void
iaf_psc_alpha::calibrate()
{
// ensures initialization in case mm connected after Simulate
B_.logger_.init();
const double h = Time::get_resolution().get_ms();
// these P are independent
V_.P11_ex_ = V_.P22_ex_ = std::exp( -h / P_.tau_ex_ );
V_.P11_in_ = V_.P22_in_ = std::exp( -h / P_.tau_in_ );
V_.P33_ = std::exp( -h / P_.Tau_ );
V_.expm1_tau_m_ = numerics::expm1( -h / P_.Tau_ );
// these depend on the above. Please do not change the order.
V_.P30_ = -P_.Tau_ / P_.C_ * numerics::expm1( -h / P_.Tau_ );
V_.P21_ex_ = h * V_.P11_ex_;
V_.P21_in_ = h * V_.P11_in_;
// these are determined according to a numeric stability criterion
V_.P31_ex_ = propagator_31( P_.tau_ex_, P_.Tau_, P_.C_, h );
V_.P32_ex_ = propagator_32( P_.tau_ex_, P_.Tau_, P_.C_, h );
V_.P31_in_ = propagator_31( P_.tau_in_, P_.Tau_, P_.C_, h );
V_.P32_in_ = propagator_32( P_.tau_in_, P_.Tau_, P_.C_, h );
V_.EPSCInitialValue_ = 1.0 * numerics::e / P_.tau_ex_;
V_.IPSCInitialValue_ = 1.0 * numerics::e / P_.tau_in_;
// TauR specifies the length of the absolute refractory period as
// a double in ms. The grid based iaf_psc_alpha can only handle refractory
// periods that are integer multiples of the computation step size (h).
// To ensure consistency with the overall simulation scheme such conversion
// should be carried out via objects of class nest::Time. The conversion
// requires 2 steps:
// 1. A time object is constructed defining representation of
// TauR in tics. This representation is then converted to computation
// time steps again by a strategy defined by class nest::Time.
// 2. The refractory time in units of steps is read out get_steps(), a
// member function of class nest::Time.
//
// The definition of the refractory period of the iaf_psc_alpha is consistent
// the one of iaf_psc_alpha_ps.
//
// Choosing a TauR that is not an integer multiple of the computation time
// step h will lead to accurate (up to the resolution h) and self-consistent
// results. However, a neuron model capable of operating with real valued
// spike time may exhibit a different effective refractory time.
V_.RefractoryCounts_ = Time( Time::ms( P_.TauR_ ) ).get_steps();
// since t_ref_ >= 0, this can only fail in error
assert( V_.RefractoryCounts_ >= 0 );
}
void
nest::iaf_psc_alpha_canon::calibrate()
{
B_.logger_.init();
V_.h_ms_ = Time::get_resolution().get_ms();
V_.PSCInitialValue_ = 1.0 * numerics::e / P_.tau_syn_;
V_.gamma_ = 1 / P_.c_m_ / ( 1 / P_.tau_syn_ - 1 / P_.tau_m_ );
V_.gamma_sq_ = 1 / P_.c_m_ / ( ( 1 / P_.tau_syn_ - 1 / P_.tau_m_ )
* ( 1 / P_.tau_syn_ - 1 / P_.tau_m_ ) );
// pre-compute matrix for full time step
V_.expm1_tau_m_ = numerics::expm1( -V_.h_ms_ / P_.tau_m_ );
V_.expm1_tau_syn_ = numerics::expm1( -V_.h_ms_ / P_.tau_syn_ );
V_.P30_ = -P_.tau_m_ / P_.c_m_ * V_.expm1_tau_m_;
// these are determined according to a numeric stability criterion
V_.P31_ = propagator_31( P_.tau_syn_, P_.tau_m_, P_.c_m_, V_.h_ms_ );
V_.P32_ = propagator_32( P_.tau_syn_, P_.tau_m_, P_.c_m_, V_.h_ms_ );
