void prepare_integrator () {
// Initialize Integrator
DEBUG_OUTPUT(2, "Initializing integrator" );
double begin_time = initial_ens.time_ranges().average;
double destination_time = cfg.optional("destination_time", begin_time + 10 * M_PI );
integ = integrator::create(cfg);
integ->set_ensemble(current_ens);
integ->set_destination_time ( destination_time );
SYNC;
}
// Since our program is short, we can put everything in the main function.
int main(int argc, char* argv[]){
// First we create our reference ensemble. We use the automatic generation using generate_ensemble function
// This function creates a very stable ensemble of systems for us.
defaultEnsemble ref = generate_ensemble(cfg);
// We have to make a copy of initial conditions. We would like to compare the results to initial conditions
// after integration
defaultEnsemble ens = ref.clone();
// Initialize Swarm library. Basically, it initializes CUDA system and default logging system.
swarm::init(cfg);
// Select and create the integrator. While you can create an integrator by calling its constructor directly.
// It is recommended to use integrator::create since it gives you more flexibility at runtime.
// The create function looks in the swarm library and finds the integrator you requested from
// the list of available plugins.
Pintegrator integ = integrator::create(cfg);
// Now we set-up the integrator for integrating.
//
// First set the ensemble. For a GPU integrator, the GPU memory will be allocated.
integ->set_ensemble(ens);
// Now set the destination time where we want to stop the integration.
integ->set_destination_time ( destination_time );
// Need to synchronize because \ref integrator::set_ensemble may upload data to GPU.
SYNC;
// Now that everything is set-up, it is safe to pull the trigger and
// call the integrate method on integrator. Note that since we didn't set
// a logger for the integrator, it will use the default logging system.
integ->integrate();
// Need to synchronize because integrate is a GPU call.
SYNC;
// Once the integration done, we need to examine the data. The easiest
// check is to see if the systems have preserved energy.
//
// find_max_energy_conservation_error is a utility function that compares
// two ensemble of systems. We compare our working ensemble ens to the
// unchanged ensemble ref.
double max_deltaE = find_max_energy_conservation_error(ens, ref );
std::cout << "Max Energy Conservation Error = " << max_deltaE << std::endl;
// This concludes the program, at this point you will need to clean up the data and ensembles.
// But most of Swarm-NG objects are stored in reference-counter pointers and will be automatically
// deallocated by C++ runtime library.
return 0;
}
void stability_test() {
defaultEnsemble &ens = current_ens;
double begin_time = ens.time_ranges().median;
double destination_time = cfg.optional("destination_time", begin_time + 10 * M_PI );
double interval = cfg.optional("interval", (destination_time-begin_time) ) ;
double logarithmic = cfg.optional("logarithmic", 0 ) ;
double allowed_deltaE = cfg.optional("allowed_deltaE", 0.01 );
if(destination_time < begin_time ) ERROR("Destination time should be larger than begin time");
if(interval < 0) ERROR("Interval cannot be negative");
if(interval < 0.001) ERROR("Interval too small");
if(logarithmic != 0 && logarithmic <= 1) ERROR("logarithm base should be greater than 1");
std::cout << "Time, Energy Conservation Factor (delta E/E), Active Systems" << std::endl;
for(double time = begin_time; time < destination_time; ) {
if(logarithmic > 1)
time = (time > 0) ? time * logarithmic : interval;
else
time += interval;
double effective_time = min(time,destination_time);
integ->set_destination_time ( effective_time );
DEBUG_OUTPUT(2, "Integrator ensemble" );
integ->integrate();
SYNC;
DEBUG_OUTPUT(2, "Check energy conservation" );
ensemble::range_t deltaE_range = energy_conservation_error_range(ens, initial_ens );
int active_systems = ens.nsys() - number_of_disabled_systems( ens );
std::cout << effective_time << ", " << deltaE_range.max << ", " << deltaE_range.median << ", " << active_systems << std::endl;
if(deltaE_range.median > allowed_deltaE){
INFO_OUTPUT(0, "At least half of systems are too unstable to conserve energy. dE/E: " << deltaE_range.median << std::endl );
exit(1);
}
}
}
int main(int argc, char* argv[] )
{
// We keep it simple, later on one can use boost::program_options to
// have more options
// but now we only use two configuration files. It is because the
// initial conditions configuration file can get really big and
// it has very little to do with other configuration options.
if(argc < 3) cout << "Usage: montecarlo_ecclimit <integration configuration> <initial conditions configuration>" << endl;
// First one is the configuration for integration
string integ_configfile = argv[1];
// the second one is the configuration for generating
// initial conditions it is used by \ref generate_ensemble_with_randomized_initial_conditions
string initc_configfile = argv[2];
cfg = config::load(integ_configfile);
// 1.read keplerian coordinates from a file
// 2.generate guesses based on the keplerian coordinates
// 3.convert keplerian coordinates to an ensemble
// The following line that is taken from swarm_tutorial_montecarlo.cpp
// does the first three steps. Its pretty amazing.
