text: import numpy as np
  
  
  # Builds a signal with circular variance and zero mean
  def get_random_signal_zero_mean_circular(var, num_nodes):
      cov_matrix = var * np.identity(num_nodes)
      mean = np.zeros((cov_matrix.shape[0],))
      return np.random.multivariate_normal(mean, cov_matrix), cov_matrix
  