hxtorch.spiking.functional.lif
Leaky-integrate and fire neurons
Classes
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Parameters for CUBA LIF integration and backward path |
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Parameters for CUBA LIF integration and backward path |
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Parameters for any (of currently available) forward and backward path. |
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Typed version of namedtuple. |
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Unterjubel hardware observables to allow correct gradient flow |
Functions
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hxtorch.spiking.functional.lif.cuba_lif_integration(input: torch.Tensor, params: Union[hxtorch.spiking.functional.lif.CalibratedCUBALIFParams, hxtorch.spiking.functional.lif.CUBALIFParams], hw_data: Optional[torch.Tensor] = None, dt: float = 1e-06) → Tuple[torch.Tensor, …] Leaky-integrate and fire neuron integration for realization of simple spiking neurons with exponential synapses. Integrates according to:
i^{t+1} = i^t * (1 - dt / au_{syn}) + x^t v^{t+1} = dt / au_{men} * (v_l - v^t + i^t) + v^t z^{t+1} = 1 if v^{t+1} > params.threshold v^{t+1} = params.reset if z^{t+1} == 1
Assumes i^0, v^0 = 0, v_leak :note: One dt synaptic delay between input and output
TODO: Issue 3992
- Parameters
input – Input spikes in shape (batch, time, neurons).
params – LIFParams object holding neuron parameters.
dt – Step width of integration.
- Returns
Returns the spike trains in shape and membrane trace as a tuple. Both tensors are of shape (batch, time, neurons).
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hxtorch.spiking.functional.lif.cuba_lif_step(z: torch.Tensor, v: torch.Tensor, i: torch.Tensor, input: torch.Tensor, z_hw: torch.Tensor, v_hw: torch.Tensor, params: Union[hxtorch.spiking.functional.lif.CalibratedCUBALIFParams, hxtorch.spiking.functional.lif.CUBALIFParams], dt: float = 1e-06) → Tuple[torch.Tensor, …] Integrate the membrane of a neurons one time step further according to the Leaky-integrate and fire dynamics.
- Parameters
z – The spike tensor at time step t.
v – The membrane tensor at time step t.
i – The current tensor at time step t.
input – The input tensor at time step t (graded spikes).
z_hw – The hardware spikes corresponding to the current time step. In case this is None, no HW spikes will be injected.
v_hw – The hardware cadc traces corresponding to the current time step. In case this is None, no HW cadc values will be injected.
params – Parameter object holding the LIF parameters.
- Returns
Returns a tuple (z, v, i) holding the tensors of time step t + 1.
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hxtorch.spiking.functional.lif.cuba_refractory_lif_integration(input: torch.Tensor, params: Union[hxtorch.spiking.functional.lif.CalibratedCUBALIFParams, hxtorch.spiking.functional.lif.CUBALIFParams], hw_data: Optional[torch.Tensor] = None, dt: float = 1e-06) → Tuple[torch.Tensor, …] Leaky-integrate and fire neuron integration for realization of simple spiking neurons with exponential synapses and refractory period.
- Integrates according to:
i^{t+1} = i^t * (1 - dt / au_{syn}) + x^t v^{t+1} = dt / au_{men} * (v_l - v^t + i^{t+1}) + v^t z^{t+1} = 1 if v^{t+1} > params.v_th v^{t+1} = params.v_reset if z^{t+1} == 1 or ref^{t+1} > 0 ref^{t+1} = params.tau_ref ref^{t+1} -= 1
Assumes i^0, v^0 = 0.
- Parameters
input – Input spikes in shape (batch, time, neurons).
params – LIFParams object holding neuron parameters.
- Returns
Returns the spike trains in shape and membrane trace as a tuple. Both tensors are of shape (batch, time, neurons).
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hxtorch.spiking.functional.lif.refractory_update(z: torch.Tensor, v: torch.Tensor, z_hw: torch.Tensor, v_hw: torch.Tensor, ref_state: torch.Tensor, params: NamedTuple, dt: float = 1e-06) → Tuple[torch.Tensor, …] Update neuron membrane and spikes to account for refractory period. This implemention is widly adopted from: https://github.com/norse/norse/blob/main/norse/torch/functional/lif_refrac.py :param z: The spike tensor at time step t. :param v: The membrane tensor at time step t. :param ref_state: The refractory state holding the number of time steps the
neurons has to remain in the refractory period.
- Parameters
z_hw – The hardware spikes corresponding to the current time step. In case this is None, no HW spikes will be injected.
v_hw – The hardware cadc traces corresponding to the current time step. In case this is None, no HW cadc values will be injected.
params – Parameter object holding the LIF parameters.
- Returns
Returns a tuple (z, v, ref_state) holding the tensors of time step t.
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hxtorch.spiking.functional.lif.spiking_threshold(input: torch.Tensor, method: str, alpha: float) → torch.Tensor Selection of the used threshold function. :param input: Input tensor to threshold function. :param method: The string indicator of the the threshold function.
Currently supported: ‘super_spike’.
- Parameters
alpha – Parameter controlling the slope of the surrogate derivative in case of ‘superspike’.
- Returns
Returns the tensor of the threshold function.