inverse_gamma.py 文件源码

def _variance(self):
    var = (math_ops.square(self.beta) /
           (math_ops.square(self.alpha - 1.) * (self.alpha - 2.)))
    if self.allow_nan_stats:
      nan = np.array(np.nan, dtype=self.dtype.as_numpy_dtype())
      return math_ops.select(
          self.alpha > 2., var,
          array_ops.fill(self.batch_shape(), nan, name="nan"))
    else:
      return control_flow_ops.with_dependencies([
          check_ops.assert_less(
              constant_op.constant(2., dtype=self.dtype), self.alpha,
              message="variance not defined for components of alpha <= 2"),
      ], var)