Activation.sigmoid constructor

Activation.sigmoid()

Sigmoid activation function

sigmoid(x) = 1/(1+e^-x)

Example:

final sigmoid = Activation.sigmoid();
final x = Matrix.row([-1, 0, 1]);
final y = sigmoid.function(x);
print(y); // output: matrix 1⨯3 [[0.2689414213699951, 0.5, 0.7310585786300049]]

Implementation

Activation.sigmoid() {
  function = (Matrix m, [dynamic param]) =>
      m.apply((double x) => 1 / (1 + math.exp(-x)));
  dfunction = (Matrix m, [dynamic param]) {
    final sigmMatrix = function(m);
    return [sigmMatrix % (-sigmMatrix.addedScalar(-1))];
  };
  name = 'sigmoid';
}