code: func calculateVVP(guess, vertex *nmVertex, sigma float64) float64 {
  	distance := -guess.euclideanDistance(vertex)
  	lhs := 1 / (math.Sqrt(2*math.Pi) * sigma)
  	rhs := 1 - math.Exp(math.Pow(distance, 2)/(2*math.Pow(sigma, 2)))
  	return rhs * lhs
  }
docs: // calculateVVP will calculate the variable variance probability
  // of the provided vertex based on the previous best guess
  // and the provided sigma.  The sigma changes with each run
  // of the optimization algorithm and accounts for a changing
  // number of guesses.
  //
  // VVP is defined as:
  // 1/((2*pi)^(1/2)*sigma)*(1-e^(-dmin^2/2*sigma^2))
  // where dmin = euclidean distance between this vertex and the best guess
  // and sigma = (3*(m^(1/n)))^-1
  //