code: protected DoubleMatrix2D[] getHessFi(DoubleMatrix1D X){
  		DoubleMatrix2D[] ret = new DoubleMatrix2D[request.getFi().length];
  		double[] x = X.toArray();
  		for(int i=0; i<request.getFi().length; i++){
  			double[][] hess = request.getFi()[i].hessian(x);
  			if(hess == FunctionsUtils.ZEROES_2D_ARRAY_PLACEHOLDER){
  				ret[i] = FunctionsUtils.ZEROES_MATRIX_PLACEHOLDER;
  			}else{
  				ret[i] = F2.make(hess);
  			}
  		}
  		return ret;
  	}
docs: Inequality functions hessians values at X.