sigmoid function

Tensor<Vector> sigmoid(
  1. Tensor<Vector> v
)

Implementation

Tensor<Vector> sigmoid(Tensor<Vector> v) {
  int N = v.data.length;
  Vector outValue = [];
  for (int i = 0; i < N; i = i + 1) {
    outValue.add(1.0 / (1.0 + exp(-v.data[i])));
  }
  Tensor<Vector> out = Tensor<Vector>(outValue);
  out.creator = Node(
    [v],
        () {
      for (int i = 0; i < N; i = i + 1) {
        double val = out.data[i];
        v.grad[i] = v.grad[i] + out.grad[i] * (val * (1.0 - val));
      }
    },
    opName: 'sigmoid_vector',
    cost: N,
  );
  return out;
}