code: def mvn_loglike_sum(x, sigma):
      """loglike multivariate normal
  
      copied from GLS and adjusted names
      not sure why this differes from mvn_loglike
      """
      nobs = len(x)
      nobs2 = nobs / 2.0
      SSR = (x**2).sum()
      llf = -np.log(SSR) * nobs2  # concentrated likelihood
      llf -= (
          1 + np.log(np.pi / nobs2)
      ) * nobs2  # with likelihood constant
      if np.any(sigma) and sigma.ndim == 2:
          # FIXME: robust-enough check?  unneeded if _det_sigma gets defined
          llf -= 0.5 * np.log(np.linalg.det(sigma))
      return llf
  
file_path: statsmodels/statsmodels/miscmodels/try_mlecov.py
imports: import numpy
  from scipy import linalg
  from scipy.linalg import toeplitz
  from statsmodels.base.model import GenericLikelihoodModel
  from statsmodels.datasets import sunspots
  from statsmodels.tsa.arima_process import ArmaProcess, arma_acovf, arma_generate_sample
label_desc: Use image node_id 1 for calling a global function with example usage: mvn_loglike_sum(x, sigma) and returns: llf