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Sigmoid

Sigmoid Activation

Maps input values to the range (0, 1) using the logistic function. Commonly used for binary classification outputs and gating mechanisms.

Shape Contract:

  • Input: [*shape] arbitrary shape
  • Output: [*shape] same shape as input

Formula: sigmoid(x) = 1 / (1 + exp(-x))

Notes:

  • Output range: (0, 1), useful for probabilities
  • Suffers from vanishing gradients for large absolute values
  • Used in LSTMs, attention gates, and output layers
  • Element-wise operation (preserves all dimensions)

Signature​

neuron Sigmoid()

Ports​

Inputs:

  • default: [*shape]

Outputs:

  • default: [*shape]

Implementation​

Source { source: "core", path: "activations/Sigmoid" }