code: def test_derivatives_complex(self):
      # regression test for gh-7381: krogh.derivatives(0) fails complex y
      x, y = np.array([-1, -1, 0, 1, 1]), np.array(
          [1, 1.0j, 0, -1, 1.0j]
      )
      func = KroghInterpolator(x, y)
      cmplx = func.derivatives(0)
  
      cmplx2 = KroghInterpolator(x, y.real).derivatives(
          0
      ) + 1j * KroghInterpolator(x, y.imag).derivatives(0)
      assert_allclose(cmplx, cmplx2, atol=1e-15)
  
imports: import warnings
  import io
  import numpy
  from numpy.testing import assert_almost_equal, assert_array_equal, assert_array_almost_equal, assert_allclose, assert_equal, assert_
  from pytest import raises
  from scipy.interpolate import KroghInterpolator, krogh_interpolate, BarycentricInterpolator, barycentric_interpolate, approximate_taylor_polynomial, CubicHermiteSpline, pchip, PchipInterpolator, pchip_interpolate, Akima1DInterpolator, CubicSpline, make_interp_spline
label_desc: Use image node_id 18 for calling the TestKrogh obj's underlying member method code with example usage: obj.test_derivatives_complex() without return types