code: def _iter_frequencies(q, frange, mismatch, dur):
      
      # work out how many frequencies we need
      minf, maxf = frange
      fcum_mismatch = log(float(maxf) / minf) * (2 + q**2)**(1/2.) / 2.
      nfreq = int(max(1, ceil(fcum_mismatch / deltam_f(mismatch))))
      fstep = fcum_mismatch / nfreq
      fstepmin = 1. / dur
      # for each frequency, yield a QTile
      for i in xrange(nfreq):
          yield (float(minf) *
                 exp(2 / (2 + q**2)**(1/2.) * (i + .5) * fstep) //
                 fstepmin * fstepmin)
      raise StopIteration()
docs: Iterate over the frequencies of this 'QPlane'
  
      Parameters
      ----------
      q:
          q value
      frange: 'list'
          upper and lower bounds of frequency range
      mismatch:
          percentage of desired fractional mismatch
      dur:
          duration of timeseries in seconds
  
      Returns
      -------
      frequencies:
          Q-Tile frequency