class Chainer::Functions::Activation::SigmoidGrad

Logistic sigmoid gradient function.

Public Class Methods

new(inputs) click to toggle source
# File lib/chainer/functions/activation/sigmoid_grad.rb, line 6
def initialize(inputs)
  @x, = inputs
end

Public Instance Methods

backward(indexes, grad_outputs) click to toggle source
# File lib/chainer/functions/activation/sigmoid_grad.rb, line 17
def backward(indexes, grad_outputs)
  y, gy = get_retained_inputs
  g, = grad_outputs
  [g * gy * ( 1 -2 * y), g * y * (1 - y)]
end
forward(inputs) click to toggle source
# File lib/chainer/functions/activation/sigmoid_grad.rb, line 10
def forward(inputs)
  retain_inputs([0, 1])
  y, gy = inputs
  one = 1
  [Utils::Array.force_array(gy * y * (one - y))]
end