public override object Clone()
{
var clone = new NormalDistribution(Dimension);
clone.constant = constant;
clone.covariance = (double[,]) covariance.Clone();
clone.mean = (double[]) mean.Clone();
clone.variance = (double[]) variance.Clone();
clone.chol = (CholeskyDecomposition) chol.Clone();
clone.svd = (svd != null) ? (SingularValueDecomposition) svd.Clone() : null;
return clone;
}