297 lines
10 KiB
Plaintext
297 lines
10 KiB
Plaintext
/*
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Copyright 2011-2012 Karsten Ahnert
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Copyright 2011-2013 Mario Mulansky
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Distributed under the Boost Software License, Version 1.0.
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(See accompanying file LICENSE_1_0.txt or
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copy at http://www.boost.org/LICENSE_1_0.txt)
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*/
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#include <iostream>
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#include <cmath>
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#include <utility>
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#include <thrust/device_vector.h>
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#include <thrust/reduce.h>
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#include <thrust/functional.h>
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#include <boost/numeric/odeint.hpp>
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#include <boost/numeric/odeint/external/thrust/thrust.hpp>
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#include <boost/random/mersenne_twister.hpp>
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#include <boost/random/uniform_real.hpp>
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#include <boost/random/variate_generator.hpp>
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using namespace std;
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using namespace boost::numeric::odeint;
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//change this to float if your device does not support double computation
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typedef double value_type;
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//change this to host_vector< ... > of you want to run on CPU
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typedef thrust::device_vector< value_type > state_type;
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typedef thrust::device_vector< size_t > index_vector_type;
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// typedef thrust::host_vector< value_type > state_type;
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// typedef thrust::host_vector< size_t > index_vector_type;
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const value_type sigma = 10.0;
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const value_type b = 8.0 / 3.0;
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//[ thrust_lorenz_parameters_define_simple_system
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struct lorenz_system
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{
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struct lorenz_functor
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{
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template< class T >
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__host__ __device__
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void operator()( T t ) const
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{
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// unpack the parameter we want to vary and the Lorenz variables
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value_type R = thrust::get< 3 >( t );
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value_type x = thrust::get< 0 >( t );
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value_type y = thrust::get< 1 >( t );
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value_type z = thrust::get< 2 >( t );
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thrust::get< 4 >( t ) = sigma * ( y - x );
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thrust::get< 5 >( t ) = R * x - y - x * z;
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thrust::get< 6 >( t ) = -b * z + x * y ;
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}
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};
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lorenz_system( size_t N , const state_type &beta )
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: m_N( N ) , m_beta( beta ) { }
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template< class State , class Deriv >
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void operator()( const State &x , Deriv &dxdt , value_type t ) const
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{
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thrust::for_each(
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) ,
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boost::begin( x ) + m_N ,
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boost::begin( x ) + 2 * m_N ,
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m_beta.begin() ,
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boost::begin( dxdt ) ,
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boost::begin( dxdt ) + m_N ,
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boost::begin( dxdt ) + 2 * m_N ) ) ,
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) + m_N ,
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boost::begin( x ) + 2 * m_N ,
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boost::begin( x ) + 3 * m_N ,
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m_beta.begin() ,
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boost::begin( dxdt ) + m_N ,
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boost::begin( dxdt ) + 2 * m_N ,
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boost::begin( dxdt ) + 3 * m_N ) ) ,
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lorenz_functor() );
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}
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size_t m_N;
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const state_type &m_beta;
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};
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//]
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struct lorenz_perturbation_system
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{
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struct lorenz_perturbation_functor
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{
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template< class T >
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__host__ __device__
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void operator()( T t ) const
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{
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value_type R = thrust::get< 1 >( t );
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value_type x = thrust::get< 0 >( thrust::get< 0 >( t ) );
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value_type y = thrust::get< 1 >( thrust::get< 0 >( t ) );
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value_type z = thrust::get< 2 >( thrust::get< 0 >( t ) );
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value_type dx = thrust::get< 3 >( thrust::get< 0 >( t ) );
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value_type dy = thrust::get< 4 >( thrust::get< 0 >( t ) );
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value_type dz = thrust::get< 5 >( thrust::get< 0 >( t ) );
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thrust::get< 0 >( thrust::get< 2 >( t ) ) = sigma * ( y - x );
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thrust::get< 1 >( thrust::get< 2 >( t ) ) = R * x - y - x * z;
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thrust::get< 2 >( thrust::get< 2 >( t ) ) = -b * z + x * y ;
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thrust::get< 3 >( thrust::get< 2 >( t ) ) = sigma * ( dy - dx );
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thrust::get< 4 >( thrust::get< 2 >( t ) ) = ( R - z ) * dx - dy - x * dz;
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thrust::get< 5 >( thrust::get< 2 >( t ) ) = y * dx + x * dy - b * dz;
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}
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};
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lorenz_perturbation_system( size_t N , const state_type &beta )
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: m_N( N ) , m_beta( beta ) { }
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template< class State , class Deriv >
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void operator()( const State &x , Deriv &dxdt , value_type t ) const
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{
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thrust::for_each(
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thrust::make_zip_iterator( thrust::make_tuple(
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) ,
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boost::begin( x ) + m_N ,
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boost::begin( x ) + 2 * m_N ,
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boost::begin( x ) + 3 * m_N ,
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boost::begin( x ) + 4 * m_N ,
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boost::begin( x ) + 5 * m_N ) ) ,
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m_beta.begin() ,
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( dxdt ) ,
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boost::begin( dxdt ) + m_N ,
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boost::begin( dxdt ) + 2 * m_N ,
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boost::begin( dxdt ) + 3 * m_N ,
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boost::begin( dxdt ) + 4 * m_N ,
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boost::begin( dxdt ) + 5 * m_N ) )
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) ) ,
