code: func RMSF64Samples(samples audio.Float64) float64 {
  	// Square and sum all input samples
  	var sumSquare float64
  	for i := range samples {
  		sumSquare += math.Pow(samples.At(i), 2)
  	}
  
  	// Multiply squared sum by length of samples slice, return square root
  	return math.Sqrt(sumSquare / float64(samples.Len()))
  }
docs: // RMSF64Samples is a SampleReduceFunc which calculates the root mean square
  // of a slice of float64 audio samples, enabling the measurement of magnitude
  // over the entire set of samples.
  //
  // Derived from: http://en.wikipedia.org/wiki/Root_mean_square.