class_docstr: Csendes objective function.
  
  This class defines the Csendes [1]_ global optimization problem. This is a
  multimodal minimization problem defined as follows:
  
  .. math::
  
      f_{\text{Csendes}}(x) = \sum_{i=1}^n x_i^6 \left[ 2 + \sin
      \left( \frac{1}{x_i} \right ) \right]
  
  
  Here, :math:`n` represents the number of dimensions and :math:`x_i \in
  [-1, 1]` for :math:`i = 1, ..., N`.
  
  *Global optimum*: :math:`f(x) = 0.0` for :math:`x_i = 0` for
  :math:`i = 1, ..., N`
  
  .. [1] Jamil, M. & Yang, X.-S. A Literature Survey of Benchmark Functions
  For Global Optimization Problems Int. Journal of Mathematical Modelling
  and Numerical Optimisation, 2013, 4, 150-194.
code: def fun(self, x, *args):
      self.nfev += 1
  
      try:
          return sum((x**6.0) * (2.0 + sin(1.0 / x)))
      except ZeroDivisionError:
          return np.nan
      except FloatingPointError:
          return np.nan
  
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 Csendes obj's underlying member method code with example usage: obj.fun(x) and returns: sum, np, np