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thrust::make_zip_iterator( thrust::make_tuple(
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) + m_N ,
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boost::begin( x ) + 2 * m_N ,
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boost::begin( x ) + 3 * m_N ,
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boost::begin( x ) + 4 * m_N ,
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boost::begin( x ) + 5 * m_N ,
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boost::begin( x ) + 6 * m_N ) ) ,
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m_beta.begin() ,
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( dxdt ) + m_N ,
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boost::begin( dxdt ) + 2 * m_N ,
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boost::begin( dxdt ) + 3 * m_N ,
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boost::begin( dxdt ) + 4 * m_N ,
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boost::begin( dxdt ) + 5 * m_N ,
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boost::begin( dxdt ) + 6 * m_N ) )
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) ) ,
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lorenz_perturbation_functor() );
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}
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size_t m_N;
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const state_type &m_beta;
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};
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struct lyap_observer
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{
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//[thrust_lorenz_parameters_observer_functor
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struct lyap_functor
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{
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template< class T >
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__host__ __device__
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void operator()( T t ) const
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{
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value_type &dx = thrust::get< 0 >( t );
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value_type &dy = thrust::get< 1 >( t );
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value_type &dz = thrust::get< 2 >( t );
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value_type norm = sqrt( dx * dx + dy * dy + dz * dz );
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dx /= norm;
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dy /= norm;
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dz /= norm;
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thrust::get< 3 >( t ) += log( norm );
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}
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};
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//]
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lyap_observer( size_t N , size_t every = 100 )
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: m_N( N ) , m_lyap( N ) , m_every( every ) , m_count( 0 )
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{
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thrust::fill( m_lyap.begin() , m_lyap.end() , 0.0 );
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}
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template< class Lyap >
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void fill_lyap( Lyap &lyap )
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{
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thrust::copy( m_lyap.begin() , m_lyap.end() , lyap.begin() );
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for( size_t i=0 ; i<lyap.size() ; ++i )
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lyap[i] /= m_t_overall;
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}
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template< class State >
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void operator()( State &x , value_type t )
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{
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if( ( m_count != 0 ) && ( ( m_count % m_every ) == 0 ) )
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{
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thrust::for_each(
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) + 3 * m_N ,
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boost::begin( x ) + 4 * m_N ,
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boost::begin( x ) + 5 * m_N ,
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m_lyap.begin() ) ) ,
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thrust::make_zip_iterator( thrust::make_tuple(
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boost::begin( x ) + 4 * m_N ,
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boost::begin( x ) + 5 * m_N ,
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boost::begin( x ) + 6 * m_N ,
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m_lyap.end() ) ) ,
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lyap_functor() );
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clog << t << "\n";
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}
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++m_count;
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m_t_overall = t;
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}
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size_t m_N;
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state_type m_lyap;
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size_t m_every;
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size_t m_count;
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value_type m_t_overall;
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};
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const size_t N = 1024*2;
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const value_type dt = 0.01;
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int main( int arc , char* argv[] )
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{
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int driver_version , runtime_version;
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cudaDriverGetVersion( &driver_version );
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cudaRuntimeGetVersion ( &runtime_version );
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cout << driver_version << "\t" << runtime_version << endl;
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//[ thrust_lorenz_parameters_define_beta
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vector< value_type > beta_host( N );
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const value_type beta_min = 0.0 , beta_max = 56.0;
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for( size_t i=0 ; i<N ; ++i )
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beta_host[i] = beta_min + value_type( i ) * ( beta_max - beta_min ) / value_type( N - 1 );
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state_type beta = beta_host;
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//]
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//[ thrust_lorenz_parameters_integration
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state_type x( 6 * N );
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// initialize x,y,z
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thrust::fill( x.begin() , x.begin() + 3 * N , 10.0 );
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// initial dx
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thrust::fill( x.begin() + 3 * N , x.begin() + 4 * N , 1.0 );
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// initialize dy,dz
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thrust::fill( x.begin() + 4 * N , x.end() , 0.0 );
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// create error stepper, can be used with make_controlled or make_dense_output
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typedef runge_kutta_dopri5< state_type , value_type , state_type , value_type > stepper_type;
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lorenz_system lorenz( N , beta );
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lorenz_perturbation_system lorenz_perturbation( N , beta );
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lyap_observer obs( N , 1 );
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// calculate transients
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integrate_adaptive( make_controlled( 1.0e-6 , 1.0e-6 , stepper_type() ) , lorenz , std::make_pair( x.begin() , x.begin() + 3 * N ) , 0.0 , 10.0 , dt );
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// calculate the Lyapunov exponents -- the main loop
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double t = 0.0;
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while( t < 10000.0 )
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{
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integrate_adaptive( make_controlled( 1.0e-6 , 1.0e-6 , stepper_type() ) , lorenz_perturbation , x , t , t + 1.0 , 0.1 );
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t += 1.0;
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obs( x , t );
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}
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vector< value_type > lyap( N );
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obs.fill_lyap( lyap );
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for( size_t i=0 ; i<N ; ++i )
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cout << beta_host[i] << "\t" << lyap[i] << "\n";
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//]
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return 0;
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}
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