class_docstr: Crowned Cross objective function.
  
  This class defines the Crowned Cross [1]_ global optimization problem. This
  is a multimodal minimization problem defined as follows:
  
  .. math::
  
      f_{\text{CrownedCross}}(x) = 0.0001 \left(\left|{e^{\left|{100
      - \frac{\sqrt{x_{1}^{2} + x_{2}^{2}}}{\pi}}\right|}
      \sin\left(x_{1}\right) \sin\left(x_{2}\right)}\right| + 1\right)^{0.1}
  
  
  with :math:`x_i \in [-10, 10]` for :math:`i = 1, 2`.
  
  *Global optimum*: :math:`f(x_i) = 0.0001`. The global minimum is found on
  the planes :math:`x_1 = 0` and :math:`x_2 = 0`
  
  ..[1] Mishra, S. Global Optimization by Differential Evolution and Particle
  Swarm Methods: Evaluation on Some Benchmark Functions Munich University,
  2006
code: def fun(self, x, *args):
      self.nfev += 1
      u = 100 - sqrt(x[0] ** 2 + x[1] ** 2) / pi
      v = sin(x[0]) * sin(x[1])
      return 0.0001 * (abs(v * exp(abs(u))) + 1) ** (0.1)
  
imports: import numpy
  from numpy import abs, asarray, cos, exp, floor, pi, sign, sin, sqrt, sum, size, tril, isnan, atleast_2d, repeat
  from numpy.testing import assert_almost_equal
  from .go_benchmark import Benchmark
label_desc: Use image node_id 2 for calling the CrownedCross obj's underlying member method code with example usage: obj.fun(x) and returns: unknown