code: import sys
  
  import numpy as np
  from scipy.stats import multivariate_normal
  
  sys.path.append('./../../')
  from src.HMC.hmcparameter import HMCParameter
  
  class VelParam(HMCParameter):
      def __init__(self, init_val):
          super().__init__(np.array(init_val))
          dim = np.array(init_val).shape
          self.mu = np.zeros(dim)
          self.sigma = 1
  
      def gen_init_value(self):
          self.value = multivariate_normal.rvs(self.mu, self.sigma)
  
      def get_energy_grad(self):
          return self.value
  
      def get_energy(self):
          return np.dot(self.value, self.value) / 2
  
      def get_energy_for_value(self, value):
          return np.dot(value, value) / 2
  
apis: numpy.array numpy.dot scipy.stats.multivariate_normal.rvs numpy.zeros