text: import numpy as np
  from scipy.optimize import bisect
  
  eta = 0.5 / 1.0e5
  
  N = 256
  
  def f( z ):
      return eta * ( z**N - 1.0 ) - ( z - 1.0 )
  
  a = 1.0001
  b = 1.8
  
  zoom = bisect( f, a, b, xtol = 1.0e-16 )
  
  print( '{:.15f}'.format( zoom ) )
  