expert_utils.py 文件源码

def _normal_distribution_cdf(x, stddev):
  """Evaluates the CDF of the normal distribution.

  Normal distribution with mean 0 and standard deviation stddev,
  evaluated at x=x.

  input and output `Tensor`s have matching shapes.

  Args:
    x: a `Tensor`
    stddev: a `Tensor` with the same shape as `x`.

  Returns:
    a `Tensor` with the same shape as `x`.

  """
  return 0.5 * (1.0 + tf.erf(x / (math.sqrt(2) * stddev + 1e-20)))