// t_ref_ is the refractory period in ms
// refractory_steps_ is the duration of the refractory period in whole
// steps, rounded down
V_.refractory_steps_ = Time( Time::ms( P_.t_ref_ ) ).get_steps();
// since t_ref_ >= sim step size, this can only fail in error
assert( V_.refractory_steps_ >= 1 );
}
void
iaf_psc_alpha_multisynapse::calibrate()
{
B_.logger_.init(); // ensures initialization in case mm connected after Simulate
const double h = Time::get_resolution().get_ms();
P_.receptor_types_.resize( P_.num_of_receptors_ );
for ( size_t i = 0; i < P_.num_of_receptors_; i++ )
{
P_.receptor_types_[ i ] = i + 1;
}
V_.P11_syn_.resize( P_.num_of_receptors_ );
V_.P21_syn_.resize( P_.num_of_receptors_ );
V_.P22_syn_.resize( P_.num_of_receptors_ );
V_.P31_syn_.resize( P_.num_of_receptors_ );
V_.P32_syn_.resize( P_.num_of_receptors_ );
S_.y1_syn_.resize( P_.num_of_receptors_ );
S_.y2_syn_.resize( P_.num_of_receptors_ );
V_.PSCInitialValues_.resize( P_.num_of_receptors_ );
B_.spikes_.resize( P_.num_of_receptors_ );
V_.P33_ = std::exp( -h / P_.Tau_ );
V_.P30_ = 1 / P_.C_ * ( 1 - V_.P33_ ) * P_.Tau_;
for ( size_t i = 0; i < P_.num_of_receptors_; i++ )
{
V_.P11_syn_[ i ] = V_.P22_syn_[ i ] = std::exp( -h / P_.tau_syn_[ i ] );
V_.P21_syn_[ i ] = h * V_.P11_syn_[ i ];
// these are determined according to a numeric stability criterion
V_.P31_syn_[ i ] = propagator_31( P_.tau_syn_[ i ], P_.Tau_, P_.C_, h );
V_.P32_syn_[ i ] = propagator_32( P_.tau_syn_[ i ], P_.Tau_, P_.C_, h );
V_.PSCInitialValues_[ i ] = 1.0 * numerics::e / P_.tau_syn_[ i ];
B_.spikes_[ i ].resize();
}
Time r = Time::ms( P_.TauR_ );
V_.RefractoryCounts_ = r.get_steps();
if ( V_.RefractoryCounts_ < 1 )
throw BadProperty( "Absolute refractory time must be at least one time step." );
}
void
iaf_psc_alpha_multisynapse::calibrate()
{
// ensures initialization in case mm connected after Simulate
B_.logger_.init();
const double h = Time::get_resolution().get_ms();
V_.P11_syn_.resize( P_.n_receptors_() );
V_.P21_syn_.resize( P_.n_receptors_() );
V_.P22_syn_.resize( P_.n_receptors_() );
V_.P31_syn_.resize( P_.n_receptors_() );
V_.P32_syn_.resize( P_.n_receptors_() );
S_.y1_syn_.resize( P_.n_receptors_() );
S_.y2_syn_.resize( P_.n_receptors_() );
V_.PSCInitialValues_.resize( P_.n_receptors_() );
B_.spikes_.resize( P_.n_receptors_() );
V_.P33_ = std::exp( -h / P_.Tau_ );
V_.P30_ = 1 / P_.C_ * ( 1 - V_.P33_ ) * P_.Tau_;
for ( size_t i = 0; i < P_.n_receptors_(); i++ )
{
V_.P11_syn_[ i ] = V_.P22_syn_[ i ] = std::exp( -h / P_.tau_syn_[ i ] );
V_.P21_syn_[ i ] = h * V_.P11_syn_[ i ];
// these are determined according to a numeric stability criterion
V_.P31_syn_[ i ] = propagator_31( P_.tau_syn_[ i ], P_.Tau_, P_.C_, h );
V_.P32_syn_[ i ] = propagator_32( P_.tau_syn_[ i ], P_.Tau_, P_.C_, h );
V_.PSCInitialValues_[ i ] = 1.0 * numerics::e / P_.tau_syn_[ i ];
B_.spikes_[ i ].resize();
}
V_.RefractoryCounts_ = Time( Time::ms( P_.refractory_time_ ) ).get_steps();
}