defaultEnsemble ens ;
if( cfg.count("input") )
{ ens = snapshot::load(cfg["input"]); }
else
{ ens = generate_ensemble_with_randomized_initial_conditions( config::load(initc_configfile) ); }
// save the ensemble as a snapshot
if(cfg.count("initial_snapshot"))
{ snapshot::save( ens, cfg["initial_snapshot"] ); }
defaultEnsemble ens_init = ens.clone() ;
std::vector<std::vector<double> > semimajor_axes_init = calc_semimajor_axes(ens);
// We want to find the ones that are really stable, so we integrate for
// a really long time and over time we get rid of unstable ones.
double destination_time = cfg.optional("destination_time", 1.0E6);
swarm::init(cfg);
Pintegrator integ = integrator::create(cfg);
integ->set_ensemble(ens);
integ->set_destination_time ( destination_time );
// We can set the following two items if we really need
// longer integrations before we stop for checking the
// ensemble and saving snapshots.
// one kernel call to allow for prompt CPU pruning of unstable systems
int max_kernel_calls_per_integrate = cfg.optional("max_kernel_calls_per_integrate",1);
// 10^2 inner orbits at 200 time steps per inner orbit
int max_itterations_per_kernel_call = cfg.optional("max_itterations_per_kernel_call",20000);
integ->set_max_attempts( max_kernel_calls_per_integrate );
integ->set_max_iterations ( max_itterations_per_kernel_call );
SYNC;
// integrate ensemble
// - drop the unstable ones as you go
// - redistribute the systems for better efficiency
// - save the results periodically
// This can be an infitie loop. but we can always get out of this
// the best way to do it is to use Ctrl-C. Further wecan
// define Ctrl-C signal handler to get out
// of this loop in a safe way. But we really want this loop
// to run for a long time
reactivate_systems(ens);
// EBF Experiment trying to expose host log.
swarm::log::ensemble(*(swarm::log::manager::default_log()->get_hostlog()),ens);
integ->flush_log();
catch_ctrl_c();
while( number_of_active_systems(ens) > 0 && integration_loop_not_aborted_yet ) {
// 1. Integrate, we could use core_integrate but the general integrate
// saves all the headache. We should only use core_integrate if we are
// going to do everything on GPU, but since we are saving a snapshot in
// the middle, there's no point. It also has a nice for loop and can
// to several kernel calls.
integ->integrate();
// 2. CPU-based tests to identify systems that can be terminated
int active_ones = number_of_active_systems(ens);
const double deltaa_frac_threshold = cfg.optional("deltaa_frac_threshold", 0.5);
disable_unstable_systems( ens, semimajor_axes_init, deltaa_frac_threshold );
// double med_deltaE = find_median_energy_conservation_error(ens, ens_init );
double max_deltaE = find_max_energy_conservation_error(ens, ens_init );
std::cerr << "# Time: " << ens.time_ranges().min << " " << ens.time_ranges().median << " " << ens.time_ranges().max << " Systems: " << ens.nsys() << ", " << active_ones << ", ";
active_ones = number_of_active_systems(ens);
std::cerr << active_ones << " max|dE/E|= " << max_deltaE << "\n";
// EBF Experiment trying to expose host log.
swarm::log::ensemble_enabled(*(swarm::log::manager::default_log()->get_hostlog()),ens);
integ->flush_log();
if (!cfg.count("input") && cfg.count("replace_unstable") )
{
int nsys_to_replace = number_of_disabled_systems( ens ) ;
if( nsys_to_replace >0 )
{
replace_disabled_systems( ens );
integ->set_ensemble( ens );
}
}
else
{
// 3. Now we need to get rid of the inactive ones. There
// should be some criteria, whatever it is we are
// going to put it in a function and call it \ref needs_shrinking
if ( needs_shrinking( ens ) )
{
// Now this function will take care of trimming for us
// We need to create a new ensemble of a smaller size
// thats why we need to call set_ensemble again. because
// the GPU ensemble should get recreated for us.
// we need better memory management to safely allow
// the following statement. Right now we don't have a
// very good automatic memory management
// std::cerr << "# Removing disabled systems\n";
ens = trim_disabled_systems( ens );
// std::cerr << "# Testing if ens has any systems left.\n";
if(ens.nsys()>0)
{
// std::cerr << "# Setting ensemble for integrator\n";
// WARNING: This appears to be the cause of SEGFAULT
// if the ensemble is empty.
integ->set_ensemble( ens );
}
// std::cerr << "# Time: " << ens.time_ranges() << " Total Systems: " << ens.nsys() << " Active Systems: " << active_ones << ", ";
// active_ones = number_of_active_systems(ens);
// std::cerr << active_ones << "\n";
}
}
// std::cerr << std::endl;
// 4. We need to save a snapshot in case system crashes or someone
// gets tired of it and hits Ctrl-C
// std::cerr << "# Saving snapshot\n";
save_snapshot( ens );
write_stable_systems(ens,ens_init);
}
// Now we are at the end of the system, before we examine
// the output we need to
// std::cerr << "# Removing disabled systems\n";
if(number_of_active_systems(ens)>0)
{
ens = trim_disabled_systems( ens );
// std::cerr << "# Saving snapshot\n";
save_snapshot( ens );
}
write_stable_systems(ens,ens_init);
}