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Optimize computation in iaf_psc_alpha_ps model #3305

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merged 7 commits into from
Sep 27, 2024
Merged

Optimize computation in iaf_psc_alpha_ps model #3305

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5023910
Optimize computation in iaf_psc_alpha_ps model
heshpdx Sep 3, 2024
de67e0a
Fix formatting
heshpdx Sep 3, 2024
b7c5e5b
Transfer code from P_ (parameters) to V_ (variables)
heshpdx Sep 6, 2024
186e72c
Fix formatting
heshpdx Sep 6, 2024
9701ed2
Update models/iaf_psc_alpha_ps.cpp
heshpdx Sep 11, 2024
c00ebac
Revert pre-compute matrix to original computation
heshpdx Sep 12, 2024
e63b1e9
One more rollback
heshpdx Sep 12, 2024
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31 changes: 19 additions & 12 deletions models/iaf_psc_alpha_ps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -268,15 +268,21 @@ nest::iaf_psc_alpha_ps::pre_run_hook()

V_.h_ms_ = Time::get_resolution().get_ms();

V_.psc_norm_ex_ = 1.0 * numerics::e / P_.tau_syn_ex_;
V_.psc_norm_in_ = 1.0 * numerics::e / P_.tau_syn_in_;
// pre-compute inverse member variables
V_.inv_c_m_ = 1.0 / P_.c_m_;
V_.inv_tau_m_ = 1.0 / P_.tau_m_;
V_.inv_tau_syn_ex_ = 1.0 / P_.tau_syn_ex_;
V_.inv_tau_syn_in_ = 1.0 / P_.tau_syn_in_;

V_.psc_norm_ex_ = 1.0 * numerics::e * V_.inv_tau_syn_ex_;
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V_.psc_norm_in_ = 1.0 * numerics::e * V_.inv_tau_syn_in_;
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// pre-compute matrix for full time step
V_.expm1_tau_m_ = numerics::expm1( -V_.h_ms_ / P_.tau_m_ );
V_.exp_tau_syn_ex_ = std::exp( -V_.h_ms_ / P_.tau_syn_ex_ );
V_.exp_tau_syn_in_ = std::exp( -V_.h_ms_ / P_.tau_syn_in_ );
V_.expm1_tau_m_ = numerics::expm1( -V_.h_ms_ * V_.inv_tau_m_ );
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V_.exp_tau_syn_ex_ = std::exp( -V_.h_ms_ * V_.inv_tau_syn_ex_ );
V_.exp_tau_syn_in_ = std::exp( -V_.h_ms_ * V_.inv_tau_syn_in_ );

V_.P30_ = -P_.tau_m_ / P_.c_m_ * V_.expm1_tau_m_;
V_.P30_ = -P_.tau_m_ * V_.inv_c_m_ * V_.expm1_tau_m_;
// these are determined according to a numeric stability criterion
propagator_ex_ = IAFPropagatorAlpha( P_.tau_syn_ex_, P_.tau_m_, P_.c_m_ );
std::tie( V_.P31_ex_, V_.P32_ex_ ) = propagator_ex_.evaluate( V_.h_ms_ );
Expand All @@ -290,6 +296,7 @@ nest::iaf_psc_alpha_ps::pre_run_hook()
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 );

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}

/* ----------------------------------------------------------------
Expand Down Expand Up @@ -500,9 +507,9 @@ nest::iaf_psc_alpha_ps::propagate_( const double dt )
// V_m_ remains unchanged at 0.0 while neuron is refractory
if ( not S_.is_refractory_ )
{
const double expm1_tau_m = numerics::expm1( -dt / P_.tau_m_ );
const double expm1_tau_m = numerics::expm1( -dt * V_.inv_tau_m_ );

const double ps_P30 = -P_.tau_m_ / P_.c_m_ * expm1_tau_m;
const double ps_P30 = -P_.tau_m_ * V_.inv_c_m_ * expm1_tau_m;

double ps_P31_ex;
double ps_P32_ex;
Expand All @@ -518,8 +525,8 @@ nest::iaf_psc_alpha_ps::propagate_( const double dt )
S_.V_m_ = ( S_.V_m_ < P_.U_min_ ? P_.U_min_ : S_.V_m_ );
}

const double ps_e_TauSyn_ex = std::exp( -dt / P_.tau_syn_ex_ );
const double ps_e_TauSyn_in = std::exp( -dt / P_.tau_syn_in_ );
const double ps_e_TauSyn_ex = std::exp( -dt * V_.inv_tau_syn_ex_ );
const double ps_e_TauSyn_in = std::exp( -dt * V_.inv_tau_syn_in_ );

// now the synaptic components
S_.I_ex_ = ps_e_TauSyn_ex * dt * S_.dI_ex_ + ps_e_TauSyn_ex * S_.I_ex_;
Expand Down Expand Up @@ -578,9 +585,9 @@ nest::iaf_psc_alpha_ps::emit_instant_spike_( Time const& origin, const long lag,
double
nest::iaf_psc_alpha_ps::threshold_distance( double t_step ) const
{
const double expm1_tau_m = numerics::expm1( -t_step / P_.tau_m_ );
const double expm1_tau_m = numerics::expm1( -t_step * V_.inv_tau_m_ );

const double ps_P30 = -P_.tau_m_ / P_.c_m_ * expm1_tau_m;
const double ps_P30 = -P_.tau_m_ * V_.inv_c_m_ * expm1_tau_m;

double ps_P31_ex;
double ps_P32_ex;
Expand Down
4 changes: 4 additions & 0 deletions models/iaf_psc_alpha_ps.h
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Expand Up @@ -407,6 +407,10 @@ class iaf_psc_alpha_ps : public ArchivingNode
double dI_ex_before_; //!< at beginning of mini-step
double dI_in_before_; //!< at beginning of mini-step
double V_m_before_; //!< at beginning of mini-step
double inv_tau_m_; //!< 1 / tau_m
double inv_tau_syn_ex_; //!< 1 / tau_syn_ex
double inv_tau_syn_in_; //!< 1 / tau_syn_in
double inv_c_m_; //!< 1 / c_m
};

// Access functions for UniversalDataLogger -------------------------------
Expand Down
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