_0/doc/html/html/boost_units/dentities.html

使用boost::fusion解决问题。

#include <iostream>
#include <vector>
#include <boost/numeric/odeint.hpp>
#include <boost/numeric/odeint/algebra/fusion_algebra.hpp>
#include <boost/numeric/odeint/algebra/fusion_algebra_dispatcher.hpp>
#include <boost/units/systems/si/length.hpp>
#include <boost/units/systems/si/time.hpp>
#include <boost/units/systems/si/velocity.hpp>
#include <boost/units/systems/si/acceleration.hpp>
#include <boost/units/systems/si/io.hpp>
#include <boost/fusion/container.hpp>
using namespace std;
using namespace boost::numeric::odeint;
namespace fusion = boost::fusion;
namespace units = boost::units;
namespace si = boost::units::si;
typedef units::quantity< si::time , double > time_type;
typedef units::quantity< si::length , double > length_type;
typedef units::quantity< si::velocity , double > velocity_type;
typedef units::quantity< si::acceleration , double > acceleration_type;
typedef units::quantity< si::frequency , double > frequency_type;
typedef fusion::vector< length_type  > state_type;
typedef fusion::vector< velocity_type > deriv_type;
void exponential_decay( const state_type &x , deriv_type &dxdt , time_type t )
{
    fusion::at_c< 0 >( dxdt ) = (-0.0001/si::second)* fusion::at_c< 0 >( x );
}
void observer(const state_type &x,const time_type &t )
{
}
int main( int argc , char**argv )
{
    typedef runge_kutta_dopri5< state_type , double , deriv_type , time_type > stepper_type;
    state_type startValue( 1.0 * si::meter );
    auto steps=integrate_adaptive(
        make_dense_output( 1.0e-6 , 1.0e-6 , stepper_type()),
        exponential_decay,
        startValue , 0.0 * si::second , 100.0 * si::second , 0.1 * si::second , observer);
    std::cout<<"steps: "<<steps<<std::endl;
    return 0;
}
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