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Diffstat (limited to 'src/boost/libs/numeric/odeint/examples/thrust/phase_oscillator_ensemble.cu')
-rw-r--r-- | src/boost/libs/numeric/odeint/examples/thrust/phase_oscillator_ensemble.cu | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/src/boost/libs/numeric/odeint/examples/thrust/phase_oscillator_ensemble.cu b/src/boost/libs/numeric/odeint/examples/thrust/phase_oscillator_ensemble.cu new file mode 100644 index 000000000..d678b8f01 --- /dev/null +++ b/src/boost/libs/numeric/odeint/examples/thrust/phase_oscillator_ensemble.cu @@ -0,0 +1,280 @@ +/* + The example how the phase_oscillator ensemble can be implemented using CUDA and thrust + + Copyright 2011-2013 Mario Mulansky + Copyright 2011 Karsten Ahnert + + Distributed under the Boost Software License, Version 1.0. + (See accompanying file LICENSE_1_0.txt or + copy at http://www.boost.org/LICENSE_1_0.txt) + */ + +#include <iostream> +#include <fstream> +#include <cmath> +#include <utility> + +#include <thrust/device_vector.h> +#include <thrust/reduce.h> +#include <thrust/functional.h> + +#include <boost/numeric/odeint.hpp> +#include <boost/numeric/odeint/external/thrust/thrust.hpp> + +#include <boost/timer.hpp> +#include <boost/random/cauchy_distribution.hpp> + +using namespace std; + +using namespace boost::numeric::odeint; + +/* + * Sorry for that dirty hack, but nvcc has large problems with boost::random. + * + * Nevertheless we need the cauchy distribution from boost::random, and therefore + * we need a generator. Here it is: + */ +struct drand48_generator +{ + typedef double result_type; + result_type operator()( void ) const { return drand48(); } + result_type min( void ) const { return 0.0; } + result_type max( void ) const { return 1.0; } +}; + +//[ thrust_phase_ensemble_state_type +//change this to float if your device does not support double computation +typedef double value_type; + +//change this to host_vector< ... > of you want to run on CPU +typedef thrust::device_vector< value_type > state_type; +// typedef thrust::host_vector< value_type > state_type; +//] + + +//[ thrust_phase_ensemble_mean_field_calculator +struct mean_field_calculator +{ + struct sin_functor : public thrust::unary_function< value_type , value_type > + { + __host__ __device__ + value_type operator()( value_type x) const + { + return sin( x ); + } + }; + + struct cos_functor : public thrust::unary_function< value_type , value_type > + { + __host__ __device__ + value_type operator()( value_type x) const + { + return cos( x ); + } + }; + + static std::pair< value_type , value_type > get_mean( const state_type &x ) + { + //[ thrust_phase_ensemble_sin_sum + value_type sin_sum = thrust::reduce( + thrust::make_transform_iterator( x.begin() , sin_functor() ) , + thrust::make_transform_iterator( x.end() , sin_functor() ) ); + //] + value_type cos_sum = thrust::reduce( + thrust::make_transform_iterator( x.begin() , cos_functor() ) , + thrust::make_transform_iterator( x.end() , cos_functor() ) ); + + cos_sum /= value_type( x.size() ); + sin_sum /= value_type( x.size() ); + + value_type K = sqrt( cos_sum * cos_sum + sin_sum * sin_sum ); + value_type Theta = atan2( sin_sum , cos_sum ); + + return std::make_pair( K , Theta ); + } +}; +//] + + + +//[ thrust_phase_ensemble_sys_function +class phase_oscillator_ensemble +{ + +public: + + struct sys_functor + { + value_type m_K , m_Theta , m_epsilon; + + sys_functor( value_type K , value_type Theta , value_type epsilon ) + : m_K( K ) , m_Theta( Theta ) , m_epsilon( epsilon ) { } + + template< class Tuple > + __host__ __device__ + void operator()( Tuple t ) + { + thrust::get<2>(t) = thrust::get<1>(t) + m_epsilon * m_K * sin( m_Theta - thrust::get<0>(t) ); + } + }; + + // ... + //<- + phase_oscillator_ensemble( size_t N , value_type g = 1.0 , value_type epsilon = 1.0 ) + : m_omega() , m_N( N ) , m_epsilon( epsilon ) + { + create_frequencies( g ); + } + + void create_frequencies( value_type g ) + { + boost::cauchy_distribution< value_type > cauchy( 0.0 , g ); +// boost::variate_generator< boost::mt19937&, boost::cauchy_distribution< value_type > > gen( rng , cauchy ); + drand48_generator d48; + vector< value_type > omega( m_N ); + for( size_t i=0 ; i<m_N ; ++i ) + omega[i] = cauchy( d48 ); +// generate( omega.begin() , omega.end() , gen ); + m_omega = omega; + } + + void set_epsilon( value_type epsilon ) { m_epsilon = epsilon; } + + value_type get_epsilon( void ) const { return m_epsilon; } + //-> + + void operator() ( const state_type &x , state_type &dxdt , const value_type dt ) const + { + std::pair< value_type , value_type > mean_field = mean_field_calculator::get_mean( x ); + + thrust::for_each( + thrust::make_zip_iterator( thrust::make_tuple( x.begin() , m_omega.begin() , dxdt.begin() ) ), + thrust::make_zip_iterator( thrust::make_tuple( x.end() , m_omega.end() , dxdt.end()) ) , + sys_functor( mean_field.first , mean_field.second , m_epsilon ) + ); + } + + // ... + //<- +private: + + state_type m_omega; + const size_t m_N; + value_type m_epsilon; + //-> +}; +//] + + +//[ thrust_phase_ensemble_observer +struct statistics_observer +{ + value_type m_K_mean; + size_t m_count; + + statistics_observer( void ) + : m_K_mean( 0.0 ) , m_count( 0 ) { } + + template< class State > + void operator()( const State &x , value_type t ) + { + std::pair< value_type , value_type > mean = mean_field_calculator::get_mean( x ); + m_K_mean += mean.first; + ++m_count; + } + + value_type get_K_mean( void ) const { return ( m_count != 0 ) ? m_K_mean / value_type( m_count ) : 0.0 ; } + + void reset( void ) { m_K_mean = 0.0; m_count = 0; } +}; +//] + + + +// const size_t N = 16384 * 128; +const size_t N = 16384; +const value_type pi = 3.1415926535897932384626433832795029; +const value_type dt = 0.1; +const value_type d_epsilon = 0.1; +const value_type epsilon_min = 0.0; +const value_type epsilon_max = 5.0; +const value_type t_transients = 10.0; +const value_type t_max = 100.0; + +int main( int arc , char* argv[] ) +{ + // initial conditions on host + vector< value_type > x_host( N ); + for( size_t i=0 ; i<N ; ++i ) x_host[i] = 2.0 * pi * drand48(); + + //[ thrust_phase_ensemble_system_instance + phase_oscillator_ensemble ensemble( N , 1.0 ); + //] + + + + boost::timer timer; + boost::timer timer_local; + double dopri5_time = 0.0 , rk4_time = 0.0; + { + //[thrust_phase_ensemble_define_dopri5 + typedef runge_kutta_dopri5< state_type , value_type , state_type , value_type > stepper_type; + //] + + ofstream fout( "phase_ensemble_dopri5.dat" ); + timer.restart(); + for( value_type epsilon = epsilon_min ; epsilon < epsilon_max ; epsilon += d_epsilon ) + { + ensemble.set_epsilon( epsilon ); + statistics_observer obs; + state_type x = x_host; + + timer_local.restart(); + + // calculate some transients steps + //[ thrust_phase_ensemble_integration + size_t steps1 = integrate_const( make_controlled( 1.0e-6 , 1.0e-6 , stepper_type() ) , boost::ref( ensemble ) , x , 0.0 , t_transients , dt ); + //] + + // integrate and compute the statistics + size_t steps2 = integrate_const( make_dense_output( 1.0e-6 , 1.0e-6 , stepper_type() ) , boost::ref( ensemble ) , x , 0.0 , t_max , dt , boost::ref( obs ) ); + + fout << epsilon << "\t" << obs.get_K_mean() << endl; + cout << "Dopri5 : " << epsilon << "\t" << obs.get_K_mean() << "\t" << timer_local.elapsed() << "\t" << steps1 << "\t" << steps2 << endl; + } + dopri5_time = timer.elapsed(); + } + + + + { + //[ thrust_phase_ensemble_define_rk4 + typedef runge_kutta4< state_type , value_type , state_type , value_type > stepper_type; + //] + + ofstream fout( "phase_ensemble_rk4.dat" ); + timer.restart(); + for( value_type epsilon = epsilon_min ; epsilon < epsilon_max ; epsilon += d_epsilon ) + { + ensemble.set_epsilon( epsilon ); + statistics_observer obs; + state_type x = x_host; + + timer_local.restart(); + + // calculate some transients steps + size_t steps1 = integrate_const( stepper_type() , boost::ref( ensemble ) , x , 0.0 , t_transients , dt ); + + // integrate and compute the statistics + size_t steps2 = integrate_const( stepper_type() , boost::ref( ensemble ) , x , 0.0 , t_max , dt , boost::ref( obs ) ); + fout << epsilon << "\t" << obs.get_K_mean() << endl; + cout << "RK4 : " << epsilon << "\t" << obs.get_K_mean() << "\t" << timer_local.elapsed() << "\t" << steps1 << "\t" << steps2 << endl; + } + rk4_time = timer.elapsed(); + } + + cout << "Dopri 5 : " << dopri5_time << " s\n"; + cout << "RK4 : " << rk4_time << "\n"; + + return 0; +} |