Squashed 'third_party/boostorg/odeint/' content from commit 6ff2719
Change-Id: If4892e29c1a5e6cf3a7aa51486a2725c251b0c7d
git-subtree-dir: third_party/boostorg/odeint
git-subtree-split: 6ff2719b6907b86596c3d43e88c1bcfdf29df560
diff --git a/examples/2d_lattice/lattice2d.hpp b/examples/2d_lattice/lattice2d.hpp
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+++ b/examples/2d_lattice/lattice2d.hpp
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+/*
+ Copyright 2011 Mario Mulansky
+ Copyright 2012-2013 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)
+ */
+
+
+/* strongly nonlinear hamiltonian lattice in 2d */
+
+#ifndef LATTICE2D_HPP
+#define LATTICE2D_HPP
+
+#include <vector>
+
+#include <boost/math/special_functions/pow.hpp>
+
+using boost::math::pow;
+
+template< int Kappa , int Lambda >
+struct lattice2d {
+
+ const double m_beta;
+ std::vector< std::vector< double > > m_omega;
+
+ lattice2d( const double beta )
+ : m_beta( beta )
+ { }
+
+ template< class StateIn , class StateOut >
+ void operator()( const StateIn &q , StateOut &dpdt )
+ {
+ // q and dpdt are 2d
+ const int N = q.size();
+
+ int i;
+ for( i = 0 ; i < N ; ++i )
+ {
+ const int i_l = (i-1+N) % N;
+ const int i_r = (i+1) % N;
+ for( int j = 0 ; j < N ; ++j )
+ {
+ const int j_l = (j-1+N) % N;
+ const int j_r = (j+1) % N;
+ dpdt[i][j] = - m_omega[i][j] * pow<Kappa-1>( q[i][j] )
+ - m_beta * pow<Lambda-1>( q[i][j] - q[i][j_l] )
+ - m_beta * pow<Lambda-1>( q[i][j] - q[i][j_r] )
+ - m_beta * pow<Lambda-1>( q[i][j] - q[i_l][j] )
+ - m_beta * pow<Lambda-1>( q[i][j] - q[i_r][j] );
+ }
+ }
+ }
+
+ template< class StateIn >
+ double energy( const StateIn &q , const StateIn &p )
+ {
+ // q and dpdt are 2d
+ const int N = q.size();
+ double energy = 0.0;
+ int i;
+ for( i = 0 ; i < N ; ++i )
+ {
+ const int i_l = (i-1+N) % N;
+ const int i_r = (i+1) % N;
+ for( int j = 0 ; j < N ; ++j )
+ {
+ const int j_l = (j-1+N) % N;
+ const int j_r = (j+1) % N;
+ energy += p[i][j]*p[i][j] / 2.0
+ + m_omega[i][j] * pow<Kappa>( q[i][j] ) / Kappa
+ + m_beta * pow<Lambda>( q[i][j] - q[i][j_l] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i][j_r] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i_l][j] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i_r][j] ) / Lambda / 2;
+ }
+ }
+ return energy;
+ }
+
+
+ template< class StateIn , class StateOut >
+ double local_energy( const StateIn &q , const StateIn &p , StateOut &energy )
+ {
+ // q and dpdt are 2d
+ const int N = q.size();
+ double e = 0.0;
+ int i;
+ for( i = 0 ; i < N ; ++i )
+ {
+ const int i_l = (i-1+N) % N;
+ const int i_r = (i+1) % N;
+ for( int j = 0 ; j < N ; ++j )
+ {
+ const int j_l = (j-1+N) % N;
+ const int j_r = (j+1) % N;
+ energy[i][j] = p[i][j]*p[i][j] / 2.0
+ + m_omega[i][j] * pow<Kappa>( q[i][j] ) / Kappa
+ + m_beta * pow<Lambda>( q[i][j] - q[i][j_l] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i][j_r] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i_l][j] ) / Lambda / 2
+ + m_beta * pow<Lambda>( q[i][j] - q[i_r][j] ) / Lambda / 2;
+ e += energy[i][j];
+ }
+ }
+ //rescale
+ e = 1.0/e;
+ for( i = 0 ; i < N ; ++i )
+ for( int j = 0 ; j < N ; ++j )
+ energy[i][j] *= e;
+ return 1.0/e;
+ }
+
+ void load_pot( const char* filename , const double W , const double gap ,
+ const size_t dim )
+ {
+ std::ifstream in( filename , std::ios::in | std::ios::binary );
+ if( !in.is_open() ) {
+ std::cerr << "pot file not found: " << filename << std::endl;
+ exit(0);
+ } else {
+ std::cout << "using pot file: " << filename << std::endl;
+ }
+
+ m_omega.resize( dim );
+ for( int i = 0 ; i < dim ; ++i )
+ {
+ m_omega[i].resize( dim );
+ for( size_t j = 0 ; j < dim ; ++j )
+ {
+ if( !in.good() )
+ {
+ std::cerr << "I/O Error: " << filename << std::endl;
+ exit(0);
+ }
+ double d;
+ in.read( (char*) &d , sizeof(d) );
+ if( (d < 0) || (d > 1.0) )
+ {
+ std::cerr << "ERROR: " << d << std::endl;
+ exit(0);
+ }
+ m_omega[i][j] = W*d + gap;
+ }
+ }
+
+ }
+
+ void generate_pot( const double W , const double gap , const size_t dim )
+ {
+ m_omega.resize( dim );
+ for( size_t i = 0 ; i < dim ; ++i )
+ {
+ m_omega[i].resize( dim );
+ for( size_t j = 0 ; j < dim ; ++j )
+ {
+ m_omega[i][j] = W*static_cast<double>(rand())/RAND_MAX + gap;
+ }
+ }
+ }
+
+};
+
+#endif