code: def elu(x, alpha=1.0):
      """Exponential Linear Unit function.
  
      For a parameter :math:`\\alpha`, it is expressed as
  
      .. math::
          f(x) = \\left \\{ \\begin{array}{ll}
          x & {\\rm if}~ x \\ge 0 \\\\
          \\alpha (\\exp(x) - 1) & {\\rm if}~ x < 0,
          \\end{array} \\right.
  
      See: https://arxiv.org/abs/1511.07289
  
      Args:
          x (:class:`~chainer.Variable` or :ref:`ndarray`):
              Input variable. A :math:`(s_1, s_2, ..., s_N)`-shaped float array.
          alpha (float): Parameter :math:`\\alpha`. Default is 1.0.
  
      Returns:
          ~chainer.Variable: Output variable. A
          :math:`(s_1, s_2, ..., s_N)`-shaped float array.
  
      .. admonition:: Example
  
          >>> x = np.array([[-1, 0], [2, -3]], np.float32)
          >>> x
          array([[-1.,  0.],
                 [ 2., -3.]], dtype=float32)
          >>> y = F.elu(x, alpha=1.)
          >>> y.array
          array([[-0.63212055,  0.        ],
                 [ 2.        , -0.95021296]], dtype=float32)
  
      """
      return ELU(alpha=alpha).apply((x,))[0]
  
file_path: chainer/chainer/functions/activation/elu.py
imports: import numpy
  from chainer.backends import cuda
  from chainer import function_node
  from chainer import utils
  from chainer.utils import type_check
label_desc: Use image node_id 1 for calling a global function with example usage: elu(x, alpha) and returns: ELU