code: def _cubic_coeff(signal):
      zi = -2 + sqrt(3)
      K = len(signal)
      yplus = zeros((K,), signal.dtype.char)
      powers = zi ** arange(K)
      yplus[0] = signal[0] + zi * add.reduce(powers * signal)
      for k in range(1, K):
          yplus[k] = signal[k] + zi * yplus[k - 1]
      output = zeros((K,), signal.dtype)
      output[K - 1] = zi / (zi - 1) * yplus[K - 1]
      for k in range(K - 2, -1, -1):
          output[k] = zi * (output[k + 1] - yplus[k])
      return output * 6.0
  
imports: from numpy import logical_and, asarray, pi, zeros_like, piecewise, array, arctan2, tan, zeros, arange, floor
  from numpy.core.umath import sqrt, exp, greater, less, cos, add, sin, less_equal, greater_equal
  from .spline import cspline2d, sepfir2d
  from scipy.special import comb
  from scipy._lib._util import float_factorial
label_desc: Use image node_id 11 for calling a global function with example usage: _cubic_coeff(signal) and returns: unknown