code: public static double multinomialGaussianPdf(double[] mean, double[][] covariance, double[] x)  {
          MultivariateNormalDistribution gaussian = new 
              MultivariateNormalDistribution(mean, covariance);
          return gaussian.density(x);
      }
docs: Calculates the PDF of Multinomial Normal Distribution for a particular x.
  
  @param mean
  @param covariance
  @param x             The x record
  @return              The multinomialGaussianPdf of x