code: def mel_to_hz(mels, htk=False):
      """Convert mel bin numbers to frequencies
      Examples
      --------
      >>> librosa.mel_to_hz(3)
      200.
      >>> librosa.mel_to_hz([1,2,3,4,5])
      array([  66.667,  133.333,  200.   ,  266.667,  333.333])
      Parameters
      ----------
      mels          : np.ndarray [shape=(n,)], float
          mel bins to convert
      htk           : bool
          use HTK formula instead of Slaney
      Returns
      -------
      frequencies   : np.ndarray [shape=(n,)]
          input mels in Hz
      See Also
      --------
      hz_to_mel
      """
  
      mels = np.asanyarray(mels)
  
      if htk:
          return 700.0 * (10.0 ** (mels / 2595.0) - 1.0)
  
      # Fill in the linear scale
      f_min = 0.0
      f_sp = 200.0 / 3
      freqs = f_min + f_sp * mels
  
      # And now the nonlinear scale
      min_log_hz = 1000.0  # beginning of log region (Hz)
      min_log_mel = (min_log_hz - f_min) / f_sp  # same (Mels)
      logstep = np.log(6.4) / 27.0  # step size for log region
  
      if mels.ndim:
          # If we have vector data, vectorize
          log_t = mels >= min_log_mel
          freqs[log_t] = min_log_hz * np.exp(
              logstep * (mels[log_t] - min_log_mel)
          )
      elif mels >= min_log_mel:
          # If we have scalar data, check directly
          freqs = min_log_hz * np.exp(logstep * (mels - min_log_mel))
  
      return freqs
  
file_path: nnAudio/Installation/nnAudio/librosa_functions.py
imports: import numpy
  import warnings
label_desc: Use image node_id 3 for calling a global function with example usage: mel_to_hz(mels, htk) and returns: freqs, unknown