Merge commit '4ebe6417a5fce5f0994fc0c31bebf732be96a07c' as 'boost'

2026-07-30 05:54:22 -04:00 · 2018-06-09 21:48:33 +01:00
parent b5eabc6d6a 4ebe6417a5
commit 5abe797e3c
12444 changed files with 2327021 additions and 0 deletions
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+/*
+ * phase_chain.cpp
+ *
+ * Example of OMP parallelization with odeint
+ *
+ * Copyright 2013 Karsten Ahnert
+ * Copyright 2013 Mario Mulansky
+ * Copyright 2013 Pascal Germroth
+ * 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 <boost/random.hpp>
+#include <boost/timer/timer.hpp>
+//[phase_chain_openmp_header
+#include <omp.h>
+#include <boost/numeric/odeint.hpp>
+#include <boost/numeric/odeint/external/openmp/openmp.hpp>
+//]
+
+using namespace std;
+using namespace boost::numeric::odeint;
+using boost::timer::cpu_timer;
+using boost::math::double_constants::pi;
+
+//[phase_chain_vector_state
+typedef std::vector< double > state_type;
+//]
+
+//[phase_chain_rhs
+struct phase_chain
+{
+    phase_chain( double gamma = 0.5 )
+    : m_gamma( gamma ) { }
+
+    void operator()( const state_type &x , state_type &dxdt , double /* t */ ) const
+    {
+        const size_t N = x.size();
+        #pragma omp parallel for schedule(runtime)
+        for(size_t i = 1 ; i < N - 1 ; ++i)
+        {
+            dxdt[i] = coupling_func( x[i+1] - x[i] ) +
+                      coupling_func( x[i-1] - x[i] );
+        }
+        dxdt[0  ] = coupling_func( x[1  ] - x[0  ] );
+        dxdt[N-1] = coupling_func( x[N-2] - x[N-1] );
+    }
+
+    double coupling_func( double x ) const
+    {
+        return sin( x ) - m_gamma * ( 1.0 - cos( x ) );
+    }
+
+    double m_gamma;
+};
+//]
+
+
+int main( int argc , char **argv )
+{
+    //[phase_chain_init
+    size_t N = 131101;
+    state_type x( N );
+    boost::random::uniform_real_distribution<double> distribution( 0.0 , 2.0*pi );
+    boost::random::mt19937 engine( 0 );
+    generate( x.begin() , x.end() , boost::bind( distribution , engine ) );
+    //]
+
+    //[phase_chain_stepper
+    typedef runge_kutta4<
+                      state_type , double ,
+                      state_type , double ,
+                      openmp_range_algebra
+                    > stepper_type;
+    //]
+
+    //[phase_chain_scheduling
+    int chunk_size = N/omp_get_max_threads();
+    omp_set_schedule( omp_sched_static , chunk_size );
+    //]
+
+    cpu_timer timer;
+    //[phase_chain_integrate
+    integrate_n_steps( stepper_type() , phase_chain( 1.2 ) ,
+                       x , 0.0 , 0.01 , 100 );
+    //]
+    double run_time = static_cast<double>(timer.elapsed().wall) * 1.0e-9;
+    std::cerr << run_time << "s" << std::endl;
+    // copy(x.begin(), x.end(), ostream_iterator<double>(cout, "\n"));
+
+    return 0;
+}