| /* |
| * Copyright 2012 Karsten Ahnert |
| * Copyright 2013 Mario Mulansky |
| * |
| * 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 <vector> |
| |
| #include <vexcl/vexcl.hpp> |
| |
| #include <boost/numeric/odeint.hpp> |
| //[ vexcl_includes |
| #include <boost/numeric/odeint/external/vexcl/vexcl.hpp> |
| //] |
| |
| namespace odeint = boost::numeric::odeint; |
| |
| //[ vexcl_state_types |
| typedef vex::vector< double > vector_type; |
| typedef vex::multivector< double, 3 > state_type; |
| //] |
| |
| |
| //[ vexcl_system |
| const double sigma = 10.0; |
| const double b = 8.0 / 3.0; |
| |
| struct sys_func |
| { |
| const vector_type &R; |
| |
| sys_func( const vector_type &_R ) : R( _R ) { } |
| |
| void operator()( const state_type &x , state_type &dxdt , double t ) const |
| { |
| dxdt(0) = -sigma * ( x(0) - x(1) ); |
| dxdt(1) = R * x(0) - x(1) - x(0) * x(2); |
| dxdt(2) = - b * x(2) + x(0) * x(1); |
| } |
| }; |
| //] |
| |
| |
| int main( int argc , char **argv ) |
| { |
| using namespace std; |
| using namespace odeint; |
| |
| //[ vexcl_main |
| // setup the opencl context |
| vex::Context ctx( vex::Filter::Type(CL_DEVICE_TYPE_GPU) ); |
| std::cout << ctx << std::endl; |
| |
| // set up number of system, time step and integration time |
| const size_t n = 1024 * 1024; |
| const double dt = 0.01; |
| const double t_max = 1000.0; |
| |
| // initialize R |
| double Rmin = 0.1 , Rmax = 50.0 , dR = ( Rmax - Rmin ) / double( n - 1 ); |
| std::vector<double> x( n * 3 ) , r( n ); |
| for( size_t i=0 ; i<n ; ++i ) r[i] = Rmin + dR * double( i ); |
| vector_type R( ctx.queue() , r ); |
| |
| // initialize the state of the lorenz ensemble |
| state_type X(ctx.queue(), n); |
| X(0) = 10.0; |
| X(1) = 10.0; |
| X(2) = 10.0; |
| |
| // create a stepper |
| runge_kutta4< state_type > stepper; |
| |
| // solve the system |
| integrate_const( stepper , sys_func( R ) , X , 0.0 , t_max , dt ); |
| //] |
| |
| std::vector< double > res( 3 * n ); |
| vex::copy( X(0) , res ); |
| for( size_t i=0 ; i<n ; ++i ) |
| cout << r[i] << "\t" << res[i] << "\t" << "\n"; |
| } |